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Sample records for space-based microlensing survey

  1. Exoplanet Demographics with a Space-Based Microlensing Survey

    NASA Astrophysics Data System (ADS)

    Gaudi, B. Scott

    2012-05-01

    Measurements of the frequency of exoplanets over a broad range of planet and host star properties provide fundamental empirical constraints on theories of planet formation and evolution. Because of its unique sensitivity to low-mass, long-period, and free-floating planets, microlensing is an essential complement to our arsenal of planet detection methods. I motivate microlensing surveys for exoplanets, and in particular describe how they can be used to test the currently-favored paradigm for planet formation, as well as inform our understanding of the frequency and potential habitability of low-mass planets located in the habitable zones of their host stars. I explain why a space-based mission is necessary to realize the full potential of microlensing, and outline the expected returns of such surveys. When combined with the results from complementary surveys such as Kepler, a space-based microlensing survey will yield a nearly complete picture of the demographics of planetary systems throughout the Galaxy.

  2. Exoplanet Demographics with Microlensing Surveys

    NASA Astrophysics Data System (ADS)

    Gaudi, B.

    2014-04-01

    Because of its unique sensitivity to low-mass, long-period, and free-floating planets, microlensing is an essential complement to our arsenal of planet detection methods. I motivate microlensing surveys for exoplanets, and in particular describe how they can be used to test models for planet formation, as well as inform our understanding of the frequency and potential habitability of low-mass planets located in the habitable zones of their host stars. I review results from current microlensing surveys, and then discuss expectations for next-generation experiments. I explain why a space-based mission is necessary to realize the full potential of microlensing. When combined with the results from complementary surveys such as Kepler, a space-based microlensing survey will yield a nearly complete picture of the demographics of planetary systems throughout the Galaxy.

  3. On the Feasibility of Characterizing Free-floating Planets with Current and Future Space-based Microlensing Surveys

    NASA Astrophysics Data System (ADS)

    Henderson, Calen B.; Shvartzvald, Yossi

    2016-10-01

    Simultaneous space- and ground-based microlensing surveys, such as K2's Campaign 9 (K2C9) and WFIRST, facilitate measuring the masses and distances of free-floating planet (FFP) candidates, which are identified as single-lens events with timescales that are of the order of 1 day. Measuring the mass and distance of an FFP lens requires determining the size of the source star ρ, measuring the microlens parallax {π }{{E}}, and using high-resolution imaging to search for the lens flux {F}{\\ell } from a possible host star. Here we investigate the accessible parameter space for each of these components considering different satellites for a range of FFP masses, Galactic distances, and source star properties. We find that at the beginning of K2C9, when its projected separation {D}\\perp from the Earth is ≲0.2 au, it will be able to measure {π }{{E}} for Jupiter-mass FFP candidates at distances larger than ∼2 kpc and to Earth-mass lenses at ∼8 kpc. At the end of K2C9, when {D}\\perp = 0.81 au, it is sensitive to planetary-mass lenses for distances ≳3.5 kpc, and even then only to those with mass ≳M Jup. From lens flux constraints we find that it will be possible to exclude hosts down to the deuterium-burning limit for events within ∼2 kpc. This indicates that the ability to characterize FFPs detected during K2C9 is optimized for events occurring toward the beginning of the campaign. WFIRST, on the other hand, will be able to detect and characterize FFP masses down to or below super-Earths throughout the Galaxy during its entire microlensing survey.

  4. Mass Measurements of Isolated Objects from Space-based Microlensing

    NASA Astrophysics Data System (ADS)

    Zhu, Wei; Calchi Novati, S.; Gould, A.; Udalski, A.; Han, C.; Shvartzvald, Y.; Ranc, C.; Jørgensen, U. G.; Poleski, R.; Bozza, V.; Beichman, C.; Bryden, G.; Carey, S.; Gaudi, B. S.; Henderson, C. B.; Pogge, R. W.; Porritt, I.; Wibking, B.; Yee, J. C.; SPITZER Team; Pawlak, M.; Szymański, M. K.; Skowron, J.; Mróz, P.; Kozłowski, S.; Wyrzykowski, Ł.; Pietrukowicz, P.; Pietrzyński, G.; Soszyński, I.; Ulaczyk, K.; OGLE Group; Choi, J.-Y.; Park, H.; Jung, Y. K.; Shin, I.-G.; Albrow, M. D.; Park, B.-G.; Kim, S.-L.; Lee, C.-U.; Cha, S.-M.; Kim, D.-J.; Lee, Y.; KMTNET Group; Friedmann, M.; Kaspi, S.; Maoz, D.; WISE Group; Hundertmark, M.; Street, R. A.; Tsapras, Y.; Bramich, D. M.; Cassan, A.; Dominik, M.; Bachelet, E.; Dong, Subo; Figuera Jaimes, R.; Horne, K.; Mao, S.; Menzies, J.; Schmidt, R.; Snodgrass, C.; Steele, I. A.; Wambsganss, J.; RoboNeT Team; Skottfelt, J.; Andersen, M. I.; Burgdorf, M. J.; Ciceri, S.; D'Ago, G.; Evans, D. F.; Gu, S.-H.; Hinse, T. C.; Kerins, E.; Korhonen, H.; Kuffmeier, M.; Mancini, L.; Peixinho, N.; Popovas, A.; Rabus, M.; Rahvar, S.; Tronsgaard, R.; Scarpetta, G.; Southworth, J.; Surdej, J.; von Essen, C.; Wang, Y.-B.; Wertz, O.; MiNDSTEP Group

    2016-07-01

    We report on the mass and distance measurements of two single-lens events from the 2015 Spitzer microlensing campaign. With both finite-source effect and microlens parallax measurements, we find that the lens of OGLE-2015-BLG-1268 is very likely a brown dwarf (BD). Assuming that the source star lies behind the same amount of dust as the Bulge red clump, we find the lens is a 45 ± 7 {M}{{J}} BD at 5.9 ± 1.0 kpc. The lens of of the second event, OGLE-2015-BLG-0763, is a 0.50 ± 0.04 {M}⊙ star at 6.9 ± 1.0 kpc. We show that the probability to definitively measure the mass of isolated microlenses is dramatically increased once simultaneous ground- and space-based observations are conducted.

  5. Faint detection of exoplanets in microlensing surveys

    SciTech Connect

    Brown, Robert A.

    2014-06-20

    We propose a new approach to discovering faint microlensing signals below traditional thresholds, and for estimating the binary-lens mass ratio and the apparent separation from such signals. The events found will be helpful in accurately estimating the true distribution of planetary semimajor axes, which is an important goal of space microlensing surveys.

  6. Planet Sensitivity from Combined Ground- and Space-based Microlensing Observations

    NASA Astrophysics Data System (ADS)

    Zhu, Wei; Gould, Andrew; Beichman, Charles; Calchi Novati, Sebastiano; Carey, Sean; Gaudi, B. Scott; Henderson, Calen B.; Penny, Matthew; Shvartzvald, Yossi; Yee, Jennifer C.; Udalski, A.; Poleski, R.; Skowron, J.; Kozłowski, S.; Mróz, P.; Pietrukowicz, P.; Pietrzyński, G.; Szymański, M. K.; Soszyński, I.; Ulaczyk, K.; Wyrzykowski, Ł.; OGLE Collaboration; Abe, F.; Barry, R. K.; Bennett, D. P.; Bhattacharya, A.; Bond, I. A.; Freeman, M.; Fukui, A.; Hirao, Y.; Itow, Y.; Koshimoto, N.; Ling, H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Ohnishi, K.; Saito, To.; Sullivan, D. J.; Sumi, T.; Suzuki, D.; Tristram, P. J.; Rattenbury, N.; Wakiyama, Y.; Yonehara, A.; MOA Collaboration; Maoz, D.; Kaspi, S.; Friedmann, M.; The Wise Group

    2015-12-01

    To move one step forward toward a Galactic distribution of planets, we present the first planet sensitivity analysis for microlensing events with simultaneous observations from space and the ground. We present this analysis for two such events, OGLE-2014-BLG-0939 and OGLE-2014-BLG-0124, which both show substantial planet sensitivity even though neither of them reached high magnification. This suggests that an ensemble of low to moderate magnification events can also yield significant planet sensitivity, and therefore probability, for detecting planets. The implications of our results to the ongoing and future space-based microlensing experiments to measure the Galactic distribution of planets are discussed.

  7. The WFIRST Microlensing Survey: Expectations and Unexpectations

    NASA Astrophysics Data System (ADS)

    Gaudi, B. Scott; Penny, Matthew

    2016-01-01

    The WFIRST microlensing survey will provide the definitive determination of the demographics of cool planets with semimajor axes > 1 AU and masses greater than that of the Earth, including free-floating planets. Together with the results from Kepler, TESS, and PLATO, WFIRST will complete the statistical census of planets in the Galaxy. These expectations are based on the most basic and conservative assumptions about the data quality, and assumes that the analysis methodologies will be similar to that used for current ground-based microlensing. Yet, in fact, the data quality will be dramatically better, and information content substantially richer, for the WFIRST microlensing survey as compared to current ground-based surveys. Thus WFIRST should allow for orders of magnitude improvement in both sensitivity and science yield. We will review some of these expected improvements and opportunities (the "known unknowns"), and provide a "to do list" of what tasks will need to be completed in order to take advantage of these opportunities. We will then speculate on the opportunities that we may not be aware of yet (the "unknown unknowns"), how we might go about determining what those opportunities are, and how we might figure out what we will need to do to take advantage of them.This work was partially supported by NASA grant NNX14AF63G.

  8. Space Based Dark Energy Surveys

    NASA Astrophysics Data System (ADS)

    Dore, Olivier

    2016-03-01

    Dark energy, the name given to the cause of the accelerating expansion of the Universe, is one of the most tantalizing mystery in modern physics. Current cosmological models hold that dark energy is currently the dominant component of the Universe, but the exact nature of DE remains poorly understood. There are ambitious ground-based surveys underway that seek to understand DE and NASA is participating in the development of significantly more ambitious space-based surveys planned for the next decade. NASA has provided mission enabling technology to the European Space Agency's (ESA) Euclid mission in exchange for US scientists to participate in the Euclid mission. NASA is also developing the Wide Field Infrared Survey Telescope-Astrophysics Focused Telescope Asset (WFIRST) mission for possible launch in 2024. WFIRST was the highest ranked space mission in the Astro2010 Decadal Survey and the current design uses a 2.4m space telescope to go beyond what was then envisioned. Understanding DE is one of the primary science goals of WFIRST-AFTA. This talk will review the state of DE, the relevant activities of the Cosmic Structure Interest Group (CoSSIG) of the PhyPAG, and detail the status and complementarity between Euclid, WFIRST and ot ambitious ground-based efforts.

  9. Testing LMC Microlensing Scenarios: The Discrimination Power of the SuperMACHO Microlensing Survey

    SciTech Connect

    Rest, A; Stubbs, C; Becker, A C; Miknaitis, G A; Miceli, A; Covarrubias, R; Hawley, S L; Smith, C; Suntzeff, N B; Olsen, K; Prieto, J; Hiriart, R; Welch, D L; Cook, K; Nikolaev, S; Proctor, G; Clocchiatti, A; Minniti, D; Garg, A; Challis, P; Keller, S C; Scmidt, B P

    2004-05-27

    Characterizing the nature and spatial distribution of the lensing objects that produce the observed microlensing optical depth toward the Large Magellanic Cloud (LMC) remains an open problem. They present an appraisal of the ability of the SuperMACHO Project, a next-generation microlensing survey pointed toward the LMC, to discriminate between various proposed lensing populations. they consider two scenarios: lensing by a uniform foreground screen of objects and self-lensing of LMC stars. The optical depth for ''screen-lensing'' is essentially constant across the face of the LMC; whereas, the optical depth for self-lensing shows a strong spatial dependence. they have carried out extensive simulations, based upon actual data obtained during the first year of the project, to assess the SuperMACHO survey's ability to discriminate between these two scenarios. In the simulations they predict the expected number of observed microlensing events for each of their fields by adding artificial stars to the images and estimating the spatial and temporal efficiency of detecting microlensing events using Monte-Carlo methods. They find that the event rate itself shows significant sensitivity to the choice of the LMC luminosity function shape and other parameters, limiting the conclusions which can be drawn from the absolute rate. By instead determining the differential event rate across the LMC, they can decrease the impact of these systematic uncertainties rendering the conclusions more robust. With this approach the SuperMACHO Project should be able to distinguish between the two categories of lens populations and provide important constraints on the nature of the lensing objects.

  10. Completing the Exoplanet Census with the WFIRST Microlensing Survey

    NASA Astrophysics Data System (ADS)

    Bennett, David P.; WFIRST Science Definition Team

    2011-09-01

    The WFIRST mission is the top rated large space mission from last year's decadal survey. It has three major science programs, a microlensing planet search program, a dark energy program, and a general observer program. WFIRST's microlensing planet search program will provide a statistical census of exoplanets with masses greater than one tenth of an Earth mass and orbital separations ranging from 0.5AU to infinity. This includes analogs to all the Solar System’s planets except for Mercury, as well as most types of planets predicted by planet formation theories. In combination with Kepler's census of planets in shorter period orbits, WFIRST's planet search program will provide a complete statistical census of the planets that populate our Galaxy. The current status of the WFIRST mission design will be presented.

  11. Determination of Microlensing Selection Criteria for the SuperMACHO Survey

    SciTech Connect

    Garg, A

    2008-10-10

    The SuperMACHO project is a 5 year survey to determine the nature of the lens population responsible for the excess microlensing rate toward the Large Magellanic Cloud observed by the MACHO project [1]. The survey probes deeper than earlier surveys unveiling many more extragalactic contaminants, particularly type Ia supernovae and active galactic nuclei. Using {approx}10{sup 7} simulated light curves of both microlensing events and type Ia supernovae we determine selection criteria optimized to maximize the microlensing detection efficiency while minimizing the contamination rate from non-microlensing events. We discuss these simulations and the selection criteria.

  12. The Exoplanet Microlensing Survey by the Proposed WFIRST Observatory

    NASA Technical Reports Server (NTRS)

    Barry, Richard; Kruk, Jeffrey; Anderson, Jay; Beaulieu, Jean-Philippe; Bennett, David P.; Catanzarite, Joseph; Cheng, Ed; Gaudi, Scott; Gehrels, Neil; Kane, Stephen; Lunine, Jonathan; Sumi, Takahiro; Tanner, Angelle; Traub, Wesley

    2012-01-01

    The New Worlds, New Horizons report released by the Astronomy and Astrophysics Decadal Survey Board in 2010 listed the Wide Field Infrared Survey Telescope (WFIRST) as the highest-priority large space mission for the . coming decade. This observatory will provide wide-field imaging and slitless spectroscopy at near infrared wavelengths. The scientific goals are to obtain a statistical census of exoplanets using gravitational microlensing. measure the expansion history of and the growth of structure in the Universe by multiple methods, and perform other astronomical surveys to be selected through a guest observer program. A Science Definition Team has been established to assist NASA in the development of a Design Reference Mission that accomplishes this diverse array of science programs with a single observatory. In this paper we present the current WFIRST payload concept and the expected capabilities for planet detection. The observatory. with science goals that are complimentary to the Kepler exoplanet transit mission, is designed to complete the statistical census of planetary systems in the Galaxy, from habitable Earth-mass planets to free floating planets, including analogs to all of the planets in our Solar System except Mercury. The exoplanet microlensing survey will observe for 500 days spanning 5 years. This long temporal baseline will enable the determination of the masses for most detected exoplanets down to 0.1 Earth masses.

  13. Microlensing Events in Gaia and other Astrometric Surveys

    NASA Astrophysics Data System (ADS)

    Baker, Claire; Di Stefano, Rosanne; Lepine, Sebastien

    2017-01-01

    The region within a kiloparsec of the Sun is a vast and mysterious place filled with uncharted planets, stars and compact objects, whose masses and properties are unknown. The Gaia space mission provides a unique opportunity to study of this region by measuring parallax distances and proper motions to millions of nearby stars, significantly advancing data available from previous astrometric surveys.We are putting this new astrometric information from the first Gaia data release to a novel use, by searching for matches between the positions of known microlensing events and the positions of stars observed by both the Gaia and the Tycho-2 missions, as listed in the Tycho-Gaia Astrometric Solution (TGAS) Catalogue.The existence of a gravitational microlensing event near a TGAS-listed star may provide information about the nature of either the source star lensed in the event, or the lens itself. For example, the source star lensed in the ‘TAGO’ event lies nearby, and is listed in the TGAS Catalogue. Other events may also have been caused by nearby TGAS-listed stars, or by their dim companions. In such cases, we can determine the lens mass and acquire information about any compact objects or planets which may exist around the lens.We report on the process of matching the positions of over 20,000 candidate microlensing events discovered by either OGLE and/or MOA, with the positions of 2 million stars from the TGAS Catalogue and stars from a range of other surveys, including Lepine's SUPERBLINK survey, and discuss the implications of the matches obtained.

  14. The Korean Microlensing Telescope Network: Expectations for a Cold Exoplanet Census through a Global Microlensing Survey

    NASA Astrophysics Data System (ADS)

    Henderson, Calen Barnett

    The Korean Microlensing Telescope Network (KMTNet) consists of three 1.6m telescopes each with a 4 deg2 field of view (FoV) and is dedicated to monitoring the Galactic bulge to detect exoplanets via gravitational microlensing. KMTNet's combination of aperture size, FoV, cadence, and longitudinal coverage will provide a unique opportunity to probe exoplanet demographics in an unbiased way. My dissertation focuses on the results of simulations I have written and analyses I have performed that together provide estimates of and facilitate intuition about the number and variety of systmes KMTNet will detect and how best to maximize their scientific yield. First I present my simulations that optimize the observing strategy for, and predict the planetary yields of, KMTNet. I estimate the planet detection rates for planets with mass and separation across the ranges 0.1 ≤Mp/M⊕ ≤1000 and 0.4 ≤ a/AU ≤ 16, respectively, and also for free-floating planets. I furthermore investigate the dependence of these detection rates on the number of observatories, the photometric precision limit, and optimistic assumptions regarding seeing, throughput, and flux measurement uncertainties. Next I explore several possible avenues for constraining the flux of the lens for these predicted KMTNet detections. I examine the potential to obtain lens flux measurements by 1) imaging the lens once it is spatially resolved from the source, 2) measuring the elongation of the point spread function of the microlensing target (lens+source) when the lens and source are still unresolved, and 3) taking prompt follow-up photometry. In each case I simulate observing programs for a representative example of current ground-based adaptive optics (AO) facilities, future ground-based AO facilities, and future space telescopes. Lastly, I provide a list of microlensing events toward the Galactic bulge with high relative lens-source proper motion that are therefore good candidates for constraining the lens

  15. Microlensing detection of extrasolar planets.

    PubMed

    Giannini, Emanuela; Lunine, Jonathan I

    2013-05-01

    We review the method of exoplanetary microlensing with a focus on two-body planetary lensing systems. The physical properties of planetary systems can be successfully measured by means of a deep analysis of lightcurves and high-resolution imaging of planetary systems, countering the concern that microlensing cannot determine planetary masses and orbital radii. Ground-based observers have had success in diagnosing properties of multi-planet systems from a few events, but space-based observations will be much more powerful and statistically more complete. Since microlensing is most sensitive to exoplanets beyond the snow line, whose statistics, in turn, allow for testing current planetary formation and evolution theories, we investigate the retrieval of semi-major axis density by a microlensing space-based survey with realistic parameters. Making use of a published statistical method for projected exoplanets quantities (Brown 2011), we find that one year of such a survey might distinguish between simple power-law semi-major axis densities. We conclude by briefly reviewing ground-based results hinting at a high abundance of free-floating planets and describing the potential contribution of space-based missions to understanding the frequency and mass distribution of these intriguing objects, which could help unveil the formation processes of planetary systems.

  16. Preparing for the WFIRST Microlensing Survey: Simulations, Requirements, Survey Strategies, and Precursor Observations

    NASA Astrophysics Data System (ADS)

    Gaudi, Bernard

    As one of the four primary investigations of the Wide Field Infrared Survey Telescope (WFIRST) mission, the microlensing survey will monitor several square degrees of the Galactic bulge for a total of roughly one year. Its primary science goal is to "Complete the statistical census of planetary systems in the Galaxy, from the outer habitable zone to free floating planets, including analogs of all of the planets in our Solar System with the mass of Mars or greater.'' WFIRST will therefore (a) measure the mass function of cold bound planets with masses greater than that of roughly twice the mass of the moon, including providing an estimate of the frequency of sub-Mars-mass embryos, (b) determine the frequency of free-floating planets with masses down to the Earth and below, (c) inform the frequency and habitability of potentially habitable worlds, and (d) revolutionize our understanding of the demographics of cold planets with its exquisite sensitivity to, and large expected yield of, planets in a broad and unexplored region of parameter space. In order for the microlensing survey to be successful, we must develop a plan to go from actual survey observations obtained by the WFIRST telescope and hardware to the final science products. This plan will involve many steps, the development of software, data reduction, and analysis tools at each step, and a list of requirements for each of these components. The overarching goal of this proposal is thus to develop a complete flowdown from the science goals of the microlensing survey to the mission design and hardware components. We have assembled a team of scientists with the breadth of expertise to achieve this primary goal. Our specific subgoals are as follows. Goal 1: We will refine the input Galactic models in order to provide improved microlensing event rates in the WFIRST fields. Goal 2: We will use the improved event rate estimates, along with improvements in our simulation methodology, to provide higher

  17. UKIRT Microlensing Surveys as a Pathfinder for WFIRST: The Detection of Five Highly Extinguished Low-∣b∣ Events

    NASA Astrophysics Data System (ADS)

    Shvartzvald, Y.; Bryden, G.; Gould, A.; Henderson, C. B.; Howell, S. B.; Beichman, C.

    2017-02-01

    Optical microlensing surveys are restricted from detecting events near the Galactic plane and center, where the event rate is thought to be the highest due to the high optical extinction of these fields. In the near-infrared (NIR), however, the lower extinction leads to a corresponding increase in event detections and is a primary driver for the wavelength coverage of the WFIRST microlensing survey. During the 2015 and 2016 bulge observing seasons, we conducted NIR microlensing surveys with UKIRT in conjunction with and in support of the Spitzer and Kepler microlensing campaigns. Here, we report on five highly extinguished ({A}H=0.81{--}1.97), low-Galactic latitude (-0.98≤slant b≤slant -0.36) microlensing events discovered from our 2016 survey. Four of them were monitored with an hourly cadence by optical surveys but were not reported as discoveries, likely due to the high extinction. Our UKIRT surveys and suggested future NIR surveys enable the first measurement of the microlensing event rate in the NIR. This wavelength regime overlaps with the bandpass of the filter in which the WFIRST microlensing survey will conduct its highest-cadence observations, making this event rate derivation critically important for optimizing its yield.

  18. MOA-2011-BLG-322Lb: a `second generation survey' microlensing planet

    NASA Astrophysics Data System (ADS)

    Shvartzvald, Y.; Maoz, D.; Kaspi, S.; Sumi, T.; Udalski, A.; Gould, A.; Bennett, D. P.; Han, C.; Abe, F.; Bond, I. A.; Botzler, C. S.; Freeman, M.; Fukui, A.; Fukunaga, D.; Itow, Y.; Koshimoto, N.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Namba, S.; Ohnishi, K.; Rattenbury, N. J.; Saito, To.; Sullivan, D. J.; Sweatman, W. L.; Suzuki, D.; Tristram, P. J.; Wada, K.; Yock, P. C. M.; Skowron, J.; Kozłowski, S.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Ulaczyk, K.; Wyrzykowski, Ł.; Poleski, R.; Pietrukowicz, P.

    2014-03-01

    Global `second-generation' microlensing surveys aim to discover and characterize extrasolar planets and their frequency, by means of round-the-clock high-cadence monitoring of a large area of the Galactic bulge, in a controlled experiment. We report the discovery of a giant planet in microlensing event MOA-2011-BLG-322. This moderate-magnification event, which displays a clear anomaly induced by a second lensing mass, was inside the footprint of our second-generation microlensing survey, involving MOA, OGLE and the Wise Observatory. The event was observed by the survey groups, without prompting alerts that could have led to dedicated follow-up observations. Fitting a microlensing model to the data, we find that the time-scale of the event was tE = 23.2 ± 0.8 d, and the mass ratio between the lens star and its companion is q = 0.028 ± 0.001. Finite-source effects are marginally detected, and upper limits on them help break some of the degeneracy in the system parameters. Using a Bayesian analysis that incorporates a Galactic structure model, we estimate the mass of the lens at 0.39^{+0.45}_{-0.19} M_{⊙}, at a distance of 7.56 ± 0.91 kpc. Thus, the companion is likely a planet of mass 11.6^{+13.4}_{-5.6} M_J, at a projected separation of 4.3^{+1.5}_{-1.2} AU, rather far beyond the snow line. This is the first pure-survey planet reported from a second-generation microlensing survey, and shows that survey data alone can be sufficient to characterize a planetary model. With the detection of additional survey-only planets, we will be able to constrain the frequency of extrasolar planets near their systems' snow lines.

  19. Space-based infrared surveys of small bodies

    NASA Astrophysics Data System (ADS)

    Mommert, M.

    2014-07-01

    Most small bodies in the Solar System are too small and too distant to be spatially resolved, precluding a direct diameter derivation. Furthermore, measurements of the optical brightness alone only allow a rough estimate of the diameter, since the surface albedo is usually unknown and can have values between about 3 % and 60 % or more. The degeneracy can be resolved by considering the thermal emission of these objects, which is less prone to albedo effects and mainly a function of the diameter. Hence, the combination of optical and thermal-infrared observational data provides a means to independently derive an object's diameter and albedo. This technique is used in asteroid thermal models or more sophisticated thermophysical models (see, e.g., [1]). Infrared observations require cryogenic detectors and/or telescopes, depending on the actual wavelength range observed. Observations from the ground are additionally compromised by the variable transparency of Earth's atmosphere in major portions of the infrared wavelength ranges. Hence, space-based infrared telescopes, providing stable conditions and significantly better sensitivities than ground-based telescopes, are now used routinely to exploit this wavelength range. Two observation strategies are used with space-based infrared observatories: Space-based Infrared All-Sky Surveys. Asteroid surveys in the thermal infrared are less prone to albedo-related discovery bias compared to surveys with optical telescopes, providing a more complete picture of small body populations. The first space-based infrared survey of Solar System small bodies was performed with the Infrared Astronomical Satellite (IRAS) for 10 months in 1983. In the course of the 'IRAS Minor Planet Survey' [2], 2228 asteroids (3 new discoveries) and more than 25 comets (6 new discoveries) were observed. More recent space-based infrared all-sky asteroid surveys were performed by Akari (launched 2006) and the Wide-field Infrared Survey Explorer (WISE

  20. The POINT-AGAPE survey: comparing automated searches of microlensing events towards M31

    NASA Astrophysics Data System (ADS)

    Tsapras, Y.; Carr, B. J.; Weston, M. J.; Kerins, E.; Baillon, P.; Gould, A.; Paulin-Henriksson, S.

    2010-05-01

    Searching for microlensing in M31 using automated superpixel surveys raises a number of difficulties which are not present in more conventional techniques. Here we focus on the problem that the list of microlensing candidates is sensitive to the selection criteria or `cuts' imposed, and some subjectivity is involved in this. Weakening the cuts will generate a longer list of microlensing candidates but with a greater fraction of spurious ones; strengthening the cuts will produce a shorter list but may exclude some genuine events. We illustrate this by comparing three analyses of the same data set obtained from a 3 yr observing run on the Isaac Newton Telescope in La Palma. The results of two of these analyses have been already reported: Belokurov et al. obtained between three and 22 candidates, depending on the strength of their cuts, while Calchi Novati et al. obtained six candidates. The third analysis is presented here for the first time and reports 10 microlensing candidates, seven of which are new. Only two of the candidates are common to all three analyses. In order to understand why these analyses produce different candidate lists, a comparison is made of the cuts used by the three groups. Particularly crucial are the method employed to distinguish between a microlensing event and a variable star, and the extent to which one encodes theoretical prejudices into the cuts. Another factor is that the superpixel technique requires the masking of resolved stars and bad pixels. Belokurov et al. and the present analysis use the same input catalogue and the same masks but Calchi Novati et al. use different ones and a somewhat less automated procedure. Because of these considerations, one expects the lists of candidates to vary and it is not possible to pronounce a candidate a definite microlensing event. Indeed we accept that several of our new candidates, especially the long time-scale ones, may not be genuine. This uncertainty also impinges on one of the most

  1. Microlens Masses from Astrometry and Parallax in Space-based Surveys: From Planets to Black Holes

    NASA Astrophysics Data System (ADS)

    Gould, Andrew; Yee, Jennifer C.

    2014-03-01

    We show that space-based microlensing experiments can recover lens masses and distances for a large fraction of all events (those with individual photometric errors <~ 0.01 mag) using a combination of one-dimensional microlens parallaxes and astrometric microlensing. This will provide a powerful probe of the mass distributions of planets, black holes, and neutron stars, the distribution of planets as a function of Galactic environment, and the velocity distributions of black holes and neutron stars. While systematics are in principle a significant concern, we show that it is possible to vet against all systematics (known and unknown) using single-epoch precursor observations with the Hubble Space Telescope roughly 10 years before the space mission.

  2. Microlens masses from astrometry and parallax in space-based surveys: From planets to black holes

    SciTech Connect

    Gould, Andrew; Yee, Jennifer C.

    2014-03-20

    We show that space-based microlensing experiments can recover lens masses and distances for a large fraction of all events (those with individual photometric errors ≲ 0.01 mag) using a combination of one-dimensional microlens parallaxes and astrometric microlensing. This will provide a powerful probe of the mass distributions of planets, black holes, and neutron stars, the distribution of planets as a function of Galactic environment, and the velocity distributions of black holes and neutron stars. While systematics are in principle a significant concern, we show that it is possible to vet against all systematics (known and unknown) using single-epoch precursor observations with the Hubble Space Telescope roughly 10 years before the space mission.

  3. Prospects for Gaia and other space-based surveys .

    NASA Astrophysics Data System (ADS)

    Bailer-Jones, Coryn A. L.

    Gaia is a fully-approved all-sky astrometric and photometric survey due for launch in 2011. It will measure accurate parallaxes and proper motions for everything brighter than G=20 (ca. 109 stars). Its primary objective is to study the composition, origin and evolution of our Galaxy from the 3D structure, 3D velocities, abundances and ages of its stars. In some respects it can be considered as a cosmological survey at redshift zero. Several other upcoming space-based surveys, in particular JWST and Herschel, will study star and galaxy formation in the early (high-redshift) universe. In this paper I briefly describe these missions, as well as SIM and Jasmine, and explain why they need to observe from space. I then discuss some Galactic science contributions of Gaia concerning dark matter, the search for substructure, stellar populations and the mass-luminosity relation. The Gaia data are complex and require the development of novel analysis methods; here I summarize the principle of the astrometric processing. In the last two sections I outline how the Gaia data can be exploited in connection with other observational and theoretical work in order to build up a more comprehensive picture of galactic evolution.

  4. Detecting extrasolar asteroid belts through their microlensing signatures

    NASA Astrophysics Data System (ADS)

    Lake, Ethan; Zheng, Zheng; Dong, Subo

    2017-02-01

    We propose that extrasolar asteroid belts can be detected through their gravitational microlensing signatures. Asteroid belt + star lens systems create so-called 'pseudo-caustics', regions in the source plane where the magnification exhibits a finite but discontinuous jump. These features allow such systems to generate distinctive signatures in the microlensing light curves for a wide range of belt configurations, with source trajectories as far as tenths of the Einstein ring radius from the centre of the lens. Sample light curves for a range of asteroid belt parameters are presented. In the near future, space-based microlensing surveys like WFIRST, which will have the power of detecting per cent-level changes in microlensing light curves even with subminute exposure times, may be able to discover extrasolar asteroid belts with masses of the order of an earth mass.

  5. MOA-2011-BLG-293Lb: A TEST OF PURE SURVEY MICROLENSING PLANET DETECTIONS

    SciTech Connect

    Yee, J. C.; Gould, A.; Skowron, J.; Collaboration: MOA Collaboration; OGLE Collaboration; muFUN Collaboration; and others

    2012-08-20

    Because of the development of large-format, wide-field cameras, microlensing surveys are now able to monitor millions of stars with sufficient cadence to detect planets. These new discoveries will span the full range of significance levels including planetary signals too small to be distinguished from the noise. At present, we do not understand where the threshold is for detecting planets. MOA-2011-BLG-293Lb is the first planet to be published from the new surveys, and it also has substantial follow-up observations. This planet is robustly detected in survey+follow-up data ({Delta}{chi}{sup 2} {approx} 5400). The planet/host mass ratio is q = (5.3 {+-} 0.2) Multiplication-Sign 10{sup -3}. The best-fit projected separation is s = 0.548 {+-} 0.005 Einstein radii. However, due to the s{r_reversible}s{sup -1} degeneracy, projected separations of s{sup -1} are only marginally disfavored at {Delta}{chi}{sup 2} = 3. A Bayesian estimate of the host mass gives M{sub L} = 0.43{sup +0.27}{sub -0.17} M{sub Sun }, with a sharp upper limit of M{sub L} < 1.2 M{sub Sun} from upper limits on the lens flux. Hence, the planet mass is m{sub p} = 2.4{sup +1.5}{sub -0.9} M{sub Jup}, and the physical projected separation is either r {approx_equal} 1.0 AU or r {approx_equal} 3.4 AU. We show that survey data alone predict this solution and are able to characterize the planet, but the {Delta}{chi}{sup 2} is much smaller ({Delta}{chi}{sup 2} {approx} 500) than with the follow-up data. The {Delta}{chi}{sup 2} for the survey data alone is smaller than for any other securely detected planet. This event suggests a means to probe the detection threshold, by analyzing a large sample of events like MOA-2011-BLG-293, which have both follow-up data and high-cadence survey data, to provide a guide for the interpretation of pure survey microlensing data.

  6. Microlensing Optical Depth towards the Galactic Bulge Using Clump Giants from the MACHO Survey

    SciTech Connect

    Popowski, P; Griest, K; Thomas, C L; Cook, K H; Bennett, D P; Becker, A C; Alves, D R; Minniti, D; Drake, A J; Alcock, C; Allsman, R A; Axelrod, T S; Freeman, K C; Geha, M; Lehner, M J; Marshall, S L; Nelson, C A; Peterson, B A; Quinn, P J; Stubbs, C W; Sutherland, W; Vandehei, T; Welch, D

    2005-07-14

    Using 7 years of MACHO survey data, we present a new determination of the optical depth to microlensing towards the Galactic bulge. We select the sample of 62 microlensing events (60 unique) on clump giant sources and perform a detailed efficiency analysis. We use only the clump giant sources because these are bright bulge stars and are not as strongly affected by blending as other events. Using a subsample of 42 clump events concentrated in an area of 4.5 deg{sup 2} with 739000 clump giant stars, we find {tau} = 2.17{sub -0.38}{sup +0.47} x 10{sup -6} at (l,b) = (1{sup o}.50, -2{sup o}.68), somewhat smaller than found in most previous MACHO studies, but in excellent agreement with recent theoretical predictions. We also present the optical depth in each of the 19 fields in which we detected events, and find limits on optical depth for fields with no events. The errors in optical depth in individual fields are dominated by Poisson noise. We measure optical depth gradients of (1.06 {+-} 0.71) x 10{sup -6}deg{sup -1} and (0.29 {+-} 0.43) x 10{sup -6}deg{sup -1} in the galactic latitude b and longitude l directions, respectively. Finally, we discuss the possibility of anomalous duration distribution of events in the field 104 centered on (l,b) = (3{sup o}.11, -3{sup o}.01) as well as investigate spatial clustering of events in all fields.

  7. Statistical searches for microlensing events in large, non-uniformly sampled time-domain surveys: A test using palomar transient factory data

    SciTech Connect

    Price-Whelan, Adrian M.; Agüeros, Marcel A.; Fournier, Amanda P.; Street, Rachel; Ofek, Eran O.; Covey, Kevin R.; Levitan, David; Sesar, Branimir; Laher, Russ R.; Surace, Jason

    2014-01-20

    Many photometric time-domain surveys are driven by specific goals, such as searches for supernovae or transiting exoplanets, which set the cadence with which fields are re-imaged. In the case of the Palomar Transient Factory (PTF), several sub-surveys are conducted in parallel, leading to non-uniform sampling over its ∼20,000 deg{sup 2} footprint. While the median 7.26 deg{sup 2} PTF field has been imaged ∼40 times in the R band, ∼2300 deg{sup 2} have been observed >100 times. We use PTF data to study the trade off between searching for microlensing events in a survey whose footprint is much larger than that of typical microlensing searches, but with far-from-optimal time sampling. To examine the probability that microlensing events can be recovered in these data, we test statistics used on uniformly sampled data to identify variables and transients. We find that the von Neumann ratio performs best for identifying simulated microlensing events in our data. We develop a selection method using this statistic and apply it to data from fields with >10 R-band observations, 1.1 × 10{sup 9} light curves, uncovering three candidate microlensing events. We lack simultaneous, multi-color photometry to confirm these as microlensing events. However, their number is consistent with predictions for the event rate in the PTF footprint over the survey's three years of operations, as estimated from near-field microlensing models. This work can help constrain all-sky event rate predictions and tests microlensing signal recovery in large data sets, which will be useful to future time-domain surveys, such as that planned with the Large Synoptic Survey Telescope.

  8. Quasar microlensing

    NASA Astrophysics Data System (ADS)

    Schmidt, R. W.; Wambsganss, J.

    2010-09-01

    Quasar microlensing deals with the effect of compact objects along the line of sight on the apparent brightness of the background quasars. Due to the relative motion between quasar, lenses and observer, the microlensing magnification changes with time which results in uncorrelated brightness variations in the various images of multiple quasar systems. The amplitudes of the signal can be more than a magnitude with time scales of weeks to months to years. The effect is due to the “granular” nature of the gravitational microlenses—stars or other compact objects in the stellar mass range. Quasar microlensing allows to study the quasar accretion disk with a resolution of tens of microarcseconds, hence quasar microlensing can be used to explore an astrophysical field that is hardly accessible by any other means. Quasar microlensing can also be used to study the lensing objects in a statistical sense, their nature (compact or smoothly distributed, normal stars or dark matter) as well as transverse velocities. Quasar microlensing light curves are now being obtained from monitoring programs across the electromagnetic spectrum from the radio through the infrared and optical range to the X-ray regime. Recently, spectroscopic microlensing was successfully applied, it provides quantitative comparisons with quasar/accretion disk models. There are now more than a handful of systems with several-year long light curves and significant microlensing signal, lending to detailed analysis. This review summarizes the current state of the art of quasar microlensing and shows that at this point in time, observational monitoring programs and complementary intense simulations provide a scenario where some of the early promises of quasar microlensing can be quantitatively applied. It has been shown, e.g., that smaller sources display more violent microlensing variability, first quantitative comparison with accretion disk models has been achieved, and quasar microlensing has been used to

  9. Microlensing Planets

    NASA Astrophysics Data System (ADS)

    Gould, Andrew

    The theory and practice of microlensing planet searches is developed in a systematic way, from an elementary treatment of the deflection of light by a massive body to a thorough discussion of the most recent results. The main concepts of planetary microlensing, including microlensing events, finite-source effects, and microlens parallax, are first introduced within the simpler context of point-lens events. These ideas are then applied to binary (and hence planetary) lenses and are integrated with concepts specific to binaries, including caustic topologies, orbital motion, and degeneracies, with an emphasis on analytic understanding. The most important results from microlensing planet searches are then reviewed, with emphasis both on understanding the historical process of discovery and the means by which scientific conclusions were drawn from light-curve analysis. Finally, the future prospects of microlensing planets searches are critically evaluated. Citations to original works provide the reader with multiple entry points into the literature.

  10. Constraining the Frequency of Free-floating Planets from a Synthesis of Microlensing, Radial Velocity, and Direct Imaging Survey Results

    NASA Astrophysics Data System (ADS)

    Clanton, Christian; Gaudi, B. Scott

    2017-01-01

    A microlensing survey by Sumi et al. exhibits an overabundance of short-timescale events (STEs; tE < 2 days) relative to what is expected from known stellar populations and a smooth power-law extrapolation down to the brown dwarf regime. This excess has been interpreted as a population of approximately Jupiter-mass objects that outnumber main-sequence stars nearly twofold; however the microlensing data alone cannot distinguish between events due to wide-separation (a ≳ 10 au) and free-floating planets. Assuming these STEs are indeed due to planetary-mass objects, we aim to constrain the fraction of these events that can be explained by bound but wide-separation planets. We fit the observed timescale distribution with a lens mass function comprised of brown dwarfs, main-sequence stars, and stellar remnants, finding and thus corroborating the initial identification of an excess of STEs. We then include a population of bound planets that are expected not to show signatures of the primary lens (host) in their microlensing light curves and that are also consistent with results from representative microlensing, radial velocity, and direct imaging surveys. We find that bound planets alone cannot explain the entire STE excess without violating the constraints from the surveys we consider and thus some fraction of these events must be due to free-floating planets, if our model for bound planets holds. We estimate a median fraction of STEs due to free-floating planets to be f = 0.67 (0.23 ≤ f ≤ 0.85 at 95% confidence) when assuming “hot-start” planet evolutionary models and f = 0.58 (0.14 ≤ f ≤ 0.83 at 95% confidence) for “cold-start” models. Assuming a delta-function distribution of free-floating planets of mass {m}p=2 {M}{Jup} yields a number of free-floating planets per main-sequence star of N = 1.4 (0.48 ≤ N ≤ 1.8 at 95% confidence) in the “hot-start” case and N = 1.2 (0.29 ≤ N ≤ 1.8 at 95% confidence) in the “cold-start” case.

  11. The Manchester Microlensing Conference: The 12th International Conference and ANGLES Microlensing Workshop

    NASA Astrophysics Data System (ADS)

    Kerins, E.; Mao, S.; Rattenbury, N.; Wyrzykowski, L.

    The Manchester Microlensing Conference (M2C) was held at the Jodrell Bank Centre for Astrophysics at Manchester University in the UK from 21st-25th January 2008. M2C comprised two elements: the ANGLES Microlensing Workshop and the 12th International Conference on gravitational microlensing. M2C began with the two-day Workshop, providing interactive Master Classes to around 60 researchers on selected hot topics in microlensing. The Master Classes were delivered by world-leading experts on each of the topics. The topics reflected the diverse techniques and applications of microlensing, such as crowded-field photometry, modelling of extra-solar planetary systems, and the use of microlensing in cosmology. The 12th International Conference on microlensing followed immediately after the Workshop and was attended by around 90 researchers. The Conference covered all aspects of current research in microlensing, including: Microlensing towards the Magellanic Clouds; Cosmological Microlensing; Stellar and Galactic Microlensing; Galactic Microlensing Surveys; Follow-up Programmes and Planetary Microlensing; M31 Microlensing; and Future Directions. The M2C Proceedings serve three functions. Through the expert master classes the M2C Proceedings provide a great starting point for those who wish to enter the field or who just wish to learn more about microlensing at a depth beyond that usually covered by a single review article. The M2C proceedings also provide a snapshot of the state-of-the art in microlensing observations and theory as of January 2008, in what is a rapidly developing field. Lastly, the M2C meeting and its Proceedings are dedicated to the memory of the late Bohdan Paczynski, a towering figure and founding father of modern day microlensing research.

  12. The Demographics of Exoplanetary Companions to M Dwarfs: Synthesizing Results from Microlensing, Radial Velocity, and Direct Imaging Surveys

    NASA Astrophysics Data System (ADS)

    Clanton, Christian Dwain

    Over the past 20 years, we have learned that exoplanets are ubiquitous throughout our Galaxy and show a diverse set of demographics, yet there is much work to be done to understand this diversity. Determining the distributions of the fundamental properties of exoplanets will provide vital clues regarding their formation and evolution. This is a difficult task, as exoplanet surveys are not uniformly sensitive to the full range of planet parameter space. Various observational biases and selection effects intrinsic to each of the different discovery techniques constrain the types of planets to which they are sensitive. Herein, I record a collection of the first studies to develop and apply the methodology of synthesizing results from multiple detection techniques to construct a statistically-complete census of planetary companions to M dwarfs that samples a wide region of their parameter space. I present a robust comparison of exoplanet discoveries from microlensing and radial velocity (RV) surveys of M dwarfs which infer giant planet frequencies that differ by more than an order of magnitude and are, prima facie, in direct conflict. I demonstrate that current, state-of-the-art RV surveys are capable of detecting only the high-mass tail of the population of planets beyond the ice line inferred by microlensing studies, engendering a large, apparent difference in giant planet frequency. This comparison further establishes that results from these types of surveys are, in fact, consistent over the region of parameter space wherein their sensitivities overlap. A synthesis of results from microlensing and RV surveys yields planet occurrence rates for M dwarfs that span several orders of magnitude in mass and orbital period. On average, each M dwarf hosts about two planets, and while Jupiter and super-Jupiter companions are relatively rare ( 3%), gas giants, in general, are quite common ( 15%). These occurrence rates are significantly lower than those inferred around FGK

  13. Optimal survey strategies and predicted planet yields for the Korean microlensing telescope network

    SciTech Connect

    Henderson, Calen B.; Gaudi, B. Scott; Skowron, Jan; Penny, Matthew T.; Gould, Andrew P.; Han, Cheongho; Nataf, David

    2014-10-10

    The Korean Microlensing Telescope Network (KMTNet) will consist of three 1.6 m telescopes each with a 4 deg{sup 2} field of view (FoV) and will be dedicated to monitoring the Galactic Bulge to detect exoplanets via gravitational microlensing. KMTNet's combination of aperture size, FoV, cadence, and longitudinal coverage will provide a unique opportunity to probe exoplanet demographics in an unbiased way. Here we present simulations that optimize the observing strategy for and predict the planetary yields of KMTNet. We find preferences for four target fields located in the central Bulge and an exposure time of t {sub exp} = 120 s, leading to the detection of ∼2200 microlensing events per year. We estimate the planet detection rates for planets with mass and separation across the ranges 0.1 ≤ M{sub p} /M {sub ⊕} ≤ 1000 and 0.4 ≤ a/AU ≤ 16, respectively. Normalizing these rates to the cool-planet mass function of Cassan et al., we predict KMTNet will be approximately uniformly sensitive to planets with mass 5 ≤ M{sub p} /M {sub ⊕} ≤ 1000 and will detect ∼20 planets per year per dex in mass across that range. For lower-mass planets with mass 0.1 ≤ M{sub p} /M {sub ⊕} < 5, we predict KMTNet will detect ∼10 planets per year. We also compute the yields KMTNet will obtain for free-floating planets (FFPs) and predict KMTNet will detect ∼1 Earth-mass FFP per year, assuming an underlying population of one such planet per star in the Galaxy. Lastly, we investigate the dependence of these detection rates on the number of observatories, the photometric precision limit, and optimistic assumptions regarding seeing, throughput, and flux measurement uncertainties.

  14. OGLE-2016-BLG-0596Lb: A High-mass Planet from a High-magnification Pure-survey Microlensing Event

    NASA Astrophysics Data System (ADS)

    Mróz, P.; Han, C.; and; Udalski, A.; Poleski, R.; Skowron, J.; Szymański, M. K.; Soszyński, I.; Pietrukowicz, P.; Kozłowski, S.; Ulaczyk, K.; Wyrzykowski, Ł.; Pawlak, M.; OGLE group; Albrow, M. D.; Cha, S.-M.; Chung, S.-J.; Jung, Y. K.; Kim, D.-J.; Kim, S.-L.; Lee, C.-U.; Lee, Y.; Park, B.-G.; Pogge, R. W.; Ryu, Y.-H.; Shin, I.-G.; Yee, J. C.; Zhu, W.; Gould, A.; (KMTNet group

    2017-04-01

    We report the discovery of a high mass ratio planet, q = 0.012, i.e., 13 times higher than the Jupiter/Sun ratio. The host mass has not yet been measured but can be determined or strongly constrained from adaptive optics imaging. The planet was discovered in a small archival study of high-magnification events in pure-survey microlensing data, which was unbiased by the presence of anomalies. The fact that it was previously unnoticed may indicate that more such planets lie in archival data and could be discovered by a similar systematic study. In order to understand the transition from predominantly survey+followup to predominately survey-only planet detections, we conduct the first analysis of these detections in the observational (s, q) plane. Here s is the projected separation in units of the Einstein radius. We find some evidence that survey+followup is relatively more sensitive to planets near the Einstein ring, but that there is no statistical difference in sensitivity by mass ratio.

  15. Synthesizing exoplanet demographics from radial velocity and microlensing surveys. II. The frequency of planets orbiting M dwarfs

    SciTech Connect

    Clanton, Christian; Gaudi, B. Scott

    2014-08-20

    In contrast to radial velocity (RV) surveys, results from microlensing surveys indicate that giant planets with masses greater than the critical mass for core accretion (∼0.1 M {sub Jup}) are relatively common around low-mass stars. Using the methodology developed in the first paper, we predict the sensitivity of M-dwarf RV surveys to analogs of the population of planets inferred by microlensing. We find that RV surveys should detect a handful of super-Jovian (>M {sub Jup}) planets at the longest periods being probed. These planets are indeed found by RV surveys, implying that the demographic constraints inferred from these two methods are consistent. Finally, we combine the results from both methods to estimate planet frequencies spanning wide regions of parameter space. We find that the frequency of Jupiters and super-Jupiters (1 ≲ m{sub p} sin i/M {sub Jup} ≲ 13) with periods 1 ≤ P/days ≤ 10{sup 4} is f{sub J}=0.029{sub −0.015}{sup +0.013}, a median factor of 4.3 (1.5-14 at 95% confidence) smaller than the inferred frequency of such planets around FGK stars of 0.11 ± 0.02. However, we find the frequency of all giant planets with 30 ≲ m{sub p} sin i/M {sub ⊕} ≲ 10{sup 4} and 1 ≤ P/days ≤ 10{sup 4} to be f{sub G}=0.15{sub −0.07}{sup +0.06}, only a median factor of 2.2 (0.73-5.9 at 95% confidence) smaller than the inferred frequency of such planets orbiting FGK stars of 0.31 ± 0.07. For a more conservative definition of giant planets (50 ≲ m{sub p} sin i/M {sub ⊕} ≲ 10{sup 4}), we find f{sub G{sup ′}}=0.11±0.05, a median factor of 2.2 (0.73-6.7 at 95% confidence) smaller than that inferred for FGK stars of 0.25 ± 0.05. Finally, we find the frequency of all planets with 1 ≤ m{sub p} sin i/M {sub ⊕} ≤ 10{sup 4} and 1 ≤ P/days ≤ 10{sup 4} to be f{sub p} = 1.9 ± 0.5.

  16. Campaign 9 of the K2 Mission: Observational Parameters, Scientific Drivers, and Community Involvement for a Simultaneous Space- and Ground-based Microlensing Survey

    NASA Astrophysics Data System (ADS)

    Henderson, Calen B.; Poleski, Radosław; Penny, Matthew; Street, Rachel A.; Bennett, David P.; Hogg, David W.; Gaudi, B. Scott; K2 Campaign 9 Microlensing Science Team; Zhu, W.; Barclay, T.; Barentsen, G.; Howell, S. B.; Mullally, F.; Udalski, A.; Szymański, M. K.; Skowron, J.; Mróz, P.; Kozłowski, S.; Wyrzykowski, Ł.; Pietrukowicz, P.; Soszyński, I.; Ulaczyk, K.; Pawlak, M.; OGLE Project, The; Sumi, T.; Abe, F.; Asakura, Y.; Barry, R. K.; Bhattacharya, A.; Bond, I. A.; Donachie, M.; Freeman, M.; Fukui, A.; Hirao, Y.; Itow, Y.; Koshimoto, N.; Li, M. C. A.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Ohnishi, K.; Oyokawa, H.; Rattenbury, N.; Saito, To.; Sharan, A.; Sullivan, D. J.; Tristram, P. J.; Yonehara, A.; MOA Collaboration; Bachelet, E.; Bramich, D. M.; Cassan, A.; Dominik, M.; Figuera Jaimes, R.; Horne, K.; Hundertmark, M.; Mao, S.; Ranc, C.; Schmidt, R.; Snodgrass, C.; Steele, I. A.; Tsapras, Y.; Wambsganss, J.; RoboNet Project, The; Bozza, V.; Burgdorf, M. J.; Jørgensen, U. G.; Calchi Novati, S.; Ciceri, S.; D'Ago, G.; Evans, D. F.; Hessman, F. V.; Hinse, T. C.; Husser, T.-O.; Mancini, L.; Popovas, A.; Rabus, M.; Rahvar, S.; Scarpetta, G.; Skottfelt, J.; Southworth, J.; Unda-Sanzana, E.; The MiNDSTEp Team; Bryson, S. T.; Caldwell, D. A.; Haas, M. R.; Larson, K.; McCalmont, K.; Packard, M.; Peterson, C.; Putnam, D.; Reedy, L.; Ross, S.; Van Cleve, J. E.; K2C9 Engineering Team; Akeson, R.; Batista, V.; Beaulieu, J.-P.; Beichman, C. A.; Bryden, G.; Ciardi, D.; Cole, A.; Coutures, C.; Foreman-Mackey, D.; Fouqué, P.; Friedmann, M.; Gelino, C.; Kaspi, S.; Kerins, E.; Korhonen, H.; Lang, D.; Lee, C.-H.; Lineweaver, C. H.; Maoz, D.; Marquette, J.-B.; Mogavero, F.; Morales, J. C.; Nataf, D.; Pogge, R. W.; Santerne, A.; Shvartzvald, Y.; Suzuki, D.; Tamura, M.; Tisserand, P.; Wang, D.

    2016-12-01

    K2's Campaign 9 (K2C9) will conduct a ˜3.7 deg2 survey toward the Galactic bulge from 2016 April 22 through July 2 that will leverage the spatial separation between K2 and the Earth to facilitate measurement of the microlens parallax {π }{{E}} for ≳ 170 microlensing events. These will include several that are planetary in nature as well as many short-timescale microlensing events, which are potentially indicative of free-floating planets (FFPs). These satellite parallax measurements will in turn allow for the direct measurement of the masses of and distances to the lensing systems. In this article we provide an overview of the K2C9 space- and ground-based microlensing survey. Specifically, we detail the demographic questions that can be addressed by this program, including the frequency of FFPs and the Galactic distribution of exoplanets, the observational parameters of K2C9, and the array of resources dedicated to concurrent observations. Finally, we outline the avenues through which the larger community can become involved, and generally encourage participation in K2C9, which constitutes an important pathfinding mission and community exercise in anticipation of WFIRST.

  17. Campaign 9 of the K2 Mission: Observational Parameters, Scientific Drivers, and Community Involvement for a Simultaneous Space- and Ground-based Microlensing Survey

    NASA Technical Reports Server (NTRS)

    Henderson, Calen B.; Poleski, Radoslaw; Penny, Matthew; Street, Rachel A.; Bennett, David P.; Hogg, David W.; Gaudi, B. Scott; Zhu, W.; Barclay, T.; Barentsen, G.; Howell, S. B.; Mullally, F.; Barry, R. K.; Bryson, S. T.; Caldwell, D. A.; Haas, M. R.; Beichman, C. A.; Bryden, G.; Van Cleve, J. E.

    2016-01-01

    K2's Campaign 9 (K2C9) will conduct a approximately 3.7 sq. deg survey toward the Galactic bulge from 2016 April 22 through July 2 that will leverage the spatial separation between K2 and the Earth to facilitate measurement of the microlens parallax Pi(sub E) for approximately greater than 170 microlensing events. These will include several that are planetary in nature as well as many short-timescale microlensing events, which are potentially indicative of free-floating planets (FFPs). These satellite parallax measurements will in turn allow for the direct measurement of the masses of and distances to the lensing systems. In this article we provide an overview of the K2C9 space- and ground-based microlensing survey. Specifically, we detail the demographic questions that can be addressed by this program, including the frequency of FFPs and the Galactic distribution of exoplanets, the observational parameters of K2C9, and the array of resources dedicated to concurrent observations. Finally, we outline the avenues through which the larger community can become involved, and generally encourage participation in K2C9, which constitutes an important pathfinding mission and community exercise in anticipation of WFIRST.

  18. OGLE-2015-BLG-0051/KMT-2015-BLG-0048Lb: A Giant Planet Orbiting a Low-mass Bulge Star Discovered by High-cadence Microlensing Surveys

    NASA Astrophysics Data System (ADS)

    Han, C.; Udalski, A.; Gould, A.; Bozza, V.; Jung, Y. K.; Albrow, M. D.; Kim, S.-L.; Lee, C.-U.; Cha, S.-M.; Kim, D.-J.; Lee, Y.; Park, B.-G.; Shin, I.-G.; KMTNet Collaboration; Szymański, M. K.; Soszyński, I.; Skowron, J.; Mróz, P.; Poleski, R.; Pietrukowicz, P.; Kozłowski, S.; Ulaczyk, K.; Wyrzykowski, Ł.; Pawlak, M.; OGLE Collaboration

    2016-10-01

    We report the discovery of an extrasolar planet detected from the combined data of a microlensing event OGLE-2015-BLG-0051/KMT-2015-BLG-0048 acquired by two microlensing surveys. Despite the fact that the short planetary signal occurred in the very early Bulge season during which the lensing event could be seen for just about an hour, the signal was continuously and densely covered. From the Bayesian analysis using models of the mass function, and matter and velocity distributions, combined with information on the angular Einstein radius, it is found that the host of the planet is located in the Galactic bulge. The planet has a mass {0.72}-0.07+0.65 {M}{{J}} and it is orbiting a low-mass M-dwarf host with a projected separation {d}\\perp =0.73+/- 0.08 {{au}}. The discovery of the planet demonstrates the capability of the current high-cadence microlensing lensing surveys in detecting and characterizing planets.

  19. The microlensing rate and distribution of free-floating planets towards the Galactic bulge

    NASA Astrophysics Data System (ADS)

    Ban, M.; Kerins, E.; Robin, A. C.

    2016-10-01

    Context. Ground-based optical microlensing surveys have provided tantalising, if inconclusive, evidence for a significant population of free-floating planets (FFPs). Both ground- and space-based facilities are being used and developed which will be able to probe the distrubution of FFPs with much better sensitivity. It is also vital to develop a high-precision microlensing simulation framework to evaluate the completeness of such surveys. Aims: We present the first signal-to-noise limited calculations of the FFP microlensing rate using the Besançon Galactic model. The microlensing distribution towards the Galactic centre is simulated for wide-area ground-based optical surveys (I-band) such as OGLE or MOA, a wide-area ground-based near-infrared survey (K-band), and a targeted space-based near-infrared survey (H-band) which could be undertaken with Euclid or WFIRST. Methods: We present a calculation framework for the computation of the optical and near-infrared microlensing rate and optical depth for simulated stellar catalogues which are signal-to-noise limited, and take account of extinction, unresolved stellar background light, and finite source size effects, which can be significant for FFPs. Results: We find that the global ground-based I-band yield over a central 200 deg2 region covering the Galactic centre ranges from 20 Earth-mass FFPs yr-1 up to 3500 yr-1 for Jupiter FFPs in the limit of 100% detection efficiency, and almost an order of magnitude larger for a K-band survey. For ground-based surveys we find that the inclusion of finite source and the unresolved background reveals a mass-dependent variation in the spatial distribution of FFPs. For a targeted space-based H-band covering 2 deg2, the yield depends on the target field but maximises close to the Galactic centre with around 76 Earth to 1700 Jupiter FFPs per year. For near-IR space-based surveys like Euclid or WFIRST the spatial distribution of FFPs is found to be largely insensitive to the FFP mass

  20. Detecting Extrasolar Asteroid Belts Through Their Microlensing Signatures

    NASA Astrophysics Data System (ADS)

    Lake, Ethan; Zheng, Zheng; Dong, Subo

    2016-03-01

    We propose that extrasolar asteroid belts can be detected through their gravitational microlensing signatures and present a simple theoretical understanding of how asteroid belts behave as gravitational lenses. Asteroid belt + star lens systems create so-called ``pseudo-caustics'', which are regions in the source plane where the magnification of the source exhibits a discontinuous jump. Such a magnification change can be associated with either a change in image multiplicity or with a sudden change in the size of an image. The existence of pseudo-caustics and the complex interplay between them and the formal caustics (which possess formally infinite magnification) lead to several interesting consequences, such as the presence of open caustics and the violation of Burke's theorem. These features allow such systems to generate very distinctive microlensing light curves across a wide region of asteroid belt parameter space and possess remarkably large lensing cross-sections. By constructing simulated light curves for a range of asteroid belt parameters, we demonstrate that upcoming space-based microlensing surveys like WFIRST are well-poised to discover extrasolar asteroid belts with masses on the order of 0 . 1M⊕ .

  1. Microlensing Event Caustic Crossing

    NASA Astrophysics Data System (ADS)

    MACHO/GMAN Collaboration

    1998-06-01

    The MACHO/GMAN Collaboration (cf. IAUC 6845) plus affiliate S.Rhie report that further observations of microlensing event MACHO-98-SMC-1 (R.A. = 0h45m35s.2, Decl. = -72o52'34" J2000) confirm the binary lens interpretation and yield a prediction for the time of the 2nd caustic crossing: June 19.2 +/- 1.5 UT. The confirming observations were obtained with the MSO 1.3m MACHO survey telescope and the CTIO 0.9-m telescope.

  2. FORECASTING COSMOLOGICAL PARAMETER CONSTRAINTS FROM NEAR-FUTURE SPACE-BASED GALAXY SURVEYS

    SciTech Connect

    Pavlov, Anatoly; Ratra, Bharat; Samushia, Lado E-mail: ratra@phys.ksu.edu

    2012-11-20

    The next generation of space-based galaxy surveys is expected to measure the growth rate of structure to a level of about one percent over a range of redshifts. The rate of growth of structure as a function of redshift depends on the behavior of dark energy and so can be used to constrain parameters of dark energy models. In this work, we investigate how well these future data will be able to constrain the time dependence of the dark energy density. We consider parameterizations of the dark energy equation of state, such as XCDM and {omega}CDM, as well as a consistent physical model of time-evolving scalar field dark energy, {phi}CDM. We show that if the standard, specially flat cosmological model is taken as a fiducial model of the universe, these near-future measurements of structure growth will be able to constrain the time dependence of scalar field dark energy density to a precision of about 10%, which is almost an order of magnitude better than what can be achieved from a compilation of currently available data sets.

  3. Discovering Exoplanets with Microlensing: Transition to the Next Generation

    NASA Astrophysics Data System (ADS)

    Gould, Andrew

    . Because microlensing sensitivity peaks at orbital radii of a few times the snow-line, it is complementary to other techniques that (like RV and transits) are most sensitive to planets that are closer in or that (like direct imaging) are sensitive to planets that are further out. But we also expect that this work will have tremendous indirect impact on the field, which is rapidly growing. In particular, high-mag events are the best means of training students and other junior people in the technically demanding skills required to model microlensing events. In fact, there are only a handful of people in the world capable of carrying out this analysis, while the number of events that will be discovered is likely to explode as new multi-site wide-angle surveys of low-mag events come on line. The disparity between planet discoveries and people to analyze them would increase even further if a satellite such as WFIRST were launched and had a significant microlensing component (the primary space recommendation of Astro2010). We note that ALL current workers in the field of planetary microlensing who obtained PhDs from US institutions in the last 15 years, were trained by our group at OSU. In addition, theoretical work on microlensing (such as the recognition of the relation of parallax and orbital motion) has largely been driven by the challenges posed by high-mag events, and we expect that this will remain so in the future. Finally, we note that, for technical reasons discussed in the proposal, high-mag events are the most robust candidates for space-based parallax measurements, which can pin down the mass and distance to the planet. This may develop into an important auxiliary application of solar-system missions that are in heliocentric orbit.

  4. Synthesizing Exoplanet Demographics: A Single Population of Long-period Planetary Companions to M Dwarfs Consistent with Microlensing, Radial Velocity, and Direct Imaging Surveys

    NASA Astrophysics Data System (ADS)

    Clanton, Christian; Gaudi, B. Scott

    2016-03-01

    We present the first study to synthesize results from five different exoplanet surveys using three independent detection methods: microlensing, radial velocity, and direct imaging. The constraints derived herein represent the most comprehensive picture of the demographics of large-separation (≳2 AU) planets orbiting the most common stars in our Galaxy that has been constructed to date. We assume a simple, joint power-law planet distribution function of the form {d}2{N}{{pl}}/(d{log} {m}p d{log} a)={ A }{({m}p/{M}{{Sat}})}α {(a/2.5{{AU}})}β with an outer cutoff radius of the separation distribution function of aout. Generating populations of planets from these models and mapping them into the relevant observables for each survey, we use actual or estimated detection sensitivities to determine the expected observations for each survey. Comparing with the reported results, we derive constraints on the parameters \\{α ,β ,{ A },{a}{{out}}\\} that describe a single population of planets that is simultaneously consistent with the results of microlensing, radial velocity, and direct imaging surveys. We find median and 68% confindence intervals of α =-{0.86}-0.19+0.21 (-{0.85}-0.19+0.21), β ={1.1}-1.4+1.9 ({1.1}-1.3+1.9), { A }={0.21}-0.15+0.20 {{dex}}-2 ({0.21}-0.15+0.20 {{dex}}-2), and {a}{{out}}={10}-4.7+26 AU ({12}-6.2+50 AU) assuming “hot-start” (“cold-start”) planet evolutionary models. These values are consistent with all current knowledge of planets on orbits beyond ∼2 AU around single M dwarfs.

  5. Dynamics and Origin of Extra-solar Planetary Systems and Microlensing Detection of Extra-solar Planets

    NASA Technical Reports Server (NTRS)

    Peale, S. J.

    2003-01-01

    We compare a space-based microlensing search for planets, with a ground based microlensing search originally proposed by D. Tytler (Beichman, et al. 1996). Perturbations of microlensing light curves when the lens star has a planetary companion are sought by one wide angle survey telescope and an array of three or four followup narrow angle telescopes distributed in longitude that follow events with high precision, high time resolution photometry. Alternative ground based programs are considered briefly. With the four 2 meter telescopes distributed in longitude in the southern hemisphere in the Tytler proposal, observational constraints on a ground-based search for planets during microlensing events toward the center of the galaxy are severe. Probably less than 100 events could be monitored per year with high precision, high time resolution photometry with only about 42% coverage on the average regardless of how many events were discovered by the survey telescope. Statistics for the occurrence and properties for Jupiter-mass planets would be meaningful but relatively meager four years after the program was started, and meaningful statistics for Earth-mass planets would be non existent. In contrast, the 14,500 events in a proposed 4 year space based program (GEST = Galactic Exoplanet Survey Telescope) would yield very sound statistics on the occurrence, masses and separations of Jupiter-mass planets, and significant constraints on similar properties for Earth-mass planets. The significance of the Jupiter statistics would be to establish the frequency of planetary systems like our own, where terrestrial planets could exist inside the orbits of the giants.

  6. The Angstrom Project: a new microlensing candidate

    NASA Astrophysics Data System (ADS)

    Kerins, E.; Darnley, M. J.; Newsam, A. M.; Duke, J. P.; Gould, A.; Street, C. Han B.-G. Park R. A.

    2008-12-01

    We report the discovery of a new microlensing candidate in M31 by the Angstrom Project M31 bulge microlensing survey using the Liverpool Telescope (La Palma). The candidate was discovered using difference imaging techniques by the Angstrom Project Alert System (APAS) in a series of Sloan i'-band images of the bulge of M31.

  7. PLANETESIMAL DISK MICROLENSING

    SciTech Connect

    Heng, Kevin; Keeton, Charles R. E-mail: keeton@physics.rutgers.ed

    2009-12-10

    Motivated by debris disk studies, we investigate the gravitational microlensing of background starlight by a planetesimal disk around a foreground star. We use dynamical survival models to construct a plausible example of a planetesimal disk and study its microlensing properties using established ideas of microlensing by small bodies. When a solar-type source star passes behind a planetesimal disk, the microlensing light curve may exhibit short-term, low-amplitude residuals caused by planetesimals several orders of magnitude below Earth mass. The minimum planetesimal mass probed depends on the photometric sensitivity and the size of the source star, and is lower when the planetesimal lens is located closer to us. Planetesimal lenses may be found more nearby than stellar lenses because the steepness of the planetesimal mass distribution changes how the microlensing signal depends on the lens/source distance ratio. Microlensing searches for planetesimals require essentially continuous monitoring programs that are already feasible and can potentially set constraints on models of debris disks, the progeny of the supposed extrasolar analogues of Kuiper Belts.

  8. Prospects for Gaia and other planned space-based Galactic surveys

    NASA Astrophysics Data System (ADS)

    Bailer-Jones, C. A. L.

    2006-08-01

    Gaia is an all sky astrometric and photometric survey mission which will observe all objects in the sky brighter than magnitude G=20 (V=20-22), some 10^ 9 stars. Gaia will achieve an astrometric accuracy of 12- 25 μas at G=15 (providing a distance accuracy of 1-2% at 1 kpc) and 100-300 μas at G=20 and will measure radial velocities to a precision of 1-10 km/s for brighter sources. To characterize all sources (which are detected in real time), each is observed via low dispersion integral field spectrophotometry. The data processing for Gaia is very complex (self-calibrating; heterogeneous data; little prior information; intrinsically iterative) and is being undertaken by a large consortium of institutes. Fully exploiting the resulting data products will likewise be a challenge: Gaia will be a first in combining photometric and 6D phase space information on such a large scale. The scientific potential is immense. For example, using the kinematics and 3D positions of large numbers of stars across the whole Galaxy we can map its large and small scale structures and thus from a chronology of its formation and evolution (e.g. merger history). Gaia will measure both the gravitational potential of the Galaxy and the stellar luminosity function, from which the distribution of dark matter can be accurately mapped on small scales (< 1 Mpc) for the first time. Accurate distances to thousands of globular and open clusters will significantly improve models of stellar structure and evolution, and the detection of tens of millions of binary systems will permit a calibration of the stellar Mass-Luminosity relation over a wide range of masses and to high accuracy. Gaia is a fully-funded ESA mission due for launch in late 2011. With a nominal mission of five years and 2-3 years planned for post-mission processing, the final catalogue will only be available in about 2020. As it is the only large scale, high-accuracy astrometry mission under construction, it will be a unique source

  9. Detection of planets in extremely weak central perturbation microlensing events via next-generation ground-based surveys

    SciTech Connect

    Chung, Sun-Ju; Lee, Chung-Uk; Koo, Jae-Rim E-mail: leecu@kasi.re.kr

    2014-04-20

    Even though the recently discovered high-magnification event MOA-2010-BLG-311 had complete coverage over its peak, confident planet detection did not happen due to extremely weak central perturbations (EWCPs, fractional deviations of ≲ 2%). For confident detection of planets in EWCP events, it is necessary to have both high cadence monitoring and high photometric accuracy better than those of current follow-up observation systems. The next-generation ground-based observation project, Korea Microlensing Telescope Network (KMTNet), satisfies these conditions. We estimate the probability of occurrence of EWCP events with fractional deviations of ≤2% in high-magnification events and the efficiency of detecting planets in the EWCP events using the KMTNet. From this study, we find that the EWCP events occur with a frequency of >50% in the case of ≲ 100 M {sub E} planets with separations of 0.2 AU ≲ d ≲ 20 AU. We find that for main-sequence and sub-giant source stars, ≳ 1 M {sub E} planets in EWCP events with deviations ≤2% can be detected with frequency >50% in a certain range that changes with the planet mass. However, it is difficult to detect planets in EWCP events of bright stars like giant stars because it is easy for KMTNet to be saturated around the peak of the events because of its constant exposure time. EWCP events are caused by close, intermediate, and wide planetary systems with low-mass planets and close and wide planetary systems with massive planets. Therefore, we expect that a much greater variety of planetary systems than those already detected, which are mostly intermediate planetary systems, regardless of the planet mass, will be significantly detected in the near future.

  10. pyLIMA : an open source microlensing software

    NASA Astrophysics Data System (ADS)

    Bachelet, Etienne

    2017-01-01

    Planetary microlensing is a unique tool to detect cold planets around low-mass stars which is approaching a watershed in discoveries as near-future missions incorporate dedicated surveys. NASA and ESA have decided to complement WFIRST-AFTA and Euclid with microlensing programs to enrich our statistics about this planetary population. Of the nany challenges in- herent in these missions, the data analysis is of primary importance, yet is often perceived as time consuming, complex and daunting barrier to participation in the field. We present the first open source modeling software to conduct a microlensing analysis. This software is written in Python and use as much as possible existing packages.

  11. Astrometric microlensing with the GAIA satellite

    NASA Astrophysics Data System (ADS)

    Belokurov, V. A.; Evans, N. W.

    2002-04-01

    GAIA is the `super-Hipparcos ' survey satellite selected as a Cornerstone 6 mission by the European Space Agency. GAIA can measure microlensing by the brightening of source stars. For the broad G -band photometer, the all-sky source-averaged photometric optical depth is ~10-7 . There are ~1300 photometric microlensing events for which GAIA will measure at least one data point on the amplified light curve. GAIA can also measure microlensing by the small excursions of the light centroid that occur during events. The all-sky source-averaged astrometric microlensing optical depth is ~2.5×10-5 . Some ~25000 sources will have a significant variation of the centroid shift, together with a closest approach, during the lifetime of the mission. This is not the actual number of events that can be extracted from the GAIA data set, as the false detection rate has not been assessed. A covariance analysis is used to study the propagation of errors and the estimation of parameters from realistic sampling of the GAIA data stream of transits in the along-scan direction during microlensing events. The mass of the lens can be calculated to good accuracy if the lens is nearby so that the angular Einstein radius θ E is large; if the Einstein radius projected on to the observer plane r~ E is approximately an astronomical unit; or if the duration of the astrometric event is long (>~1yr) or the source star is bright . Monte Carlo simulations are used to study the ~2500 events for which the mass can be recovered with an error of <50 per cent. These high-quality events are dominated by disc lenses within a few tens of parsecs and source stars within a few hundred parsecs. We show that the local mass function can be recovered from the high-quality sample to good accuracy. GAIA is the first instrument with the capability of measuring the mass locally in very faint objects such as black holes and very cool white and brown dwarfs. For only ~5 per cent of all astrometric events will GAIA record

  12. Gravitational Microlensing Events as a Target for the SETI project

    NASA Astrophysics Data System (ADS)

    Rahvar, Sohrab

    2016-09-01

    The detection of signals from a possible extrasolar technological civilization is one of the most challenging efforts of science. In this work, we propose using natural telescopes made of single or binary gravitational lensing systems to magnify leakage of electromagnetic signals from a remote planet that harbors Extraterrestrial Intelligent (ETI) technology. Currently, gravitational microlensing surveys are monitoring a large area of the Galactic bulge to search for microlensing events, finding more than 2000 events per year. These lenses are capable of playing the role of natural telescopes, and, in some instances, they can magnify radio band signals from planets orbiting around the source stars in gravitational microlensing systems. Assuming that the frequency of electromagnetic waves used for telecommunication in ETIs is similar to ours, we propose follow-up observation of microlensing events with radio telescopes such as the Square Kilometre Array (SKA), the Low Frequency Demonstrators, and the Mileura Wide-Field Array. Amplifying signals from the leakage of broadcasting by an Earth-like civilization will allow us to detect them as far as the center of the Milky Way galaxy. Our analysis shows that in binary microlensing systems, the probability of amplification of signals from ETIs is more than that in single microlensing events. Finally, we propose the use of the target of opportunity mode for follow-up observations of binary microlensing events with SKA as a new observational program for searching ETIs. Using optimistic values for the factors of the Drake equation provides detection of about one event per year.

  13. Theory of dispersive microlenses

    NASA Technical Reports Server (NTRS)

    Herman, B.; Gal, George

    1993-01-01

    A dispersive microlens is a miniature optical element which simultaneously focuses and disperses light. Arrays of dispersive mircolenses have potential applications in multicolor focal planes. They have a 100 percent optical fill factor and can focus light down to detectors of diffraction spot size, freeing up areas on the focal plane for on-chip analog signal processing. Use of dispersive microlenses allows inband color separation within a pixel and perfect scene registration. A dual-color separation has the potential for temperature discrimination. We discuss the design of dispersive microlenses and present sample results for efficient designs.

  14. Microlenses of smectic flowers

    NASA Astrophysics Data System (ADS)

    Serra, Francesca; Gharbi, Mohamed-Amine; Liu, Iris B.; Luo, Yimin; Bade, Nathan D.; Kamien, Randall D.; Yang, Shu; Stebe, Kathleen J.

    2015-03-01

    The search for new and tunable optical components finds suitable candidates in liquid crystals, which have both reconfigurability and unique optical properties. Here we discuss smectic liquid crystals arranged in focal conic domains (FCDs), which can work as gradient-refractive index microlenses. We exploit this property to create an assembly of microlenses that resembles an insect compound eye. The system consists of a thin layer of smectics on a substrate patterned with microposts. The smectic film is pinned at the microposts, creating a curved interface that induces a hierarchical assembly of FCDs called the ''flower pattern'': each FCD resembles the petal of a flower around the micropost. The arrangement of FCDs, with the largest FCDs pinned at the top of the microposts and the smallest FCDs in the low-curvature regions far from the post, is mirrored into a hierarchy of focal lengths of the microlenses. This structure is reconfigurable by melting and cooling and it allows visualizing objects placed at different distances, hence it can be exploited for 3D image reconstruction. Similarly to the insect eyes, the flower pattern is sensitive to light polarization: the large FCDs, with the largest eccentricity, only work as microlenses for one direction of light polarization. We thank the MRSEC NSF Grant DMR11-20901.

  15. Evaluating the effect of stellar multiplicity on the point spread function of space-based weak lensing surveys

    NASA Astrophysics Data System (ADS)

    Kuntzer, T.; Courbin, F.; Meylan, G.

    2016-02-01

    The next generation of space-based telescopes used for weak lensing surveys will require exquisite point spread function (PSF) determination. Previously negligible effects may become important in the reconstruction of the PSF, in part because of the improved spatial resolution. In this paper, we show that unresolved multiple star systems can affect the ellipticity and size of the PSF and that this effect is not cancelled even when using many stars in the reconstruction process. We estimate the error in the reconstruction of the PSF due to the binaries in the star sample both analytically and with image simulations for different PSFs and stellar populations. The simulations support our analytical finding that the error on the size of the PSF is a function of the multiple stars distribution and of the intrinsic value of the size of the PSF, i.e. if all stars were single. Similarly, the modification of each of the complex ellipticity components (e1,e2) depends on the distribution of multiple stars and on the intrinsic complex ellipticity. Using image simulations, we also show that the predicted error in the PSF shape is a theoretical limit that can be reached only if large number of stars (up to thousands) are used together to build the PSF at any desired spatial position. For a lower number of stars, the PSF reconstruction is worse. Finally, we compute the effect of binarity for different stellar magnitudes and show that bright stars alter the PSF size and ellipticity more than faint stars. This may affect the design of PSF calibration strategies and the choice of the related calibration fields.

  16. Microlensing Signature of Binary Black Holes

    NASA Technical Reports Server (NTRS)

    Schnittman, Jeremy; Sahu, Kailash; Littenberg, Tyson

    2012-01-01

    We calculate the light curves of galactic bulge stars magnified via microlensing by stellar-mass binary black holes along the line-of-sight. We show the sensitivity to measuring various lens parameters for a range of survey cadences and photometric precision. Using public data from the OGLE collaboration, we identify two candidates for massive binary systems, and discuss implications for theories of star formation and binary evolution.

  17. THE MICROLENSING PROPERTIES OF A SAMPLE OF 87 LENSED QUASARS

    SciTech Connect

    Mosquera, A. M.; Kochanek, C. S.

    2011-09-01

    Gravitational microlensing is a powerful tool for probing the physical properties of quasar accretion disks and properties of the lens galaxy such as its dark matter fraction and mean stellar mass. Unfortunately, the number of lensed quasars ({approx}90) exceeds our monitoring capabilities. Thus, estimating their microlensing properties is important for identifying good microlensing candidates as well as for the expectations of future surveys. In this work, we estimate the microlensing properties of a sample of 87 lensed quasars. While the median Einstein radius crossing timescale is 20.6 years, the median source crossing timescale is 7.3 months. Broadly speaking, this means that on {approx}10 year timescales roughly half the lenses will be quiescent, with the source in a broad demagnified valley, and roughly half will be active with the source lying in the caustic ridges. We also found that the location of the lens system relative to the cosmic microwave background dipole has a modest effect on microlensing timescales, and in theory microlensing could be used to confirm the kinematic origin of the dipole. As a corollary of our study we analyzed the accretion rate parameters in a sub-sample of 32 lensed quasars. At fixed black hole mass, it is possible to sample a broad range of luminosities (i.e., Eddington factors) if it becomes feasible to monitor fainter lenses.

  18. Extrasolar planets detections and statistics through gravitational microlensing

    NASA Astrophysics Data System (ADS)

    Cassan, A.

    2014-10-01

    -mass objects, including free-floating planets of about Jupiter's mass, were also detected trough microlensing. Detections and non-detections inform us on the abundance of planets as a function of planetary mass and orbital distance. Recent microlensing studies imply that low-mass planets, in particular super-Earths, are far more abundant than giant planets, and reveal that there are, on average, one or more bound planets per Milky Way star. Future microlensing surveys will dramatically increase the number of microlensing alerts, thus providing unprecedented constraints on the planetary mass function, down to the mass of the Earth.

  19. Astrophysical applications of quasar microlensing

    NASA Astrophysics Data System (ADS)

    Mediavilla, E.; Jiménez-Vicente, J.; Muñoz, J. A.

    2017-03-01

    We present a quick overview of several examples that illustrate the application of quasar microlensing to various problems of great interest in Astrophysics and Cosmology. We start introducing the main tool for simulating quasar microlensing, the magnification map. Then, the flux magnification statistics obtained from the magnification maps is used to study the quasar accretion disk size and temperature profile with results that challenge the thin disk model. The microlensing flux magnification statistics is also useful to determine the radial slope of the dark matter distribution in lens galaxies. The extremely high microlensing magnification at caustics allows to scan with horizon scale accuracy the quasar accretion disk, spiraling around the central super massive black hole, resolving the innermost stable circular orbit. Finally, transverse peculiar velocities of the lens galaxies, of great interest in cosmology, can be inferred either counting peaks in the microlensing light curves or directly from astrometric measurements of the highly magnified relative motions between lensed quasar images.

  20. Resolving Microlensing Events with Triggered VLBI

    NASA Astrophysics Data System (ADS)

    Karami, Mansour; Broderick, Avery E.; Rahvar, Sohrab; Reid, Mark

    2016-12-01

    Microlensing events provide a unique capacity to study the stellar remnant population of the Galaxy. Optical microlensing suffers from a near-complete degeneracy between mass, velocity, and distance. However, a subpopulation of lensed stars, Mira variable stars, are also radio-bright, exhibiting strong SiO masers. These are sufficiently bright and compact to permit direct imaging using existing very long baseline interferometers such as the Very Long Baseline Array (VLBA). We show that these events are relatively common, occurring at a rate of ≈ 2 {{yr}}-1 of which 0.1 {{yr}}-1 are associated with Galactic black holes. Features in the associated images, e.g., the Einstein ring, are sufficiently well resolved to fully reconstruct the lens properties, enabling the measurement of mass, distance, and tangential velocity of the lensing object to a precision better than 15%. Future radio microlensing surveys conducted with upcoming radio telescopes combined with modest improvements in the VLBA could increase the rate of Galactic black hole events to roughly 10 {{yr}}-1, sufficient to double the number of known stellar mass black holes in a couple of years, and permitting the construction of distribution functions of stellar mass black hole properties.

  1. Polarimetric microlensing of circumstellar discs

    NASA Astrophysics Data System (ADS)

    Sajadian, Sedighe; Rahvar, Sohrab

    2015-12-01

    We study the benefits of polarimetry observations of microlensing events to detect and characterize circumstellar discs around the microlensed stars located at the Galactic bulge. These discs which are unresolvable from their host stars make a net polarization effect due to their projected elliptical shapes. Gravitational microlensing can magnify these signals and make them be resolved. The main aim of this work is to determine what extra information about these discs can be extracted from polarimetry observations of microlensing events in addition to those given by photometry ones. Hot discs which are closer to their host stars are more likely to be detected by microlensing, owing to more contributions in the total flux. By considering this kind of discs, we show that although the polarimetric efficiency for detecting discs is similar to the photometric observation, but polarimetry observations can help to constraint the disc geometrical parameters e.g. the disc inner radius and the lens trajectory with respect to the disc semimajor axis. On the other hand, the time-scale of polarimetric curves of these microlensing events generally increases while their photometric time-scale does not change. By performing a Monte Carlo simulation, we show that almost four optically thin discs around the Galactic bulge sources are detected (or even characterized) through photometry (or polarimetry) observations of high-magnification microlensing events during 10-yr monitoring of 150 million objects.

  2. VizieR Online Data Catalog: OGLE microlensing events in Galactic Bulge (Udalski+, 2000)

    NASA Astrophysics Data System (ADS)

    Udalski, A.; Zebrun, K.; Szymanski, M.; Kubiak, M.; Pietrzynski, G.; Soszynski, I.; Wozniak, P.

    2006-09-01

    We present the Catalog of microlensing events detected toward the Galactic bulge in three observing seasons, 1997-1999, during the OGLE-II microlensing survey. The search for microlensing events was performed using a database of about 4x109 photometric measurements of about 20.5 million stars from the Galactic bulge. The Catalog comprises 214 microlensing events found in the fields covering about 11 square degrees on the sky and distributed in different parts of the Galactic bulge. The sample includes 20 binary microlensing events, 14 of them are caustic crossing. In one case a double star is likely lensed. We present distribution of the basic parameters of microlensing events and show preliminary rate of microlensing in different regions of the Galactic bulge. The latter reveals clear dependence on the Galactic coordinates. The dependence on l indicates that the majority of lenses toward the Galactic bulge are located in the Galactic bar. Models of the Galactic bar seem to reasonably predict the observed spatial distribution of microlensing events in the Galactic bulge. All data presented in the Catalog and photometry of all events are available from the OGLE Internet archive. (3 data files).

  3. A new parameter space study of cosmological microlensing

    NASA Astrophysics Data System (ADS)

    Vernardos, G.; Fluke, C. J.

    2013-09-01

    Cosmological gravitational microlensing is a useful technique for understanding the structure of the inner parts of a quasar, especially the accretion disc and the central supermassive black hole. So far, most of the cosmological microlensing studies have focused on single objects from ˜90 currently known lensed quasars. However, present and planned all-sky surveys are expected to discover thousands of new lensed systems. Using a graphics processing unit (GPU) accelerated ray-shooting code, we have generated 2550 magnification maps uniformly across the convergence (κ) and shear (γ) parameter space of interest to microlensing. We examine the effect of random realizations of the microlens positions on map properties such as the magnification probability distribution (MPD). It is shown that for most of the parameter space a single map is representative of an average behaviour. All of the simulations have been carried out on the GPU Supercomputer for Theoretical Astrophysics Research.

  4. Possibly high amplification microlensing event

    NASA Astrophysics Data System (ADS)

    Szymanski, Michal; Udalski, Andrzej

    1998-06-01

    The OGLE team informs about a microlensing event in progress - OGLE-1998-BUL-18 (17:54:21.79, -29:53:24.0, J2000) which is presently about 2 days before maximum. It is relatively bright star (I0=15.5), rising rapidly. Preliminary microlensing fit to the light curve predicts large maximum magnification to be reached on JD=2450971.831 (1998-06-07.33 UT) Follow-up observations, both photometric and spectroscopic, are strongly encouraged.

  5. BINARY ASTROMETRIC MICROLENSING WITH GAIA

    SciTech Connect

    Sajadian, Sedighe

    2015-04-15

    We investigate whether or not Gaia can specify the binary fractions of massive stellar populations in the Galactic disk through astrometric microlensing. Furthermore, we study whether or not some information about their mass distributions can be inferred via this method. In this regard, we simulate the binary astrometric microlensing events due to massive stellar populations according to the Gaia observing strategy by considering (i) stellar-mass black holes, (ii) neutron stars, (iii) white dwarfs, and (iv) main-sequence stars as microlenses. The Gaia efficiency for detecting the binary signatures in binary astrometric microlensing events is ∼10%–20%. By calculating the optical depth due to the mentioned stellar populations, the numbers of the binary astrometric microlensing events being observed with Gaia with detectable binary signatures, for the binary fraction of about 0.1, are estimated to be 6, 11, 77, and 1316, respectively. Consequently, Gaia can potentially specify the binary fractions of these massive stellar populations. However, the binary fraction of black holes measured with this method has a large uncertainty owing to a low number of the estimated events. Knowing the binary fractions in massive stellar populations helps with studying the gravitational waves. Moreover, we investigate the number of massive microlenses for which Gaia specifies masses through astrometric microlensing of single lenses toward the Galactic bulge. The resulting efficiencies of measuring the mass of mentioned populations are 9.8%, 2.9%, 1.2%, and 0.8%, respectively. The numbers of their astrometric microlensing events being observed in the Gaia era in which the lens mass can be inferred with the relative error less than 0.5 toward the Galactic bulge are estimated as 45, 34, 76, and 786, respectively. Hence, Gaia potentially gives us some information about the mass distribution of these massive stellar populations.

  6. The MACHO Project HST Follow-Up: The Large Magellanic Cloud Microlensing Source Stars

    SciTech Connect

    Nelson, C.A.; Drake, A.J.; Cook, K.H.; Bennett, D.P.; Popowski, P.; Dalal, N.; Nikolaev, S.; Alcock, C.; Axelrod, T.S.; Becker, A.C. Freeman, K.C.; Geha, M.; Griest, K.; Keller, S.C.; Lehner, M.J.; Marshall, S.L.; Minniti, D.; Pratt, M.R.; Quinn, P.J.; Stubbs, C.W.; Sutherland, W.; /Oxford U. /Oran, Sci. Tech. U. /Garching, Max Planck Inst. /McMaster U.

    2009-06-25

    We present Hubble Space Telescope (HST) WFPC2 photometry of 13 microlensed source stars from the 5.7 year Large Magellanic Cloud (LMC) survey conducted by the MACHO Project. The microlensing source stars are identified by deriving accurate centroids in the ground-based MACHO images using difference image analysis (DIA) and then transforming the DIA coordinates to the HST frame. None of these sources is coincident with a background galaxy, which rules out the possibility that the MACHO LMC microlensing sample is contaminated with misidentified supernovae or AGN in galaxies behind the LMC. This supports the conclusion that the MACHO LMC microlensing sample has only a small amount of contamination due to non-microlensing forms of variability. We compare the WFPC2 source star magnitudes with the lensed flux predictions derived from microlensing fits to the light curve data. In most cases the source star brightness is accurately predicted. Finally, we develop a statistic which constrains the location of the Large Magellanic Cloud (LMC) microlensing source stars with respect to the distributions of stars and dust in the LMC and compare this to the predictions of various models of LMC microlensing. This test excludes at {approx}> 90% confidence level models where more than 80% of the source stars lie behind the LMC. Exotic models that attempt to explain the excess LMC microlensing optical depth seen by MACHO with a population of background sources are disfavored or excluded by this test. Models in which most of the lenses reside in a halo or spheroid distribution associated with either the Milky Way or the LMC are consistent which these data, but LMC halo or spheroid models are favored by the combined MACHO and EROS microlensing results.

  7. A Space-Based Near-Earth Object Survey Telescope in Support of Human Exploration, Solar System Science, and Planetary Defense

    NASA Technical Reports Server (NTRS)

    Abell, Paul A.

    2011-01-01

    Human exploration of near-Earth objects (NEOs) beginning in 2025 is one of the stated objectives of U.S. National Space Policy. Piloted missions to these bodies would further development of deep space mission systems and technologies, obtain better understanding of the origin and evolution of our Solar System, and support research for asteroid deflection and hazard mitigation strategies. As such, mission concepts have received much interest from the exploration, science, and planetary defense communities. One particular system that has been suggested by all three of these communities is a space-based NEO survey telescope. Such an asset is crucial for enabling affordable human missions to NEOs circa 2025 and learning about the primordial population of objects that could present a hazard to the Earth in the future.

  8. Liquid Tunable Microlenses based on MEMS techniques

    PubMed Central

    Zeng, Xuefeng; Jiang, Hongrui

    2013-01-01

    The recent rapid development in microlens technology has provided many opportunities for miniaturized optical systems, and has found a wide range of applications. Of these microlenses, tunable-focus microlenses are of special interest as their focal lengths can be tuned using micro-scale actuators integrated with the lens structure. Realization of such tunable microlens generally relies on the microelectromechanical system (MEMS) technologies. Here, we review the recent progress in tunable liquid microlenses. The underlying physics relevant to these microlenses are first discussed, followed by description of three main categories of tunable microlenses involving MEMS techniques, mechanically driven, electrically driven, and those integrated within microfluidic systems. PMID:24163480

  9. PERIODIC SIGNALS IN BINARY MICROLENSING EVENTS

    SciTech Connect

    Guo, Xinyi; Stefano, Rosanne Di; Esin, Ann; Taylor, Jeffrey

    2015-08-20

    Gravitational microlensing events are powerful tools for the study of stellar populations. In particular, they can be used to discover and study a variety of binary systems. A large number of binary lenses have already been found through microlensing surveys and a few of these systems show strong evidence of orbital motion on the timescale of the lensing event. We expect that more binary lenses of this kind will be detected in the future. For binaries whose orbital period is comparable to the event duration, the orbital motion can cause the lensing signal to deviate drastically from that of a static binary lens. The most striking property of such light curves is the presence of quasi-periodic features, which are produced as the source traverses the same regions in the rotating lens plane. These repeating features contain information about the orbital period of the lens. If this period can be extracted, then much can be learned about the lensing system even without performing time-consuming, detailed light-curve modeling. However, the relative transverse motion between the source and the lens significantly complicates the problem of period extraction. To resolve this difficulty, we present a modification of the standard Lomb–Scargle periodogram analysis. We test our method for four representative binary lens systems and demonstrate its efficiency in correctly extracting binary orbital periods.

  10. Microlensing Parallax for Observers in Heliocentric Motion

    NASA Astrophysics Data System (ADS)

    Calchi Novati, S.; Scarpetta, G.

    2016-06-01

    Motivated by the ongoing Spitzer observational campaign, and the forthcoming K2 one, we revisit, working in an heliocentric reference frame, the geometrical foundation for the analysis of the microlensing parallax, as measured with the simultaneous observation of the same microlensing event from two observers with relative distance of order au. For the case of observers at rest, we discuss the well-known fourfold microlensing parallax degeneracy and determine an equation for the degenerate directions of the lens trajectory. For the case of observers in motion, we write down an extension of the Gould relationship between the microlensing parallax and the observable quantities and, at the same time, highlight the functional dependence of these same quantities from the timescale of the underlying microlensing event. Furthermore, through a series of examples, we show the importance of taking into account themotion of the observers to correctly recover the parameters of the underlying microlensing event. In particular, we discuss the cases of the amplitude of the microlensing parallax and that of the difference of the timescales between the observed microlensing events, which are key to understand the breaking of the microlensing parallax degeneracy. Finally, we consider the case of the simultaneous observation of the same microlensing event from the ground and two satellites, a case relevant for the expected joint K2 and Spitzer observational programs in 2016.

  11. The effect of macromodel uncertainties on microlensing modelling of lensed quasars

    NASA Astrophysics Data System (ADS)

    Vernardos, G.; Fluke, C. J.

    2014-12-01

    Cosmological gravitational microlensing has been proven to be a powerful tool to constrain the structure of multiply imaged quasars, especially the accretion disc and central supermassive black hole system. However, the derived constraints on models may be affected by large systematic errors introduced in the various stages of modelling, namely, the macromodels, the microlensing magnification maps, and the convolution with realistic disc profiles. In particular, it has been known that different macromodels of the galaxy lens that fit the observations equally well, can lead to different values of convergence, κ, and shear, γ, required to generate magnification maps. So far, ˜25 microlensed quasars have been studied using microlensing techniques, where each system has been modelled and analysed individually, or in small samples. This is about to change due to the upcoming synoptic all-sky surveys, which are expected to discover thousands of quasars suitable for microlensing studies. In this study, we investigate the connection between macromodels of the galaxy lens and microlensing magnification maps throughout the parameter space in preparation for future studies of large statistical samples of systems displaying microlensing. In particular, we use 55 900 maps produced by the GERLUMPH parameter survey (available online at http://gerlumph.swin.edu.au) and identify regions of parameter space where macromodel uncertainties (Δκ, Δγ) lead to statistically different magnification maps. Strategies for mitigating the effect of Δκ, Δγ uncertainties are discussed in order to understand and control this potential source of systematic errors in accretion disc constraints derived from microlensing.

  12. Exoplanet searches with gravitational microlensing

    NASA Astrophysics Data System (ADS)

    Zakharov, Alexander

    2012-07-01

    Depending on gravitational lens masses, people are speaking about different regimes of gravitational lensing or more precisely, different regimes correspond to different angular distances, assuming that lenses and sources are located at cosmological distances. If a gravitational lens has a stellar mass, the regime is called microlensing. Since a distance between images depends on a square root of a lens mass, a regime for a lens with a planet mass (10^{-6} M_{⊙}) is called nanolensing. Therefore, searches for light exoplanets with gravitational lensing may be called nanolensing. There are different techniques to find exoplanets such as Doppler shift measurements, transits, pulsar timing, astrometrical measurements. It was noted that gravitational microlensing is the most promising technique to find exoplanets near the habitable zone with a temperature at exoplanet surface in the range 1 - 100° C (or in the temperature range for temperature of liquid water).

  13. Possible high magnification microlensing event

    NASA Astrophysics Data System (ADS)

    Udalski, Andrzej; Szymanski, Michal

    1998-05-01

    The OGLE team informs about a microlensing event in progress - OGLE-1998-BUL-15 (18:07:20.83, -27:34:10.8, J2000) which is presently about 4 days before maximum and is rising rapidly (already more than 2 mag above the normal level). Preliminary fit to the light curve predicts possible maximum magnification as large as 10 mag and maximum on JD=2450945.2. Follow up observations, both photometric and spectroscopic, are strongly encouraged.

  14. Measuring polarization in microlensing events

    NASA Astrophysics Data System (ADS)

    Ingrosso, G.; Calchi Novati, S.; De Paolis, F.; Jetzer, Ph.; Nucita, A. A.; Strafella, F.

    2015-01-01

    We reconsider the polarization of the star light that may arise during microlensing events due to the high gradient of magnification across the atmosphere of the source star, by exploring the full range of microlensing and stellar physical parameters. Since it is already known that only cool evolved giant stars give rise to the highest polarization signals, we follow the model by Simmons et al. to compute the polarization as due to the photon scattering on dust grains in the stellar wind. Motivated by the possibility to perform a polarization measurement during an ongoing microlensing event, we consider the recently reported event catalogue by the Optical Gravitational Lensing Experiment (OGLE) collaboration covering the 2001-2009 campaigns (OGLE-III events), that makes available the largest and more comprehensive set of single-lens microlensing events towards the Galactic bulge. The study of these events, integrated by a Monte Carlo analysis, allows us to estimate the expected polarization profiles and to predict for which source stars and at which time is most convenient to perform a polarization measurement in an ongoing event. We find that about two dozens of OGLE-III events (about 1 per cent of the total) have maximum polarization degree in the range 0.1 < Pmax < 1 per cent, corresponding to source stars with apparent magnitude I ≲ 14.5, being very cool red giants. This signal is measurable by using the FOcal Reducer and low dispersion Spectrograph (FORS2) polarimeter at Very Large Telescope (VLT) telescope with about 1 h integration time.

  15. The Microlensing Planet Search Program of the WFIRST Mission

    NASA Astrophysics Data System (ADS)

    Bennett, David P.

    2011-01-01

    The recently Decadal Survey report, "New Worlds, New Horizons in Astronomy and Astrophysics" recommends a new mission called WFIRST as its top ranked large space mission for the next decade. The WFIRST mission is to have two major science programs that will drive the design requirements: a dark energy program and a microlensing planet search program. WFIRST's microlensing planet search program will provide a statistical census of exoplanets with masses greater than one tenth of an Earth mass and orbital separations ranging from 0.5AU to infinity. This includes analogs to all the Solar System's planets except for Mercury, as well as most types of planets predicted by planet formation theories. In combination with Kepler's census of planets in shorter period orbits, WFIRST's planet search program will provide a complete statistical census of the planets that populate our Galaxy.

  16. The Microlensing Planet Search Program of the WFIRST Mission

    NASA Astrophysics Data System (ADS)

    Bennett, David P.

    2010-10-01

    The recently Decadal Survey report, "New Worlds, New Horizons in Astronomy and Astrophysics" recommends a new mission called WFIRST as its top ranked large space mission for the next decade. The WFIRST mission is to have two major science programs that will drive the design requirements: a dark energy program and a microlensing planet search program. WFIRST's microlensing planet search program will provide a statistical census of exoplanets with masses greater than one tenth of an Earth mass and orbital separations ranging from 0.5AU to infinity. This includes analogs to all the Solar System's planets except for Mercury, as well as most types of planets predicted by planet formation theories. In combination with Kepler's census of planets in shorter period orbits, WFIRST's planet search program will provide a complete statistical census of the planets that populate our Galaxy.

  17. Microlensing by Kuiper, Oort, and Free-Floating Planets

    NASA Astrophysics Data System (ADS)

    Gould, Andrew

    2016-08-01

    Microlensing is generally thought to probe planetary systems only out to a few Einstein radii. Microlensing events generated by bound planets beyond about 10 Einstein radii generally do not yield any trace of their hosts, and so would be classified as free floating planets (FFPs). I show that it is already possible, using adaptive optics (AO), to constrain the presence of potential hosts to FFP candidates at separations comparable to the Oort Cloud. With next-generation telescopes, planets at Kuiper-Belt separations can be probed. Next generation telescopes will also permit routine vetting for all FFP candidates, simply by obtaining second epochs 4-8 years after the event.At present, the search for such hosts is restricted to within the ``confusion limit'' of θ_\\confus ˜ 0.25'' but future WFIRST (Wide Field Infrared Survey Telescope) observations will allow one to probe beyond this confusion limit as well.

  18. Microlensing search towards M 31

    NASA Astrophysics Data System (ADS)

    Calchi Novati, S.; Iovane, G.; Marino, A. A.; Aurière, M.; Baillon, P.; Bouquet, A.; Bozza, V.; Capaccioli, M.; Capozziello, S.; Cardone, V.; Covone, G.; De Paolis, F.; de Ritis, R.; Giraud-Héraud, Y.; Gould, A.; Ingrosso, G.; Jetzer, Ph.; Kaplan, J.; Lambiase, G.; Le Du, Y.; Mancini, L.; Piedipalumbo, E.; Re, V.; Roncadelli, M.; Rubano, C.; Scarpetta, G.; Scudellaro, P.; Sereno, M.; Strafella, F.

    2002-01-01

    We present the first results of the analysis of data collected during the 1998-99 observational campaign at the 1.3 meter McGraw-Hill Telescope, towards the Andromeda galaxy (M 31), aimed to detect gravitational microlensing effects as a probe for the presence of dark matter in our Galaxy and in the M 31 halo. The analysis is performed using the pixel lensing technique, which consists of the study of flux variations of unresolved sources and has been proposed and implemented by the AGAPE collaboration. We carry out a shape analysis by demanding that the detected flux variations be achromatic and compatible with a Paczyński light curve. We apply the Durbin-Watson hypothesis test to the residuals. Furthermore, we consider the background of variables sources. Finally five candidate microlensing events emerge from our selection. Comparing with the predictions of a Monte Carlo simulation, assuming a standard spherical model for the M 31 and Galactic haloes, and typical values for the MACHO mass, we find that our events are only marginally consistent with the distribution of observable parameters predicted by the simulation.

  19. Space based OTV servicing

    NASA Technical Reports Server (NTRS)

    Mcallister, J. G.

    1984-01-01

    Space based servicing of an orbit transfer vehicle (OTV) was previously outlined in sufficient detail to arrive at OTV and support system servicing requirements. Needed space station facilities and their functional requirements were identified. The impact of logistics and space serviceable design on the OTV design is detailed herein. RL10 derivative rocket engine inspection task times are enumerated.

  20. GERLUMPH Data Release 2: 2.5 Billion Simulated Microlensing Light Curves

    NASA Astrophysics Data System (ADS)

    Vernardos, G.; Fluke, C. J.; Bate, N. F.; Croton, D.; Vohl, D.

    2015-04-01

    In the upcoming synoptic all-sky survey era of astronomy, thousands of new multiply imaged quasars are expected to be discovered and monitored regularly. Light curves from the images of gravitationally lensed quasars are further affected by superimposed variability due to microlensing. In order to disentangle the microlensing from the intrinsic variability of the light curves, the time delays between the multiple images have to be accurately measured. The resulting microlensing light curves can then be analyzed to reveal information about the background source, such as the size of the quasar accretion disk. In this paper we present the most extensive and coherent collection of simulated microlensing light curves; we have generated \\gt 2.5 billion light curves using the GERLUMPH high resolution microlensing magnification maps. Our simulations can be used to train algorithms to measure lensed quasar time delays, plan future monitoring campaigns, and study light curve properties throughout parameter space. Our data are openly available to the community and are complemented by online eResearch tools, located at http://gerlumph.swin.edu.au.

  1. The Angstrom Project: M31 microlensing alert ANG-08B-M31-07

    NASA Astrophysics Data System (ADS)

    Darnley, M. J.; Kerins, E.; Newsam, A. M.; Duke, J. P.; Gould, A.; Street, C. Han B.-G. Park R. A.

    2008-12-01

    We report an ongoing microlensing candidate in M31 by the Angstrom Project M31 bulge microlensing survey using the Liverpool Telescope (La Palma). The candidate was detected from difference imaging photometry generated by the Angstrom Project Alert System (APAS) in a series of Sloan i'-band images of the bulge of M31.

  2. Microlenses and their applications in endoscopes

    NASA Astrophysics Data System (ADS)

    Zeng, Xuefeng

    Microlenses have been developed in the past and play an important role in many fields, including optical communication, photolithography, imaging systems and lab on chips. Microlenses with fixed focal length and tunable focus have their individual applications. Several methods and mechanisms have been reported to realize microlenses; however, they have their advantages and disadvantages. In this work, two kinds of microlenses are studied: microlens arrays with fixed focal length and liquid tunable-focus microlenses actuated by stimuli-responsive hydrogels. The design, fabrication, testing and applications of these microlenses are explored. The gist of these microlenses is to utilize surface tension of liquid-air and/or immiscible liquid-liquid interfaces because surface tension dominates over gravity at the micro-scale. Microlens arrays with fixed focal length, made of polydimethylsiloxane (PDMS), are fabricated through liquid-phase photopolymerization and molding. Liquid menisci of photopolymerizable solutions at liquid-air interfaces are first formed and cured under ultraviolet (UV) radiance to obtain the mold. The resultant polymerized mold is then transferred to PDMS utilizing two molding steps to form a microlens array. The liquid tunable-focus microlens is formed by a water-oil interface that is pinned at a hydrophobic-hydrophilic boundary at the top edge of an aperture. Multiple hydrogel microstructures, whose volume is responsive to a certain stimuli, are formed around the lens aperture under UV radiance and regulate the pressure across the meniscus of the water-oil interface, varying the focal length of the microlens. The liquid tunable-focus microlenses responsive to infrared (IR) light are integrated at the end of fiber endoscopes and can scan the areas of interest with minimal back-and-forth movements of the scopes themselves. The operation of the microlens and the image acquisition are realized through light transmitted via optical fibers. Benefitting

  3. Possible microlensing in the Galactic Disk

    NASA Astrophysics Data System (ADS)

    Udalski, Andrzej; Szymanski, Michal

    1999-02-01

    The OGLE Early Warning System triggered a microlensing candidate located in the Galactic disk field in Carina. The I=18.0 mag (V=19.6) star designated CAR_SC2 24589 (RA2000=11:07:26.72, DEC2000=-61:22:30.6, l=290.8,b=-1.0) is currently brightening with the light curve consistent with microlensing rise of brightness.

  4. Predicting the 4th caustic crossing in Gaia16aye binary microlensing event

    NASA Astrophysics Data System (ADS)

    Mroz, P.; Wyrzykowski, L.; Rybicki, K.; Altavilla, G.; Bakis, V.; Bendjoya, P.; Birenbaum, G.; Blagorodnova, N.; Blanco-Cuaresma, S.; Bonanos, A.; Bozza, V.; Britavskiy, N.; Burgaz, U.; Butterley, T.; Capuozzo, P.; Carrasco, J. M.; Chruslinska, M.; Damljanovic, G.; Dennefeld, M.; Dhillon, V. S.; Dominik, M.; Esenoglu, H.; Fossey, S.; Gomboc, A.; Hallokoun, N.; Hamanowicz, A.; Hardy, L. K.; Hudec, R.; Khamitov, I.; Klencki, J.; Kolaczkowski, Z.; Kolb, U.; Leonini, S.; Leto, G.; Lewis, F.; Liakos, A.; Littlefair, S. P.; Maoz, D.; Maund, J. R.; Mikolajczyk, P.; Palaversa, L.; Pawlak, M.; Penny, M.; Piascik, A.; Reig, P.; Rhodes, L.; Russell, D.; Sanchez, R. Z.; Shappee, B.; Shvartzvald, Y.; Sitek, M.; Sniegowska, M.; Sokolovsky, K.; Steele, I.; Street, R.; Tomasella, L.; Trascinelli, L.; Wiersema, K.; Wilson, R. W.; Zharkov, I.; Zola, S.; Zubareva, A.

    2016-11-01

    Gaia16aye, nicknamed Ayers Rock (19:40:01.13 +30:07:53.4, J2000) is a spectacular binary microlensing event in the Northern Galactic Plane. The event has been observed by Gaia, ASAS-SN survey and a network of follow-up telescopes, coordinated by the Time Domain WP of the EC's OPTICON grant.

  5. The Angstrom Project: two new microlensing/nova transients

    NASA Astrophysics Data System (ADS)

    Kerins, Eamonn

    2008-11-01

    We report the discovery of two new optical transients in M31 by the Angstrom Project M31 bulge microlensing survey using the Liverpool Telescope (La Palma). These transients were discovered using difference imaging techniques by the Angstrom Project Alert System (APAS) in a series of Sloan i'-band images of the bulge of M31.

  6. Stellar Rotation Effects in Polarimetric Microlensing

    NASA Astrophysics Data System (ADS)

    Sajadian, Sedighe

    2016-07-01

    It is well known that the polarization signal in microlensing events of hot stars is larger than that of main-sequence stars. Most hot stars rotate rapidly around their stellar axes. The stellar rotation creates ellipticity and gravity-darkening effects that break the spherical symmetry of the source's shape and the circular symmetry of the source's surface brightness respectively. Hence, it causes a net polarization signal for the source star. This polarization signal should be considered in polarimetric microlensing of fast rotating stars. For moderately rotating stars, lensing can magnify or even characterize small polarization signals due to the stellar rotation through polarimetric observations. The gravity-darkening effect due to a rotating source star creates asymmetric perturbations in polarimetric and photometric microlensing curves whose maximum occurs when the lens trajectory crosses the projected position of the rotation pole on the sky plane. The stellar ellipticity creates a time shift (i) in the position of the second peak of the polarimetric curves in transit microlensing events and (ii) in the peak position of the polarimetric curves with respect to the photometric peak position in bypass microlensing events. By measuring this time shift via polarimetric observations of microlensing events, we can evaluate the ellipticity of the projected source surface on the sky plane. Given the characterizations of the FOcal Reducer and low dispersion Spectrograph (FORS2) polarimeter at the Very Large Telescope, the probability of observing this time shift is very small. The more accurate polarimeters of the next generation may well measure these time shifts and evaluate the ellipticity of microlensing source stars.

  7. Space Based Communications

    NASA Technical Reports Server (NTRS)

    Simpson, James; Denson, Erik; Valencia, Lisa; Birr, Richard

    2003-01-01

    Current space lift launches on the Eastern and Western Range require extensive ground-based real-time tracking, communications and command/control systems. These are expensive to maintain and operate and cover only limited geographical areas. Future spaceports will require new technologies to provide greater launch and landing opportunities, support simultaneous missions, and offer enhanced decision support models and simulation capabilities. These ranges must also have lower costs and reduced complexity while continuing to provide unsurpassed safety to the public, flight crew, personnel, vehicles and facilities. Commercial and government space-based assets for tracking and communications offer many attractive possibilities to help achieve these goals. This paper describes two NASA proof-of-concept projects that seek-to exploit the advantages of a space-based range: Iridium Flight Modem and Space-Based Telemetry and Range Safety (STARS). Iridium Flight Modem uses the commercial satellite system Iridium for extremely low cost, low rate two-way communications and has been successfully tested on four aircraft flights. A sister project at Goddard Space Flight Center's (GSFC) Wallops Flight Facility (WFF) using the Globalstar system has been tested on one rocket. The basic Iridium Flight Modem system consists of a L1 carrier Coarse/Acquisition (C/A)-Code Global Positioning System (GPS) receiver, an on-board computer, and a standard commercial satellite modem and antennas. STARS uses the much higher data rate NASA owned Tracking and Data Relay Satellite System (TDRSS), a C/A-Code GPS receiver, an experimental low-power transceiver, custom built command and data handler processor, and digitized flight termination system (FTS) commands. STARS is scheduled to fly on an F-15 at Dryden Flight Research Center in the spring of 2003, with follow-on tests over the next several years.

  8. Stochastic Microlensing: Mathematical Theory and Applications

    NASA Astrophysics Data System (ADS)

    Teguia, Alberto Mokak

    Stochastic microlensing is a central tool in probing dark matter on galactic scales. From first principles, we initiate the development of a mathematical theory of stochastic microlensing. We first construct a natural probability space for stochastic microlensing and characterize the general behaviour of the random time delay functions' random critical sets. Next we study stochastic microlensing in two distinct random microlensing scenarios: The uniform stars' distribution with constant mass spectrum and the spatial stars' distribution with general mass spectrum. For each scenario, we determine exact and asymptotic (in the large number of point masses limit) stochastic properties of the random time delay functions and associated random lensing maps and random shear tensors, including their moments and asymptotic density functions. We use these results to study certain random observables, such as random fixed lensed images, random bending angles, and random magnifications. These results are relevant to the theory of random fields and provide a platform for further generalizations as well as analytical limits for checking astrophysical studies of stochastic microlensing. Continuing our development of a mathematical theory of stochastic microlensing, we study the stochastic version of the Image Counting Problem, first considered in the non-random setting by Einstein and generalized by Petters. In particular, we employ the Kac-Rice formula and Morse theory to deduce general formulas for the expected total number of images and the expected number of saddle images for a general random lensing scenario. We further generalize these results by considering random sources defined on a countable compact covering of the light source plane. This is done to introduce the notion of global expected number of positive parity images due to a general lensing map. Applying the result to the uniform stars' distribution random microlensing scenario, we calculate the asymptotic global

  9. Candidate gravitational microlensing events for future direct lens imaging

    SciTech Connect

    Henderson, C. B.; Gould, A.; Gaudi, B. S.; Park, H.; Han, C.; Sumi, T.; Koshimoto, N.; Udalski, A.; Tsapras, Y.; Bozza, V.; Abe, F.; Fukunaga, D.; Itow, Y.; Masuda, K.; Bennett, D. P.; Bond, I. A.; Ling, C. H.; Botzler, C. S.; Freeman, M.; Fukui, A.; Collaboration: MOA Collaboration; OGLE Collaboration; μFUN Collaboration; RoboNet Collaboration; and others

    2014-10-10

    The mass of the lenses giving rise to Galactic microlensing events can be constrained by measuring the relative lens-source proper motion and lens flux. The flux of the lens can be separated from that of the source, companions to the source, and unrelated nearby stars with high-resolution images taken when the lens and source are spatially resolved. For typical ground-based adaptive optics (AO) or space-based observations, this requires either inordinately long time baselines or high relative proper motions. We provide a list of microlensing events toward the Galactic bulge with high relative lens-source proper motion that are therefore good candidates for constraining the lens mass with future high-resolution imaging. We investigate all events from 2004 to 2013 that display detectable finite-source effects, a feature that allows us to measure the proper motion. In total, we present 20 events with μ ≳ 8 mas yr{sup –1}. Of these, 14 were culled from previous analyses while 6 are new, including OGLE-2004-BLG-368, MOA-2005-BLG-36, OGLE-2012-BLG-0211, OGLE-2012-BLG-0456, MOA-2012-BLG-532, and MOA-2013-BLG-029. In ≲12 yr from the time of each event the lens and source of each event will be sufficiently separated for ground-based telescopes with AO systems or space telescopes to resolve each component and further characterize the lens system. Furthermore, for the most recent events, comparison of the lens flux estimates from images taken immediately to those estimated from images taken when the lens and source are resolved can be used to empirically check the robustness of the single-epoch method currently being used to estimate lens masses for many events.

  10. Candidate Gravitational Microlensing Events for Future Direct Lens Imaging

    NASA Astrophysics Data System (ADS)

    Henderson, C. B.; Park, H.; Sumi, T.; Udalski, A.; Gould, A.; Tsapras, Y.; Han, C.; Gaudi, B. S.; Bozza, V.; Abe, F.; Bennett, D. P.; Bond, I. A.; Botzler, C. S.; Freeman, M.; Fukui, A.; Fukunaga, D.; Itow, Y.; Koshimoto, N.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Namba, S.; Ohnishi, K.; Rattenbury, N. J.; Saito, To; Sullivan, D. J.; Suzuki, D.; Sweatman, W. L.; Tristram, P. J.; Tsurumi, N.; Wada, K.; Yamai, N.; Yock, P. C. M.; Yonehara, A.; MOA Collaboration; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Skowron, J.; Kozłowski, S.; Poleski, R.; Ulaczyk, K.; Wyrzykowski, Ł.; Pietrukowicz, P.; OGLE Collaboration; Almeida, L. A.; Bos, M.; Choi, J.-Y.; Christie, G. W.; Depoy, D. L.; Dong, S.; Friedmann, M.; Hwang, K.-H.; Jablonski, F.; Jung, Y. K.; Kaspi, S.; Lee, C.-U.; Maoz, D.; McCormick, J.; Moorhouse, D.; Natusch, T.; Ngan, H.; Pogge, R. W.; Shin, I.-G.; Shvartzvald, Y.; Tan, T.-G.; Thornley, G.; Yee, J. C.; μFUN Collaboration; Allan, A.; Bramich, D. M.; Browne, P.; Dominik, M.; Horne, K.; Hundertmark, M.; Figuera Jaimes, R.; Kains, N.; Snodgrass, C.; Steele, I. A.; Street, R. A.; RoboNet Collaboration

    2014-10-01

    The mass of the lenses giving rise to Galactic microlensing events can be constrained by measuring the relative lens-source proper motion and lens flux. The flux of the lens can be separated from that of the source, companions to the source, and unrelated nearby stars with high-resolution images taken when the lens and source are spatially resolved. For typical ground-based adaptive optics (AO) or space-based observations, this requires either inordinately long time baselines or high relative proper motions. We provide a list of microlensing events toward the Galactic bulge with high relative lens-source proper motion that are therefore good candidates for constraining the lens mass with future high-resolution imaging. We investigate all events from 2004 to 2013 that display detectable finite-source effects, a feature that allows us to measure the proper motion. In total, we present 20 events with μ >~ 8 mas yr-1. Of these, 14 were culled from previous analyses while 6 are new, including OGLE-2004-BLG-368, MOA-2005-BLG-36, OGLE-2012-BLG-0211, OGLE-2012-BLG-0456, MOA-2012-BLG-532, and MOA-2013-BLG-029. In lsim12 yr from the time of each event the lens and source of each event will be sufficiently separated for ground-based telescopes with AO systems or space telescopes to resolve each component and further characterize the lens system. Furthermore, for the most recent events, comparison of the lens flux estimates from images taken immediately to those estimated from images taken when the lens and source are resolved can be used to empirically check the robustness of the single-epoch method currently being used to estimate lens masses for many events.

  11. A PUZZLE INVOLVING GALACTIC BULGE MICROLENSING EVENTS

    SciTech Connect

    Cohen, Judith G.; Gould, Andrew; Johnson, Jennifer A.; Thompson, Ian B.; Feltzing, Sofia; Bensby, Thomas; Huang Wenjin; Melendez, Jorge; Lucatello, Sara; Asplund, Martin E-mail: gould@astronomy.ohio-state.edu E-mail: ian@obs.carnegiescience.edu E-mail: tbensby@eso.org E-mail: jorge@astro.up.pt E-mail: asplund@MPA-Garching.MPG.DE

    2010-03-01

    We study a sample of 16 microlensed Galactic bulge main-sequence turnoff region stars for which high-dispersion spectra have been obtained with detailed abundance analyses. We demonstrate that there is a very strong and highly statistically significant correlation between the maximum magnification of the microlensed bulge star and the value of the [Fe/H] deduced from the high resolution spectrum of each object. Physics demands that this correlation, assuming it to be real, be the result of some sample bias. We suggest several possible explanations, but are forced to reject them all, and are left puzzled. To obtain a reliable metallicity distribution in the Galactic bulge based on microlensed dwarf stars, it will be necessary to resolve this issue through the course of additional observations.

  12. Direct Laser Printing of Tailored Polymeric Microlenses.

    PubMed

    Florian, Camilo; Piazza, Simonluca; Diaspro, Alberto; Serra, Pere; Duocastella, Martí

    2016-07-13

    We report a laser-based approach for the fast fabrication of high-optical-quality polymeric microlenses and microlens arrays with controllable geometry and size. Our strategy consists of the direct laser printing of microdroplets of a highly viscous UV prepolymer at targeted positions, followed by photocuring. We study the morphological characteristics and imaging performance of the microlenses as a function of the substrate and laser parameters and investigate optimal printing conditions and printing mechanisms. We show that the microlens size and focusing properties can be easily tuned by the laser pulse energy, with minimum volumes below 20 fL and focal lengths ranging from 7 to 50 μm.

  13. Extracting Binary Orbital Periods Using Timing Analysis of Microlensing Lightcurves

    NASA Astrophysics Data System (ADS)

    Guo, Xinyi; Esin, A.; Di Stefano, R.

    2012-01-01

    Gravitational microlensing events provide unique opportunities to discover and study binaries. A large number of binary lenses have already been found by the microlensing surveys. For the majority of these systems, the binary orbital period is much longer than the duration of the lensing event, so orbital motion can be safely ignored. However, a few lenses have already been discovered that show strong evidence of orbital motion on the timescale of the lensing event. We expect that more such systems will be seen in the future. For binaries whose orbital period is comparable to the event duration, the orbital motion can cause the lensing signal to deviate drastically from that of a static binary lens. The most striking property of such lightcurves is the presence of quasi-periodic features, produced as the source traverses the same regions in the rotating lens plane. Those repeated features contain information about the orbital period of the lens. If this period can be extracted, we immediately learn a lot about the lensing system even without performing the detailed lightcurve modeling. However, the relative transverse motion between the source and the lens significantly complicates the problem of period extraction. To resolve this difficulty, we present a modification to the standard Lomb-Scargle periodogram analysis. We test our method for 6 representative binary lens systems and demonstrate its efficiency in correctly extracting binary orbital periods.

  14. SPACE BASED INTERCEPTOR SCALING

    SciTech Connect

    G. CANAVAN

    2001-02-01

    Space Based Interceptor (SBI) have ranges that are adequate to address rogue ICBMs. They are not overly sensitive to 30-60 s delay times. Current technologies would support boost phase intercept with about 150 interceptors. Higher acceleration and velocity could reduce than number by about a factor of 3 at the cost of heavier and more expensive Kinetic Kill Vehicles (KKVs). 6g SBI would reduce optimal constellation costs by about 35%; 8g SBI would reduce them another 20%. Interceptor ranges fall rapidly with theater missile range. Constellations increase significantly for ranges under 3,000 km, even with advanced interceptor technology. For distributed launches, these estimates recover earlier strategic scalings, which demonstrate the improved absentee ratio for larger or multiple launch areas. Constellations increase with the number of missiles and the number of interceptors launched at each. The economic estimates above suggest that two SBI per missile with a modest midcourse underlay is appropriate. The SBI KKV technology would appear to be common for space- and surface-based boost phase systems, and could have synergisms with improved midcourse intercept and discrimination systems. While advanced technology could be helpful in reducing costs, particularly for short range theater missiles, current technology appears adequate for pressing rogue ICBM, accidental, and unauthorized launches.

  15. Augmenting WFIRST Microlensing with a Ground-Based Telescope Network

    NASA Astrophysics Data System (ADS)

    Zhu, Wei; Gould, Andrew

    2016-06-01

    Augmenting the Wide Field Infrared Survey Telescope (WFIRST) microlensing campaigns with intensive observations from a ground-based network of wide-field survey telescopes would have several major advantages. First, it would enable full two-dimensional (2-D) vector microlens parallax measurements for a substantial fraction of low-mass lenses as well as planetary and binary events that show caustic crossing features. For a significant fraction of the free-floating planet (FFP) events and all caustic-crossing planetary/binary events, these 2-D parallax measurements directly lead to complete solutions (mass, distance, transverse velocity) of the lens object (or lens system). For even more events, the complementary ground-based observations will yield 1-D parallax measurements. Together with the 1-D parallaxes from WFIRST alone, they can probe the entire mass range M > M_Earth. For luminous lenses, such 1-D parallax measurements can be promoted to complete solutions (mass, distance, transverse velocity) by high-resolution imaging. This would provide crucial information not only about the hosts of planets and other lenses, but also enable a much more precise Galactic model. Other benefits of such a survey include improved understanding of binaries (particularly with low mass primaries), and sensitivity to distant ice-giant and gas-giant companions of WFIRST lenses that cannot be detected by WFIRST itself due to its restricted observing windows. Existing ground-based microlensing surveys can be employed if WFIRST is pointed at lower-extinction fields than is currently envisaged. This would come at some cost to the event rate. Therefore the benefits of improved characterization of lenses must be weighed against these costs.

  16. Chalcogenide glass microlenses by inkjet printing

    SciTech Connect

    Sanchez, Eric A.; Waldmann, Maike; Arnold, Craig B.

    2011-05-10

    We demonstrate micrometer scale mid-IR lenses for integrated optics, using solution-based inkjet printing techniques and subsequent processing. Arsenic sulfide spherical microlenses with diameters of 10-350 {mu}m and focal lengths of 10-700 {mu}m have been fabricated. The baking conditions can be used to tune the precise focal length.

  17. Space-based detectors

    NASA Astrophysics Data System (ADS)

    Sesana, A.; Weber, W. J.; Killow, C. J.; Perreur-Lloyd, M.; Robertson, D. I.; Ward, H.; Fitzsimons, E. D.; Bryant, J.; Cruise, A. M.; Dixon, G.; Hoyland, D.; Smith, D.; Bogenstahl, J.; McNamara, P. W.; Gerndt, R.; Flatscher, R.; Hechenblaikner, G.; Hewitson, M.; Gerberding, O.; Barke, S.; Brause, N.; Bykov, I.; Danzmann, K.; Enggaard, A.; Gianolio, A.; Vendt Hansen, T.; Heinzel, G.; Hornstrup, A.; Jennrich, O.; Kullmann, J.; Møller-Pedersen, S.; Rasmussen, T.; Reiche, J.; Sodnik, Z.; Suess, M.; Armano, M.; Sumner, T.; Bender, P. L.; Akutsu, T.; Sathyaprakash, B. S.

    2014-12-01

    The parallel session C5 on Space-Based Detectors gave a broad overview over the planned space missions related to gravitational wave detection. Overviews of the revolutionary science to be expected from LISA was given by Alberto Sesana and Sasha Buchman. The launch of LISA Pathfinder (LPF) is planned for 2015. This mission and its payload "LISA Technology Package" will demonstrate key technologies for LISA. In this context, reference masses in free fall for LISA, and gravitational physics in general, was described by William Weber, laser interferometry at the pico-metre level and the optical bench of LPF was presented by Christian Killow and the performance of the LPF optical metrology system by Paul McNamara. While LPF will not yet be sensitive to gravitational waves, it may nevertheless be used to explore fundamental physics questions, which was discussed by Michele Armano. Some parts of the LISA technology that are not going to be demonstrated by LPF, but under intensive development at the moment, were presented by Oliver Jennrich and Oliver Gerberding. Looking into the future, Japan is studying the design of a mid-frequency detector called DECIGO, which was discussed by Tomotada Akutsu. Using atom interferometry for gravitational wave detection has also been recently proposed, and it was critically reviewed by Peter Bender. In the nearer future, the launch of GRACE Follow-On (for Earth gravity observation) is scheduled for 2017, and it will include a Laser Ranging Interferometer as technology demonstrator. This will be the first inter-spacecraft laser interferometer and has many aspects in common with the LISA long arm, as discussed by Andrew Sutton.

  18. Data analysis of MOA for Gravitational Microlensing events with durations Less than 2 days by using brown dwarf population

    NASA Astrophysics Data System (ADS)

    Hassani, Sh.

    2016-12-01

    Gravitational Microlensing is one of the most powerful methods of detecting very low mass objects like Exoplanets and Brown dwarfs. The most important parameter that we can extract from a microlensing event is the Einstein radius crossing time tE. In this work, by performing Monte-Carlo simulation, we obtain tE distribution for brown dwarf population. Then we show that this population can be a good candidate for very short microlensing events with tE<2 days. The data set used in this analysis was taken in 2006 and 2007 seasons by the MOA-II survey, using the 1.8-m MOA-II telescope located at the Mt. John University Observatory, New Zealand.

  19. The Next Generation Microlensing Search: SuperMacho

    SciTech Connect

    Drake, A; Cook, K; Hiriart, R; Keller, S; Miknaitis, G; Nilolaev, S; Olsen, K; Prochter, G; Rest, A; Schmidt, B; Smith, C; Stubbs, C; Suntzeff, N; Welch, D; Becker, A; Clocchiati, A; Covarrubias, R

    2003-10-27

    Past microlensing experiments such as the MACHO project have discovered the presence of a larger than expected number of microlensing events toward the Large Magellanic Cloud (LMC). These events could represent a large fraction of the dark matter in the halo of our Galaxy, if they are indeed due to halo lenses. However the locations of most of the lenses are poorly defined. The SuperMacho project will detect and follow up {approx}60 microlensing events exhibiting special properties due to binarity, etc., will allow us to better determine the location and nature of the lenses causing the LMC microlensing events.

  20. Microlensing of quasar ultraviolet iron emission

    SciTech Connect

    Guerras, E.; Mediavilla, E.; Kochanek, C. S.; Muñoz, J. A.; Falco, E.; Motta, V.; Rojas, K.

    2013-12-01

    We measure the differential microlensing of the UV Fe II and Fe III emission line blends between 14 quasar image pairs in 13 gravitational lenses. We find that the UV iron emission is strongly microlensed in four cases with amplitudes comparable to that of the continuum. Statistically modeling the magnifications, we infer a typical size of r{sub s}∼4√(M/M{sub ⊙}) light-days for the Fe line-emitting regions, which is comparable to the size of the region generating the UV continuum (∼3-7 light-days). This may indicate that a significant part of the UV Fe II and Fe III emission originates in the quasar accretion disk.

  1. Halo cold dark matter and microlensing

    SciTech Connect

    Gates, Evalyn; Turner, Michael S.

    1993-12-01

    There is good evidence that most of the baryons in the Universe are dark and some evidence that most of the matter in the Universe is nonbaryonic with cold dark matter (cdm) being a promising possibility. We discuss expectations for the abundance of baryons and cdm in the halo of our galaxy and locally. We show that in plausible cdm models the local density of cdm is at least $10^{-25}\\gcmm3$. We also discuss what one can learn about the the local cdm density from microlensing of stars in the LMC by dark stars in the halo and, based upon a suite of reasonable two-component halo models, conclude that microlensing is not a sensitive probe of the local cdm density.

  2. The MACHO project: Microlensing and variable stars

    SciTech Connect

    Alcock, C.; Alves, D. R.; Axelrod, T. S.; Bennett, D. P.; Marshall, S. L.; Minniti, D.

    1996-10-01

    The MACHO Project monitors millions of stars in the Large Magellanic Cloud, the Small Magellanic Cloud and the bulge of the Milky Way searching for the gravitational microlensing signature of baryonic dark matter. This Project has yielded surprising results. An analysis of two years of data monitoring the Large Magellanic Cloud points to {approximately} 50% of the mass of the Milky Way`s halo in compact objects of {approximately} 0.5 solar mass. An analysis of one year of monitoring the bulge has yielded more microlensing than predicted without invocation of a massive bar or significant disk dark matter. The huge database of light curves created by this search is yielding information on extremely rare types of astrophysical variability as well as providing temporal detail for the study of well known variable astrophysical phenomena. The variable star catalog created from this database is previewed and example light curves are presented. 31 refs., 7 figs., 1 tab.

  3. Fitting Photometry of Blended Microlensing Events

    NASA Astrophysics Data System (ADS)

    Thomas, Christian L.; Griest, Kim

    2006-03-01

    We reexamine the usefulness of fitting blended light-curve models to microlensing photometric data. We find agreement with previous workers (e.g., Woźniak & Paczyński) that this is a difficult proposition because of the degeneracy of blend fraction with other fit parameters. We show that follow-up observations at specific point along the light curve (peak region and wings) of high-magnification events are the most helpful in removing degeneracies. We also show that very small errors in the baseline magnitude can result in problems in measuring the blend fraction and study the importance of non-Gaussian errors in the fit results. The biases and skewness in the distribution of the recovered blend fraction is discussed. We also find a new approximation formula relating the blend fraction and the unblended fit parameters to the underlying event duration needed to estimate microlensing optical depth.

  4. Real Time Gravitational Microlensing in OGLE experiment

    NASA Astrophysics Data System (ADS)

    Udalski, Andrzej; Szymanski, Michal

    1998-05-01

    The Early Warning System (EWS) designed for detection of microlensing events in progress has been implemented for the second phase of the Optical Gravitational Lensing Experiment - OGLE-2. Information about detected events in progress is available on WWW page and Anonymous FTP. Astronomers interested in e-mail notification, are requested to send an e-mail to ogle-ews@sirius.astrouw.edu.pl.

  5. Dark Matter Detection with Gravitational Microlensing

    NASA Astrophysics Data System (ADS)

    Pratt, Mark Robin

    There is overwhelming evidence that the majority of the mass in ordinary galaxies like our own is undetected by its absorption or emission of light. If this mass is in the form of massive compact halo objects (Machos) it can be detected through its gravitational microlensing of background stars. The MACHO Project is searching for this Galactic dark matter by monitoring millions of stars in the Magellanic Clouds and Galactic bulge in an attempt to detect rare microlensing events caused by otherwise invisible Machos. Analysis of two years of photometry on 8.5 million stars in the Large Magellanic Cloud (LMC) reveals 8 candidate microlensing events. Detailed calibrations including characterization of our confusion limited photometry allow us to calculate a mass for the entire lensing population and to compare the observed event rate with both that expected from known stars and that expected for the dark matter. We find that only ~1 event should be expected from lensing by stars in known galactic populations. From these eight events we estimate the optical depth towards the LMC from events with duration 2microlensing events allows us to exclude Machos in the mass range ~10-4-0.03Msolar as significant contributors to the Galactic dark matter.

  6. Microlensing for extrasolar planets : improving the photometry

    NASA Astrophysics Data System (ADS)

    Bajek, David J.

    2013-08-01

    Gravitational Microlensing, as a technique for detecting Extrasolar Planets, is recognised for its potential in discovering small-mass planets similar to Earth, at a distance of a few Astronomical Units from their host stars. However, analysing the data from microlensing events (which statistically rarely reveal planets) is complex and requires continued and intensive use of various networks of telescopes working together in order to observe the phenomenon. As such the techniques are constantly being developed and refined; this project outlines some steps of the careful analysis required to model an event and ensure the best quality data is used in the fitting. A quantitative investigation into increasing the quality of the original photometric data available from any microlensing event demonstrates that 'lucky imaging' can lead to a marked improvement in the signal to noise ratio of images over standard imaging techniques, which could result in more accurate models and thus the calculation of more accurate planetary parameters. In addition, a simulation illustrating the effects of atmospheric turbulence on exposures was created, and expanded upon to give an approximation of the lucky imaging technique. This further demonstrated the advantages of lucky images which are shown to potentially approach the quality of those expected from diffraction limited photometry. The simulation may be further developed for potential future use as a 'theoretical lucky imager' in our research group, capable of producing and analysing synthetic exposures through customisable conditions.

  7. IMPROVED THEORETICAL PREDICTIONS OF MICROLENSING RATES FOR THE DETECTION OF PRIMORDIAL BLACK HOLE DARK MATTER

    SciTech Connect

    Cieplak, Agnieszka M.; Griest, Kim

    2013-04-20

    Primordial black holes (PBHs) remain a dark matter (DM) candidate of the Standard Model of Particle Physics. Previously, we proposed a new method of constraining the remaining PBH DM mass range using microlensing of stars monitored by NASA's Kepler mission. We improve this analysis using a more accurate treatment of the population of the Kepler source stars, their variability, and limb darkening. We extend the theoretically detectable PBH DM mass range down to 2 Multiplication-Sign 10{sup -10} M{sub Sun }, two orders of magnitude below current limits and one-third order of magnitude below our previous estimate. We address how to extract the DM properties, such as mass and spatial distribution, if PBH microlensing events were detected. We correct an error in a well-known finite-source limb-darkening microlensing formula and also examine the effects of varying the light curve cadence on PBH DM detectability. We also introduce an approximation for estimating the predicted rate of detection per star as a function of the star's properties, thus allowing for selection of source stars in future missions, and extend our analysis to planned surveys, such as the Wide-Field Infrared Survey Telescope.

  8. Adventures in the microlensing cloud: Large datasets, eResearch tools, and GPUs

    NASA Astrophysics Data System (ADS)

    Vernardos, G.; Fluke, C. J.

    2014-10-01

    As astronomy enters the petascale data era, astronomers are faced with new challenges relating to storage, access and management of data. A shift from the traditional approach of combining data and analysis at the desktop to the use of remote services, pushing the computation to the data, is now underway. In the field of cosmological gravitational microlensing, future synoptic all-sky surveys are expected to bring the number of multiply imaged quasars from the few tens that are currently known to a few thousands. This inflow of observational data, together with computationally demanding theoretical modeling via the production of microlensing magnification maps, requires a new approach. We present our technical solutions to supporting the GPU-Enabled, High Resolution cosmological MicroLensing parameter survey (GERLUMPH). This extensive dataset for cosmological microlensing modeling comprises over 70 000 individual magnification maps and ˜106 related results. We describe our approaches to hosting, organizing, and serving ˜ 30 TB of data and metadata products. We present a set of online analysis tools developed with PHP, JavaScript and WebGL to support access and analysis of GELRUMPH data in a Web browser. We discuss our use of graphics processing units (GPUs) to accelerate data production, and we release the core of the GPU-D direct inverse ray-shooting code (Thompson et al., 2010, 2014) used to generate the magnification maps. All of the GERLUMPH data and tools are available online from http://gerlumph.swin.edu.au. This project made use of gSTAR, the GPU Supercomputer for Theoretical Astrophysical Research.

  9. Gravitational microlensing searches and results

    SciTech Connect

    Alcock, C.

    1997-05-08

    Baryonic matter, in the form of Machos (MAssive Compact Halo Objects), might be a significant constituent of the dark matter that dominates the Milky Way. This article describes how surveys for Machos exploit the gravitational microlens magnification of extragalactic stars. The experimental searches for this effect monitor millions of stars, in some cases every night, looking for magnification events. The early results of these surveys indicate that Machos make up a significant fraction of the dark matter in the Milky Way, and that these objects have stellar masses. Truly substellar objects do not contribute much to the total. Additionally, the relatively high event rate towards the Galactic bulge seems to require that the bulge be elongated, and massive.

  10. Microlensing events from the 11-year Observations of the Wendelstein Calar Alto Pixellensing Project

    NASA Astrophysics Data System (ADS)

    Lee, C.-H.; Riffeser, A.; Seitz, S.; Bender, R.; Koppenhoefer, J.

    2015-06-01

    We present the results of the decade-long M31 observation from the Wendelstein Calar Alto Pixellensing Project (WeCAPP). WeCAPP has monitored M31 from 1997 until 2008 in both R- and I-filters, and thus provides the longest baseline of all M31 microlensing surveys. The data are analyzed with difference imaging analysis, which is most suitable for studying variability in crowded stellar fields. We extracted light curves based on each pixel, and devised selection criteria that are optimized to identify microlensing events. This leads to 10 new events, and adds up to a total of 12 microlensing events from WeCAPP, for which we derive their timescales, flux excesses, and colors from their light curves. The colors of the lensed stars fall in the range (R - I) = 0.56 to 1.36, with a median of 1.0 mag, in agreement with our expectation that the sources are most likely bright, red stars at the post-main-sequence stage. The event FWHM timescales range from 0.5 to 14 days, with a median of 3 days, in good agreement with predictions based on the model of Riffeser et al.

  11. Detecting and Measuring the Masses of Isolated Black Holes and Neutron Stars through Astrometric Microlensing

    NASA Astrophysics Data System (ADS)

    Sahu, Kailash

    2011-10-01

    We propose a 3-year program of monitoring of 12 fields in the Galactic bulge, containing a total of 1.5 million stars down to V=28. Our primary aim is to detect microlensing events caused by non-luminous isolated black holes {BHs} and neutron stars {NSs} in the Galactic disk and bulge.The unique capability of HST imaging for microlensing observations is the addition of high-precision astrometry, allowing detection of the astrometric shift of the source during the event. Combined with the lens parallax, provided by the HST event light curve, the astrometric shift provides a direct measurement of the lens mass. We will detect 120 microlensing events, of which 45% will show astrometric deflections, leading to direct determinations of the lens masses. Of these, about 18 lenses are expected to be BHs and 14 of them NSs, along with about 22 events due to main-sequence stars.To date, BH and NS masses have been directly measured only in binaries; no isolated BH has been detected unambiguously within our Galaxy. A survey of the scope proposed here is the only means available at present for measuring the mass function of isolated BHs and NSs, and moreover one that is normalized to that of luminous stars. The results will provide a quantitative estimate of the mass content in the form of stellar remnants in the young Galactic disk and old bulge, and important constraints on SN/GRB explosion mechanisms that produce NSs and BHs.Our data will also be useful for other investigations, including a more accurate determination of the microlensing optical depth, faint variable stars, bulge proper motions and kinematics, and a deep luminosity function of the disk and bulge stars.

  12. Detecting and Measuring the Masses of Isolated Black Holes and Neutron Stars through Astrometric Microlensing

    NASA Astrophysics Data System (ADS)

    Sahu, Kailash

    2012-10-01

    We propose a 3-year program of monitoring of 12 fields in the Galactic bulge, containing a total of 1.5 million stars down to V=28. Our primary aim is to detect microlensing events caused by non-luminous isolated black holes {BHs} and neutron stars {NSs} in the Galactic disk and bulge.The unique capability of HST imaging for microlensing observations is the addition of high-precision astrometry, allowing detection of the astrometric shift of the source during the event. Combined with the lens parallax, provided by the HST event light curve, the astrometric shift provides a direct measurement of the lens mass. We will detect 120 microlensing events, of which 45% will show astrometric deflections, leading to direct determinations of the lens masses. Of these, about 18 lenses are expected to be BHs and 14 of them NSs, along with about 22 events due to main-sequence stars.To date, BH and NS masses have been directly measured only in binaries; no isolated BH has been detected unambiguously within our Galaxy. A survey of the scope proposed here is the only means available at present for measuring the mass function of isolated BHs and NSs, and moreover one that is normalized to that of luminous stars. The results will provide a quantitative estimate of the mass content in the form of stellar remnants in the young Galactic disk and old bulge, and important constraints on SN/GRB explosion mechanisms that produce NSs and BHs.Our data will also be useful for other investigations, including a more accurate determination of the microlensing optical depth, faint variable stars, bulge proper motions and kinematics, and a deep luminosity function of the disk and bulge stars.

  13. Detecting and Measuring the Masses of Isolated Black Holes and Neutron Stars through Astrometric Microlensing

    NASA Astrophysics Data System (ADS)

    Sahu, Kailash

    2013-10-01

    We propose a 3-year program of monitoring of 12 fields in the Galactic bulge, containing a total of 1.5 million stars down to V=28. Our primary aim is to detect microlensing events caused by non-luminous isolated black holes {BHs} and neutron stars {NSs} in the Galactic disk and bulge.The unique capability of HST imaging for microlensing observations is the addition of high-precision astrometry, allowing detection of the astrometric shift of the source during the event. Combined with the lens parallax, provided by the HST event light curve, the astrometric shift provides a direct measurement of the lens mass. We will detect 120 microlensing events, of which 45% will show astrometric deflections, leading to direct determinations of the lens masses. Of these, about 18 lenses are expected to be BHs and 14 of them NSs, along with about 22 events due to main-sequence stars.To date, BH and NS masses have been directly measured only in binaries; no isolated BH has been detected unambiguously within our Galaxy. A survey of the scope proposed here is the only means available at present for measuring the mass function of isolated BHs and NSs, and moreover one that is normalized to that of luminous stars. The results will provide a quantitative estimate of the mass content in the form of stellar remnants in the young Galactic disk and old bulge, and important constraints on SN/GRB explosion mechanisms that produce NSs and BHs.Our data will also be useful for other investigations, including a more accurate determination of the microlensing optical depth, faint variable stars, bulge proper motions and kinematics, and a deep luminosity function of the disk and bulge stars.

  14. Planetary Caustic Perturbations of a Close-separation Planet on Microlensing

    NASA Astrophysics Data System (ADS)

    Ryu, Yoon-Hyun; Kim, Han-Seek; Chung, Sun-Ju; Kim, Dong-Jin

    2016-09-01

    Most planetary events discovered up to date by the planetary caustic of close-separation planets have low-mass ratios. In next-generation microlensing experiments with a wider field of view and a higher cadence, it is possible to obtain densely covered planetary signals induced by the planetary caustic of close-separation planets without missing events. Therefore, the planetary caustic perturbation of close-separation planets would be the more important channel to detect low-mass exoplanets in the next generation of microlensing surveys. In this paper, we investigate the theoretical properties and detection conditions for the planetary caustic perturbation of close-separation planets. To find the properties of the planetary caustic perturbation, we construct deviation maps by subtracting the single-lensing magnification of the lens star from the planetary lensing magnification for various lensing parameters. We find that each deviation area of the positive and negative perturbations disappears at the same normalized source radius according to a given deviation threshold regardless of mass ratio but disappears at a different normalized source radius according to the separation. We also estimate the upper limit of the normalized source radius to detect the planetary caustic perturbation. We find simple relations between the upper limit of the normalized source radius and the lensing parameters. From the relations, we obtain an analytic condition for the theoretical detection limit of the planet, which shows that we can sufficiently discover a planet with a sub-Earth-mass for typical microlensing events. Therefore, we conclude that our planet-detection condition of can be used as an important criteria for maximal planet detections, considering the source type and the photometric accuracy and expect that a number of low-mass planets will be added from the next-generation microlensing experiments.

  15. "Rare" Microlensing Events: how frequent are they? what can they teach us?

    NASA Astrophysics Data System (ADS)

    Di Stefano, Rosanne; Bryk, William; Ginsburg, Idan; Greiner, Jochen; Lepine, Sebastien; Oprescu, Antonia; Primini, Francis A.; Tunbridge, Ben

    2014-06-01

    Today's microlensing teams discover roughly 2000 candidate microlensing events per year. Many of these exhibit the standard point-source/point-lens form, and are caused by distant lenses we cannot detect. In our poster we report on the preliminary results of a long term program of analysis designed to identify and study "rare" gravitational lensing events. We have focused on those rare events with light curve profiles that differ from the point-source/point-lens form. These unusual light curves provide additional information about the lens or source. We devote special effort to the study of a small set of events that appear to have been caused by nearby lenses. Nearby lenses are interesting, whatever the form of the light curve they generate. We show that some unusual events are common enough that their systematic study can be scientifically fruitful, allowing lensing programs to identify nearby (closer than a kiloparsec) compact objects and measure their masses, and to also identify and measure masses in nearby planetary systems. We have developed methods that should prove useful in a wide range of ground-based and space-based lensing studies.

  16. MICROLENSING BINARIES WITH CANDIDATE BROWN DWARF COMPANIONS

    SciTech Connect

    Shin, I.-G.; Han, C.; Gould, A.; Skowron, J.; Udalski, A.; Szymanski, M. K.; Kubiak, M.; Soszynski, I.; Pietrzynski, G.; Poleski, R.; Ulaczyk, K.; Pietrukowicz, P.; Kozlowski, S.; Wyrzykowski, L.; Sumi, T.; Dominik, M.; Beaulieu, J.-P.; Tsapras, Y.; Bozza, V.; Abe, F.; Collaboration: OGLE Collaboration; MOA Collaboration; muFUN Collaboration; and others

    2012-12-01

    Brown dwarfs are important objects because they may provide a missing link between stars and planets, two populations that have dramatically different formation histories. In this paper, we present the candidate binaries with brown dwarf companions that are found by analyzing binary microlensing events discovered during the 2004-2011 observation seasons. Based on the low mass ratio criterion of q < 0.2, we found seven candidate events: OGLE-2004-BLG-035, OGLE-2004-BLG-039, OGLE-2007-BLG-006, OGLE-2007-BLG-399/MOA-2007-BLG-334, MOA-2011-BLG-104/OGLE-2011-BLG-0172, MOA-2011-BLG-149, and MOA-201-BLG-278/OGLE-2011-BLG-012N. Among them, we are able to confirm that the companions of the lenses of MOA-2011-BLG-104/OGLE-2011-BLG-0172 and MOA-2011-BLG-149 are brown dwarfs by determining the mass of the lens based on the simultaneous measurement of the Einstein radius and the lens parallax. The measured masses of the brown dwarf companions are 0.02 {+-} 0.01 M {sub Sun} and 0.019 {+-} 0.002 M {sub Sun} for MOA-2011-BLG-104/OGLE-2011-BLG-0172 and MOA-2011-BLG-149, respectively, and both companions are orbiting low-mass M dwarf host stars. More microlensing brown dwarfs are expected to be detected as the number of lensing events with well-covered light curves increases with new-generation searches.

  17. Refractive microlenses for ultraflat photolithographic projection systems

    NASA Astrophysics Data System (ADS)

    Voelkel, Reinhard; Eisner, Martin; Ossmann, Christian; Weible, Kenneth J.

    2000-08-01

    We report on the fabrication of high quality microlens arrays on 4', 6' and 8'-fused silica wafers. Refractive, plano-convex microlenses are fabricated by using photolithography; a reflow or melting resist technique and reactive ion etching. A diffraction-limited optical performance (p-v wave aberrations of < (lambda) /8, Strehl ratio GTR 0.97) is achieved. Aspherical lens profiles are obtained by varying the etch parameters during the reactive ion etching transfer. The microlens arrays are used for Microlens Projection Lithography (MPL) and within UV-light illumination systems. Microlens Projection Lithography is an innovative technique using KARL SUSS Mask Aligners equipped with an ultra-flat microlens-based projection system. The projection system consists of 500.000 identical micro-objectives side- by-side. Each micro-objective consists of 3 to 4 microlenses. A fully symmetrical optical design eliminates coma, distortion and lateral color. The lens system is frontal- and backside telecentric to provide a unit magnification (+1) over the whole depth of focus. Each micro- objective images a small part of the photomask pattern onto the wafer. The partial images from different channels overlap consistently and form a complete aerial image of the photomask. Microlens Projection Lithography provides an increased depth of focus (GTR 50 microns) at a larger working distance ($GTR 1 mm)than standard proximity printing. Microlens Projection Lithography allows photolithography on curved on non-planar substrates, in V-grooves, holes, etc. using a KARL SUSS Mask Aligner.

  18. Sharpening the tools of gravitational microlensing

    NASA Astrophysics Data System (ADS)

    Poindexter, Shawn D.

    We attempt to identify all microlensing parallax events for which the parallax fit improves Deltachi2 > 100 relative to a standard microlensing model. We outline a procedure to identify three types of discrete degeneracies (including a new one that we dub the "ecliptic degeneracy") and find many new degenerate solutions in 16 previously published and 6 unpublished events. Only four events have one unique solution and the other 18 events have a total of 44 solutions. Our sample includes three previously identified black-hole (BH) candidates. We consider the newly discovered degenerate solutions and determine the relative likelihood that each of these is a BH. We find the lens of event MACHO-99-BLG-22 is a strong BH candidate (78%), event MACHO-96-BLG-5 is a marginal BH candidate (37%), and MACHO-98-BLG-6 is a weak BH candidate (2.2%). The lens of event OGLE-2003-BLG-84 may be a Jupiter-mass free-floating planet candidate based on a weak 3sigma detection of finite-source effects. We find that event MACHO-179-A is a brown dwarf candidate within ˜100 pc of the Sun, mostly due to its very small projected Einstein radius, r˜E = 0.23 +/- 0.05 AU. As expected, these microlensing parallax events are biased toward lenses that are heavier and closer than average. These events were examined for xallarap (or binary-source motion), which can mimic parallax. We find that 23% of these events are strongly affected by xallarap. The mid-IR flux ratios FA/F B = 2.84 +/- 0.06 of the two images of the gravitationally lensed quasar HE 1104--1805 show no wavelength dependence to within 3% across 3.6--8.0 mum, no time dependence over 6 months and agree with the broad emission line flux ratios. This indicates that the mid-IR emission likely comes from scales large enough to be little affected by microlensing and that there is little differential extinction between the images. We measure a revised time-delay between these two images of 152.2+2.8-3.0 (1sigma) days from R and V-band data

  19. Halo Microlensing and Dark Baryons

    NASA Astrophysics Data System (ADS)

    Crotts, A. P. S.

    1993-12-01

    (While Pierce lectures review past accomplishments, customarily, this talk concerns efforts which we have pursued for some years and which are now reaching fruition. We present elsewhere at this meeting results from research cited for the Prize.) Dark matter exists in the halos of spiral galaxies, and the least radical alternative for its identity is normal matter produced by primordial nucleosynthesis. This matter could easily be hidden in large, condensed objects. Paczynski pointed out in 1986 that if condensations of Galactic halo matter are sufficiently massive, they will produce detectable amplification of background starlight by gravitational lensing. Several groups recently reported possible detections of this effect after surveying large numbers of stars in the Galactic Bulge and LMC. The connection between these events and massive, dark halos is unclear and likely to remain so for some time, given the rate at which they are detected. Following Paczynski's realization, we stressed that a much higher event rate, a statistical control sample, sensitivity to a much broader mass range, and modulation of the predicted lensing rate with galactocentric distance can all be realized by a different experiment: observing the halo of M31 (and the Galaxy) using stars in M31. In some ways, M31 is a more difficult target than the LMC or the Bulge, given the faintness of its stars, but our observations in 1991 and 1993 indicate that these problems have been surmounted. We can detect stellar variability even under extremely crowded conditions like those in M31's inner disk, and can monitor a sufficient number of stars to study halo lensing. We present results from our initial survey which indicates that the required sensitivity can be reached to confirm or reject the hypothesis that sub-solar masses like those detected in our Galaxy make up the missing spiral galaxy mass. It is possible that we may use the data already obtained (and still being analyzed) to place

  20. Resolving the Nature of the LMC Microlensing Event LMC-5

    SciTech Connect

    Drake, A J; Cook, K H; Keller, S C

    2004-04-22

    The authors present the results from an analysis of Hubble Space Telescope High Resolution Camera data for the Large Magellanic Cloud microlensing event MACHO-LMC-5. By determining the parallax and proper motion of this object they find that the lens is an M dwarf star at a distance of 578{sub -53}{sup +65}pc with a proper motion of 21.39 {+-} 0.04 mas/yr. Based on the kinematics and location of this star is it more likely to be part of the Galactic thick disk than thin disk population. They confirm that the microlensing event LMC-5 is a jerk-parallax microlensing event.

  1. Earth: Space-based Observations

    NASA Astrophysics Data System (ADS)

    Herring, D.; King, M.; Murdin, P.

    2002-04-01

    In the wake of World War II, the US Naval Research Laboratory began experimenting with German-designed V-2 rockets as well as smaller, lighter launch vehicles called `sounding rockets'. In order to monitor which way the rockets were pointing during their flights, scientists began putting aircraft gun cameras on them. During one of these flights, on 7 March 1947, the first space-based picture of E...

  2. Advanced Space-Based Detectors

    DTIC Science & Technology

    2014-07-17

    Research Laboratory 8. PERFORMING ORGANIZATION REPORT NUMBER Space Vehicles Directorate 3550 Aberdeen Ave., SE Kirtland AFB, NM 87117-5776 AFRL -RV...Suite 0944 Ft Belvoir, VA 22060-6218 1 cy AFRL /RVIL Kirtland AFB, NM 87117-5776 2 cys Official... AFRL -RV-PS- AFRL -RV-PS- TR-2014-0010 TR-2014-0010 ADVANCED SPACE-BASED DETECTORS David Cardimona 17 Jul 2014 Final Report APPROVED FOR PUBLIC

  3. MOA-II Galactic microlensing constraints: the inner Milky Way has a low dark matter fraction and a near maximal disc

    NASA Astrophysics Data System (ADS)

    Wegg, Christopher; Gerhard, Ortwin; Portail, Matthieu

    2016-11-01

    Microlensing provides a unique tool to break the stellar to dark matter degeneracy in the inner Milky Way. We combine N-body dynamical models fitted to the Milky Way's Boxy/Peanut bulge with exponential disc models outside this, and compute the microlensing properties. Considering the range of models consistent with the revised MOA-II data, we find low dark matter fractions in the inner Galaxy: at the peak of their stellar rotation curve a fraction fv = (0.88 ± 0.07) of the circular velocity is baryonic (at 1σ, fv > 0.72 at 2σ). These results are in agreement with constraints from the EROS-II microlensing survey of brighter resolved stars, where we find fv = (0.9 ± 0.1) at 1σ. Our fiducial model of a disc with scale length 2.6 kpc, and a bulge with a low dark matter fraction of 12 per cent, agrees with both the revised MOA-II and EROS-II microlensing data. The required baryonic fractions, and the resultant low contribution from dark matter, are consistent with the NFW profiles produced by dissipationless cosmological simulations in Milky Way mass galaxies. They are also consistent with recent prescriptions for the mild adiabatic contraction of Milky Way mass haloes without the need for strong feedback, but there is some tension with recent measurements of the local dark matter density. Microlensing optical depths from the larger OGLE-III sample could improve these constraints further when available.

  4. High-throughput plastic microlenses fabricated using microinjection molding techniques

    NASA Astrophysics Data System (ADS)

    Appasamy, Sreeram; Li, Weizhuo; Lee, Se Hwan; Boyd, Joseph T.; Ahn, Chong H.

    2005-12-01

    A novel fabrication scheme to develop high-throughput plastic microlenses using injection-molding techniques is realized. The initial microlens mold is fabricated using the well-known reflow technique. The reflow process is optimized to obtain reliable and repeatable microlens patterns. The master mold insert for the injection-molding process is fabricated using metal electroforming. The electroplating process is optimized for obtaining a low stress electroform. Two new plastic materials, cyclo olefin copolymer (COC) and Poly IR 2 are introduced in this work for fabricating microlenses. The plastic microlenses have been characterized for their focal lengths that range from 200 µm to 1.9 mm. This technique enables high-volume production of plastic microlenses with cycle times for a single chip being of the order of 60 s.

  5. Gravitational microlensing by a single star plus external shear

    NASA Technical Reports Server (NTRS)

    Mao, Shude

    1992-01-01

    Gravitational microlensing by a single star plus external shear is considered. It is shown that for a general cusp the magnification probability distribution follows pc(A)dA of about (A exp -7/2)dA for sufficiently large magnifications. An adaptive grid technique is developed to calculate the magnification probability distributions. The results could be useful for cases of microlensing where the surface-mass density is low.

  6. Application of Compressive Sensing to Gravitational Microlensing Experiments

    NASA Technical Reports Server (NTRS)

    Korde-Patel, Asmita; Barry, Richard K.; Mohsenin, Tinoosh

    2016-01-01

    Compressive Sensing is an emerging technology for data compression and simultaneous data acquisition. This is an enabling technique for significant reduction in data bandwidth, and transmission power and hence, can greatly benefit spaceflight instruments. We apply this process to detect exoplanets via gravitational microlensing. We experiment with various impact parameters that describe microlensing curves to determine the effectiveness and uncertainty caused by Compressive Sensing. Finally, we describe implications for spaceflight missions.

  7. Speeding up low-mass planetary microlensing simulations and modeling: The caustic region of influence

    SciTech Connect

    Penny, Matthew T.

    2014-08-01

    Extensive simulations of planetary microlensing are necessary both before and after a survey is conducted: before to design and optimize the survey and after to understand its detection efficiency. The major bottleneck in such computations is the computation of light curves. However, for low-mass planets, most of these computations are wasteful, as most light curves do not contain detectable planetary signatures. In this paper, I develop a parameterization of the binary microlens that is conducive to avoiding light curve computations. I empirically find analytic expressions describing the limits of the parameter space that contain the vast majority of low-mass planet detections. Through a large-scale simulation, I measure the (in)completeness of the parameterization and the speed-up it is possible to achieve. For Earth-mass planets in a wide range of orbits, it is possible to speed up simulations by a factor of ∼30-125 (depending on the survey's annual duty-cycle) at the cost of missing ∼1% of detections (which is actually a smaller loss than for the arbitrary parameter limits typically applied in microlensing simulations). The benefits of the parameterization probably outweigh the costs for planets below 100 M{sub ⊕}. For planets at the sensitivity limit of AFTA-WFIRST, simulation speed-ups of a factor ∼1000 or more are possible.

  8. Space-Based Lidar Systems

    NASA Technical Reports Server (NTRS)

    Sun, Xiaoli

    2012-01-01

    An overview of space-based lidar systems is presented. from the first laser altimeter on APOLLO 15 mission in 1971 to the Mercury Laser Altimeter on MESSENGER mission currently in orbit, and those currently under development. Lidar, which stands for Light Detection And Ranging, is a powerful tool in remote sensing from space. Compared to radars, lidars operate at a much shorter wavelength with a much narrower beam and much smaller transmitter and receiver. Compared to passive remote sensing instruments. lidars carry their own light sources and can continue measuring day and night. and over polar regions. There are mainly two types of lidars depending on the types of measurements. lidars that are designed to measure the distance and properties of hard targets are often called laser rangers or laser altimeters. They are used to obtain the surface elevation and global shape of a planet from the laser pulse time-of-night and the spacecraft orbit position. lidars that are designed to measure the backscattering and absorption of a volume scatter, such as clouds and aerosols, are often just called lidars and categorized by their measurements. such as cloud and aerosol lidar, wind lidar, CO2 lidar, and so on. The advantages of space-based lidar systems over ground based lidars are the abilities of global coverage and continuous measurements.

  9. Space based astronomy: Teacher's guide with activities

    NASA Technical Reports Server (NTRS)

    Rosenberg, Carla B. (Editor); Weiler, Edward; Morrow, Cherilyn; Bacon, Pamela M.; Thorne, Muriel; Blanchard, Paul A.; Howard, Sethane; Pengra, Patricia R.; Brown, Deborah A.; Winrich, Ralph

    1994-01-01

    This curriculum guide uses hands-on activities to help students and teachers understand the significance of space-based astronomy - astronomical observations made from outer space. The guide contains few of the traditional activities found in many astronomy guides such as constellation studies, lunar phases, and planetary orbits. Instead, it tells the story of why it is important to observe celestial objects from outer space and how to study the entire electromagnetic spectrum. The guide begins with a survey of astronomy related NASA spacecraft. This is followed by a collection of activities in four units: (1) the atmospheric filter; (2) the electromagnetic spectrum; (3) collecting electromagnetic radiation; and (4) down to Earth. A curriculum index identifies the curriculum areas each activity addresses. The guide concludes with a glossary, reference list, a NASA Resources list, and an evaluation card. It is designed for students in grades 5 through 8.

  10. Space-Based Astronomy: A Teacher's Guide with Activities.

    ERIC Educational Resources Information Center

    National Aeronautics and Space Administration, Washington, DC.

    This curriculum guide uses hands-on activities to help grade 5-8 students and teachers understand the significance of space-based astronomy--astronomical observations made from outside the Earth's atmosphere. The guide begins with a survey of astronomy-related spacecraft that the National Aeronautics and Space Administration (NASA) has sent into…

  11. Observation of the microlensing toward the Andromeda galaxy

    NASA Astrophysics Data System (ADS)

    Shulga, V. V.; Sazhin, M. V.; Gorbatko, N. P.

    Observation of the Andromeda galaxy (M31) stars microlensed by dark bodies in the halo of our Galaxy is considered. Observations toward the Andromeda galaxy significantly increase the probability to reveal microlensing effects in comparison with MACHO and EROS procedures for observations of LMC and SMC. This is due to: greater amount of background stars (stars from M31) for which it is possible to observe the microlensing effect; greater distance to M31 (690 kps). This fact allows us to consider ALL the dark bodies in our Galaxy whereas LMC and SMC are actually situated INSIDE (55 kps) the halo of the Galaxy. The probability of microlensing effects, their characteristic times and the maximum factor of M31 star brightness amplification are estimated for different models. If the mass of a dark body in the halo of our Galaxy is of the order of 1M, it is possible to detect 5-6 microlensing events in one year. When the maximum factor of brightness amplification is 10, the characteristic time of the event is 7-10 days. If masses of dark bodies is of the order of 10-3 M it is possible detect 175-200 events per year and duration of these events is 0.2-0.3 days provided that the maximum amplification factor is 10. Procedures of real astronomical observations to search for the microlensing effect are discussed in detail. Information about observational series obtained is given. This series was obtained with the telescope AFR-1 in observatory at Mount Majdanak in 1990-1992 (total duration of the series is about 1.5 years). Processing of long observational series is being performed for the purpose of revealing microlensing effect. Preliminary results of the processing are presented.

  12. MEASURING MICROLENSING USING SPECTRA OF MULTIPLY LENSED QUASARS

    SciTech Connect

    Motta, V.; Mediavilla, E.; Munoz, J. A. E-mail: emg@iac.es E-mail: jmunoz@uv.es

    2012-08-10

    We report on a program of spectroscopic observations of gravitationally lensed QSOs with multiple images. We seek to establish whether microlensing is occurring in each QSO image using only single-epoch observations. We calculate flux ratios for the cores of emission lines in image pairs to set a baseline for no microlensing. The offset of the continuum flux ratios relative to this baseline yields the microlensing magnification free from extinction, as extinction affects the continuum and the lines equally. When we find chromatic microlensing, we attempt to constrain the size of the QSO accretion disk. SDSSJ1004+4112 and HE1104-1805 show chromatic microlensing with amplitudes 0.2 < |{Delta}m| < 0.6 and 0.2 < |{Delta}m| < 0.4 mag, respectively. Modeling the accretion disk with a Gaussian source (I{proportional_to}exp (- R{sup 2}/2r{sup 2}{sub s})) of size r{sub s} {proportional_to}{lambda}{sup p} and using magnification maps to simulate microlensing, we find r{sub s} ({lambda}3363) = 7 {+-} 3 lt-day(18.1 {+-} 7.8 Multiplication-Sign 10{sup 15} cm) and p = 1.1 {+-} 0.4 for SDSS1004+4112, and r{sub s} ({lambda}3363) = 6 {+-} 2 lt-day(15.5 {+-} 5.2 Multiplication-Sign 10{sup 15} cm) and p = 0.7 {+-} 0.1 for HE1104-1805. For SDSSJ1029+2623, we find strong chromaticity of {approx}0.4 mag in the continuum flux ratio, which probably arises from microlensing, although not all the available data fit within this explanation. For Q0957+561, we measure B - A magnitude differences of 0.4 mag, much greater than the {approx}0.05 mag amplitude usually inferred from light-curve variability. It may substantially modify the current interpretations of microlensing in this system, likely favoring the hypothesis of smaller sources and/or larger microdeflectors. For HS0818+1227, our data yield possible evidence of microlensing.

  13. Short duration microlensing events: Searching for rogue planets

    NASA Astrophysics Data System (ADS)

    St. Laurent, Kathryn E.; Di Stefano, Rosanne; Primini, Francis A.; Lew, Wei Peng; Gau, Lai Su; Benson, Sophie

    2015-01-01

    Einstein described gravitational microlensing in 1936, at the same time suggesting it to be an unobservable phenomenon. He did not foresee technological advancements that would lead to microlensing becoming a productive tool for astronomy. Of particular interest may be the role it has begun to play in the discovery of rogue planets - exoplanets that are not bound to a star or stars. Rogue planets may be formed independently, or they may be formed in the confines of a stellar system and then ejected by gravitational interactions. Currently fewer than a dozen rogue planets are known but estimates of their abundance conservatively start at double the number of stars in our galaxy.The Optical Gravitational Lensing Experiment (OGLE) and Microlensing Observations in Astrophysics (MOA) teams have collectively detected approximately 2500 events this year alone. A significant portion of these events are of short duration, with an Einstein crossing time of less than 10 days. Microlensing events generally occur on a timescale of weeks to months, so short duration events are an interesting class for study, particularly with regard to searches for rogue planets. We have undertaken a systematic study and categorization of the short duration microlensing events from recent OGLE and MOA alerts, with a special eye to identifying exoplanet candidates.

  14. Free-floating planets from core accretion theory: microlensing predictions

    NASA Astrophysics Data System (ADS)

    Ma, Sizheng; Mao, Shude; Ida, Shigeru; Zhu, Wei; Lin, Douglas N. C.

    2016-09-01

    We calculate the microlensing event rate and typical time-scales for the free-floating planet (FFP) population that is predicted by the core accretion theory of planet formation. The event rate is found to be ˜1.8 × 10-3 of that for the stellar population. While the stellar microlensing event time-scale peaks at around 20 d, the median time-scale for FFP events (˜0.1 d) is much shorter. Our values for the event rate and the median time-scale are significantly smaller than those required to explain the Sumi et al. result, by factors of ˜13 and ˜16, respectively. The inclusion of planets at wide separations does not change the results significantly. This discrepancy may be too significant for standard versions of both the core accretion theory and the gravitational instability model to explain satisfactorily. Therefore, either a modification to the planet formation theory is required or other explanations to the excess of short-time-scale microlensing events are needed. Our predictions can be tested by ongoing microlensing experiment such as Korean Microlensing Telescope Network, and by future satellite missions such as WFIRST and Euclid.

  15. Random scattering approach to gravitational microlensing

    NASA Technical Reports Server (NTRS)

    Katz, N.; Balbus, S.; Paczynski, B.

    1986-01-01

    Small random deflections of a narrow beam of radiation due to gravitational scattering by stars randomly distributed within the deflector plane are considered. Using a Fouriere transform method, the probability of scattering is obtained as a function of scattering angle for an arbitrary number of stars with an arbitrary distribution of masses. The probability density, expressed in proper units, depends on one parameter only: the effective number of stars. At small scattering angles the density is a Gaussian, and at large angles it falls off as the scattering angle to the minus fourth power. The probability distribution for scatterings is simply related to the angular distribution of the surface brightness of a macroimage, averaged over many microimages. The isophotes are ellipses, with the ratio of the major axis to the minor axis, determined by the dimensionless surface mass density and the shear of the lensing system. The number of stars that has to be included in the modeling of microlensing is proportional to the amplification due to the macrolens, and to the square of the dimensionless surface mass density.

  16. GRAVITATIONAL MICROLENSING BY THE ELLIS WORMHOLE

    SciTech Connect

    Abe, F.

    2010-12-10

    A method to calculate light curves of the gravitational microlensing of the Ellis wormhole is derived in the weak-field limit. In this limit, lensing by the wormhole produces one image outside the Einstein ring and another image inside. The weak-field hypothesis is a good approximation in Galactic lensing if the throat radius is less than 10{sup 11} km. The light curves calculated have gutters of approximately 4% immediately outside the Einstein ring crossing times. The magnification of the Ellis wormhole lensing is generally less than that of Schwarzschild lensing. The optical depths and event rates are calculated for the Galactic bulge and Large Magellanic Cloud fields according to bound and unbound hypotheses. If the wormholes have throat radii between 100 and 10{sup 7} km, are bound to the galaxy, and have a number density that is approximately that of ordinary stars, detection can be achieved by reanalyzing past data. If the wormholes are unbound, detection using past data is impossible.

  17. Reconfigurable and responsive droplet-based compound micro-lenses

    NASA Astrophysics Data System (ADS)

    Nagelberg, Sara; Zarzar, Lauren D.; Nicolas, Natalie; Subramanian, Kaushikaram; Kalow, Julia A.; Sresht, Vishnu; Blankschtein, Daniel; Barbastathis, George; Kreysing, Moritz; Swager, Timothy M.; Kolle, Mathias

    2017-03-01

    Micro-scale optical components play a crucial role in imaging and display technology, biosensing, beam shaping, optical switching, wavefront-analysis, and device miniaturization. Herein, we demonstrate liquid compound micro-lenses with dynamically tunable focal lengths. We employ bi-phase emulsion droplets fabricated from immiscible hydrocarbon and fluorocarbon liquids to form responsive micro-lenses that can be reconfigured to focus or scatter light, form real or virtual images, and display variable focal lengths. Experimental demonstrations of dynamic refractive control are complemented by theoretical analysis and wave-optical modelling. Additionally, we provide evidence of the micro-lenses' functionality for two potential applications--integral micro-scale imaging devices and light field display technology--thereby demonstrating both the fundamental characteristics and the promising opportunities for fluid-based dynamic refractive micro-scale compound lenses.

  18. Reconfigurable and responsive droplet-based compound micro-lenses

    PubMed Central

    Nagelberg, Sara; Zarzar, Lauren D.; Nicolas, Natalie; Subramanian, Kaushikaram; Kalow, Julia A.; Sresht, Vishnu; Blankschtein, Daniel; Barbastathis, George; Kreysing, Moritz; Swager, Timothy M.; Kolle, Mathias

    2017-01-01

    Micro-scale optical components play a crucial role in imaging and display technology, biosensing, beam shaping, optical switching, wavefront-analysis, and device miniaturization. Herein, we demonstrate liquid compound micro-lenses with dynamically tunable focal lengths. We employ bi-phase emulsion droplets fabricated from immiscible hydrocarbon and fluorocarbon liquids to form responsive micro-lenses that can be reconfigured to focus or scatter light, form real or virtual images, and display variable focal lengths. Experimental demonstrations of dynamic refractive control are complemented by theoretical analysis and wave-optical modelling. Additionally, we provide evidence of the micro-lenses' functionality for two potential applications—integral micro-scale imaging devices and light field display technology—thereby demonstrating both the fundamental characteristics and the promising opportunities for fluid-based dynamic refractive micro-scale compound lenses. PMID:28266505

  19. Microlensing Effects on Emission Lines from Homologously Expanding Winds

    NASA Astrophysics Data System (ADS)

    Ignace, R.; Bryce, H. M.; Hendry, M. A.

    2004-12-01

    We have been investigating the influence of microlensing on a variety of spectroscopic signatures relevant to circumstellar flows. Here we report on recent results for line profiles that form in spherically symmetric winds during a microlensing event. As a convenient test case, we have adopted a homologous velocity law (v ∝ r, from r=Rphot to rmax). Results are discussed for resonance scattering P Cygni lines and recombination emission lines. Somewhat surprisingly, the rectified line profiles show rather mild variations in response to microlensing. The reason is that both the line emission from the extended wind and the stellar photosphere are lensed, so that the strong magnification effects of lensing seen in either component are partially supressed when showing the continuum normalized spectrum (which is the common form of display for such data). Still, significant and observable variations in the line equivalent width do result. This research has been supported in part by NSF grant AST-0354261.

  20. Discovery of a Jupiter/Saturn Analog with Gravitational Microlensing

    SciTech Connect

    Gaudi, B; Bennett, D; Udalski, A; Gould, A; Christie, G; Maoz, D; Dong, S; McCormick, J; Szymanski, M; Tristram, P; Nikolaev, S; Paczynski, B; Kubiak, M; Pietrzynski, G; Soszynski, I; Szewczyk, O; Ulaczyk, K; Wyrzykowski, L; DePoy, D; Han, C; Kaspi, S; Lee, C; Mallia, F; Natusch, T; Pogge, R; Park, B; Abe, F; Bond, I; Botzler, C; Fukui, A; Hearnshaw, J; Itow, Y; Kamiya, K; Korpela, A; Kilmartin, P; Lin, W; Masuda, K; Matsubara, Y; Motomura, M; Muraki, Y; Nakamura, S; Okumura, T; Ohnishi, K; Rattenbury, N; Sako, T; Saito, T; Sato, S; Skuljan, L; Sullivan, D; Sumi, T; Sweatman, W; Yock, P; Albrow, M; Beaulieu, J; Burgdorf, M; Cook, K; Coutures, C; Dominik, M; Dieters, S; Fouque, P; Greenhill, J; Horne, K; Steele, I; Tsapras, Y; Chaboyer, B; Crocker, A; Frank, S; Macintosh, B

    2007-11-08

    Searches for extrasolar planets have uncovered an astonishing diversity of planetary systems, yet the frequency of solar system analogs remains unknown. The gravitational microlensing planet search method is potentially sensitive to multiple-planet systems containing analogs of all the solar system planets except Mercury. We report the first detection of a multiple-planet system with microlensing. We identify two planets with masses of {approx} 0.71 and {approx} 0.27 times the mass of Jupiter and orbital separations of {approx} 2.3 and {approx} 4.6 astronomical units orbiting a primary of mass {approx} 0.50 solar masses. This system resembles a scaled version of our solar system in that the mass ratio, separation ratio, and equilibrium temperatures of the planets are similar to those of Jupiter and Saturn. These planets could not have been detected with other techniques; their discovery from only 6 confirmed microlensing planet detections suggests that solar system analogs may be common.

  1. Liquid crystal bubbles forming a tunable micro-lenses array

    NASA Astrophysics Data System (ADS)

    Hamdi, R.; Petriashvili, G.; Lombardo, G.; De Santo, M. P.; Barberi, R.

    2011-10-01

    Cholesteric liquid crystals with long pitch confined in homeotropic cells can be used to generate stable but distorted and localized liquid crystal structures exhibiting spherulitic textures, known as "bubbles." As these bubbles can be induced by an external electric field with a narrow range following the confinement ratio C=d/p ≈1 (d representing cell thickness and p representing cholesteric pitch), it is possible to obtain electrically controlled micro-lenses. Here we investigated the optical and electro-optical properties of such liquid crystal bubbles for creating an array of micro-lenses with electrically tunable focal length.

  2. CHARACTERIZATION OF MICROLENSING PLANETS WITH MODERATELY WIDE SEPARATIONS

    SciTech Connect

    Han, Cheongho

    2009-08-01

    In future high-cadence microlensing surveys, planets can be detected through a new channel of an independent event produced by the planet itself. The two populations of planets to be detected through this channel are wide-separation planets and free-floating planets. Although they appear as similar short timescale events, the two populations of planets are widely different in nature and thus distinguishing them is important. In this paper, we investigate the lensing properties of events produced by planets with moderately wide separations from host stars. We find that the lensing behavior of these events is well described by the Chang-Refsdal lensing, and the shear caused by the primary not only produces a caustic but also makes the magnification contour elongated along the primary-planet axis. The elongated magnification contour implies that the light curves of these planetary events are generally asymmetric, and thus the asymmetry can be used to distinguish the events from those produced by free-floating planets. The asymmetry can be noticed from the overall shape of the light curve and thus can hardly be missed unlike the very short duration central perturbation caused by the caustic. In addition, the asymmetry occurs regardless of the event magnification, and thus the bound nature of the planet can be identified for majority of these events. The close approximation of the lensing light curve to that of the Chang-Refsdal lensing implies that the analysis of the light curve yields only the information about the projected separation between the host star and the planet.

  3. The OGLE view of microlensing towards the Magellanic Clouds - II. OGLE-II Small Magellanic Cloud data

    NASA Astrophysics Data System (ADS)

    Wyrzykowski, Ł.; Kozłowski, S.; Skowron, J.; Belokurov, V.; Smith, M. C.; Udalski, A.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Szewczyk, O.

    2010-09-01

    The primary goal of this paper is to provide evidence that can prove true or false the hypothesis that dark matter in the Galactic halo can clump into stellar-mass compact objects. If such objects exist, they would act as lenses to external sources in the Magellanic Clouds, giving rise to an observable effect of microlensing. We present the results of our search for such events, based on data from the second phase of the OGLE survey (1996-2000) towards the Small Magellanic Cloud (SMC). The data set we used comprises 2.1 million monitored sources distributed over an area of 2.4deg2. We found only one microlensing event candidate, however its poor-quality light curve limited our discussion of the exact distance to the lensing object. Given a single event, taking blending (crowding of stars) into account for the detection-efficiency simulations and deriving the Hubble Space Telescope (HST)-corrected number of monitored stars, the microlensing optical depth is τ = (1.55 +/- 1.55) × 10-7. This result is consistent with the expected SMC self-lensing signal, with no need to introduce dark matter microlenses. Rejecting the unconvincing event leads to an upper limit on the fraction of dark matter in the form of massive compact halo objects (MACHOs) of f < 20 per cent for deflector masses around 0.4Msolar and f < 11 per cent for masses between 0.003 and 0.2Msolar (95 per cent confidence limit). Our result indicates that the Milky Way's dark matter is unlikely to be clumpy and to form compact objects in the subsolar-mass range. Based on observations obtained with the 1.3-m Warsaw Telescope at the Las Campanas Observatory of the Carnegie Institution of Washington. E-mail: wyrzykow@ast.cam.ac.uk ‡ Name pronunciation: Woocash Vizhikovsky

  4. Reevaluating the feasibility of ground-based Earth-mass microlensing planet detections

    SciTech Connect

    Jung, Youn Kil; Park, Hyuk; Han, Cheongho; Hwang, Kyu-Ha; Shin, In-Gu; Choi, Joon-Young

    2014-05-10

    An important strength of the microlensing method to detect extrasolar planets is its high sensitivity to low-mass planets. However, many believe that microlensing detections of Earth-mass planets from ground-based observation would be difficult because of limits set by finite-source effects. This view comes from the previous estimation of planet detection probability based on the fractional deviation of planetary signals; however, a proper probability estimation is required when considering the source brightness, which is directly related to the photometric precision. In this paper, we reevaluate the feasibility of low-mass planet detections by considering photometric precision for different populations of source stars. From this, we find that the contribution of improved photometric precision to the planetary signal of a giant-source event is large enough to compensate for the decrease in magnification excess caused by finite-source effects. As a result, we conclude that giant-source events are suitable targets for Earth-mass planet detections with significantly higher detection probability than events involved with source stars of smaller radii, and we predict that Earth-mass planets could be detected by prospective high-cadence surveys.

  5. Photometric, astrometric and polarimetric observations of gravitational microlensing events

    NASA Astrophysics Data System (ADS)

    Sajadian, Sedighe; Rahvar, Sohrab

    2015-09-01

    Gravitational microlensing can be used as a unique astrophysical tool to study the atmospheres of stars thousands of parsec away from us. This capability results from the bending of light rays in the gravitational field of a lens that can magnify the light of a background source star during the lensing. Moreover, one of the consequences of this light bending is that the circular symmetry of the source is broken because distorted images are produced at either side of the lens position. This property makes it possible to observe polarization, and also the light centroid shift of images. Assigning vectors for these two parameters, they are perpendicular to each other in simple and binary microlensing events, except in fold singularities. In this work, we investigate the advantages of polarimetric and astrometric observations during microlensing events (i) for studying the surface of the source star and spots on it and (ii) for obtaining extra information to determine the trajectory of source stars with respect to the lens. Finally, we analyse the largest sample of microlensing events from the Optical Gravitational Lensing Experiment (OGLE) catalogue and show that, for almost ˜4.3 per cent of events in the direction of the Galactic bulge, the polarization signals would be observable with large telescopes.

  6. Gravitational Microlensing in Modified Gravity Theories - Inverse-Square Theorem

    NASA Astrophysics Data System (ADS)

    Asada, H.

    2011-02-01

    Microlensing studies are usually based on the lens equation that is valid only to the first order in the gravitational constant G and lens mass M. We consider corrections to the conventional lens equation in terms of differentiable functions, so that they can express not only the second-order effects of GM in general relativity but also modified gravity theories. As a generalization of Ebina et al. (Prog. Theor. Phys. 104 (2000), 1317), we show that, provided that the spacetime is static, spherically symmetric and asymptotically flat, the total amplification by microlensing remains unchanged at the linear order of the correction to the deflection angle, if and only if the correction takes a particular form as the inverse square of the impact parameter, whereas the magnification factor for each image is corrected. It is concluded that the light curve shape by microlensing is inevitably changed and will thus allow us to probe modified gravity, unless a modificati on to the deflection angle takes the particular form. No systematic deviation in microlensing observations has been reported. For instance, therefore, the Yukawa-type correction is constrained as the characteristic length > 10^{14} m.

  7. Microlenses with tuned focal characteristics for optical wireless imaging

    NASA Astrophysics Data System (ADS)

    Jin, Xian; Guerrero, Daniel; Klukas, Richard; Holzman, Jonathan F.

    2014-07-01

    Microlenses are fabricated and investigated for integrated imaging applications. The microlenses are fabricated by an in situ polymer electro-dispensing technique that enables user-controlled microlens sizes and shapes, by direct-dispensing and voltage-tuning with a metal micro-needle tip in a filler solution. Theoretical and experimental analyses are carried out for three limiting-cases of electro-dispensed microlenses: an acute-angle microlens with a 30° contact angle, a right-angle microlens with a 90° contact angle, and an obtuse-angle microlens with a 120° contact angle. It is found that the right-angle microlens, with a 500 μm diameter, yields an especially short focal length (700 μm) and exceedingly large numerical aperture (0.533). These characteristics can meet the needs of emerging applications, such as optical wireless devices, which demand compact device integration and broad field-of-view imaging. The microlenses are tested in optical wireless imaging receivers, for signal-to-noise ratio performance, and it is found that the right-angle microlens can offer significant (10 dB) performance enhancements.

  8. Effect of Binary Source Companions on the Microlensing Optical Depth Determination toward the Galactic Bulge Field

    NASA Astrophysics Data System (ADS)

    Han, Cheongho

    2005-11-01

    Currently, gravitational microlensing survey experiments toward the Galactic bulge field use two different methods of minimizing the blending effect for the accurate determination of the optical depth τ. One is measuring τ based on clump giant (CG) source stars, and the other is using ``difference image analysis'' (DIA) photometry to measure the unblended source flux variation. Despite the expectation that the two estimates should be the same assuming that blending is properly considered, the estimates based on CG stars systematically fall below the DIA results based on all events with source stars down to the detection limit. Prompted by the gap, we investigate the previously unconsidered effect of companion-associated events on τ determination. Although the image of a companion is blended with that of its primary star and thus not resolved, the event associated with the companion can be detected if the companion flux is highly magnified. Therefore, companions work effectively as source stars to microlensing, and thus the neglect of them in the source star count could result in a wrong τ estimation. By carrying out simulations based on the assumption that companions follow the same luminosity function as primary stars, we estimate that the contribution of the companion-associated events to the total event rate is ~5fbi% for current surveys and can reach up to ~6fbi% for future surveys monitoring fainter stars, where fbi is the binary frequency. Therefore, we conclude that the companion-associated events comprise a nonnegligible fraction of all events. However, their contribution to the optical depth is not large enough to explain the systematic difference between the optical depth estimates based on the two different methods.

  9. Microlensing of Sub-parsec Massive Binary Black Holes in Lensed QSOs: Light Curves and Size-Wavelength Relation

    NASA Astrophysics Data System (ADS)

    Yan, Chang-Shuo; Lu, Youjun; Yu, Qingjuan; Mao, Shude; Wambsganss, Joachim

    2014-04-01

    Sub-parsec binary massive black holes (BBHs) have long been thought to exist in many QSOs but remain observationally elusive. In this paper, we propose a novel method to probe sub-parsec BBHs through microlensing of lensed QSOs. If a QSO hosts a sub-parsec BBH in its center, it is expected that the BBH is surrounded by a circumbinary disk, each component of the BBH is surrounded by a small accretion disk, and a gap is opened by the secondary component in between the circumbinary disk and the two small disks. Assuming such a BBH structure, we generate mock microlensing light curves for some QSO systems that host BBHs with typical physical parameters. We show that microlensing light curves of a BBH QSO system at the infrared-optical-UV bands can be significantly different from those of corresponding QSO system with a single massive black hole (MBH), mainly because of the existence of the gap and the rotation of the BBH (and its associated small disks) around the center of mass. We estimate the half-light radii of the emission region at different wavelengths from mock light curves and find that the obtained half-light radius versus wavelength relations of BBH QSO systems can be much flatter than those of single MBH QSO systems at a wavelength range determined by the BBH parameters, such as the total mass, mass ratio, separation, accretion rates, etc. The difference is primarily due to the existence of the gap. Such unique features on the light curves and half-light radius-wavelength relations of BBH QSO systems can be used to select and probe sub-parsec BBHs in a large number of lensed QSOs to be discovered by current and future surveys, including the Panoramic Survey Telescope and Rapid Response System, the Large Synoptic Survey telescope, and Euclid.

  10. Microlensing of sub-parsec massive binary black holes in lensed QSOs: Light curves and size-wavelength relation

    SciTech Connect

    Yan, Chang-Shuo; Lu, Youjun; Mao, Shude; Yu, Qingjuan; Wambsganss, Joachim E-mail: luyj@nao.cas.cn

    2014-04-01

    Sub-parsec binary massive black holes (BBHs) have long been thought to exist in many QSOs but remain observationally elusive. In this paper, we propose a novel method to probe sub-parsec BBHs through microlensing of lensed QSOs. If a QSO hosts a sub-parsec BBH in its center, it is expected that the BBH is surrounded by a circumbinary disk, each component of the BBH is surrounded by a small accretion disk, and a gap is opened by the secondary component in between the circumbinary disk and the two small disks. Assuming such a BBH structure, we generate mock microlensing light curves for some QSO systems that host BBHs with typical physical parameters. We show that microlensing light curves of a BBH QSO system at the infrared-optical-UV bands can be significantly different from those of corresponding QSO system with a single massive black hole (MBH), mainly because of the existence of the gap and the rotation of the BBH (and its associated small disks) around the center of mass. We estimate the half-light radii of the emission region at different wavelengths from mock light curves and find that the obtained half-light radius versus wavelength relations of BBH QSO systems can be much flatter than those of single MBH QSO systems at a wavelength range determined by the BBH parameters, such as the total mass, mass ratio, separation, accretion rates, etc. The difference is primarily due to the existence of the gap. Such unique features on the light curves and half-light radius-wavelength relations of BBH QSO systems can be used to select and probe sub-parsec BBHs in a large number of lensed QSOs to be discovered by current and future surveys, including the Panoramic Survey Telescope and Rapid Response System, the Large Synoptic Survey telescope, and Euclid.

  11. Exotic gravitational microlensing effects as a probe of stellar and galactic structure

    NASA Astrophysics Data System (ADS)

    Becker, Andrew Cameron

    The nature of the "dark matter" which comprises the majority of the mass of our Universe is one of the most elusive, yet fundamental, cosmological properties. Its presence has been inferred on a variety of scales by indirect observational measurements. It remains to be seen whether or not this dark matter is composed of discrete units (Machos---Massive Compact Halo Objects) or is a sea of fundamental particles (WIMPS---Weakly Interacting Massive Particles). The MACHO project was founded to test for Machos orbiting in the halo of our Milky Way Galaxy. The experiment makes use of the one property we know about dark matter---it exerts a gravitational force on its surroundings. Einstein's theory of general relativity implies the region of influence sensitive to dark matter includes the fundamental fabric of space-time itself. A bizarre consequence of this is that matter may warp space, splitting the light from a background source into multiple images on the sky, hence acting as a gravitational lens. Millions of source stars in the Large and Small Magellanic Clouds have been observed for signatures of intervening, lensing dark matter. Approximately 20 events have been discovered. Several hundred additional events have been seen towards our Galactic bulge. Given the dearth of lensing events, the focus of the gravitational microlensing field has evolved from passive surveys to an aggressive pursuit of lightcurve fine structure. Embedded in each microlensing lightcurve are clues to the nature of the lensing system. Recognizing these features in real-time requires frequent sampling and high precision measurements. This dissertation includes the development and maintenance of the MACHO Alert System, which recognized these rare events in real-time. This Alert System required daily vigilance between its inception in 1995 and the completion of the MACHO Survey in 1999. However, the focus of this dissertation was the Global Microlensing Alert Network (GMAN). This system

  12. Reflection aspherical microlenses for planar optics fabricated by electron-beam lithography.

    PubMed

    Shiono, T; Ogawa, H

    1992-04-15

    Reflection aspherical microlenses are proposed for planar optics. These microlenses have the structure of a nonconcentric elliptical concave mirror. Broadband light can be used for these microlenses because these microlenses have no chromatic aberration. The microlens fabricated by electron-beam lithography and Ag deposition was found to have a smooth surface as designed. The focal length of the microlens was constant independent of the wavelength. The measured spot sizes agreed with diffraction-limited values at two different wavelengths. By using the array of this microlens, multiple images with excellent contrast were obtained under incoherent white-light illumination.

  13. Broadband Plasmonic Microlenses based on Patches of Nanoholes

    PubMed Central

    Gao, Hanwei; Hyun, Jerome K.; Lee, Min Hyung; Yang, Jiun-Chan; Lauhon, Lincoln J.; Odom, Teri W.

    2010-01-01

    This paper reports a new type of diffractive microlens based on finite-areas of 2D arrays of circular nanoholes (patches). The plasmonic microlenses can focus single wavelengths of light across the entire visible spectrum as well as broadband white light with little divergence. The focal length is determined primarily by the overall size of the patch and is tolerant to significant changes in patch substructure, including lattice geometry and local order of the circular nanoholes. The optical throughput, however, depends sensitively on the patch substructure and is determined by the wavelengths of surface plasmon resonances. This simple diffractive lens design enables millions of broadband plasmonic microlenses to be fabricated in parallel using soft nanolithographic techniques. PMID:20839781

  14. A method for the microlensed flux variance of QSOs

    NASA Astrophysics Data System (ADS)

    Goodman, Jeremy; Sun, Ai-Lei

    2014-06-01

    A fast and practical method is described for calculating the microlensed flux variance of an arbitrary source by uncorrelated stars. The required inputs are the mean convergence and shear due to the smoothed potential of the lensing galaxy, the stellar mass function, and the absolute square of the Fourier transform of the surface brightness in the source plane. The mathematical approach follows previous authors but has been generalized, streamlined, and implemented in publicly available code. Examples of its application are given for Dexter and Agol's inhomogeneous-disc models as well as the usual Gaussian sources. Since the quantity calculated is a second moment of the magnification, it is only logarithmically sensitive to the sizes of very compact sources. However, for the inferred sizes of actual quasi-stellar objects (QSOs), it has some discriminatory power and may lend itself to simple statistical tests. At the very least, it should be useful for testing the convergence of microlensing simulations.

  15. Space-Based Research in Fundamental Physics and Quantum Technologies

    NASA Astrophysics Data System (ADS)

    Turyshev, Slava G.; Israelsson, Ulf E.; Shao, Michael; Yu, Nan; Kusenko, Alexander; Wright, Edward L.; Everitt, C. W. Francis; Kasevich, Mark; Lipa, John A.; Mester, John C.; Reasenberg, Robert D.; Walsworth, Ronald L.; Ashby, Neil; Gould, Harvey; Paik, Ho Jung

    Space offers unique experimental conditions and a wide range of opportunities to explore the foundations of modern physics with an accuracy far beyond that of ground-based experiments. Space-based experiments today can uniquely address important questions related to the fundamental laws of Nature. In particular, high-accuracy physics experiments in space can test relativistic gravity and probe the physics beyond the Standard Model; they can perform direct detection of gravitational waves and are naturally suited for investigations in precision cosmology and astroparticle physics. In addition, atomic physics has recently shown substantial progress in the development of optical clocks and atom interferometers. If placed in space, these instruments could turn into powerful high-resolution quantum sensors greatly benefiting fundamental physics. We discuss the current status of space-based research in fundamental physics, its discovery potential, and its importance for modern science. We offer a set of recommendations to be considered by the upcoming National Academy of Sciences' Decadal Survey in Astronomy and Astrophysics. In our opinion, the Decadal Survey should include space-based research in fundamental physics as one of its focus areas. We recommend establishing an Astronomy and Astrophysics Advisory Committee's interagency "Fundamental Physics Task Force" to assess the status of both ground- and space-based efforts in the field, to identify the most important objectives, and to suggest the best ways to organize the work of several federal agencies involved. We also recommend establishing a new NASA-led interagency program in fundamental physics that will consolidate new technologies, prepare key instruments for future space missions, and build a strong scientific and engineering community. Our goal is to expand NASA's science objectives in space by including "laboratory research in fundamental physics" as an element in the agency's ongoing space research efforts.

  16. Microlensing in the Q0957 + 561 gravitational mirage

    SciTech Connect

    Schild, R.E.; Smith, R.C. )

    1991-03-01

    Analysis of the 10 yr record from monitoring the continuum brightness of Q0957 + 561 A, B shows a systematic increase of the B relative to the A component. The B brightness has leveled off in the last 2 yr at a value 32 percent higher than would be predicted from the ratio of Mg II 2798 A emission line strengths. This is taken to be the signature of microlensing by a star or stars in the lens galaxy. 11 refs.

  17. Astrometric microlensing and rotation of extragalactic reference frame

    NASA Astrophysics Data System (ADS)

    Zhdanov, V. I.; Alexandrov, A. N.; Fedorova, E. V.

    Gravitational field of foreground stars of the Galaxy causes additional motion of images of extragalactic sources. We estimate characteristics of stochastic and average motions of these images. The probability distribution for the image motions and their changes is obtained for general spatial density of microlenses. We show that collective motion of stars induces small nonzero dragging velocity of the reference frame. The results obtained are compared to the other relativistic effects in optical satellite-oriented reference frame.

  18. Polarimetry Microlensing of Close-in Planetary Systems

    NASA Astrophysics Data System (ADS)

    Sajadian, Sedighe; Hundertmark, Markus

    2017-04-01

    A close-in giant planetary (CGP) system has a net polarization signal whose value varies depending on the orbital phase of the planet. This polarization signal is either caused by the stellar occultation or by reflected starlight from the surface of the orbiting planet. When the CGP system is located in the Galactic bulge, its polarization signal becomes too weak to be measured directly. One method for detecting and characterizing these weak polarization signatures due to distant CGP systems is gravitational microlensing. In this work, we focus on potential polarimetric observations of highly magnified microlensing events of CGP systems. When the lens is passing directly in front of the source star with its planetary companion, the polarimetric signature caused by the transiting planet is magnified. As a result, some distinct features in the polarimetry and light curves are produced. In the same way, microlensing amplifies the reflection-induced polarization signal. While the planet-induced perturbations are magnified whenever these polarimetric or photometric deviations vanish for a moment, the corresponding magnification factor of the polarization component(s) is related to the planet itself. Finding these exact times in the planet-induced perturbations helps us to characterize the planet. In order to evaluate the observability of such systems through polarimetric or photometric observations of high-magnification microlensing events, we simulate these events by considering confirmed CGP systems as their source stars and conclude that the efficiency for detecting the planet-induced signal with the state-of-the-art polarimetric instrument (FORS2/VLT) is less than 0.1%. Consequently, these planet-induced polarimetry perturbations can likely be detected under favorable conditions by the high-resolution and short-cadence polarimeters of the next generation.

  19. Predictions for microlensing planetary events from core accretion theory

    SciTech Connect

    Zhu, Wei; Mao, Shude; Penny, Matthew; Gould, Andrew; Gendron, Rieul

    2014-06-10

    We conduct the first microlensing simulation in the context of a planet formation model. The planet population is taken from the Ida and Lin core accretion model for 0.3 M {sub ☉} stars. With 6690 microlensing events, we find that for a simplified Korea Microlensing Telescopes Network (KMTNet), the fraction of planetary events is 2.9%, out of which 5.5% show multiple-planet signatures. The numbers of super-Earths, super-Neptunes, and super-Jupiters detected are expected to be almost equal. Our simulation shows that high-magnification events and massive planets are favored by planet detections, which is consistent with previous expectation. However, we notice that extremely high-magnification events are less sensitive to planets, which is possibly because the 10 minute sampling of KMTNet is not intensive enough to capture the subtle anomalies that occur near the peak. This suggests that while KMTNet observations can be systematically analyzed without reference to any follow-up data, follow-up observations will be essential in extracting the full science potential of very high magnification events. The uniformly high-cadence observations expected for KMTNet also result in ∼55% of all detected planets not being caustic crossing, and more low-mass planets even down to Mars mass being detected via planetary caustics. We also find that the distributions of orbital inclinations and planet mass ratios in multiple-planet events agree with the intrinsic distributions.

  20. Predictions for Microlensing Planetary Events from Core Accretion Theory

    NASA Astrophysics Data System (ADS)

    Zhu, Wei; Penny, Matthew; Mao, Shude; Gould, Andrew; Gendron, Rieul

    2014-06-01

    We conduct the first microlensing simulation in the context of a planet formation model. The planet population is taken from the Ida & Lin core accretion model for 0.3 M ⊙ stars. With 6690 microlensing events, we find that for a simplified Korea Microlensing Telescopes Network (KMTNet), the fraction of planetary events is 2.9%, out of which 5.5% show multiple-planet signatures. The numbers of super-Earths, super-Neptunes, and super-Jupiters detected are expected to be almost equal. Our simulation shows that high-magnification events and massive planets are favored by planet detections, which is consistent with previous expectation. However, we notice that extremely high-magnification events are less sensitive to planets, which is possibly because the 10 minute sampling of KMTNet is not intensive enough to capture the subtle anomalies that occur near the peak. This suggests that while KMTNet observations can be systematically analyzed without reference to any follow-up data, follow-up observations will be essential in extracting the full science potential of very high magnification events. The uniformly high-cadence observations expected for KMTNet also result in ~55% of all detected planets not being caustic crossing, and more low-mass planets even down to Mars mass being detected via planetary caustics. We also find that the distributions of orbital inclinations and planet mass ratios in multiple-planet events agree with the intrinsic distributions.

  1. Detecting Earth-Mass Planets with Gravitational Microlensing

    NASA Astrophysics Data System (ADS)

    Bennett, David P.; Rhie, Sun Hong

    1996-11-01

    We show that Earth-mass planets orbiting stars in the Galactic disk and bulge can be detected by monitoring microlensed stars in the Galactic bulge. The star and its planet act as a binary lens which generates a light curve that can differ substantially from the light curve due only to the star itself. We show that the planetary signal remains detectable for planetary masses as small as an Earth mass when realistic source star sizes are included in the light curve calculation. These planets are detectable if they reside in the "lensing zone," which is centered between 1 and 4 AU from the lensing star and spans about a factor of 2 in distance. If we require a minimum deviation of 4% from the standard point-lens microlensing light curve, then we find that more than 2% of all M⊕ planets and 10% of all 10 M⊕ in the lensing zone can be detected. If a third of all lenses have no planets, a third have 1 M⊕ planets, and the remaining third have 10 M⊕ planets then we estimate that an aggressive ground-based microlensing planet search program could find one Earth-mass planet and half a dozen 10 M⊕ planets per year.

  2. Discovery of a Jupiter/Saturn analog with gravitational microlensing.

    PubMed

    Gaudi, B S; Bennett, D P; Udalski, A; Gould, A; Christie, G W; Maoz, D; Dong, S; McCormick, J; Szymanski, M K; Tristram, P J; Nikolaev, S; Paczynski, B; Kubiak, M; Pietrzynski, G; Soszynski, I; Szewczyk, O; Ulaczyk, K; Wyrzykowski, L; Depoy, D L; Han, C; Kaspi, S; Lee, C-U; Mallia, F; Natusch, T; Pogge, R W; Park, B-G; Abe, F; Bond, I A; Botzler, C S; Fukui, A; Hearnshaw, J B; Itow, Y; Kamiya, K; Korpela, A V; Kilmartin, P M; Lin, W; Masuda, K; Matsubara, Y; Motomura, M; Muraki, Y; Nakamura, S; Okumura, T; Ohnishi, K; Rattenbury, N J; Sako, T; Saito, To; Sato, S; Skuljan, L; Sullivan, D J; Sumi, T; Sweatman, W L; Yock, P C M; Albrow, M D; Allan, A; Beaulieu, J-P; Burgdorf, M J; Cook, K H; Coutures, C; Dominik, M; Dieters, S; Fouqué, P; Greenhill, J; Horne, K; Steele, I; Tsapras, Y; Chaboyer, B; Crocker, A; Frank, S; Macintosh, B

    2008-02-15

    Searches for extrasolar planets have uncovered an astonishing diversity of planetary systems, yet the frequency of solar system analogs remains unknown. The gravitational microlensing planet search method is potentially sensitive to multiple-planet systems containing analogs of all the solar system planets except Mercury. We report the detection of a multiple-planet system with microlensing. We identify two planets with masses of approximately 0.71 and approximately 0.27 times the mass of Jupiter and orbital separations of approximately 2.3 and approximately 4.6 astronomical units orbiting a primary star of mass approximately 0.50 solar mass at a distance of approximately 1.5 kiloparsecs. This system resembles a scaled version of our solar system in that the mass ratio, separation ratio, and equilibrium temperatures of the planets are similar to those of Jupiter and Saturn. These planets could not have been detected with other techniques; their discovery from only six confirmed microlensing planet detections suggests that solar system analogs may be common.

  3. Space-based optical image encryption.

    PubMed

    Chen, Wen; Chen, Xudong

    2010-12-20

    In this paper, we propose a new method based on a three-dimensional (3D) space-based strategy for the optical image encryption. The two-dimensional (2D) processing of a plaintext in the conventional optical encryption methods is extended to a 3D space-based processing. Each pixel of the plaintext is considered as one particle in the proposed space-based optical image encryption, and the diffraction of all particles forms an object wave in the phase-shifting digital holography. The effectiveness and advantages of the proposed method are demonstrated by numerical results. The proposed method can provide a new optical encryption strategy instead of the conventional 2D processing, and may open up a new research perspective for the optical image encryption.

  4. Requirements for Space-Based Wind Lidar

    NASA Technical Reports Server (NTRS)

    Atlas, Robert M.; Einaudi, Franco (Technical Monitor)

    2002-01-01

    Global wind profiles are needed for a wide range of meteorological applications. Since the 1980's, observing system simulation experiments have been conducted in order to evaluate the potential impact of space-based wind profiler data on numerical weather prediction, and to evaluate trade-offs in lidar design. These experiments indicated tremendous potential for satellite lidar observations to improve atmospheric analyses and forecasts. More recent experiments are aimed at assessing the precise requirements for space-based lidar wind profile data and to evaluate the potential for alternative technologies. At the workshop, OSSE methodology, and results from experiments conducted at the DAO to the define requirements for space-based lidar wind will be presented.

  5. Seismology and space-based geodesy

    NASA Technical Reports Server (NTRS)

    Tralli, David M.; Tajima, Fumiko

    1993-01-01

    The potential of space-based geodetic measurement of crustal deformation in the context of seismology is explored. The achievements of seismological source theory and data analyses, mechanical modeling of fault zone behavior, and advances in space-based geodesy are reviewed, with emphasis on realizable contributions of space-based geodetic measurements specifically to seismology. The fundamental relationships between crustal deformation associated with an earthquake and the geodetically observable data are summarized. The response and spatial and temporal resolution of the geodetic data necessary to understand deformation at various phases of the earthquake cycle is stressed. The use of VLBI, SLR, and GPS measurements for studying global geodynamics properties that can be investigated to some extent with seismic data is discussed. The potential contributions of continuously operating strain monitoring networks and globally distributed geodetic observatories to existing worldwide modern digital seismographic networks are evaluated in reference to mutually addressable problems in seismology, geophysics, and tectonics.

  6. Exoplanets and brown dwarfs detections through gravitational microlensing. Study of interferometric observations.

    NASA Astrophysics Data System (ADS)

    Ranc, Clément

    2015-09-01

    Gravitational microlensing effect has become a unique tool to detect and characterise exoplanets. A microlensing effect occurs when a foreground star (the microlens) and a background star (the source) are aligned with the Earth on the same line of sight. The light from the furthest star, usually in the Galactic bulge, is deflected by the microlens located on the disk. During this phenomenon, multiple images of the source are created by the lens, bigger than the source that consequently seems amplified. When one of these images are located in the vicinity of an exoplanet, a short amplification jump occurs revealing its presence. After a quick overview of the exoplanets field of research, I highlight the specificities of microlensing comparing to the other planets detection techniques. Then, I describe in details the modelling of microlensing effects, from a theoretical to a numerical point of view. In a third part, I describe the detection of the first brown dwarf orbiting a solar-type star using microlensing, strengthening the recent idea that microlensing will lead to a better understanding of the mechanisms involved in the brown dwarfs formation, still not fully understood. Finally, I investigate the potential of interferometric observations of microlensing events that will give, in the future, new original constraints on the microlens physical properties. First, we introduce a new formalism that closely combines interferometric and microlensing observable quantities. Secondly, we determine an average number of events that are at reach of long baseline interferometers every year.

  7. Space Based Infrared System High (SBIRS High)

    DTIC Science & Technology

    2015-12-01

    Selected Acquisition Report (SAR) RCS: DD-A&T(Q&A)823-210 Space Based Infrared System High (SBIRS High) As of FY 2017 President’s Budget Defense...Program Office Estimate RDT&E - Research, Development, Test, and Evaluation SAR - Selected Acquisition Report SCP - Service Cost Position TBD - To Be

  8. Gravitational microlensing by double stars and planetary systems

    NASA Technical Reports Server (NTRS)

    Mao, Shunde; Paczynski, Bohdan

    1991-01-01

    Almost all stars are in binary systems. When the separation between the two components is comparable to the Einstein ring radius corresponding to the combined mass of the binary acting as a gravitational lens, then an extra pair of images can be created, and the light curve of a lensed source becomes complicated. It is estimated that about 10 percent of all lensing episodes of the Galactic bulge stars will strongly display the binary nature of the lens. The effect is strong even if the companion is a planet. A massive search for microlensing of the Galactic bulge stars may lead to a discovery of the first extrasolar planetary systems.

  9. The OGLE view of microlensing towards the Magellanic Clouds - I. A trickle of events in the OGLE-II LMC data

    NASA Astrophysics Data System (ADS)

    Wyrzykowski, Ł.; Kozłowski, S.; Skowron, J.; Belokurov, V.; Smith, M. C.; Udalski, A.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Szewczyk, O.; Żebruń, K.

    2009-08-01

    We present the results from the Optical Gravitational Lensing Experiment II (OGLE-II) survey (1996-2000) towards the Large Magellanic Cloud (LMC), which has the aim of detecting the microlensing phenomena caused by dark matter compact objects in the Galactic halo [massive compact halo objects (MACHOs)]. We use high-resolution Hubble Space Telescope images of the OGLE fields and derive the correction for the number of monitored stars in each field. This also yields blending distributions which we use in `catalogue-level' Monte Carlo simulations of the microlensing events in order to calculate the detection efficiency of the events. We detect two candidates for microlensing events in the All Stars Sample, which translates into an optical depth of 0.43 +/- 0.33 × 10-7. If both events were due to MACHO, the fraction of mass of compact dark matter objects in the Galactic halo would be 8 +/- 6 per cent. This optical depth, however, along with the characteristics of the events seems to be consistent with the self-lensing scenario, i.e. self-lensing alone is sufficient to explain the observed microlensing signal. Our results indicate the non-detection of MACHOs lensing towards the LMC with an upper limit on their abundance in the Galactic halo of 19 per cent for M = 0.4Msolar and 10 per cent for masses between 0.01 and 0.2Msolar. Based on observations obtained with the 1.3-m Warsaw Telescope at the Las Campanas Observatory of the Carnegie Institution of Washington. E-mail: wyrzykow@ast.cam.ac.uk ‡ Name pronunciation: Woocash Vizhikovsky.

  10. Adaptive control of space based robot manipulators

    NASA Technical Reports Server (NTRS)

    Walker, Michael W.; Wee, Liang-Boon

    1991-01-01

    For space based robots in which the base is free to move, motion planning and control is complicated by uncertainties in the inertial properties of the manipulator and its load. A new adaptive control method is presented for space based robots which achieves globally stable trajectory tracking in the presence of uncertainties in the inertial parameters of the system. A partition is made of the fifteen degree of freedom system dynamics into two parts: a nine degree of freedom invertible portion and a six degree of freedom noninvertible portion. The controller is then designed to achieve trajectory tracking of the invertible portion of the system. This portion consist of the manipulator joint positions and the orientation of the base. The motion of the noninvertible portion is bounded, but unpredictable. This portion consist of the position of the robot's base and the position of the reaction wheel.

  11. Toward a Space based Gravitational Wave Observatory

    NASA Technical Reports Server (NTRS)

    Stebbins, Robin T.

    2015-01-01

    A space-based GW observatory will produce spectacular science. The LISA mission concept: (a) Long history, (b) Very well-studied, including de-scopes, (c) NASAs Astrophysics Strategic Plan calls for a minority role in ESAs L3 mission opportunity. To that end, NASA is Participating in LPF and ST7 Developing appropriate technology for a LISA-like mission Preparing to seek an endorsement for L3 participation from the 2020 decadal review.

  12. Caustic Structures and Detectability of Circumbinary Planets in Microlensing

    NASA Astrophysics Data System (ADS)

    Luhn, Jacob K.; Penny, Matthew T.; Gaudi, B. Scott

    2016-08-01

    Recent discoveries of circumbinary planets in Kepler data show that there is a viable channel of planet formation around binary main-sequence stars. Motivated by these discoveries, we have investigated the caustic structures and detectability of circumbinary planets in microlensing events. We have produced a suite of animations of caustics as a function of the projected separation and angle of the binary host to efficiently explore caustic structures over the entire circumbinary parameter space. Aided by these animations, we have derived a semi-empirical analytic expression for the location of planetary caustics, which are displaced in circumbinary lenses relative to those of planets with a single host. We have used this expression to show that the dominant source of caustic motion will be due to the planet’s orbital motion and not that of the binary star. Finally, we estimate the fraction of circumbinary microlensing events that are recognizable as such to be significant (5%-50%) for binary projected separations in the range 0.1-0.5 in units of Einstein radii.

  13. Microlensing planet detection via geosynchronous and low Earth orbit satellites

    NASA Astrophysics Data System (ADS)

    Mogavero, F.; Beaulieu, J. P.

    2016-01-01

    Planet detection through microlensing is usually limited by a well-known degeneracy in the Einstein timescale tE, which prevents mass and distance of the lens to be univocally determined. It has been shown that a satellite in geosynchronous orbit could provide masses and distances for most standard planetary events (tE ≈ 20 days) via a microlens parallax measurement. This paper extends the analysis to shorter Einstein timescales, tE ≈ 1 day, when dealing with the case of Jupiter-mass lenses. We then study the capabilities of a low Earth orbit satellite on even shorter timescales, tE ≈ 0.1 days. A Fisher matrix analysis is employed to predict how the 1-σ error on parallax depends on tE and the peak magnification of the microlensing event. It is shown that a geosynchronous satellite could detect parallaxes for Jupiter-mass free floaters and discover planetary systems around very low-mass brown dwarfs. Moreover, a low Earth orbit satellite could lead to the discovery of Earth-mass free-floating planets. Limitations to these results can be the strong requirements on the photometry, the effects of blending, and in the case of the low orbit, the Earth's umbra.

  14. Galactic Bulge Microlensing Events from the MACHO Collaboration

    SciTech Connect

    Thomas, C L; Griest, K; Popowski, P; Cook, K H; Drake, A J; Minniti, D; Myer, D G; Alcock, C; Allsman, R A; Alves, D R; Axelrod, T S; Becker, A C; Bennett, D P; Freeman, K C; Geha, M; Lehner, M J; Marshall, S L; Nelson, C A; Peterson, B A; Quinn, P J; Stubbs, C W; Sutherland, W; Vandehei, T; Welch, D L

    2005-06-16

    The authors present a catalog of 450 relatively high signal-to-noise microlensing events observed by the MACHO collaboration between 1993 and 1999. The events are distributed throughout the fields and, as expected, they show clear concentration toward the Galactic center. No optical depth is given for this sample since no blending efficiency calculation has been performed, and they find evidence for substantial blending. In a companion paper they give optical depths for the sub-sample of events on clump giant source stars, where blending is a less significant effect. Several events with sources that may belong to the Sagittarius dwarf galaxy are identified. For these events even relatively low dispersion spectra could suffice to classify these events as either consistent with Sagittarius membership or as non-Sagittarius sources. Several unusual events, such as microlensing of periodic variable source stars, binary lens events, and an event showing extended source effects are identified. They also identify a number of contaminating background events as cataclysmic variable stars.

  15. Empirical study of simulated two-planet microlensing events

    SciTech Connect

    Zhu, Wei; Gould, Andrew; Penny, Matthew; Mao, Shude; Gendron, Rieul

    2014-10-10

    We undertake the first study of two-planet microlensing models recovered from simulations of microlensing events generated by realistic multiplanet systems in which 292 planetary events, including 16 two-planet events, were detected from 6690 simulated light curves. We find that when two planets are recovered, their parameters are usually close to those of the two planets in the system most responsible for the perturbations. However, in 1 of the 16 examples, the apparent mass of both detected planets was more than doubled by the unmodeled influence of a third, massive planet. This fraction is larger than but statistically consistent with the roughly 1.5% rate of serious mass errors due to unmodeled planetary companions for the 274 cases from the same simulation in which a single planet is recovered. We conjecture that an analogous effect due to unmodeled stellar companions may occur more frequently. For 7 out of 23 cases in which two planets in the system would have been detected separately, only one planet was recovered because the perturbations due to the two planets had similar forms. This is a small fraction (7/274) of all recovered single-planet models, but almost a third of all events that might plausibly have led to two-planet models. Still, in these cases, the recovered planet tends to have parameters similar to one of the two real planets most responsible for the anomaly.

  16. Detectability of GW150914-like events by gravitational microlensing

    NASA Astrophysics Data System (ADS)

    Eilbott, Daniel; Riley, Alexander; Cohn, Jonathan; Kesden, Michael H.; King, Lindsay J.

    2017-01-01

    The recent discovery of gravitational waves from stellar-mass binary black holes (BBHs) provided direct evidence of the existence of these systems. These BBHs would have gravitational microlensing signatures that are, due to their large masses and small separations, distinct from single-lens signals. We apply Bayesian statistics to examine the distinguishability of BBH microlensing events from single-lens events under ideal observing conditions, using modern photometric and astrometric capabilities. Given one year of ideal observations, a source star at the Galactic center, a GW150914-like BBH lens (total mass 65 M⊙, mass ratio 0.8) at half that distance, and an impact parameter of 0.4 Einstein radii, we find that BBH separations down to 0.00634 Einstein radii are detectable, which is < 0.00716 Einstein radii, the limit at which the BBH would merge within the age of the universe. We encourage analyses of LSST data to search for similar modulation in all long-duration events, providing a new channel for the discovery of short-period BBHs in our Galaxy.

  17. The Effect of Micro-lensing in Eclipsing Binary-star Systems

    NASA Astrophysics Data System (ADS)

    Hoffman, Kelsey L.; Rowe, J.; Hansen, B.

    2013-04-01

    Using photometric observations from the Kepler Space Telescope of eclipsing binary star systems where one component is a white dwarf we have investigated the strength of the micro-lensing effect. We have examined the stellar binary KOI-81 from the Kepler mission. KOI-81 is composed of a white dwarf and a A-type main-sequence star in a 24 day circular orbit and have found that micro-lensing is detectable. We use our lightcurve models to measure the strength of the micro-lensing signal and refine the radius of the eclipsing white dwarf.

  18. OGLE-2015-BLG-0196: Ground-based Gravitational Microlens Parallax Confirmed by Space-based Observation

    NASA Astrophysics Data System (ADS)

    Han, C.; Udalski, A.; Gould, A.; Zhu, Wei; and; Szymański, M. K.; Soszyński, I.; Skowron, J.; Mróz, P.; Poleski, R.; Pietrukowicz, P.; Kozłowski, S.; Ulaczyk, K.; Pawlak, M.; The OGLE Collaboration; Yee, J. C.; Beichman, C.; Calchi Novati, S.; Carey, S.; Bryden, C.; Fausnaugh, M.; Gaudi, B. S.; Henderson, Calen B.; Shvartzvald, Y.; Wibking, B.; The Spitzer Microlensing Team

    2017-01-01

    In this paper, we present an analysis of the binary gravitational microlensing event OGLE-2015-BLG-0196. The event lasted for almost a year, and the light curve exhibited significant deviations from the lensing model based on the rectilinear lens-source relative motion, enabling us to measure the microlens parallax. The ground-based microlens parallax is confirmed by the data obtained from space-based microlens observations using the Spitzer telescope. By additionally measuring the angular Einstein radius from the analysis of the resolved caustic crossing, the physical parameters of the lens are determined up to the twofold degeneracy, u0 < 0 and u0 > 0, solutions caused by the well-known “ecliptic” degeneracy. It is found that the binary lens is composed of two M dwarf stars with similar masses, M1 = 0.38 ± 0.04 M⊙ (0.50 ± 0.05 M⊙) and M2 = 0.38 ± 0.04 M⊙ (0.55 ± 0.06 M⊙), and the distance to the lens is DL = 2.77 ± 0.23 kpc (3.30 ± 0.29 kpc). Here the physical parameters outside and inside the parentheses are for the u0 < 0 and u0 > 0 solutions, respectively.

  19. Quasar structure from microlensing in gravitationally lensed quasars

    NASA Astrophysics Data System (ADS)

    Morgan, Christopher Warren

    2008-02-01

    I analyze microlensing in gravitationally lensed quasars to yield measurements of the structure of their continuum emission regions. I first describe our lensed quasar monitoring program and RETROCAM, the auxiliary port camera I built for the 2.4m Hiltner telescope to monitor lensed quasars. I describe the application of our Monte Carlo microlensing analysis technique to SDSS 0924+0219, a system with a highly anomalous optical flux ratio. For an inclination angle i, I find an optical scale radius log[( r s /cm)[Special characters omitted.] ] = [Special characters omitted.] . I extrapolate the best-fitting light curves into the future to find a roughly 45% probability that the anomalous image (D) will brighten by at least an order of magnitude during the next decade. I expand our method to make simultaneous estimates of the time delays and structure of HE1104-1805 and QJ0158-4325, two doubly-imaged quasars with microlensing and intrinsic variability on comparable time scales. For HE1104- 1805 I find a time delay of D t AB = t A - t B = [Special characters omitted.] days and estimate a scale radius of log[( r s /cm)[Special characters omitted.] ] = [Special characters omitted.] at 0.2mm in the rest frame. I am unable to measure a time delay for QJ0158-4325, but the scale radius is log[( r s /cm) [Special characters omitted.] ] = 14.9 ±1 0.3 at 0.3mm in the rest frame. I then apply our Monte Carlo microlensing analysis technique to the optical light curves of 11 lensed quasar systems to show that quasar accretion disk sizes at 2500Å are related to black hole mass ( M BH ) by log( R 2500 /cm) = (15.7 ± 0.16) + (0.64± 0.18) log( M BH /10 9 [Special characters omitted.] ). This scaling is consistent with the expectation from thin disk theory (R 0( [Special characters omitted.] ), but it implies that black holes radiate with relatively low efficiency, log(e) = -1.54 ± 0.36 + log( L/L E ) where e=3D L / ( M c 2 ). These sizes are also larger, by a factor of ~ 3, than

  20. Exoplanets mass measurement using gravitational microlensing

    NASA Astrophysics Data System (ADS)

    Ranc, Clement; Cassan, Arnaud

    2015-07-01

    Thousands of extrasolar planets have been discovered so far, and after the pioneer era, when the discovery of a single planet was a notable event, the interest is moving to the more complex work of planet and planetary system taxonomy, trying to put some order and eventually understand why they are so different from each others. The characterization of planets is tied to the knowledge of their host stars. Nearly all planets known so far however belong to isolated field stars, and their mass and radius are affected by large errors that transfer directly onto the precision of the planet parameters. On the contrary, distances, ages, mass and overall characteristics of stars in Open Clusters are much better measured than for field stars. OC stars are chemically homogeneous, so we can effectively investigate the effect of the presence of a planetary systems on the host star chemistry, e.g. if the observed trend of chemical elements with respect to their condensation temperature is effectively related to the presence planets. Curiously, at the present time, only less than ten planets have been confirmed or validated around Main Sequence stars in OCs. In this proposed talk I will give a short historical review on previous searches for exoplanets in OCs, then I will introduce our on-going survey aimed at detecting Neptune-mass planets around close, intermediate-age OC stars with HARPS (8 night/year) and HARPS-N (5 nights/semester, within the GAPS program). I will discuss our observational strategy and how we are dealing with activity, the main limiting factor in this kind of research, and the impact of the forth-coming K2 observations on our search. I will finally present our latest discoveries, including the first planetary multiple system around a OC star.

  1. Space Based Range Demonstration and Certification (SBRDC)

    NASA Technical Reports Server (NTRS)

    Sakahara, Robert

    2005-01-01

    This viewgraph presentation describes the development, utilization and testing of technologies for range safety and range user systems. The contents include: 1) Space Based Range (SBR) Goals and Objectives; 2) Today s United States Range; 3) Future Range; 4) Another Vision for the Future Range; 5) STARS Project Goals; 6) STARS Content; 7) STARS Configuration Flight Demonstrations 1 & 2; 8) Spaceport And Range Technologies STARS Objectives and Results; 9) Spaceport And Range Technologies STARS FD2 Objectives; 10) Range Safety Hardware; 11) Range User Hardware; and 12) Past/Future Flight Demo Plans

  2. Microlensing of circumstellar envelopes. III. Line profiles from stellar winds in homologous expansion

    NASA Astrophysics Data System (ADS)

    Hendry, M. A.; Ignace, R.; Bryce, H. M.

    2006-05-01

    This paper examines line profile evolution due to the linear expansion of circumstellar material obsverved during a microlensing event. This work extends our previous papers on emission line profile evolution from radial and azimuthal flow during point mass lens events and fold caustic crossings. Both "flavours" of microlensing were shown to provide effective diagnostics of bulk motion in circumstellar envelopes. In this work a different genre of flow is studied, namely linear homologous expansion, for both point mass lenses and fold caustic crossings. Linear expansion is of particular relevance to the effects of microlensing on supernovae at cosmological distances. We derive line profiles and equivalent widths for the illustrative cases of pure resonance and pure recombination lines, modelled under the Sobolev approximation. The efficacy of microlensing as a diagnostic probe of the stellar environs is demonstrated and discussed.

  3. High Probabilities of Planet Detection during Microlensing Events.

    NASA Astrophysics Data System (ADS)

    Peale, S. J.

    2000-10-01

    The averaged probability of detecting a planetary companion of a lensing star during a gravitational microlensing event toward the Galactic center when the planet-lens mass ratio is 0.001 is shown to have a maximum exceeding 20% for a distribution of source-lens impact parameters that is determined by the efficiency of event detection, and a maximum exceeding 10% for a uniform distribution of impact parameters. The probability varies as the square root of the planet-lens mass ratio. A planet is assumed detectable if the perturbation of the light curve exceeds 2/(S/N) for a significant number of data points, where S/N is the signal-to noise ratio for the photometry of the source. The probability peaks at a planetary semimajor axis a that is close to the mean Einstein ring radius of the lenses of about 2 AU along the line of sight, and remains significant for 0.6<= a<= 10 AU. The low value of the mean Einstein ring radius results from the dominance of M stars in the mass function of the lenses. The probability is averaged over the distribution of the projected position of the planet onto the lens plane, over the lens mass function, over the distribution of impact parameters, over the distribution of lens along the line of sight to the source star, over the I band luminosity function of the sources adjusted for the source distance, and over the source distribution along the line of sight. If two or more parameters of the lensing event are known, such as the I magnitude of the source and the impact parameter, the averages over these parameters can be omitted and the probability of detection determined for a particular event. The calculated probabilities behave as expected with variations in the line of sight, the mass function of the lenses, the extinction and distance to and magnitude of the source, and with a more demanding detection criterion. The relatively high values of the probabilities are robust to plausible variations in the assumptions. The high

  4. Space-based Operations Grid Prototype

    NASA Technical Reports Server (NTRS)

    Bradford, Robert N.; Welch, Clara L.

    2003-01-01

    The Space based Operations Grid is intended to integrate the "high end" network services and compute resources that a remote payload investigator needs. This includes integrating and enhancing existing services such as access to telemetry, payload commanding, payload planning and internet voice distribution as well as the addition of services such as video conferencing, collaborative design, modeling or visualization, text messaging, application sharing, and access to existing compute or data grids. Grid technology addresses some of the greatest challenges and opportunities presented by the current trends in technology, i.e. how to take advantage of ever increasing bandwidth, how to manage virtual organizations and how to deal with the increasing threats to information technology security. We will discuss the pros and cons of using grid technology in space-based operations and share current plans for the prototype. It is hoped that early on the prototype can incorporate many of the existing as well as future services that are discussed in the first paragraph above to cooperating International Space Station Principle Investigators both nationally and internationally.

  5. Space-based Science Operations Grid Prototype

    NASA Technical Reports Server (NTRS)

    Bradford, Robert N.; Welch, Clara L.; Redman, Sandra

    2004-01-01

    Grid technology is the up and coming technology that is enabling widely disparate services to be offered to users that is very economical, easy to use and not available on a wide basis. Under the Grid concept disparate organizations generally defined as "virtual organizations" can share services i.e. sharing discipline specific computer applications, required to accomplish the specific scientific and engineering organizational goals and objectives. Grids are emerging as the new technology of the future. Grid technology has been enabled by the evolution of increasingly high speed networking. Without the evolution of high speed networking Grid technology would not have emerged. NASA/Marshall Space Flight Center's (MSFC) Flight Projects Directorate, Ground Systems Department is developing a Space-based Science Operations Grid prototype to provide to scientists and engineers the tools necessary to operate space-based science payloads/experiments and for scientists to conduct public and educational outreach. In addition Grid technology can provide new services not currently available to users. These services include mission voice and video, application sharing, telemetry management and display, payload and experiment commanding, data mining, high order data processing, discipline specific application sharing and data storage, all from a single grid portal. The Prototype will provide most of these services in a first step demonstration of integrated Grid and space-based science operations technologies. It will initially be based on the International Space Station science operational services located at the Payload Operations Integration Center at MSFC, but can be applied to many NASA projects including free flying satellites and future projects. The Prototype will use the Internet2 Abilene Research and Education Network that is currently a 10 Gb backbone network to reach the University of Alabama at Huntsville and several other, as yet unidentified, Space Station based

  6. Can gravitational microlensing be used to probe geometry of a massive black-hole?

    NASA Astrophysics Data System (ADS)

    Popović, Luka Č.; Jovanović, Predrag

    2007-04-01

    Astronomical Observatory, Belgrade, Yugoslavia (Serbia and Montenegro) Here we discuss the possibility to use gravitational microlensing in order to probe the geometry around a massive black hole. Taking into account that lensed quasars are emitting X-rays which come from the heart of these objects (around a massive black hole), we investigated the influence of microlensing on the shape of the X-ray continuum/Fe K-alpha line variability due to microlensing by stars from a foreground galaxy [1,2]. We considered an X-ray accretion disk in Schwarzschild and Kerr metrics that is microlensed by a straight-fold caustic and a magnification pattern [2]. We found that the changes in the shape of the X-ray continuum as well as Fe K-alpha line due to microlensing depend on assumed metrics. This shows that microlensing can be used to investigate an unresolved X-ray emitting region geometry around massive black holes. [1] Popović, L.Č., Mediavilla, E.G.; Jovanović, P., Muñoz, J.A. 2003 A& A...398..975P [2] Popović, L. Č., Jovanović, P., Mediavilla, E.; Zakharov, A. F.; Abajas, C.; Muñoz, J. A.; Chartas, G. 2005, ApJ (to be published in February 2006; astro-ph /0510271).

  7. Gravitational Microlensing by Ellis Wormhole: Second Order Effects

    NASA Astrophysics Data System (ADS)

    Lukmanova, Regina; Kulbakova, Aliya; Izmailov, Ramil; Potapov, Alexander A.

    2016-11-01

    Gravitational lensing is the effect of light bending in a gravitational field. It can be used as a possible observational method to detect or exclude the existence of wormholes. In this work, we extend the work by Abe on gravitational microlensing by Ellis wormhole by including the second order deflection term. Using the lens equation and definition of Einstein radius, we find the angular locations of the physical image inside and outside Einstein ring. The work contains a comparative analysis of light curves between the Schwarzschild black hole and the Ellis wormhole that can be used to distinguish such objects though such distinctions are too minute to be observable even in the near future. We also tabulate the optical depth and event rate for lensing by bulge and Large Magellanic Cloud (LMC) stars.

  8. Finding Free-Floating Black Holes using Astrometric Microlensing

    NASA Astrophysics Data System (ADS)

    Lu, Jessica R.; Ofek, Eran Oded; Sinukoff, Evan; Udalski, Andrzej; Kozlowski, Szymon

    2017-01-01

    Our Galaxy most likely hosts 10-100 million stellar mass black holes. The exact number and mass function of these black holes contains important information regarding our Galaxy's star formation history, stellar mass function, and the fate of very massive stars. However, isolated stellar black holes have yet to be detected. To date, stellar mass black holes have only been definitively detected in binary systems with accreting companions or merging to produce gravitational waves. In principle, the presence of isolated black holes can be inferred from astrometric and photometric signatures produced when they lens light from a background star. We attempt to detect the astrometric lensing signatures of several photometrically identified microlensing events, toward the Galactic Bulge. Long-duration events (t_Einstein > 100 days) were selected as the most likely black hole candidates and were observed using several years of laser-guided adaptive optics observations from the W. M. Keck telescopes. We present results from this search.

  9. Liquid microlenses and waveguides from bulk nematic birefringent profiles.

    PubMed

    Čančula, Miha; Ravnik, Miha; Muševič, Igor; Žumer, Slobodan

    2016-09-19

    We demonstrate polarization-selective microlensing and waveguiding of laser beams by birefringent profiles in bulk nematic fluids using numerical modelling. Specifically, we show that radial escaped nematic director profiles with negative birefringence focus and guide light with radial polarization, whereas the opposite - azimuthal - polarization passes through unaffected. A converging lens is realized in a nematic with negative birefringence, and a diverging lens in a positive birefringence material. Tuning of such single-liquid lenses by an external low-frequency electric field and by adjusting the profile and intensity of the beam itself is demonstrated, combining external control with intrinsic self-adaptive focusing. Escaped radial profiles of birefringence are shown to act as single-liquid waveguides with a single distinct eigenmode and low attenuation. Finally, this work is an approach towards creating liquid photonic elements for all-soft matter photonics.

  10. Chromatic aberration control for tunable all-silicone membrane microlenses.

    PubMed

    Waibel, Philipp; Mader, Daniel; Liebetraut, Peter; Zappe, Hans; Seifert, Andreas

    2011-09-12

    Tunable multi-chamber microfluidic membrane microlenses with achromaticity over a given focal length range are demonstrated. In analogy to a fixed-focus achromatic doublet lens, the multi-lens system is based on a stack of microfluidic cavities filled with optically optimized liquids with precisely defined refractive index and Abbe number, and these are independently pneumatically actuated. The membranes separating the cavities form the refractive optical surfaces, and the curvatures as a function of pressure are calculated using a mechanical model for deformation of flexible plates. The results are combined with optical ray tracing simulations of the multi-lens system to yield chromatic aberration behavior, which is verified experimentally. A focal length tuning range of 5-40 mm and reduction in chromatic aberration of over 30% is demonstrated, limited by the availability of optical fluids.

  11. Adaptive liquid microlenses activated by stimuli-responsive hydrogels

    NASA Astrophysics Data System (ADS)

    Dong, Liang; Agarwal, Abhishek K.; Beebe, David J.; Jiang, Hongrui

    2006-08-01

    Despite its compactness, the human eye can easily focus on different distances by adjusting the shape of its lens with the help of ciliary muscles. In contrast, traditional man-made optical systems achieve focusing by physical displacement of the lenses used. But in recent years, advances in miniaturization technology have led to optical systems that no longer require complicated mechanical systems to tune and adjust optical performance. These systems have found wide use in photonics, displays and biomedical systems. They are either based on arrays of microlenses with fixed focal lengths, or use external control to adjust the microlens focal length. An intriguing example is the tunable liquid lens, where electrowetting or external pressure manipulates the shape of a liquid droplet and thereby adjusts its optical properties. Here we demonstrate a liquid lens system that allows for autonomous focusing. The central component is a stimuli-responsive hydrogel integrated into a microfluidic system and serving as the container for a liquid droplet, with the hydrogel simultaneously sensing the presence of stimuli and actuating adjustments to the shape-and hence focal length-of the droplet. By working at the micrometre scale where ionic diffusion and surface tension scale favourably, we can use pinned liquid-liquid interfaces to obtain stable devices and realize response times of ten to a few tens of seconds. The microlenses, which can have a focal length ranging from -∞ to +∞ (divergent and convergent), are also readily integrated into arrays that may find use in applications such as sensing, medical diagnostics and lab-on-a-chip technologies.

  12. Quasar Structure from Microlensing in Gravitationally Lensed Quasars

    NASA Astrophysics Data System (ADS)

    Morgan, Christopher W.

    2007-12-01

    I investigate microlensing in gravitationally lensed quasars and discuss the use of its signal to probe quasar structure on small angular scales. I describe our lensed quasar optical monitoring program and RETROCAM, the optical camera I built for the 2.4m Hiltner telescope to monitor lensed quasars. I use the microlensing variability observed in 11 gravitationally lensed quasars to show that the accretion disk size at 2500Å is related to the black hole mass by log(R2500/cm) = (15.70±0.16) + (0.64±0.18)log(MBH/109M⊙). This scaling is consistent with the expectation from thin disk theory (R ∝ MBH2/3), but it implies that black holes radiate with relatively low efficiency, log(η) = -1.54±0.36 + log(L/LE) where η=L/(Mdotc2). With one exception, these sizes are larger by a factor of 4 than the size needed to produce the observed 0.8µm quasar flux by thermal radiation from a thin disk with the same T ∝ R-3/4 temperature profile. More sophisticated disk models are clearly required, particularly as our continuing observations improve the precision of the measurements and yield estimates of the scaling with wavelength and accretion rate. This research made extensive use of a Beowulf computer cluster obtained through the Cluster Ohio program of the Ohio Supercomputer Center. Support for program HST-GO-9744 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS-5-26666.

  13. Observational limits on Omega in stars, brown dwarfs, and stellar remnants from gravitational microlensing

    NASA Technical Reports Server (NTRS)

    Dalcanton, Julianne J.; Canizares, Claude R.; Granados, Arno; Steidel, Charles C.; Stocke, John T.

    1994-01-01

    Microlensing by compact objects with masses between approximately 0.001 solar masses and approximately 300 solar masses will amplify the continuum emission of a quasar, without significantly changing its line emission. Thus, compact objects with masses associated with stars, subdwarfs, and stellar remnants will reduce the apparent equivalent widths of quasar emission lines. It is possible to detect this population of lenses by searching for an increase in the number of small equivalent width quasars with redshift. This increase was looked for, but not found, in quasar samples taken from the Einstein Medium Sensitivity Survey and the Steidel & Sargent absorption-line studies. Thus, Omega(sub c), the cosmological density of compact objects relative to the critical density, is less than or approximately equal to 0.1 in the mass range 0.01 solar masses-20 solar masses (for Omega less than 0.6). For any value of Omega, Omega(sub c) less than or approximately equal to 0.2 in the larger mass range 0.001 solar masses-60 solar masses, and Omega(sub c) less than 1 for 0.001 solar masses-300 solar masses. Subdwarfs, stellar objects, or their remnants (e.g., MACHOS) cannot close the universe.

  14. Space Based Gravitational Wave Observatories (SGOs)

    NASA Technical Reports Server (NTRS)

    Livas, Jeff

    2014-01-01

    Space-based Gravitational-wave Observatories (SGOs) will enable the systematic study of the frequency band from 0.0001 - 1 Hz of gravitational waves, where a rich array of astrophysical sources is expected. ESA has selected The Gravitational Universe as the science theme for the L3 mission opportunity with a nominal launch date in 2034. This will be at a minimum 15 years after ground-based detectors and pulsar timing arrays announce their first detections and at least 18 years after the LISA Pathfinder Mission will have demonstrated key technologies in a dedicated space mission. It is therefore important to develop mission concepts that can take advantage of the momentum in the field and the investment in both technology development and a precision measurement community on a more near-term timescale than the L3 opportunity. This talk will discuss a mission concept based on the LISA baseline that resulted from a recent mission architecture study.

  15. Astronomical and space-based systems engineering

    NASA Astrophysics Data System (ADS)

    Mosser, Benoît; Abergel, Alain

    2011-06-01

    The Master's degree ``Outils et Systèmes de l'Astronomie et de l'Espace'' (OSAE, ``Astronomical and Space-based Systems Engineering'') is intended for students interested in Astronomy and Space technology. Students undergo a comprehensive training in partnership with international-level laboratories and with leading private companies. The degree provides physicists with a wide range of skills, appropriate for those whose intention is to participate in subsystems, equipment and engineering systems, and also for future project managers, working in the aerospace industry or similar technological industries or in national and European agencies. The 1-year course is given in collaboration with national and international institutions, laboratories and industries. It includes an extended training period (5 to 6 months) and a theoretical and practical specialization given by university and industrial teachers. It benefits from the network of laboratories associated with the Astronomy and Astrophysics doctorate school of the Île-de-France.

  16. Microlensing of the Broad Line Region in the Most Anomalous Lensed Quasar

    NASA Astrophysics Data System (ADS)

    Keeton, Charles

    2009-07-01

    The gravitationally lensed quasar SDSS J0924+0219 has highly anomalous flux ratios: image D is more than a factor of 10 fainter than expected if the lens galaxy has a smooth mass distribution. From previous HST spectra {Keeton et al. 2006} and photometric variability {Morgan et al. 2006} we know the anomalous continuum flux ratios are caused by microlensing by stars in the lens galaxy. However, with existing data we do not know whether the anomalous emission line flux ratios are caused by microlensing by stars or millilensing by dark matter clumps. With just four orbits we can measure spectra at two more epochs and determine unambiguously whether the quasar's broad line region {BLR} is microlensed. If the emission line flux ratios vary, that would prove the BLR is microlensed and make SDSS0924 only the second known quasar with microlensing of an optical broad emission line. In this case we would be able to constrain the BLR size and and relative densities of stars and dark matter in the lens galaxy. Conversely, if the emission line flux ratios do not vary, that would prove the BLR is millilensed rather than microlensed, and make SDSS0924 the first lens known to have both microlensing {of the continuum} and millilensing {of the BLR}. This would usher in a new and rich field of multiscale lensing. The conclusions about small-scale structure in galaxies and quasars will be exciting in either case. This experiment is infeasible with ground-based telescopes, but with HST it is easy and fast to make this powerful test of small-scale structure in SDSS0924.

  17. Effects of Kerr strong gravity on quasar x-ray microlensing

    SciTech Connect

    Chen, Bin; Dai, Xinyu; Baron, E.; Kantowski, R.

    2013-06-01

    Recent quasar microlensing observations have constrained the sizes of X-ray emission regions to be within about 10 gravitational radii of the central supermassive black hole. Therefore, the X-ray emission from lensed quasars is first strongly lensed by the black hole before it is lensed by the foreground galaxy and star fields. We present a scheme that combines the initial strong lensing of a Kerr black hole with standard linearized microlensing by intervening stars. We find that X-ray microlensed light curves incorporating Kerr strong gravity can differ significantly from standard curves. The amplitude of the fluctuations in the light curves can increase or decrease by ∼0.65-0.75 mag by including Kerr strong gravity. Larger inclination angles give larger amplitude fluctuations in the microlensing light curves. Consequently, current X-ray microlensing observations can under or overestimate the sizes of the X-ray emission regions. We estimate this bias using a simple metric based on the amplitude of magnitude fluctuations. The half-light radius of the X-ray emission region can be underestimated by up to ∼50% or overestimated by up to ∼20% depending on the spin of the black hole, the emission profile, and the inclination angle of the observer. Underestimates were found in most situations we investigated. The only exception was for a disk with large spin and a radially flat emission profile, observed nearly face-on. We thus conclude that more accurate microlensing size constraints should be obtainable by including Kerr lensing. We also find that the caustic crossing time can differ by months when Kerr strong gravity is included. A simultaneous monitoring of gravitational lensed quasars in both X-ray and optical bands with densely sampled X-ray light curves should reveal this feature. We conclude that it should be possible to constrain important parameters such as inclination angles and black hole spins from combined Kerr and microlensing effects.

  18. TIME DELAY AND ACCRETION DISK SIZE MEASUREMENTS IN THE LENSED QUASAR SBS 0909+532 FROM MULTIWAVELENGTH MICROLENSING ANALYSIS

    SciTech Connect

    Hainline, Laura J.; Morgan, Christopher W.; MacLeod, Chelsea L.; Landaal, Zachary D.; Kochanek, C. S.; Harris, Hugh C.; Tilleman, Trudy; Goicoechea, L. J.; Shalyapin, V. N.

    2013-09-01

    We present three complete seasons and two half-seasons of Sloan Digital Sky Survey (SDSS) r-band photometry of the gravitationally lensed quasar SBS 0909+532 from the U.S. Naval Observatory, as well as two seasons each of SDSS g-band and r-band monitoring from the Liverpool Robotic Telescope. Using Monte Carlo simulations to simultaneously measure the system's time delay and model the r-band microlensing variability, we confirm and significantly refine the precision of the system's time delay to {Delta}t{sub AB} = 50{sub -4}{sup +2} days, where the stated uncertainties represent the bounds of the formal 1{sigma} confidence interval. There may be a conflict between the time delay measurement and a lens consisting of a single galaxy. While models based on the Hubble Space Telescope astrometry and a relatively compact stellar distribution can reproduce the observed delay, the models have somewhat less dark matter than we would typically expect. We also carry out a joint analysis of the microlensing variability in the r and g bands to constrain the size of the quasar's continuum source at these wavelengths, obtaining log {l_brace}(r{sub s,r}/cm)[cos i/0.5]{sup 1/2}{r_brace} = 15.3 {+-} 0.3 and log {l_brace}(r{sub s,g}/cm)[cos i/0.5]{sup 1/2}{r_brace} = 14.8 {+-} 0.9, respectively. Our current results do not formally constrain the temperature profile of the accretion disk but are consistent with the expectations of standard thin disk theory.

  19. Time Delay and Accretion Disk Size Measurements in the Lensed Quasar SBS 0909+532 from Multiwavelength Microlensing Analysis

    NASA Astrophysics Data System (ADS)

    Hainline, Laura J.; Morgan, Christopher W.; MacLeod, Chelsea L.; Landaal, Zachary D.; Kochanek, C. S.; Harris, Hugh C.; Tilleman, Trudy; Goicoechea, L. J.; Shalyapin, V. N.; Falco, Emilio E.

    2013-09-01

    We present three complete seasons and two half-seasons of Sloan Digital Sky Survey (SDSS) r-band photometry of the gravitationally lensed quasar SBS 0909+532 from the U.S. Naval Observatory, as well as two seasons each of SDSS g-band and r-band monitoring from the Liverpool Robotic Telescope. Using Monte Carlo simulations to simultaneously measure the system's time delay and model the r-band microlensing variability, we confirm and significantly refine the precision of the system's time delay to \\Delta t_{AB} = 50^{+2}_{-4}\\,{days}, where the stated uncertainties represent the bounds of the formal 1σ confidence interval. There may be a conflict between the time delay measurement and a lens consisting of a single galaxy. While models based on the Hubble Space Telescope astrometry and a relatively compact stellar distribution can reproduce the observed delay, the models have somewhat less dark matter than we would typically expect. We also carry out a joint analysis of the microlensing variability in the r and g bands to constrain the size of the quasar's continuum source at these wavelengths, obtaining log {(r s, r /cm)[cos i/0.5]1/2} = 15.3 ± 0.3 and log {(r s, g /cm)[cos i/0.5]1/2} = 14.8 ± 0.9, respectively. Our current results do not formally constrain the temperature profile of the accretion disk but are consistent with the expectations of standard thin disk theory.

  20. DISCOVERY OF ENERGY-DEPENDENT X-RAY MICROLENSING IN Q2237+0305

    SciTech Connect

    Chen Bin; Dai Xinyu; Kochanek, C. S.; Blackburne, Jeffrey A.; Chartas, George; Kozlowski, Szymon

    2011-10-20

    We present our long-term Chandra X-ray monitoring data for the gravitationally lensed quasar Q2237+0305 with 20 epochs spanning 10 years. We easily detect microlensing variability between the images in the full (0.2-8 keV), soft (0.2-2 keV), and hard (2-8 keV) bands at very high confidence. We also detect, for the first time, chromatic microlensing differences between the soft and hard X-ray bands. The hard X-ray band is more strongly microlensed than the soft band, suggesting that the corona above the accretion disk thought to generate the X-rays has a non-uniform electron distribution, in which the hotter and more energetic electrons occupy more compact regions surrounding the black holes. Both the hard and soft X-ray bands are more strongly microlensed than the optical (rest-frame UV) emission, indicating that the X-ray emission is more compact than the optical, confirming the microlensing results from other lenses.

  1. The OGLE view of microlensing towards the Magellanic Clouds - III. Ruling out subsolar MACHOs with the OGLE-III LMC data

    NASA Astrophysics Data System (ADS)

    Wyrzykowski, Ł.; Kozłowski, S.; Skowron, J.; Udalski, A.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Szewczyk, O.; Ulaczyk, K.; Poleski, R.

    2011-05-01

    In the third part of the series presenting the Optical Gravitational Lensing Experiment (OGLE) microlensing studies of the dark matter halo compact objects (MACHOs), we describe results of the OGLE-III monitoring of the Large Magellanic Cloud (LMC). This unprecedented data set contains almost continuous photometric coverage over 8 years of about 35 million objects spread over 40 deg2. We report a detection of two candidate microlensing events found with the automated pipeline and an additional two, less probable, candidate events found manually. The optical depth derived for the two main candidates was calculated following a detailed blending examination and detection efficiency determination and was found to be τ= (0.16 ± 0.12) × 10-7. If the microlensing signal we observe originates from MACHOs, then it means their masses are around 0.2 M⊙ and they comprise only f= 3 ± 2 per cent of the mass of the Galactic halo. However, the more likely explanation of our detections does not involve dark matter compact objects at all and relies on the natural effect of self-lensing of LMC stars by LMC lenses. In such a scenario, we can almost completely rule out MACHOs in the subsolar mass range with an upper limit at f < 7 per cent reaching its minimum of f < 4 per cent at M= 0.1 M⊙. For masses around M= 10 M⊙, the constraints on the MACHOs are more lenient with f˜ 20 per cent. Owing to limitations of the survey, there is no reasonable limit found for heavier masses, leaving only a tiny window of mass spectrum still available for dark matter compact objects. Based on observations obtained with the 1.3-m Warsaw telescope at the Las Campanas Observatory of the Carnegie Institution of Washington.

  2. Uniform color space based on color matching

    NASA Astrophysics Data System (ADS)

    Liao, Shih-Fang; Yang, Tsung-Hsun; Lee, Cheng-Chung

    2007-09-01

    This research intends to explore with a uniform color space based on the CIE 1931 x-y chromatic coordinate system. The goal is to improve the non-uniformity of the CIE 1931 x-y chromaticity diagram such as to approach the human color sensation as possible; however, its simple methodology still can be kept. In spite of the existence of various kinds of the uniform color coordinate systems built up early (CIE u'-v', CIE Lab, CIE LUV, etc.), the establishment of a genuine uniform color space is actually still an important work both for the basic research in color science and the practical applications of colorimetry, especially for recent growing request in illumination engineering and in display technology. In this study, the MacAdam ellipses and the Munsell color chips are utilized for the comparison with the human color sensation. One specific linear transformation matrix is found for the CIE 1931 color matching functions (see manuscript) to become the novel uniform ones. With the aid of the optimization method, the transformation matrix can be easily discovered and makes the 25 MacAdam ellipses are similar to each other in the novel uniform color space. On the other hand, the perfectiveness of the equal-hue curves and the equal-chroma contours from the Mnusell color chips evaluates for the best optimization conditions among several different definitions for the similarity of all the MacAdam ellipses. Finally, the color difference between any two colors can be simply measured by the Euclidean distance in the novel uniform color space and is still fitted to the human color sensation.

  3. MICROLENSING BINARIES DISCOVERED THROUGH HIGH-MAGNIFICATION CHANNEL

    SciTech Connect

    Shin, I.-G.; Choi, J.-Y.; Park, S.-Y.; Han, C.; Gould, A.; Gaudi, B. S.; Sumi, T.; Udalski, A.; Beaulieu, J.-P.; Dominik, M.; Allen, W.; Bos, M.; Christie, G. W.; Depoy, D. L.; Dong, S.; Drummond, J.; Gal-Yam, A.; Hung, L.-W.; Janczak, J.; Kaspi, S.; Collaboration: muFUN Collaboration; MOA Collaboration; OGLE Collaboration; PLANET Collaboration; RoboNet Collaboration; MiNDSTEp Consortium; and others

    2012-02-20

    Microlensing can provide a useful tool to probe binary distributions down to low-mass limits of binary companions. In this paper, we analyze the light curves of eight binary-lensing events detected through the channel of high-magnification events during the seasons from 2007 to 2010. The perturbations, which are confined near the peak of the light curves, can be easily distinguished from the central perturbations caused by planets. However, the degeneracy between close and wide binary solutions cannot be resolved with a 3{sigma} confidence level for three events, implying that the degeneracy would be an important obstacle in studying binary distributions. The dependence of the degeneracy on the lensing parameters is consistent with a theoretical prediction that the degeneracy becomes severe as the binary separation and the mass ratio deviate from the values of resonant caustics. The measured mass ratio of the event OGLE-2008-BLG-510/MOA-2008-BLG-369 is q {approx} 0.1, making the companion of the lens a strong brown dwarf candidate.

  4. Probing the gravitational Faraday rotation using quasar X-ray microlensing.

    PubMed

    Chen, Bin

    2015-11-17

    The effect of gravitational Faraday rotation was predicted in the 1950s, but there is currently no practical method for measuring this effect. Measuring this effect is important because it will provide new evidence for correctness of general relativity, in particular, in the strong field limit. We predict that the observed degree and angle of the X-ray polarization of a cosmologically distant quasar microlensed by the random star field in a foreground galaxy or cluster lens vary rapidly and concurrently with flux during caustic-crossing events using the first simulation of quasar X-ray microlensing polarization light curves. Therefore, it is possible to detect gravitational Faraday rotation by monitoring the X-ray polarization of gravitationally microlensed quasars. Detecting this effect will also confirm the strong gravity nature of quasar X-ray emission.

  5. Probing the gravitational Faraday rotation using quasar X-ray microlensing

    PubMed Central

    Chen, Bin

    2015-01-01

    The effect of gravitational Faraday rotation was predicted in the 1950s, but there is currently no practical method for measuring this effect. Measuring this effect is important because it will provide new evidence for correctness of general relativity, in particular, in the strong field limit. We predict that the observed degree and angle of the X-ray polarization of a cosmologically distant quasar microlensed by the random star field in a foreground galaxy or cluster lens vary rapidly and concurrently with flux during caustic-crossing events using the first simulation of quasar X-ray microlensing polarization light curves. Therefore, it is possible to detect gravitational Faraday rotation by monitoring the X-ray polarization of gravitationally microlensed quasars. Detecting this effect will also confirm the strong gravity nature of quasar X-ray emission. PMID:26574051

  6. New limits on primordial black hole dark matter from an analysis of Kepler source microlensing data.

    PubMed

    Griest, Kim; Cieplak, Agnieszka M; Lehner, Matthew J

    2013-11-01

    We present new limits on the allowed masses of a dark matter (DM) halo consisting of primordial black holes (PBH) (or any other massive compact halo object). We analyze two years of data from the Kepler satellite, searching for short-duration bumps caused by gravitational microlensing. After removing background events consisting of variable stars, flare events, and comets or asteroids moving through the Kepler field, we find no microlensing candidates. We measure the efficiency of our selection criteria by adding millions of simulated microlensing lensing events into the Kepler light curves. We find that PBH DM with masses in the range 2 × 10(-9) M[Symbol: see text] to 10(-7)M[Symbol: see text] cannot make up the entirety of the DM in the Milky Way. At the low-mass end, this decreases the allowed mass range by more than an order of magnititude.

  7. Microlensing of Kepler stars as a method of detecting primordial black hole dark matter.

    PubMed

    Griest, Kim; Lehner, Matthew J; Cieplak, Agnieszka M; Jain, Bhuvnesh

    2011-12-02

    If the dark matter consists of primordial black holes (PBHs), we show that gravitational lensing of stars being monitored by NASA's Kepler search for extrasolar planets can cause significant numbers of detectable microlensing events. A search through the roughly 150,000 light curves would result in large numbers of detectable events for PBHs in the mass range 5×10(-10) M(⊙) to 10(-4) M(⊙). Nondetection of these events would close almost 2 orders of magnitude of the mass window for PBH dark matter. The microlensing rate is higher than previously noticed due to a combination of the exceptional photometric precision of the Kepler mission and the increase in cross section due to the large angular sizes of the relatively nearby Kepler field stars. We also present a new formalism for calculating optical depth and microlensing rates in the presence of large finite-source effects.

  8. VizieR Online Data Catalog: Microlensing optical depth & event rates from MOA-II (Sumi+, 2016)

    NASA Astrophysics Data System (ADS)

    Sumi, T.; Penny, M. T.

    2016-11-01

    We use the same data set as Sumi+ (2013, J/ApJ/778/150), which used the data taken in the 2006 and 2007 seasons by the MOA-II survey, with the 1.8m MOA-II telescope located at the Mt. John University Observatory, New Zealand. The centers of the 22 Galactic bulge (GB) fields of the MOA-II survey are listed in Table 1. The images were taken using the custom MOA-Red wide-band filter, which is equivalent to the sum of the standard Kron/Cousins R and I bands. Each field is divided into 80 subfields and each subfield is individually calibrated using the red clump giant (RCG) feature in each subfield CMD more precisely. The number of subfields used in the final analysis is 1536 in total and also given in Table 1 for each field. The coordinates and other properties of the subfields are listed in Table 4. The OGLE (Udalski 2003AcA....53..291U) also conducts a microlensing survey toward the GB with the 1.3m Warsaw telescope at the Las Campanas Observatory in Chile. The median seeing is about 1.3 arcsec. Most observations are taken in the standard Kron-Cousin I band with occasional observations in the Johnson V band. (1 data file).

  9. Flat Panel Space Based Space Surveillance Sensor

    NASA Astrophysics Data System (ADS)

    Kendrick, R.; Duncan, A.; Wilm, J.; Thurman, S. T.; Stubbs, D. M.; Ogden, C.

    2013-09-01

    limited telescope is, therefore, replaced by in-process integration and test as part of the PIC fabrication that substantially reduces associated schedule and cost. The low profile and low SWaP of a SPIDER system enables high resolution imaging with a payload that is similar in size and aspect ratio to a solar panel. This allows high resolution low cost options for space based space surveillance telescopes. The low SWaP design enables hosted payloads, cubesat designs as well as traditional bus options that are lower cost. We present a description of the concept and preliminary simulation and experimental data that demonstrate the imaging capabilities of the SPIDER technique.

  10. A Space Based Solar Power Satellite System

    NASA Astrophysics Data System (ADS)

    Engel, J. M.; Polling, D.; Ustamujic, F.; Yaldiz, R.; et al.

    2002-01-01

    . Based on the expected revenues from about 300 customers, SPoTS needs a significant contribution from public funding to be commercial viable. However, even though the system might seem to be a huge investment first, it provides a unique steppingstone for future space based wireless transfer of energy to the Earth. Also the public funding is considered as an interest free loan and is due to be paid back over de lifetime period of SPoTS. These features make the SPoTS very attractive in comparison to other space projects of the same science field.

  11. Galactic Distribution of Planets From High-Magnification Microlensing Events

    NASA Astrophysics Data System (ADS)

    Gould, Andrew; Yee, Jennifer; Carey, Sean

    2015-10-01

    We will use Spitzer to measure microlens parallaxes for ~14 microlensing events that are high-magnification (as seen from Earth), in order to determine the Galactic distribution of planets. Simultaneous observations from Spitzer and Earth yield parallaxes because they are separated by ~1 AU, which is of order the size of the Einstein radius projected on the observer plane. Hence, Earth and Spitzer see substantially different lightcurves for the same event. These Spitzer parallaxes enable measurements of the distances to the lenses (and their masses), which is a crucial element for measuring the Galactic distribution of planets. High-mag events are exceptionally sensitive to planets: Gould+ (2010) detected 6 planets from 13 high-mag events. However, previously it was believed impossible to measure their parallaxes using Spitzer: scheduling constraints imply a 3-10 day delay from event recognition to first observation, while high-mag events are typically recognized only 1-2 days before peak. By combining aggressive observing protocols, a completely new photometry pipeline, and new mathematical techniques, we successfully measured parallaxes for 7 events with peak magnification A>100 and another ~7 with 50

  12. Magnetic space-based field measurements

    NASA Technical Reports Server (NTRS)

    Langel, R. A.

    1981-01-01

    Because the near Earth magnetic field is a complex combination of fields from outside the Earth of fields from its core and of fields from its crust, measurements from space prove to be the only practical way to obtain timely, global surveys. Due to difficulty in making accurate vector measurements, early satellites such as Sputnik and Vanguard measured only the magnitude survey. The attitude accuracy was 20 arc sec. Both the Earth's core fields and the fields arising from its crust were mapped from satellite data. The standard model of the core consists of a scalar potential represented by a spherical harmonics series. Models of the crustal field are relatively new. Mathematical representation is achieved in localized areas by arrays of dipoles appropriately located in the Earth's crust. Measurements of the Earth's field are used in navigation, to map charged particles in the magnetosphere, to study fluid properties in the Earth's core, to infer conductivity of the upper mantels, and to delineate regional scale geological features.

  13. First Space-based Microlens Parallax Measurement of an Isolated Star: Spitzer Observations of OGLE-2014-BLG-0939

    NASA Astrophysics Data System (ADS)

    Yee, J. C.; Udalski, A.; Calchi Novati, S.; Gould, A.; Carey, S.; Poleski, R.; Gaudi, B. S.; Pogge, R. W.; Skowron, J.; Kozłowski, S.; Mróz, P.; Pietrukowicz, P.; Pietrzyński, G.; Szymański, M. K.; Soszyński, I.; Ulaczyk, K.; Wyrzykowski, Ł.

    2015-04-01

    We present the first space-based microlens parallax measurement of an isolated star. From the striking differences in the lightcurve as seen from Earth and from Spitzer (˜ 1 AU to the west), we infer a projected velocity {{\\tilde{v}}hel}˜ 250 km {{s}-1}, which strongly favors a lens in the Galactic Disk with mass M=0.23+/- 0.07 {{M}⊙ } and distance {{D}L}=3.1+/- 0.4 kpc. An ensemble of such measurements drawn from our ongoing program could be used to measure the single-lens mass function including dark objects, and also is necessary for measuring the Galactic distribution of planets since the ensemble reflects the underlying Galactic distribution of microlenses. We study the application of the many ideas to break the four-fold degeneracy first predicted by Refsdal 50 years ago. We find that this degeneracy is clearly broken, but by two unanticipated mechanisms: a weak constraint on the orbital parallax from the ground-based data and a definitive measurement of the source proper motion.

  14. Limits on the Mass and Abundance of Primordial Black Holes from Quasar Gravitational Microlensing

    NASA Astrophysics Data System (ADS)

    Mediavilla, E.; Jiménez-Vicente, J.; Muñoz, J. A.; Vives-Arias, H.; Calderón-Infante, J.

    2017-02-01

    The idea that dark matter can be made of intermediate-mass primordial black holes (PBHs) in the 10 M ⊙ ≲ M ≲ 200 M ⊙ range has recently been reconsidered, particularly in the light of the detection of gravitational waves by the LIGO experiment. The existence of even a small fraction of dark matter in black holes should nevertheless result in noticeable quasar gravitational microlensing. Quasar microlensing is sensitive to any type of compact objects in the lens galaxy, to their abundance, and to their mass. We have analyzed optical and X-ray microlensing data from 24 gravitationally lensed quasars to estimate the abundance of compact objects in a very wide range of masses. We conclude that the fraction of mass in black holes or any type of compact objects is negligible outside of the 0.05 M ⊙ ≲ M ≲ 0.45 M ⊙ mass range and that it amounts to 20% ± 5% of the total matter, in agreement with the expected masses and abundances of the stellar component. Consequently, the existence of a significant population of intermediate-mass PBHs appears to be inconsistent with current microlensing observations. Therefore, primordial massive black holes are a very unlikely source of the gravitational radiation detected by LIGO.

  15. Digital holographic characterization of liquid microlenses array fabricated in electrode-less configuration

    NASA Astrophysics Data System (ADS)

    Miccio, L.; Vespini, V.; Grilli, S.; Paturzo, M.; Finizio, A.; De Nicola, S.; Ferraro, P.

    2009-06-01

    We show how thin liquid film on polar dielectric substrate can form an array of liquid micro-lenses. The effect is driven by the pyroelectric effect leading to a new concept in electro-wetting (EW). EW is a viable method for actuation of liquids in microfluidic systems and requires the design and fabrication of complex electrodes for suitable actuation of liquids. When compared to conventional electrowetting devices, the pyroelectric effect allowed to have an electrode-less and circuitless configuration. In our case the surface electric charge induced by the thermal stimulus is able to pattern selectively the surface wettability according to geometry of the ferroelectric domains micro-engineered into the lithium niobate crystal. We show that different geometries of liquid microlenses can be obtained showing also a tuneability of the focal lenses down to 1.6 mm. Thousand of liquid microlenses, each with 100 μm diameter, can be formed and actuated. Also different geometries such as hemi-cylindrical and toroidal liquid structures can be easily obtained. By means of a digital holography method, an accurate characterization of the micro-lenses curvature is performed and presented. The preliminary results concerning the imaging capability of the micro-lens array are also reported. Microlens array can find application in medical stereo-endoscopy, imaging, telecommunication and optical data storage too.

  16. Using HST to Detect Isolated Black Holes and Neutron Stars through Astrometric Microlensing

    NASA Astrophysics Data System (ADS)

    Sahu, Kailash C.; Albrow, M.; Anderson, J.; Bond, H. E.; Bond, I.; Brown, T. M.; Casertano, S.; Dominik, M.; Ferguson, H. C.; Fryer, C.; Livio, M.; Mao, S.; Perrott, Y.; Udalski, A.; Yock, P.

    2012-05-01

    To date, Black Hole (BH) and Neutron Star (NS) masses have been directly measured only in binaries; no isolated stellar-mass BH has been detected unambiguously within our Galaxy. We have underway a large, 3-year HST program (192 orbits) designed to detect microlensing events caused by non-luminous isolated BHs and NSs in the direction of the Galactic bulge. Our program consists of monitoring of 12 fields in the Sagittarius window of the Galactic bulge, containing a total of 1.5 million stars down to V=28. Our observations have a typical cadence of one observation every two weeks, and are primarily targeted towards detecting microlensing events caused by non-luminous isolated BHs and NSs in the Galactic disk and bulge. The unique capability of HST imaging for microlensing observations is the addition of high-precision astrometry, allowing detection of the astrometric shift of the source during the event. Combined with the lens parallax, which can be determined from the light curve as measured by HST (and supplemented by GEMINI) observations, the astrometric shift provides a direct measurement of the lens mass. Our program is optimized to detect long-duration events, which are more likely to be caused by massive lenses. We expect to detect a few dozen long-duration microlensing events, of which 45% will show astrometric deflections, leading to direct determinations of the lens masses.

  17. RTT-150 detected the new brightening of the Gaia16aye binary microlensing system

    NASA Astrophysics Data System (ADS)

    Khamitov, I.; Bikmaev, I.; Burenin, R.; Grebenev, S.; Tkachenko, A.; Irtuganov, E.; Melnikov, S.; Sakhibullin, N.; Pavlinsky, M.; Sunyaev, R.; Esenoglu, H.; Koseoglu, D.; Bakis, V.; Sipahi, E.

    2016-11-01

    The 1.5-m Russian-Turkish optical telescope RTT-150 (Antalya, Turkey) monitored the Galactic transient Gaia16aye, suspected to be the first binary microlensing event ever discovered towards the Galactic Plane (ATel #9376, #9507), since Sep. 25, 2016.

  18. Gradient-index microlenses: numerical investigation of different spherical index profiles with the wave propagation method.

    PubMed

    Singer, W; Testorf, M; Brenner, K H

    1995-05-01

    Ion-exchange microlenses are available with different gradient-index profiles. We investigate the dependence of the imaging properties on the steepness of the index profiles. Therefore we model the index distribution by the Fermi function as radial distribution with spherical symmetry. The results are compared to index profiles according to the Doremus model.

  19. Spectroscopic characterisation of microlensing events. Towards a new interpretation of OGLE-2011-BLG-0417

    NASA Astrophysics Data System (ADS)

    Santerne, A.; Beaulieu, J.-P.; Rojas Ayala, B.; Boisse, I.; Schlawin, E.; Almenara, J.-M.; Batista, V.; Bennett, D.; Díaz, R. F.; Figueira, P.; James, D. J.; Herter, T.; Lillo-Box, J.; Marquette, J. B.; Ranc, C.; Santos, N. C.; Sousa, S. G.

    2016-11-01

    The microlensing event OGLE-2011-BLG-0417 is an exceptionally bright lens binary that was predicted to present radial velocity variation at the level of several km s-1. Pioneer radial velocity follow-up observations with the UVES spectrograph at the ESO-VLT of this system clearly ruled out the large radial velocity variation, leaving a discrepancy between the observation and the prediction. In this paper, we further characterise the microlensing system by analysing its spectral energy distribution (SED) derived using the UVES spectrum and new observations with the ARCoIRIS (CTIO) near-infrared spectrograph and the Keck adaptive optics instrument NIRC2 in the J, H, and Ks-bands. We determine the mass and distance of the stars independently from the microlensing modelling. We find that the SED is compatible with a giant star in the Galactic bulge and a foreground star with a mass of 0.94 ± 0.09 M⊙ at a distance of 1.07 ± 0.24 kpc. We find that this foreground star is likely the lens. Its parameters are not compatible with the ones previously reported in the literature (0.52 ± 0.04 M⊙ at 0.95 ± 0.06 kpc), based on the microlensing light curve. A thoughtful re-analysis of the microlensing event is mandatory to fully understand the reason of this new discrepancy. More importantly, this paper demonstrates that spectroscopic follow-up observations of microlensing events are possible and provide independent constraints on the parameters of the lens and source stars, hence breaking some degeneracies in the analysis. UV-to-NIR low-resolution spectrographs like X-shooter (ESO-VLT) could substantially contribute to this follow-up efforts, with magnitude limits above all microlensing events detected so far. Based on observations made with ESO Telescope at the Paranal Observatory under program ID 092.C-0763(A) and 093.C-0532(A).Based on observations at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, which is operated by the Association of

  20. Gravitational lens system SDSS J1339+1310: microlensing factory and time delay

    NASA Astrophysics Data System (ADS)

    Goicoechea, L. J.; Shalyapin, V. N.

    2016-12-01

    We spectroscopically re-observed the gravitational lens system SDSS J1339+1310 using OSIRIS on the GTC. We also monitored the r-band variability of the two quasar images (A and B) with the LT over 143 epochs in the period 2009-2016. These new data in both the wavelength and time domains have confirmed that the system is an unusual microlensing factory. The C iv emission line is remarkably microlensed, since the microlensing magnification of B relative to that for A, μBA, reaches a value of 1.4 ( 0.4 mag) for its core. Moreover, the B image shows a red wing enhancement of C iv flux (relative to A), and μBA = 2 (0.75 mag) for the C iv broad-line emission. Regarding the nuclear continuum, we find a chromatic behaviour of μBA, which roughly varies from 5 (1.75 mag) at 7000 Å to 6 (1.95 mag) at 4000 Å. We also detect significant microlensing variability in the r band, and this includes a number of microlensing events on timescales of 50-100 d. Fortunately, the presence of an intrinsic 0.7 mag dip in the light curves of A and B, permitted us to measure the time delay between both quasar images. This delay is ΔtAB = 47 d (1σ confidence interval; A is leading), in good agreement with predictions of lens models. Tables 1-3 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/596/A77

  1. The first radial velocity measurements of a microlensing event: no evidence for the predicted binary⋆

    NASA Astrophysics Data System (ADS)

    Boisse, I.; Santerne, A.; Beaulieu, J.-P.; Fakhardji, W.; Santos, N. C.; Figueira, P.; Sousa, S. G.; Ranc, C.

    2015-10-01

    The gravitational microlensing technique allows the discovery of exoplanets around stars distributed in the disk of the galaxy towards the bulge. The alignment of two stars that led to the discovery is unique over the timescale of a human life, however, and cannot be re-observed. Moreover, the target host is often very faint and located in a crowded region. These difficulties hamper and often make impossible the follow up of the target and study of its possible companions. A radial-velocity curve was predicted for the binary system, OGLE-2011-BLG-0417, discovered and characterised from a microlensing event. We used the UVES spectrograph mounted at the VLT, ESO to derive precise radial-velocity measurements of OGLE-2011-BLG-0417. To gather high-precision radial velocities on faint targets of microlensing events, we proposed to use the source star as a reference to measure the lens radial velocities. We obtained ten radial velocities on the putative V = 18 lens with a dispersion of ~100 m s-1, spread over one year. Our measurements do not confirm the microlensing prediction for this binary system. The most likely scenario is that the putative V = 18 mag lens is actually a blend and not the primary lens which is 2 mag fainter. Further observations and analyses are needed to understand the microlensing observation and infer on the nature and characteristics of the lens itself. Based on observations made with ESO Telescope at the Paranal Observatory under program ID 092.C-0763(A) and 093.C-0532(A).Appendix A is available in electronic form at http://www.aanda.org

  2. Combined Space-Based Observations of Geostationary Satellites

    NASA Astrophysics Data System (ADS)

    Scott, R.; Bernard, K.; Thorsteinson, S.

    2016-09-01

    One of the Space Situational Awareness (SSA) science experiments of the NEOSSat mission is to learn the practicalities of combining space-based metric observations with the Sapphire system. To answer this question, an experiment was performed observing clustered Canadian geostationary satellites using both Sapphire and NEOSSat in early 2016. Space-based tracking data was collected during tracking intervals where both NEOSSat and Sapphire had visibility on the geostationary objects enabling astrometric (orbit determination) and photometric (object characterization) observations to be performed. We describe the orbit determination accuracies using live data collected from orbit for different collection cases; a) NEOSSat alone, b) Sapphire alone, and c) Combined observations from both platforms. We then discuss the practicalities of using space-based sensors to reduce risk of orbital collisions of Canadian geostationary satellites by proactively tasking space based sensors in response to conjunction data warnings in GEO.

  3. Self-aligned process for forming microlenses at the tips of vertical silicon nanowires by atomic layer deposition

    SciTech Connect

    Dan, Yaping Chen, Kaixiang; Crozier, Kenneth B.

    2015-01-01

    The microlens is a key enabling technology in optoelectronics, permitting light to be efficiently coupled to and from devices such as image sensors and light-emitting diodes. Their ubiquitous nature motivates the development of new fabrication techniques, since existing methods face challenges as microlenses are scaled to smaller dimensions. Here, the authors demonstrate the formation of microlenses at the tips of vertically oriented silicon nanowires via a rapid atomic layer deposition process. The nature of the process is such that the microlenses are centered on the nanowires, and there is a self-limiting effect on the final sizes of the microlenses arising from the nanowire spacing. Finite difference time domain electromagnetic simulations are performed of microlens focusing properties, including showing their ability to enhance visible-wavelength absorption in silicon nanowires.

  4. OGLE-2013-BLG-0578L: A Microlensing Binary Composed of a Brown Dwarf and an M Dwarf

    NASA Astrophysics Data System (ADS)

    Park, H.; Udalski, A.; Han, C.; Poleski, R.; Skowron, J.; Kozłowski, S.; Wyrzykowski, Ł.; Szymański, M. K.; Pietrukowicz, P.; Pietrzyński, G.; Soszyński, I.; Ulaczyk, K.; OGLE Collaboration

    2015-06-01

    Determining the physical parameters of binary microlenses is hampered by the lack of information about the angular Einstein radius due to the difficulty involved in resolving caustic crossings. In this paper, we present an analysis of the binary microlensing event OGLE-2013-BLG-0578, for which the caustic exit was precisely predicted in advance from real-time analysis, enabling us to densely resolve the caustic crossing and to measure the Einstein radius. From the mass measurement of the lens system based on the Einstein radius, combined with additional information about the lens parallax, we determine that the lens is a binary composed of a late-type M dwarf primary and a substellar brown dwarf companion. This event demonstrates the capability of current real-time microlensing modeling and the usefulness of microlensing for detecting and characterizing faint or dark objects in the Galaxy.

  5. Prospects for Observing Ultracompact Binaries with Space-Based Gravitational Wave Interferometers and Optical Telescopes

    NASA Technical Reports Server (NTRS)

    Littenberg, T. B.; Larson, S. L.; Nelemans, G.; Cornish, N. J.

    2012-01-01

    Space-based gravitational wave interferometers are sensitive to the galactic population of ultracompact binaries. An important subset of the ultracompact binary population are those stars that can be individually resolved by both gravitational wave interferometers and electromagnetic telescopes. The aim of this paper is to quantify the multimessenger potential of space-based interferometers with arm-lengths between 1 and 5 Gm. The Fisher information matrix is used to estimate the number of binaries from a model of the Milky Way which are localized on the sky by the gravitational wave detector to within 1 and 10 deg(exp 2) and bright enough to be detected by a magnitude-limited survey.We find, depending on the choice ofGW detector characteristics, limiting magnitude and observing strategy, that up to several hundred gravitational wave sources could be detected in electromagnetic follow-up observations.

  6. Stellar, Remnant, Planetary, and Dark-Object Masses from Astrometric Microlensing

    NASA Technical Reports Server (NTRS)

    Gould, Andrew P.; Bennett, David P.; Boden, Andrew; Depoy, Darren L.; Gaudi, Scott B.; Griest, Kim; Han, Cheongho; Paczynski, Bohdan; Reid, I. Neill

    2004-01-01

    The primary goal of our project is to make a complete census of the stellar population of the Galaxy. We are broadening the term stellar here to include both ordinary stars and dark stars. Ordinary stars, burning their nuclear fuel and shining, can perhaps best be studied with traditional astronomical techniques, but dark stars, by which we include old brown dwarfs, black holes, old white dwarfs, neutron stars, and perhaps exotic objects such as mirror matter stars or primordial black holes, can only be studied by their gravitational effects. Traditionally, these objects have been probed in binaries, and thus selected in a way that may or may not be representative of their respective field populations. The only way to examine the field population of these stars is through microlensing, the deflection of light from a visible star in the background by an object (dark or not) in the foreground. When lensed, there are two images of the background star. Although these images cannot be resolved when the lens has a stellar mass, the lensing effect can be detected in two ways: photometrically, i.e. by measuring the magnification of the source by the lens, and astrometrically, i.e. by measuring the shift in the centroid of the two images. Photometric microlensing experiments have detected hundreds of microlensing events over the past decade. Despite its successes, photometric microlensing has so far been somewhat frustrating because these events are difficult to interpret. Almost nothing is known about the masses of individual lenses and very little is known about the statistical properties of the lenses treated as a whole, such as their average mass. Although probably over 100 of the lenses are in fact dark objects, we can't determine which they are, let alone investigate finer details such as what their masses are, and where they are in the Galaxy. With SIM, we will break the microlensing degeneracy, and allow detailed interpretation of individual microlensing events. We

  7. A super-jupiter orbiting a late-type star: A refined analysis of microlensing event OGLE-2012-BLG-0406

    SciTech Connect

    Tsapras, Y.; Street, R. A.; Choi, J.-Y.; Han, C.; Bozza, V.; Gould, A.; Dominik, M.; Browne, P.; Horne, K.; Hundertmark, M.; Beaulieu, J.-P.; Udalski, A.; Jørgensen, U. G.; Sumi, T.; Bramich, D. M.; Kains, N.; Ipatov, S.; Alsubai, K. A.; Snodgrass, C.; Steele, I. A.; Collaboration: RoboNet Collaboration; MiNDSTEp Collaboration; OGLE Collaboration; PLANET Collaboration; μFUN Collaboration; MOA Collaboration; and others

    2014-02-10

    We present a detailed analysis of survey and follow-up observations of microlensing event OGLE-2012-BLG-0406 based on data obtained from 10 different observatories. Intensive coverage of the light curve, especially the perturbation part, allowed us to accurately measure the parallax effect and lens orbital motion. Combining our measurement of the lens parallax with the angular Einstein radius determined from finite-source effects, we estimate the physical parameters of the lens system. We find that the event was caused by a 2.73 ± 0.43 M {sub J} planet orbiting a 0.44 ± 0.07 M {sub ☉} early M-type star. The distance to the lens is 4.97 ± 0.29 kpc and the projected separation between the host star and its planet at the time of the event is 3.45 ± 0.26 AU. We find that the additional coverage provided by follow-up observations, especially during the planetary perturbation, leads to a more accurate determination of the physical parameters of the lens.

  8. Future Photovoltaic Power Generation for Space-Based Power Utilities

    NASA Astrophysics Data System (ADS)

    Bailey, S.; Landis, G.; Raffaelle, R.; Hepp, A.

    2002-01-01

    A recent NASA program, Space Solar Power Exploratory Research and Technology (SERT), investigated the technologies needed to provide cost-competitive ground baseload electrical power from space based solar energy conversion. This goal mandated low cost, light weight gigawatt (GW) power generation. Investment in solar power generation technologies would also benefit high power military, commercial and science missions. These missions are generally those involving solar electric propulsion, surface power systems to sustain an outpost or a permanent colony on the surface of the moon or mars, space based lasers or radar, or as large earth orbiting power stations which can serve as central utilities for other orbiting spacecraft, or as in the SERT program, potentially beaming power to the earth itself. This paper will discuss requirements for the two latter options, the current state of the art of space solar cells, and a variety of both evolving thin film cells as well as new technologies which may impact the future choice of space solar cells for a high power mission application. The space world has primarily transitioned to commercially available III-V (GaInP/GaAs/Ge) cells with 24-26% air mass zero (AMO) efficiencies. Research in the III-V multi-junction solar cells has focused on fabricating either lattice-mismatched materials with optimum stacking bandgaps or new lattice matched materials with optimum bandgaps. In the near term this will yield a 30% commercially available space cell and in the far term possibly a 40% cell. Cost reduction would be achieved if these cells could be grown on a silicon rather than a germanium substrate since the substrate is ~65% of the cell cost or, better yet, on a polyimide or possibly a ceramic substrate. An overview of multi-junction cell characteristics will be presented here. Thin film cells require substantially less material and have promised the advantage of large area, low cost manufacturing. However, space cell requirements

  9. Red Noise Versus Planetary Interpretations in the Microlensing Event Ogle-2013-BLG-446

    NASA Astrophysics Data System (ADS)

    Bachelet, E.; Bramich, D. M.; Han, C.; Greenhill, J.; Street, R. A.; Gould, A.; D'Ago, G.; AlSubai, K.; Dominik, M.; Figuera Jaimes, R.; Horne, K.; Hundertmark, M.; Kains, N.; Snodgrass, C.; Steele, I. A.; Tsapras, Y.; RoboNet Collaboration; Albrow, M. D.; Batista, V.; Beaulieu, J.-P.; Bennett, D. P.; Brillant, S.; Caldwell, J. A. R.; Cassan, A.; Cole, A.; Coutures, C.; Dieters, S.; Dominis Prester, D.; Donatowicz, J.; Fouqué, P.; Hill, K.; Marquette, J.-B.; Menzies, J.; Pere, C.; Ranc, C.; Wambsganss, J.; Warren, D.; PLANET Collaboration; de Almeida, L. Andrade; Choi, J.-Y.; DePoy, D. L.; Dong, S.; Hung, L.-W.; Hwang, K.-H.; Jablonski, F.; Jung, Y. K.; Kaspi, S.; Klein, N.; Lee, C.-U.; Maoz, D.; Muñoz, J. A.; Nataf, D.; Park, H.; Pogge, R. W.; Polishook, D.; Shin, I.-G.; Shporer, A.; Yee, J. C.; μFUN Collaboration; Abe, F.; Bhattacharya, A.; Bond, I. A.; Botzler, C. S.; Freeman, M.; Fukui, A.; Itow, Y.; Koshimoto, N.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Ohnishi, K.; Philpott, L. C.; Rattenbury, N.; Saito, To.; Sullivan, D. J.; Sumi, T.; Suzuki, D.; Tristram, P. J.; Yonehara, A.; MOA Collaboration; Bozza, V.; Calchi Novati, S.; Ciceri, S.; Galianni, P.; Gu, S.-H.; Harpsøe, K.; Hinse, T. C.; Jørgensen, U. G.; Juncher, D.; Korhonen, H.; Mancini, L.; Melchiorre, C.; Popovas, A.; Postiglione, A.; Rabus, M.; Rahvar, S.; Schmidt, R. W.; Scarpetta, G.; Skottfelt, J.; Southworth, John; Stabile, An.; Surdej, J.; Wang, X.-B.; Wertz, O.; MiNDSTEp Collaboration

    2015-10-01

    For all exoplanet candidates, the reliability of a claimed detection needs to be assessed through a careful study of systematic errors in the data to minimize the false positives rate. We present a method to investigate such systematics in microlensing data sets using the microlensing event OGLE-2013-BLG-0446 as a case study. The event was observed from multiple sites around the world and its high magnification (Amax ˜ 3000) allowed us to investigate the effects of terrestrial and annual parallax. Real-time modeling of the event while it was still ongoing suggested the presence of an extremely low-mass companion (˜3M⊕) to the lensing star, leading to substantial follow-up coverage of the light curve. We test and compare different models for the light curve and conclude that the data do not favor the planetary interpretation when systematic errors are taken into account.

  10. Preparation of plastic spherical microlenses by use of a fluoropolymer stencil and oil-bath heating.

    PubMed

    Tamura, Hiromoto; Kojima, Ryousuke; Usui, Hiroaki

    2003-07-01

    A new method for fabricating plastic spherical microlenses was developed, which allowed self-alignment of lenses and self-organized formation of a spherical shape. First a low-surface-energy fluoropolymer thin film was deposited and patterned as a stencil. Then photosensitive phenol resin was patterned on it as the lens material. Finally the resin was annealed in an oil bath to form a sphere. The molten phenol resin spontaneously formed a sphere and positioned itself in the center of the fluoropolymer ring pattern as a result of the difference of surface free energy and the equivalently zero-gravity condition in the oil bath. When a light-emitting-diode printer head was loaded with spherical microlenses, its optical output increased by 1 order of magnitude.

  11. RED NOISE VERSUS PLANETARY INTERPRETATIONS IN THE MICROLENSING EVENT OGLE-2013-BLG-446

    SciTech Connect

    Bachelet, E.; Bramich, D. M.; AlSubai, K.; Han, C.; Greenhill, J.; Street, R. A.; Tsapras, Y.; Gould, A.; Batista, V.; D’Ago, G.; Dominik, M.; Jaimes, R. Figuera; Horne, K.; Hundertmark, M.; Kains, N.; Snodgrass, C.; Steele, I. A.; Albrow, M. D.; Beaulieu, J.-P.; Bennett, D. P. E-mail: p.yock@auckland.ac.nz E-mail: abe@stelab.nagoya-u.ac.jp E-mail: itow@stelab.nagoya-u.ac.jp; Collaboration: RoboNet collaboration; PLANET collaboration; μFUN collaboration; MOA collaboration; MiNDSTEp collaboration; and others

    2015-10-20

    For all exoplanet candidates, the reliability of a claimed detection needs to be assessed through a careful study of systematic errors in the data to minimize the false positives rate. We present a method to investigate such systematics in microlensing data sets using the microlensing event OGLE-2013-BLG-0446 as a case study. The event was observed from multiple sites around the world and its high magnification (A{sub max} ∼ 3000) allowed us to investigate the effects of terrestrial and annual parallax. Real-time modeling of the event while it was still ongoing suggested the presence of an extremely low-mass companion (∼3M{sub ⨁}) to the lensing star, leading to substantial follow-up coverage of the light curve. We test and compare different models for the light curve and conclude that the data do not favor the planetary interpretation when systematic errors are taken into account.

  12. Characteristics of stand-alone microlenses in fiber-based fluorescence imaging applications.

    PubMed

    Mirkhalaf, M; Murukeshan, V M; Tor, Shu Beng; Shinoj, V K; Sathiyamoorthy, K

    2011-04-01

    Microlens-ended fibers, which have found tremendous interest in the recent past, find potential biomedical applications, in particular, in endoscopic imaging. The work presented in this paper focuses on the stand-alone microlenses along with custom-fabricated specialty optical fiber, such as imaging fiber, for probe imaging applications. Stand-alone self-aligned microlenses have been fabricated employing microcompression molding and then attached at the end facet of imaging fiber. A detailed characterization of the fabricated microlens is carried and it demonstrates appropriate focusing ability, high fluorescence collection efficiency and imaging ability for biomedical applications. The surface roughness of the microlens is found to be 25 nm with a minimum spot size of 38 μm. The probe imaging system is found to be able to image the fluorescence microspheres of 10 μm size. The collection efficiency of the fiber probe with lens found to be enhanced by three times approximately.

  13. An efficient method to compute microlensed light curves for point sources

    NASA Technical Reports Server (NTRS)

    Witt, Hans J.

    1993-01-01

    We present a method to compute microlensed light curves for point sources. This method has the general advantage that all microimages contributing to the light curve are found. While a source moves along a straight line, all micro images are located either on the primary image track or on the secondary image tracks (loops). The primary image track extends from - infinity to + infinity and is made of many sequents which are continuously connected. All the secondary image tracks (loops) begin and end on the lensing point masses. The method can be applied to any microlensing situation with point masses in the deflector plane, even for the overcritical case and surface densities close to the critical. Furthermore, we present general rules to evaluate the light curve for a straight track arbitrary placed in the caustic network of a sample of many point masses.

  14. Precision compression molding of glass microlenses and microlens arrays--an experimental study.

    PubMed

    Firestone, G C; Yi, A Y

    2005-10-10

    An innovative manufacturing process utilizing high-temperature compression molding to fabricate aspherical microlenses by using optical glasses, such as BK7, K-PG325, and soda-lime glass, is investigated. In a departure from conventional approaches, a unique hollow contactless mold design is adopted. Polished glass substrates and the mold assembly are heated above the glass transition temperature first, followed by initial forming, then annealing. The forming rate is controlled in real time to ensure mold position accuracy. Mold materials used include tungsten carbides, 316 stainless steel, 715 copper nickel, and aluminum alloys. The geometric control of the microlenses or microlens arrays can be precisely controlled by the forming temperature, forming speed, mold design, and annealing time.

  15. Confirmation of the Planetary Origin of the Gravitational Microlensing Event OGLE-2006-BLG-0169

    NASA Astrophysics Data System (ADS)

    Barry, Richard K.; Bennett, David P.; Bhattacharya, Aparna; Anderson, Jay; Bond, Ian; Anderson, Nyki; Batista, Virgini; Beaulieu, Jean-philippe; Depoy, Darren L.; Dong, Subo; Gaudi, B. Scott; Gould, Andrew; Gilbert, Emily; Pfeifle, Ryan; Pogge, Richard W.; Terry, Sean; Udalski, Andrzej

    2016-01-01

    We present Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) observations of the source and lens stars for planetary microlensing event OGLE-2005-BLG-169, which confirm the relative proper motion prediction due to the planetary light curve signal observed for this event. This (and the companion Keck result) provide the first confirmation of a planetary microlensing signal, for which the deviation was only 2%. The follow-up observations determine the flux of the planetary host star in multiple passbands and remove light curve model ambiguity caused by sparse sampling of part of the light curve. This leads to a precise determination of the properties of the OGLE-2005-BLG-169Lb planetary system.

  16. A NEW MICROLENSING EVENT IN THE DOUBLY IMAGED QUASAR Q 0957+561

    SciTech Connect

    Hainline, Laura J.; Morgan, Christopher W.; Beach, Joseph N.; Le, Truong X.; Kochanek, C. S.; Harris, Hugh C.; Tilleman, Trudy; Fadely, Ross; Falco, Emilio E. E-mail: cmorgan@usna.edu E-mail: m113678@usna.edu E-mail: hch@nofs.navy.mil E-mail: rfadely@haverford.edu

    2012-01-10

    We present evidence for ultraviolet/optical microlensing in the gravitationally lensed quasar Q 0957+561. We combine new measurements from our optical monitoring campaign at the United States Naval Observatory, Flagstaff, with measurements from the literature and find that the time-delay-corrected r-band flux ratio m{sub A} - m{sub B} has increased by {approx}0.1 mag over a period of five years beginning in the fall of 2005. We apply our Monte Carlo microlensing analysis procedure to the composite light curves, obtaining a measurement of the optical accretion disk size, log ((r{sub s} /cm)[cos (i)/0.5]{sup 1/2}) = 16.2 {+-} 0.5, that is consistent with the quasar accretion disk size-black hole mass relation.

  17. A simple focal-length measurement technique for adaptive microlenses using z-scan

    NASA Astrophysics Data System (ADS)

    Abdelaziez, Yasser; Banerjee, Partha P.

    2004-10-01

    A simple technique for focal length measurements of adaptive micro-lenses using z-scan is reported. Focal length is one of the most important parameters of any lens. The effective focal length is measured with reference to the principal points that are not easy to find especially for micro-lenses. In addition, variable focal length microlenses pose a different challenge that makes the process of determining their exact focal length a tedious and difficult process. Classical methods such as nodal slide and magnification have been used for focal length determination. Also, advanced Interference techniques such as Talbot, Moire, Digital Speckle, Zygo and Joint Fourier Transform were used for focal length measurements. These techniques require more elaborate setups and difficult to implement, especially for microlenses. Recently a power meter was used to find the focal length of an unknown lens. Most of the techniques mentioned above proof to be not simple for microlens characterization. The z-scan technique has been implemented, for quite sometimes, to characterize the third-order effects of a nonlinear optical material. The z-scan provides information on both the sign and magnitude of the non-linear refractive index and offer advantage of simplicity. We have used a regular lens to collimate and focus light unto the lens under test. By scanning the lens under test and measuring the on-axis intensity, one can find the focal length. This is because the on-axis intensity is proportional to the phase of the lens and therefore the focal length. In the case of an adaptive lens with its focal length is a function of the applied voltage, the scanning occurs for each voltage value that will correspond to the on-axis refractive index change and therefore the far field on-axis intensity. This described technique above is easy to implement and can achieve good accuracy due to the inherent sensitivity of the z-scan.

  18. REVEALING THE STRUCTURE OF AN ACCRETION DISK THROUGH ENERGY-DEPENDENT X-RAY MICROLENSING

    SciTech Connect

    Chartas, G.; Moore, D.; Kochanek, C. S.; Mosquera, A. M.; Blackburne, J. A.; Dai, X.

    2012-10-01

    We present results from monitoring observations of the gravitationally lensed quasar RX J1131-1231 performed with the Chandra X-Ray Observatory. The X-ray observations were planned with relatively long exposures that allowed a search for energy-dependent microlensing in the soft (0.2-2 keV) and hard (2-10 keV) light curves of the images of RX J1131-1231. We detect significant microlensing in the X-ray light curves of images A and D, and energy-dependent microlensing of image D. The magnification of the soft band appears to be larger than that in the hard band by a factor of {approx}1.3 when image D becomes more magnified. This can be explained by the difference between a compact, softer-spectrum corona that is producing a more extended, harder spectrum reflection component off the disk. This is supported by the evolution of the fluorescent iron line in image D over three consecutive time-averaged phases of the light curve. In the first period, an Fe line at E = 6.35{sup +0.14}{sub -0.14} keV is detected (at >99% confidence). In the second period, two Fe lines are detected, one at E = 5.50{sup +0.03}{sub -0.08} keV (detected at >99% confidence) and another at E = 6.04{sup +0.10}{sub -0.07} keV (marginally detected at >90% confidence), and in the third period, a broadened Fe line at 6.42{sup +0.16}{sub -0.14} keV is detected (at >99% confidence). This evolution of the Fe line profile during the microlensing event is consistent with the line distortion expected when a caustic passes over the inner disk where the shape of the fluorescent Fe line is distorted by general relativistic and Doppler effects.

  19. Detection of the 4th caustic crossing in the Gaia16aye binary microlensing system

    NASA Astrophysics Data System (ADS)

    Khamitov, I.; Bikmaev, I.; Burenin, R.; Grebenev, S.; Tanriver, M.; Avci, A.; Kaynar, S.; Gumus, D.; Kocak, M.; Ãzisik, T.; Dindar, M.; Esenoglu, H.; Kirbiyik, H.; Okuyan, O.; Saygac, T.; Semena, A.; Tkachenko, A.; Irtuganov, E.; Melnikov, S.; Pavlinsky, M.; Sakhibullin, N.; Sunyaev, R.

    2016-11-01

    Following the brightening recently detected in the direction of the Gaia16aye binary microlensing system (ATel #9753) and the subsequent prediction for it of the close caustic crossing (ATel #9770) we organized regular observations of the system with the RTT-150 and T-100 telescopes (Antalya, Turkey) and detected the caustic crossing on Nov. 21, 2016, at 17:54 UTC (JD 2457714.246).

  20. Space-based aperture array for ultra-long wavelength radio astronomy

    NASA Astrophysics Data System (ADS)

    Rajan, Raj Thilak; Boonstra, Albert-Jan; Bentum, Mark; Klein-Wolt, Marc; Belien, Frederik; Arts, Michel; Saks, Noah; van der Veen, Alle-Jan

    2016-02-01

    The past decade has seen the advent of various radio astronomy arrays, particularly for low-frequency observations below 100 MHz. These developments have been primarily driven by interesting and fundamental scientific questions, such as studying the dark ages and epoch of re-ionization, by detecting the highly red-shifted 21 cm line emission. However, Earth-based radio astronomy observations at frequencies below 30 MHz are severely restricted due to man-made interference, ionospheric distortion and almost complete non-transparency of the ionosphere below 10 MHz. Therefore, this narrow spectral band remains possibly the last unexplored frequency range in radio astronomy. A straightforward solution to study the universe at these frequencies is to deploy a space-based antenna array far away from Earths' ionosphere. In the past, such space-based radio astronomy studies were principally limited by technology and computing resources, however current processing and communication trends indicate otherwise. Furthermore, successful space-based missions which mapped the sky in this frequency regime, such as the lunar orbiter RAE-2, were restricted by very poor spatial resolution. Recently concluded studies, such as DARIS (Disturbuted Aperture Array for Radio Astronomy In Space) have shown the ready feasibility of a 9 satellite constellation using off the shelf components. The aim of this article is to discuss the current trends and technologies towards the feasibility of a space-based aperture array for astronomical observations in the Ultra-Long Wavelength (ULW) regime of greater than 10 m i.e., below 30 MHz. We briefly present the achievable science cases, and discuss the system design for selected scenarios such as extra-galactic surveys. An extensive discussion is presented on various sub-systems of the potential satellite array, such as radio astronomical antenna design, the on-board signal processing, communication architectures and joint space-time estimation of the

  1. Technology for a NASA Space-Based Science Operations Grid

    NASA Technical Reports Server (NTRS)

    Bradford, Robert N.; Redman, Sandra H.

    2003-01-01

    This viewgraph representation presents an overview of a proposal to develop a space-based operations grid in support of space-based science experiments. The development of such a grid would provide a dynamic, secure and scalable architecture based on standards and next-generation reusable software and would enable greater science collaboration and productivity through the use of shared resources and distributed computing. The authors propose developing this concept for use on payload experiments carried aboard the International Space Station. Topics covered include: grid definitions, portals, grid development and coordination, grid technology and potential uses of such a grid.

  2. Intelligibility and Space-based Voice with Relaxed Delay Constraints

    NASA Technical Reports Server (NTRS)

    Nguyen, Sam; Okino, Clayton; Cheng, Michael

    2008-01-01

    The inherent aspects and flaws surrounding space based communication is technically described and the math surrounding encoding and decoding LT Codes is examined. Utilizing LT codes as a means of reducing packet erasures due to corrupted packets on an RF link can result in higher voice quality. PESQ-MOS measure was used to analyze voice degradation over space links tested for LT codec size and number of 10ms per packet.Extensions utilizing LT codes to improve the packet erasure performance and combining the use of ASR could provide for a solid means of identifying the benefit in terms of intelligibility of voice communications in space-based networks

  3. Control of Space-Based Electron Beam Free Form Fabrication

    NASA Technical Reports Server (NTRS)

    Seifzer. W. J.; Taminger, K. M.

    2007-01-01

    Engineering a closed-loop control system for an electron beam welder for space-based additive manufacturing is challenging. For earth and space based applications, components must work in a vacuum and optical components become occluded with metal vapor deposition. For extraterrestrial applications added components increase launch weight, increase complexity, and increase space flight certification efforts. Here we present a software tool that closely couples path planning and E-beam parameter controls into the build process to increase flexibility. In an environment where data collection hinders real-time control, another approach is considered that will still yield a high quality build.

  4. Space-based augmentation for global navigation satellite systems.

    PubMed

    Grewal, Mohinder S

    2012-03-01

    This paper describes space-based augmentation for global navigation satellite systems (GNSS). Space-based augmentations increase the accuracy and integrity of the GNSS, thereby enhancing users' safety. The corrections for ephemeris, ionospheric delay, and clocks are calculated from reference station measurements of GNSS data in wide-area master stations and broadcast via geostationary earth orbit (GEO) satellites. This paper discusses the clock models, satellite orbit determination, ionospheric delay estimation, multipath mitigation, and GEO uplink subsystem (GUS) as used in the Wide Area Augmentation System developed by the FAA.

  5. THE EFFECT OF A TIME-VARYING ACCRETION DISK SIZE ON QUASAR MICROLENSING LIGHT CURVES

    SciTech Connect

    Blackburne, Jeffrey A.; Kochanek, Christopher S. E-mail: ckochanek@astronomy.ohio-state.ed

    2010-08-01

    Microlensing perturbations to the magnification of gravitationally lensed quasar images are dependent on the angular size of the quasar. If quasar variability at visible wavelengths is caused by a change in the area of the accretion disk, it will affect the microlensing magnification. We derive the expected signal, assuming that the luminosity scales with some power of the disk area, and estimate its amplitude using simulations. We discuss the prospects for detecting the effect in real-world data and for using it to estimate the logarithmic slope of the luminosity's dependence on disk area. Such an estimate would provide a direct test of the standard thin accretion disk model. We tried fitting six seasons of the light curves of the lensed quasar HE 0435-1223 including this effect as a modification to the Kochanek et al. approach to estimating time delays. We find a dramatic improvement in the goodness of fit and relatively plausible parameters, but a robust estimate will require a full numerical calculation in order to correctly model the strong correlations between the structure of the microlensing magnification patterns and the magnitude of the effect. We also comment briefly on the effect of this phenomenon for the stability of time-delay estimates.

  6. Planets, Moons, and Multiple Stars - Gravitational Microlensing by Three-Body Systems

    NASA Astrophysics Data System (ADS)

    Heyrovsky, David; Danek, Kamil

    2017-01-01

    Gravitational microlensing has proved to be a useful tool for detecting exoplanets, particularly those separated a few AU from the lens star. Of the 43 microlensing-detected planets published so far, four are members of two-planet systems, and a further three are associated with binary stars (two circumprimary and one circumbinary). While the lensing by a single star with a single planet is well understood, systematic insight into the substantially more diverse lensing by three-body systems is still lacking. We introduce efficient methods for studying and visualizing the different regimes of lensing by a triple lens with a given combination of masses. For illustration, we present here full analyses of critical-curve regimes of the following lenses in arbitrary spatial configuration: an equal-mass triple, an equal-mass binary with a planet, and a hierarchical star-planet-moon system. Such studies can facilitate the interpretation and analysis of observed microlensing light curves due to triple lenses.

  7. Black hole, neutron star and white dwarf candidates from microlensing with OGLE-III

    NASA Astrophysics Data System (ADS)

    Wyrzykowski, Ł.; Kostrzewa-Rutkowska, Z.; Skowron, J.; Rybicki, K. A.; Mróz, P.; Kozłowski, S.; Udalski, A.; Szymański, M. K.; Pietrzyński, G.; Soszyński, I.; Ulaczyk, K.; Pietrukowicz, P.; Poleski, R.; Pawlak, M.; Iłkiewicz, K.; Rattenbury, N. J.

    2016-05-01

    Most stellar remnants so far have been found in binary systems, where they interact with matter from their companions. Isolated neutron stars and black holes are difficult to find as they are dark, yet they are predicted to exist in our Galaxy in vast numbers. We explored the OGLE-III data base of 150 million objects observed in years 2001-2009 and found 59 microlensing events exhibiting a parallax effect due to the Earth's motion around the Sun. Combining parallax and brightness measurements from microlensing light curves with expected proper motions in the Milky Way, we identified 13 microlensing events which are consistent with having a white dwarf, neutron star or a black hole lens and we estimated their masses and distances. The most massive of our black hole candidates has 9.3 M⊙ and is at a distance of 2.4 kpc. The distribution of masses of our candidates indicates a continuum in mass distribution with no mass gap between neutron stars and black holes. We also present predictions on how such events will be observed by the astrometric Gaia mission.

  8. Limits on Planetary Companions in Microlensing Event OGLE-BUL-98-14

    NASA Astrophysics Data System (ADS)

    Gaudi, B. S.; Albrow, M. D.; Beaulieu, J. P.; Caldwell, J. A. R.; Depoy, D. L.; Dominik, M.; Gould, A.; Greenhill, J.; Hill, K.; Kane, S.; Martin, R.; Menzies, J.; Naber, R. M.; Pogge, R. W.; Pollard, K.; Sackett, P. D.; Sahu, K. C.; Vermaak, P.; Watson, R.; Williams, A.

    1998-12-01

    As part of an ongoing effort to detect second order effects in gravitational microlensing events, the Probing Lensing Anomalies NETwork (PLANET) collaboration has obtained nearly continuous photometry of the microlensing event OGLE-BUL-98-14 with four telescopes located in Tasmania, Perth, South Africa and Chile. The complete data set consists of over 500 points in I and 200 in V taken over a period of ~ 120 days, making this one of the most well sampled microlensing events to date. The scatter in I is ~ 2% (1 sigma). OGLE-BUL-98-14 was a high magnification event (maximum magnification > 10) with a timescale of ~ 40 days. These facts, combined with the high sampling rate and good photometry, make this an extremely promising event for detection of second order effects. We find that the observed lightcurve is completely consistent with a point-source point-lens model. We can rule out the presence of a companion with mass ratio >10(-3) over a substantial range of projected separations. Furthermore, the lack of detected finite-source or parallax effects allows us to put a lower limit on the mass of the lens, Mlens > 0.1 Msun.

  9. Limits on MACHOs from microlensing in the double quasar Q0957+561

    NASA Astrophysics Data System (ADS)

    Schmidt, Robert; Wambsganss, Joachim

    1998-07-01

    The light curves of the two images of the double quasar Q0957+561 as obtained by Kundicet al. (1997) are almost identical, except for an overall time delay and scaling factor. This allows us to put limits on the amount of microlensing that took place during the time interval corresponding to the monitoring observations. We perform numerical simulations in which we model the microlensing behaviour of the (halo of the) lensing galaxy in the system. We test ``MACHO-masses'' ranging from 10(-8) to 10(-1) Msun and quasar sizes from 10(14) to 3x 10(15) cm. Statistically comparing the expected microlensing-induced changes from 100 000 simulated light curves over a period of 160 days with the (lack of) observed fluctuations, we can constrain regions in the parameter space of MACHO mass and quasar size with various degrees of confidence. In particular, a halo consisting of objects at the low end of our mass scale can be ruled out with high confidence for a small quasar size. A halo consisting of objects with 10(-2) or 10(-1) Msun cannot be ruled out yet, but it should produce MACHO induced fluctuations in future observations. We also test halos with only 50% or 25% of the mass in compact objects; constraints here are a bit less stringent.

  10. OGLE-III MICROLENSING EVENTS AND THE STRUCTURE OF THE GALACTIC BULGE

    SciTech Connect

    Wyrzykowski, Łukasz; Rynkiewicz, Alicja E.; Skowron, Jan; Kozłowski, Szymon; Udalski, Andrzej; Szymański, Michał K.; Kubiak, Marcin; Soszyński, Igor; Pietrzyński, Grzegorz; Poleski, Radosław; Pietrukowicz, Paweł; Pawlak, Michał

    2015-01-01

    We present and study the largest and most comprehensive catalog of microlensing events ever constructed. The sample of standard microlensing events comprises 3718 unique events from 2001-2009 with 1409 events that had not been detected before in real-time by the Early Warning System of the Optical Gravitational Lensing Experiment. The search pipeline uses machine learning algorithms to help find rare phenomena among 150 million objects and to derive the detection efficiency. Applications of the catalog can be numerous, from analyzing individual events to large statistical studies of the Galactic mass, kinematics distributions, and planetary abundances. We derive maps of the mean Einstein ring crossing time of events spanning 31 deg{sup 2} toward the Galactic center and compare the observed distributions with the most recent models. We find good agreement within the observed region and we see the signature of the tilt of the bar in the microlensing data. However, the asymmetry of the mean timescales seems to rise more steeply than predicted, indicating either a somewhat different orientation of the bar or a larger bar width. The map of events with sources in the Galactic bulge shows a dependence of the mean timescale on the Galactic latitude, signaling an increasing contribution from disk lenses closer to the plane relative to the height of the disk. Our data present a perfect set for comparing and enhancing new models of the central parts of the Milky Way and creating a three-dimensional picture of the Galaxy.

  11. Gravitational microlensing by low-mass objects in the globular cluster M22.

    PubMed

    Sahu, K C; Casertano, S; Livio, M; Gilliland, R L; Panagia, N; Albrow, M D; Potter, M

    2001-06-28

    Gravitational microlensing offers a means of determining directly the masses of objects ranging from planets to stars, provided that the distances and motions of the lenses and sources can be determined. A globular cluster observed against the dense stellar field of the Galactic bulge presents ideal conditions for such observations because the probability of lensing is high and the distances and kinematics of the lenses and sources are well constrained. The abundance of low-mass objects in a globular cluster is of particular interest, because it may be representative of the very early stages of star formation in the Universe, and therefore indicative of the amount of dark baryonic matter in such clusters. Here we report a microlensing event associated with the globular cluster M22. We determine the mass of the lens to be 0.13(+0.03)(-0.02) solar masses. We have also detected six events that are unresolved in time. If these are also microlensing events, they imply that a non-negligible fraction of the cluster mass resides in the form of free-floating planetary-mass objects.

  12. One or more bound planets per Milky Way star from microlensing observations.

    PubMed

    Cassan, A; Kubas, D; Beaulieu, J-P; Dominik, M; Horne, K; Greenhill, J; Wambsganss, J; Menzies, J; Williams, A; Jørgensen, U G; Udalski, A; Bennett, D P; Albrow, M D; Batista, V; Brillant, S; Caldwell, J A R; Cole, A; Coutures, Ch; Cook, K H; Dieters, S; Prester, D Dominis; Donatowicz, J; Fouqué, P; Hill, K; Kains, N; Kane, S; Marquette, J-B; Martin, R; Pollard, K R; Sahu, K C; Vinter, C; Warren, D; Watson, B; Zub, M; Sumi, T; Szymański, M K; Kubiak, M; Poleski, R; Soszynski, I; Ulaczyk, K; Pietrzyński, G; Wyrzykowski, L

    2012-01-11

    Most known extrasolar planets (exoplanets) have been discovered using the radial velocity or transit methods. Both are biased towards planets that are relatively close to their parent stars, and studies find that around 17-30% (refs 4, 5) of solar-like stars host a planet. Gravitational microlensing, on the other hand, probes planets that are further away from their stars. Recently, a population of planets that are unbound or very far from their stars was discovered by microlensing. These planets are at least as numerous as the stars in the Milky Way. Here we report a statistical analysis of microlensing data (gathered in 2002-07) that reveals the fraction of bound planets 0.5-10 AU (Sun-Earth distance) from their stars. We find that 17(+6)(-9)% of stars host Jupiter-mass planets (0.3-10 M(J), where M(J) = 318 M(⊕) and M(⊕) is Earth's mass). Cool Neptunes (10-30 M(⊕)) and super-Earths (5-10 M(⊕)) are even more common: their respective abundances per star are 52(+22)(-29)% and 62(+35)(-37)%. We conclude that stars are orbited by planets as a rule, rather than the exception.

  13. National Coordination Office for Space-Based PNT

    NASA Astrophysics Data System (ADS)

    Shaw, M. E.

    2008-12-01

    In December 2004, President Bush issued the US Policy on space-based positioning, navigation, and timing (PNT), providing guidance on the management of the Global Positioning System (GPS) and other space- based PNT systems. The policy established the National Executive Committee (EXCOM) to advise and coordinate federal agencies on matters related to space-based PNT. Chaired jointly by the deputy secretaries of defense and transportation, the EXCOM includes equivalent level officials from the Departments of State, the Interior, Agriculture, Commerce, and Homeland Security, the Joint Chiefs of Staff, and the National Aeronautics and Space Administration (NASA). A National Coordination Office (NCO) supports the EXCOM through an interagency staff. Since establishing the EXCOM and NCO in 2005, the organizations have quickly grown in influence and effectiveness, leading or managing many interagency initiatives including the development of a Five-Year National Space-Based PNT Plan, the Space-Based PNT Interference Detection and Mitigation (IDM) Plan, and other strategic documents. The NCO has also facilitated interagency coordination on numerous policy issues and on external communications intended to spread a consistent, positive US message about space-based PNT. Role of the NCO - The purpose of the EXCOM is to provide top-level guidance to US agencies regarding space-based PNT infrastructure. The president established it at the deputy secretary level to ensure its strategic recommendations effect real change in agency budgets. Recognizing such high-level officials could only meet every few months, the president directed the EXCOM to establish an NCO to carry out its day-to-day business, including overseeing the implementation of EXCOM action items across the member agencies. These range from the resolution of funding issues to the assessment of strategic policy options. They also include the completion of specific tasks and documents requested by the EXCOM co

  14. REANALYSES OF ANOMALOUS GRAVITATIONAL MICROLENSING EVENTS IN THE OGLE-III EARLY WARNING SYSTEM DATABASE WITH COMBINED DATA

    SciTech Connect

    Jeong, J.; Park, H.; Han, C.; Gould, A.; Poleski, R.; Udalski, A.; Szymański, M. K.; Pietrzyński, G.; Soszyński, I.; Ulaczyk, K.; Wyrzykowski, Ł.; Abe, F.; Fukunaga, D.; Itow, Y.; Bennett, D. P.; Bond, I. A.; Botzler, C. S.; Freeman, M.; Fukui, A.; Koshimoto, N.; Collaboration:; and others

    2015-05-01

    We reanalyze microlensing events in the published list of anomalous events that were observed from the Optical Gravitational Lensing Experiment (OGLE) lensing survey conducted during the 2004–2008 period. In order to check the existence of possible degenerate solutions and extract extra information, we conduct analyses based on combined data from other survey and follow-up observation and consider higher-order effects. Among the analyzed events, we present analyses of eight events for which either new solutions are identified or additional information is obtained. We find that the previous binary-source interpretations of five events are better interpreted by binary-lens models. These events include OGLE-2006-BLG-238, OGLE-2007-BLG-159, OGLE-2007-BLG-491, OGLE-2008-BLG-143, and OGLE-2008-BLG-210. With additional data covering caustic crossings, we detect finite-source effects for six events including OGLE-2006-BLG-215, OGLE-2006-BLG-238, OGLE-2006-BLG-450, OGLE-2008-BLG-143, OGLE-2008-BLG-210, and OGLE-2008-BLG-513. Among them, we are able to measure the Einstein radii of three events for which multi-band data are available. These events are OGLE-2006-BLG-238, OGLE-2008-BLG-210, and OGLE-2008-BLG-513. For OGLE-2008-BLG-143, we detect higher-order effects induced by the changes of the observer’s position caused by the orbital motion of the Earth around the Sun. In addition, we present degenerate solutions resulting from the known close/wide or ecliptic degeneracy. Finally, we note that the masses of the binary companions of the lenses of OGLE-2006-BLG-450 and OGLE-2008-BLG-210 are in the brown-dwarf regime.

  15. Reanalyses of Anomalous Gravitational Microlensing Events in the OGLE-III Early Warning System Database with Combined Data

    NASA Astrophysics Data System (ADS)

    Jeong, J.; Park, H.; Han, C.; Gould, A.; Udalski, A.; Szymański, M. K.; Pietrzyński, G.; Soszyński, I.; Poleski, R.; Ulaczyk, K.; Wyrzykowski, Ł.; OGLE Collaboration; Abe, F.; Bennett, D. P.; Bond, I. A.; Botzler, C. S.; Freeman, M.; Fukui, A.; Fukunaga, D.; Itow, Y.; Koshimoto, N.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Namba, S.; Ohnishi, K.; Rattenbury, N. J.; Saito, To.; Sullivan, D. J.; Sweatman, W. L.; Sumi, T.; Suzuki, D.; Tristram, P. J.; Tsurumi, N.; Wada, K.; Yamai, N.; Yock, P. C. M.; Yonehara, A.; MOA Collaboration; Albrow, M. D.; Batista, V.; Beaulieu, J.-P.; Caldwell, J. A. R.; Cassan, A.; Cole, A.; Coutures, C.; Dieters, S.; Dominik, M.; Dominis Prester, D.; Donatowicz, J.; Fouqué, P.; Greenhill, J.; Hoffman, M.; Huber, M.; Jørgensen, U. G.; Kane, S. R.; Kubas, D.; Martin, R.; Marquette, J.-B.; Menzies, J.; Pitrou, C.; Pollard, K.; Sahu, K. C.; Vinter, C.; Wambsganss, J.; Williams, A.; PLANET Collaboration; Allen, W.; Bolt, G.; Choi, J.-Y.; Christie, G. W.; DePoy, D. L.; Drummond, J.; Gaudi, B. S.; Hwang, K.-H.; Jung, Y. K.; Lee, C.-U.; Mallia, F.; Maoz, D.; Maury, A.; McCormick, J.; Monard, L. A. G.; Moorhouse, D.; Natusch, T.; Ofek, E. O.; Park, B.-G.; Pogge, R. W.; Santallo, R.; Shin, I.-G.; Thornley, G.; Yee, J. C.; μFUN Collaboration; Bramich, D. M.; Burgdorf, M.; Horne, K.; Hundertmark, M.; Kains, N.; Snodgrass, C.; Steele, I.; Street, R.; Tsapras, Y.; RoboNet Collaboration

    2015-05-01

    We reanalyze microlensing events in the published list of anomalous events that were observed from the Optical Gravitational Lensing Experiment (OGLE) lensing survey conducted during the 2004-2008 period. In order to check the existence of possible degenerate solutions and extract extra information, we conduct analyses based on combined data from other survey and follow-up observation and consider higher-order effects. Among the analyzed events, we present analyses of eight events for which either new solutions are identified or additional information is obtained. We find that the previous binary-source interpretations of five events are better interpreted by binary-lens models. These events include OGLE-2006-BLG-238, OGLE-2007-BLG-159, OGLE-2007-BLG-491, OGLE-2008-BLG-143, and OGLE-2008-BLG-210. With additional data covering caustic crossings, we detect finite-source effects for six events including OGLE-2006-BLG-215, OGLE-2006-BLG-238, OGLE-2006-BLG-450, OGLE-2008-BLG-143, OGLE-2008-BLG-210, and OGLE-2008-BLG-513. Among them, we are able to measure the Einstein radii of three events for which multi-band data are available. These events are OGLE-2006-BLG-238, OGLE-2008-BLG-210, and OGLE-2008-BLG-513. For OGLE-2008-BLG-143, we detect higher-order effects induced by the changes of the observer’s position caused by the orbital motion of the Earth around the Sun. In addition, we present degenerate solutions resulting from the known close/wide or ecliptic degeneracy. Finally, we note that the masses of the binary companions of the lenses of OGLE-2006-BLG-450 and OGLE-2008-BLG-210 are in the brown-dwarf regime.

  16. Microlensing on extended structures having a spherically-symmetric mass distribution

    NASA Astrophysics Data System (ADS)

    Zhdanov, V.; Alexandrov, A.; Stashko, O.

    2016-06-01

    Different dark matter (DM) models predict various clustering properties, i.e. the possibility of DM to form massive objects on different scales. The lower mass limit of these objects according to [1, 2]. may be of the order of planetary masses. The gravitational microlensing can be used to confirm or to reject the existence of such structures and therefore to argue in favor or against concrete DM theories. There are observational programs (OGLE, EROS etc) yielding the light curves of a remote objects in high amplification events (HAE) due to microlensing on foreground masses of the Galaxy. In case when the foreground mass is an extended one, then the light curve in HAE must differ from the light curve due to ordinary microlensing on a point mass. However the question is: what is the value of this difference and is it possible to register this difference with modern observational facilities. This question has been studied elsewhere [3–5] by means of special model lens mappings. In this paper we study this problem starting directly from mass distribution of the extended structure. Namely, we consider microlensing on an extended DM clump with the cored spherically-symmetric mass profile (without a singularity in the center). We present examples of the amplification curves in both cases. Then we generate the amplification curves in case of the extended clump model for different values R, γ when the clump moves uniformly with respect to the line of sight with some impact parameter p and velocity V. These curves are then fitted with the point microlens model (with free parameters p and V) and we estimate the difference between the curves. The general outcome is that the amplification curves in case of the extended clumps are very similar to those in case of the point microlens (with appropriately chosen parameters p and V that cannot be derived from observations independently), and it would be difficult to distinguish them on the basis of observations if we deal with

  17. Audiovisual temporal recalibration: space-based versus context-based.

    PubMed

    Yuan, Xiangyong; Li, Baolin; Bi, Cuihua; Yin, Huazhan; Huang, Xiting

    2012-01-01

    Recalibration of perceived simultaneity has been widely accepted to minimise delay between multisensory signals owing to different physical and neural conduct times. With concurrent exposure, temporal recalibration is either contextually or spatially based. Context-based recalibration was recently described in detail, but evidence for space-based recalibration is scarce. In addition, the competition between these two reference frames is unclear. Here, we examined participants who watched two distinct blob-and-tone couples that laterally alternated with one asynchronous and the other synchronous and then judged their perceived simultaneity and sequence when they swapped positions and varied in timing. For low-level stimuli with abundant auditory location cues space-based aftereffects were significantly more apparent (8.3%) than context-based aftereffects (4.2%), but without such auditory cues space-based aftereffects were less apparent (4.4%) and were numerically smaller than context-based aftereffects (6.0%). These results suggested that stimulus level and auditory location cues were both determinants of the recalibration frame. Through such joint judgments and the simple reaction time task, our results further revealed that criteria from perceived simultaneity to successiveness profoundly shifted without accompanying perceptual latency changes across adaptations, hence implying that criteria shifts, rather than perceptual latency changes, accounted for space-based and context-based temporal recalibration.

  18. Carbon Fiber Reinforced Glass Matrix Composites for Space Based Applications.

    DTIC Science & Technology

    1987-08-31

    Nardone , "Carbon Fiber Reinforced Glass Matrix Composites for Space Based Applications", Office of Naval Research Contract N00014-85-C-0332, Report R86... Nardone and K M. Prewo, "Tensile Performance of Carbon Fiber Reinforced Glass", J. Mater. Sci. accepted for publication, 1987. 27. R. F. Cooper and K

  19. Relativity effects for space-based coherent lidar experiments

    NASA Technical Reports Server (NTRS)

    Gudimetla, V. S. Rao

    1996-01-01

    An effort was initiated last year in the Astrionics Laboratory at Marshall Space Flight Center to examine and incorporate, if necessary, the effects of relativity in the design of space-based lidar systems. A space-based lidar system, named AEOLUS, is under development at Marshall Space Flight Center and it will be used to accurately measure atmospheric wind profiles. Effects of relativity were also observed in the performance of space-based systems, for example in case of global positioning systems, and corrections were incorporated into the design of instruments. During the last summer, the effects of special relativity on the design of space-based lidar systems were studied in detail, by analyzing the problem of laser scattering off a fixed target when the source and a co-located receiver are moving on a spacecraft. Since the proposed lidar system uses a coherent detection system, errors even in the order of a few microradians must be corrected to achieve a good signal-to-noise ratio. Previous analysis assumed that the ground is flat and the spacecraft is moving parallel to the ground, and developed analytical expressions for the location, direction and Doppler shift of the returning radiation. Because of the assumptions used in that analysis, only special relativity effects were involved. In this report, that analysis is extended to include general relativity and calculate its effects on the design.

  20. The different origins of high- and low-ionization broad emission lines revealed by gravitational microlensing in the Einstein cross

    NASA Astrophysics Data System (ADS)

    Braibant, L.; Hutsemékers, D.; Sluse, D.; Anguita, T.

    2016-07-01

    We investigate the kinematics and ionization structure of the broad emission line region of the gravitationally lensed quasar QSO2237+0305 (the Einstein cross) using differential microlensing in the high- and low-ionization broad emission lines. We combine visible and near-infrared spectra of the four images of the lensed quasar and detect a large-amplitude microlensing effect distorting the high-ionization CIV and low-ionization Hα line profiles in image A. While microlensing only magnifies the red wing of the Balmer line, it symmetrically magnifies the wings of the CIV emission line. Given that the same microlensing pattern magnifies both the high- and low-ionization broad emission line regions, these dissimilar distortions of the line profiles suggest that the high- and low-ionization regions are governed by different kinematics. Since this quasar is likely viewed at intermediate inclination, we argue that the differential magnification of the blue and red wings of Hα favors a flattened, virialized, low-ionization region whereas the symmetric microlensing effect measured in CIV can be reproduced by an emission line formed in a polar wind, without the need of fine-tuned caustic configurations. Based on observations made with the ESO-VLT, Paranal, Chile; Proposals 076.B-0197 and 076.B-0607 (PI: Courbin).

  1. Three-dimensional profilometry of microlenses by phase shifting interferometery using nematic liquid crystal material filled cell as a phase modulator.

    PubMed

    Inam, M; Srivastava, V; Mehta, D S

    2015-02-10

    In this paper, we report the use of a nematic liquid crystal material filled cell in transmission mode as a voltage controlled phase modulator for the characterization of microlenses. In one arm of the Mach-Zehnder interferometer, a nematic liquid crystal filled cell with DC voltage connection was placed, and in another arm of the interferometer microlenses with a 4-F imaging system were placed. Interference takes place between the light beams coming from the two arms of the Mach-Zehnder interferometer, one after passing through the nematic liquid crystal cell and another after passing through microlenses. Interference patterns were recorded by a CCD camera. By applying DC voltage to the nematic liquid crystal filled cell, various phase shifted interferograms were recorded, and from phase shifted interferograms, the shape and size of microlenses were determined. The results of the reconstructed profile of the microlenses are compared with white-light profilometry.

  2. Distant Retrograde Orbits for space-based Near Earth Objects detection

    NASA Astrophysics Data System (ADS)

    Stramacchia, Michele; Colombo, Camilla; Bernelli-Zazzera, Franco

    2016-09-01

    We analyse a concept for the detection of Potentially Hazardous Asteroids (PHAs) from a space-based network of telescopes on retrograde Distant Periodic Orbits. Planar periodic orbits are designed in the Sun-Earth circular restricted three-body problem, starting from initial conditions in the Hill's problem available from the literature. A family of retrograde orbits centred at the Earth is selected as baseline, based on their maximum distance from Earth, larger than the Earth-L2 distance. Indeed, spacecraft on such orbits can detect PHAs incoming from the Sun direction, which could not otherwise be monitored from current Earth-based systems. A trade-off on the orbit amplitude, asteroid diameter to be detected, and the constellation size is performed considering current visible sensor telescope technology. The Chelyabinsk meteor scenario is studied and the potential warning time that could be gained with a space-based survey system with respect to an Earth based-survey system is shown.

  3. Two Stars Two Ways: Confirming a Microlensing Binary Lens Solution with a Spectroscopic Measurement of the Orbit

    NASA Astrophysics Data System (ADS)

    Yee, Jennifer C.; Johnson, John Asher; Skowron, Jan; Gould, Andrew; Pineda, J. Sebastian; Eastman, Jason; Vanderburg, Andrew; Howard, Andrew

    2016-04-01

    Light curves of microlensing events involving stellar binaries and planetary systems can provide information about the orbital elements of the system due to orbital modulations of the caustic structure. Accurately measuring the orbit in either the stellar or planetary case requires detailed modeling of subtle deviations in the light curve. At the same time, the natural, Cartesian parameterization of a microlensing binary is partially degenerate with the microlens parallax. Hence, it is desirable to perform independent tests of the predictions of microlens orbit models using radial velocity (RV) time series of the lens binary system. To this end, we present 3.5 years of RV monitoring of the binary lens system OGLE-2009-BLG-020 L, for which Skowron et al. constrained all internal parameters of the 200-700 day orbit. Our RV measurements reveal an orbit that is consistent with the predictions of the microlens light curve analysis, thereby providing the first confirmation of orbital elements inferred from microlensing events.

  4. Space-based Earth science to be reviewed

    NASA Astrophysics Data System (ADS)

    Robb, David W.

    The White House Office of Science and Technology Policy (OSTP) has begun a study of agency roles in space-based earth science research for the next decade, 1985-1995. The study will be made on the basis of discussions with policy-level personnel at eight federal agencies, as well as with working scientists and other standing earth science committees.According to Richard Johnson, OSTP Assistant Director for Space Science and Technology and chairman of the evaluation, the study will involve “fine-tuning agency roles” in the space-based earth sciences. “Further definition” and “providing a clearer statement of what their roles are,” said Johnson, “will improve the stability of funding” and should help avoid the “peaks and valleys” seen in the past.

  5. Design Analysis of a Space Based Chromotomographic Hyperspectral Imaging Experiment

    DTIC Science & Technology

    2010-03-01

    Tilt Platforms S-340 Platform Recommended Models Mirror Aluminum Aluminum S-340.Ax Invar Zerodur glass S-340.ix Titanium BK7 glass S-340.Tx Steel S-340...composed of a telescope, two grating spectrometers, calibration lamps, and focal plane electronics and cooling system. The telescope is a three mirror ...advanced hyperspectral imager for coastal bathymetry is that the experiment will closely mirror that of the proposed space-based chromotomographic hy

  6. Technology for subsystems of space-based plant growth facilities

    NASA Technical Reports Server (NTRS)

    Bula, R. J.; Morrow, R. C.; Tibbitts, T. W.; Corey, R. B.

    1990-01-01

    Technologies for different subsystems of space-based plant growth facilities are being developed at the Wisconsin Center for Space Automation and Robotics, a NASA Center for the Commercial Development of Space. The technologies include concepts for water and nutrient delivery, for nutrient composition control, and for irradiation. Effort is being concentrated on these subsystems because available technologies cannot be effectively utilized for space applications.

  7. Enhancing Arctic Surveillance With Space-Based Radars

    DTIC Science & Technology

    2013-06-01

    Gigahertz GMTI Ground Moving Target Indicator IMO International Maritime Organization IR Infrared ISA Italian Space Agency ISR Intelligence...constellation with 24 or more satellites (a.k.a 24 ball constellation) in 8 different orbital planes was likely to detect (and track with ground moving...offer unique advantages over other space-based surveillance from electro-optical ( EO ) or infra-red ( IR ) payloads. SAR surveillance is not inhibited by

  8. VizieR Online Data Catalog: Microlensing maps for a cusp configuration (Sluse+, 2013)

    NASA Astrophysics Data System (ADS)

    Sluse, D.; Kishimoto, M.; Anguita, T.; Wucknitz, O.; Wambsganss, J.

    2013-03-01

    The microlensing maps (see maps.dat) are generated with the inverse ray-shooting code developped by Prof. J. Wambsganss (Wambsganss 1990, PhD thesis). They are computed for a saddle-point image with (kappa,gamma)=(0.47,0.57) and for a minimum image with (kappa,gamma)=(0.42,0.50). Those values match those found for images A & B of the lensed AGN J1131-1231 (assuming a Singular Isothermal Ellipsoid+shear lens model). Each map has been computed for 3 different fraction of kappa_star (i.e. convergence in form of compact objects): 0.07, 0.30, 1.0. For each case, there is a high resolution map of 100eta0x100eta0 (eta0 = microlensing Einstein radius =3*10+16cm) and a low resolution map of 250eta0x250eta0. Source profiles (sources.dat) are calculated for the same two resolution (i.e. low/high). Three source brightness profiles are provided: a uniform disc, a ring-like uniform compact torus, a ring-like extended torus. The torus characteristics are described in Table 1 of the main paper. The source profile is calculated for 3 different luminosities (10+44.2, 10+45, 10+46erg/s/cm2) and rest-frame wavelengths (1.0, 2.2, 4.4um) as described in sources.dat. Source profiles which are larger that the microlensing maps are not calculated and are listed in nosources.dat. (4 data files).

  9. VizieR Online Data Catalog: Abundances of microlensed Bulge dwarf stars. V. (Bensby+, 2013)

    NASA Astrophysics Data System (ADS)

    Bensby, T.; Yee, J. C.; Feltzing, S.; Johnson, J. A.; Gould, A.; Cohen, J. G.; Asplund, M.; Melendez, J.; Lucatello, S.; Han, C.; Thompson, I.; Gal-Yam, A.; Udalski, A.; Benett, D. P.; Bond, I. A.; Kohei, W.; Sumi, T.; Suzuki, D.; Suzuki, K.; Takino, S.; Tristram, P.; Yamai, N.; Yonehara, A.

    2012-11-01

    For each spectral line we give the lower excitation potential, measured equivalent widths, and derived absolute abundances. We also give median abundances for each star, normalised to the Sun, and errors in the median abundances. These tables contain data for all so far 58 microlensed dwarf stars, and superseeds the tables in Bensby+ (2009, Cat. J/A+A/499/737), Bensby+ (2010, Cat. J/A+A/512/A41), and Bensby+ (2011, Cat. J/A+A/533/A134). (4 data files).

  10. Is the Large Magellanic Cloud Microlensing Due to an Intervening Dwarf Galaxy?

    NASA Astrophysics Data System (ADS)

    Alcock, C.; Allsman, R. A.; Alves, D. R.; Axelrod, T. S.; Becker, A. C.; Bennett, D. P.; Cook, K. H.; Freeman, K. C.; Griest, K.; Lehner, M. J.; Marshall, S. L.; Minniti, D.; Peterson, B. A.; Pratt, M. R.; Quinn, P. J.; Rodgers, A. W.; Rorabeck, A.; Stubbs, C. W.; Sutherland, W.; Tomaney, A. B.; Vandehei, T.; Welch, D. L.

    1997-11-01

    The recent suggestion that the microlensing events observed toward the Large Magellanic Cloud are due to an intervening Sgr-like dwarf galaxy is examined. A search for foreground RR Lyrae in the MACHO photometry database yields 20 stars whose distance distribution follow the expected halo density profile. Cepheid and red giant branch clump stars in the MACHO database are consistent with membership in the LMC. There is also no evidence in the literature for a distinct kinematic population, for intervening gas, or for the turnoff of such a hypothetical galaxy. We conclude that if the lenses are in a foreground galaxy, it must be a particularly dark galaxy.

  11. Application of Compressive Sensing to Gravitational Microlensing Data and Implications for Miniaturized Space Observatories

    NASA Technical Reports Server (NTRS)

    Korde-Patel, Asmita (Inventor); Barry, Richard K.; Mohsenin, Tinoosh

    2016-01-01

    Compressive Sensing is a technique for simultaneous acquisition and compression of data that is sparse or can be made sparse in some domain. It is currently under intense development and has been profitably employed for industrial and medical applications. We here describe the use of this technique for the processing of astronomical data. We outline the procedure as applied to exoplanet gravitational microlensing and analyze measurement results and uncertainty values. We describe implications for on-spacecraft data processing for space observatories. Our findings suggest that application of these techniques may yield significant, enabling benefits especially for power and volume-limited space applications such as miniaturized or micro-constellation satellites.

  12. Strong chromatic microlensing in HE0047–1756 and SDSS1155+6346

    SciTech Connect

    Rojas, K.; Motta, V.; Mediavilla, E.; Jiménez-Vicente, J.; Muñoz, J. A. E-mail: veronica.motta@uv.cl E-mail: falco@cfa.harvard.edu E-mail: jmunoz@uv.es

    2014-12-10

    We use spectra of the double-lensed quasars HE0047–1756 and SDSS1155+6346 to study their unresolved structure through the impact of microlensing. There is no significant evidence of microlensing in the emission line profiles except for the Lyα line of SDSS1155+6346, which shows strong differences in the shapes for images A and B. However, the continuum of the B image spectrum in SDSS1155+6346 is strongly contaminated by the lens galaxy, and these differences should be considered with caution. Using the flux ratios of the emission lines for image pairs as a baseline to remove macro-magnification and extinction, we have detected strong chromatic microlensing in the continuum measured by CASTLES (www.cfa.harvard.edu/castles/) in both lens systems, with amplitudes 0.09(λ16000) ≲ |Δm| ≲ 0.8(λ5439) for HE0047–1756, and 0.2(λ16000) ≲ |Δm| ≲ 0.8(λ5439) for SDSS1155+6346. Using magnification maps to simulate microlensing and modeling the accretion disk as a Gaussian source (I ∝ exp(–R {sup 2}/2r {sub s}{sup 2})) of size r {sub s} ∝ λ {sup p}, we find r {sub s} = 2.5{sub −1.4}{sup +3.0} √(M/0.3M{sub ⊙}) lt-day and p = 2.3 ± 0.8 at the rest frame for λ = 2045 for HE0047–1756 (log prior) and r {sub s} = 5.5{sub −3.3}{sup +8.2} √(M/0.3M{sub ⊙}) lt-day and p = 1.5 ± 0.6 at the rest frame of λ = 1398 for SDSS1155+6346 (log prior). Contrary to other studied lens systems, the chromaticity detected in HE0047–1756 and SDSS1155+6346 is large enough to fulfill the thin disk prediction. The inferred sizes, however, are very large compared to the predictions of this model, especially in the case of SDSS1155+6346.

  13. Design of binary diffractive microlenses with subwavelength structures using the genetic algorithm.

    PubMed

    Shirakawa, Tatsuya; Ishikawa, Kenichi L; Suzuki, Shuichi; Yamada, Yasufumi; Takahashi, Hiroyuki

    2010-04-12

    We present a method to design binary diffractive microlenses with subwavelength structures, based on the finite-difference time-domain method and the genetic algorithm, also accounting for limitations on feature size and aspect ratio imposed by fabrication. The focusing efficiency of the microlens designed by this method is close to that of the convex lens and much higher than that of the binary Fresnel lens designed by a previous method. Although the optimized structure appears to be a binary Fresnel lens qualitatively, it is hard to quantitatively derive directly from the convex Fresnel lens. The design of a microlens with reduced chromatic aberration is also presented.

  14. Comet/Asteroid Protection System (CAPS): Preliminary Space-Based Concept and Study Results

    NASA Technical Reports Server (NTRS)

    Mazanek, Daniel D.; Roithmayr, Carlos M.; Antol, Jeffrey; Park, Sang-Young; Koons, Robert H.; Bremer, James C.; Murphy, Douglas G.; Hoffman, James A.; Kumar, Renjith R.; Seywald, Hans

    2005-01-01

    There exists an infrequent, but significant hazard to life and property due to impacting asteroids and comets. There is currently no specific search for long-period comets, smaller near-Earth asteroids, or smaller short-period comets. These objects represent a threat with potentially little or no warning time using conventional ground-based telescopes. These planetary bodies also represent a significant resource for commercial exploitation, long-term sustained space exploration, and scientific research. The Comet/Asteroid Protection System (CAPS) is a future space-based system concept that provides permanent, continuous asteroid and comet monitoring, and rapid, controlled modification of the orbital trajectories of selected bodies. CAPS would expand the current detection effort to include long-period comets, as well as small asteroids and short-period comets capable of regional destruction. A space-based detection system, despite being more costly and complex than Earth-based initiatives, is the most promising way of expanding the range of detectable objects, and surveying the entire celestial sky on a regular basis. CAPS would provide an orbit modification system capable of diverting kilometer class objects, and modifying the orbits of smaller asteroids for impact defense and resource utilization. This Technical Memorandum provides a compilation of key related topics and analyses performed during the CAPS study, which was performed under the Revolutionary Aerospace Systems Concepts (RASC) program, and discusses technologies that could enable the implementation of this future system.

  15. Shield Design for a Space Based Vapor Core Reactor

    SciTech Connect

    Knight, Travis; Anghaie, Samim

    2002-07-01

    Innovative shielding strategies were sought to reduce the mass of the required shielding for a space based vapor core reactor system with magnetohydrodynamic energy conversion. Gamma-rays directly resultant from fission were found to play no role in the dose rate, while secondary gamma-rays from fission neutron interactions were the dominant contributor to the dose rate. Hydrogen containing materials such as polyethylene were utilized to provide shielding of both radiation from the reactor complex and also solar and galactic cosmic radiation. This shield design was found to contribute 0.125 kg/kWe to the baseline vapor core reactor system specific mass. (authors)

  16. Space-Based Gravitational-wave Mission Concept Studies

    NASA Technical Reports Server (NTRS)

    Livas, Jeffrey C.

    2012-01-01

    The LISA Mission Concept has been under study for over two decades as a spacebased gravitational-wave detector capable of observing astrophysical sources in the 0.0001 to 1 Hz band. The concept has consistently received strong recommendations from various review panels based on the expected science, most recently from the US Astr02010 Decadal Review. Budget constraints have led both the US and European Space agencies to search for lower cost options. We report results from the US effort to explore the tradeoffs between mission cost and science return, and in particular a family of mission concepts referred to as SGO (Space-based Gravitational-wave Observatory).

  17. Two Phase Flow and Space-Based Applications

    NASA Technical Reports Server (NTRS)

    McQuillen, John

    1999-01-01

    A reduced gravity environment offers the ability to remove the effect of buoyancy on two phase flows whereby density differences that normally would promote relative velocities between the phases and also alter the shape of the interface are removed. However, besides being a potent research tool, there are also many space-based technologies that will either utilize or encounter two-phase flow behavior, and as a consequence, several questions must be addressed. This paper presents some of these technologies missions. Finally, this paper gives a description of web-sites for some funding.

  18. A space-based concept for a collision warning sensor

    NASA Technical Reports Server (NTRS)

    Talent, David L.; Vilas, Faith

    1990-01-01

    This paper describes a concept for a space-based collision warning sensor experiment, the Debris Collision Warning Sensor (DCWS) experiment, in which the sensor will rely on passive sensing of debris in optical and IR passband. The DCWS experiment will be carried out under various conditions of solar phase angle and pass geometry; debris from 1.5 m to 1 mm diam will be observable. The mission characteristics include inclination in the 55-60 deg range and an altitude of about 500 km. The results of the DCWS experiment will be used to generate collision warning scenarios for the Space Station Freedom.

  19. Submillimeter-wavelength space-based imaging radar. Interim report

    SciTech Connect

    Manheimer, W.M.

    1988-05-31

    This report considers the use of a submillimeter wavelength space-based imaging radar. The main application envisioned is midcourse decoy discrimination for strategic defense, for which it would have the capability of producing a series of images, in real time, at strategic ranges, with less than meter-scale resolution and with modest power requirements. Undoubtedly, there are other applications. The requirements for a SAR and ISAR imaging radar at submillimeter wavelength are determined, and the prospect for the development of rf sources to power the radar is examined.

  20. Fiber-optic applications for space-based rocket engines

    NASA Astrophysics Data System (ADS)

    Sovie, Amy L.; Bewley, Douglas P.; Millis, Marc G.

    1991-09-01

    The use of fiber-optic technology is discussed with respect to the instrumentation systems for space-based rocket engines. Optical fiber technologies are reviewed with specific attention given to the reliability, light weight, small fiber diameter, and operating life of the components in the space environment. An optical system can facilitate the incorporation of an optical health-monitoring system, increase the space available for necessary redundancy, and safe high-bandwidth communications that are immune to the effects of electromagnetic radiation.

  1. Detecting binarity of GW150914-like lenses in gravitational microlensing events

    NASA Astrophysics Data System (ADS)

    Kesden, Michael; Eilbott, Daniel; Riley, Alexander; Cohn, Jonathan; King, Lindsay

    2017-01-01

    The recent discovery of gravitational waves from stellar-mass binary black holes (BBHs) provided direct evidence of the existence of these systems. These BBHs would have gravitational microlensing signatures that are, due to their large masses and small separations, distinct from single-lens signals. We apply Bayesian statistics to examine the distinguishability of BBH microlensing events from single-lens events under ideal observing conditions, using modern photometric and astrometric capabilities. Given one year of ideal observations, a source star at the Galactic center, a GW150914-like BBH lens (total mass 65 solar masses, mass ratio 0.8) at half that distance, and an impact parameter of 0.4 Einstein radii, we find that BBHs with separations down to 0.00634 Einstein radii are detectable, marginally below the separation at which such systems would merge due to gravitational radiation with the age of the Universe. Supported by Alfred P Sloan Foundation Grant No. RG- 2015-65299 and NSF Grant No. PHY-1607031.

  2. Interpretation of a short-term anomaly in the gravitational microlensing event MOA-2012-BLG-486

    SciTech Connect

    Hwang, K.-H.; Choi, J.-Y.; Han, C.; Bond, I. A.; Sumi, T.; Koshimoto, N.; Gaudi, B. S.; Gould, A.; Bozza, V.; Beaulieu, J.-P.; Tsapras, Y.; Abe, F.; Fukunaga, D.; Itow, Y.; Bennett, D. P.; Botzler, C. S.; Freeman, M.; Chote, P.; Harris, P.; Fukui, A.; Collaboration: MOA Collaboration; μFUN Collaboration; PLANET Collaboration; RoboNet Collaboration; and others

    2013-11-20

    A planetary microlensing signal is generally characterized by a short-term perturbation to the standard single lensing light curve. A subset of binary-source events can produce perturbations that mimic planetary signals, thereby introducing an ambiguity between the planetary and binary-source interpretations. In this paper, we present the analysis of the microlensing event MOA-2012-BLG-486, for which the light curve exhibits a short-lived perturbation. Routine modeling not considering data taken in different passbands yields a best-fit planetary model that is slightly preferred over the best-fit binary-source model. However, when allowed for a change in the color during the perturbation, we find that the binary-source model yields a significantly better fit and thus the degeneracy is clearly resolved. This event not only signifies the importance of considering various interpretations of short-term anomalies, but also demonstrates the importance of multi-band data for checking the possibility of false-positive planetary signals.

  3. Central engine of a gamma-ray blazar resolved through the magnifying glass of gravitational microlensing

    NASA Astrophysics Data System (ADS)

    Neronov, Andrii; Vovk, Ievgen; Malyshev, Denys

    2015-08-01

    Gamma-ray emission from blazars is known to originate from jets emitted by supermassive black holes. However, the exact location and size of the γ-ray emitting part of the jets is uncertain. The main difficulty is the very small angular size of these sources, beyond the angular resolution of γ-ray telescopes. Here, we report a measurement of the projected size of the γ-ray jet, revealed by the detection of microlensing in the gravitationally lensed blazar PKS 1830-211. This measurement is consistent with a constraint from the intrinsic variability timescale of the blazar. Our measurement shows that the γ-ray emission originates from the vicinity of the central supermassive black hole. Combining the X-ray and γ-ray data, we use the microlensing effect to constrain the size of the X-ray source. We show that the effect of pair production of γ-rays on X-ray photons does not make the source opaque, owing to the large size of the X-ray emission region.

  4. MACHO project 2nd year LMC microlensing results and dark matter implications

    SciTech Connect

    Alcock, C.; Allsman, R.A.; Alves, D.

    1996-02-01

    The MACHO Project is searching for galactic dark matter in the form of massive compact halo objects (Machos). Millions of stars in the Large Magellanic Cloud (LMC), Small Magellanic Cloud (SMC), and Galactic bulge are photometrically monitored in an attempt to detect rare gravitational microlensing events caused by otherwise invisible Machos. Analysis of two years of photometry on 8.5 million stars in the LMC reveals 8 candidate microlensing events, far more than the one event expected from lensing by low-mass stars in known galactic populations. Five these eight events we estimate the optical depth towards the LMC from events with 2 < i < 200 days to be r2 280 about 2.9+1 4/-0.8 X 10-7. This exceeds the optical depth of 0.5 x 10-7 expected for known stars and is to be compared with an optical depth of 4.7 X 10-7 predicted for a `standard` halo composed entirely of Machos. The total mass in this lensing population is 2 +1.2/-0.7 x 10+11 Mo (within 50 kpc from the Galactic center). Event timescales yield a most probable Macho Mass of 0.5 +0.3/-0.2 Mo, although this value is quite model dependent. -0.2

  5. Study of dynamical formation and shape of microlenses formed by the reflow method

    NASA Astrophysics Data System (ADS)

    Audran, S.; Faure, B.; Mortini, B.; Aumont, C.; Tiron, R.; Zinck, C.; Sanchez, Y.; Fellous, C.; Regolini, J.; Reynard, J. P.; Schlatter, G.; Hadziioannou, G.

    2006-03-01

    Microlenses arrays are commonly used in CMOS images sensors to focus the incident light onto the photosensitive area of the pixel. These microlenses are fabricated using a thermal reflow method. Currently, due to the fast evolution of CMOS Imager technology, the understanding of the mechanisms involved in microlens formation becomes essential to better control what occurs during the process. We have seen in a previous study that the complexity of the reflow method comes from the competition between two phenomena occurring during the melt bake step: on one hand the surface tension tends to push the resist patterns into a spherical shape, on the other hand the resist crosslinking reaction drastically increases the resist viscosity hindering the microlens formation. In this paper the influence of resist crosslinking, resist volume and resist/substrate interface on the final shape of the microlens has been investigated. It appears that the contact angle between microlens and substrate varies depending on substrate wettability but is the same whatever the resist volume for a given substrate/resist combination. The microlens shape depends also significantly on bake temperature and crosslinking kinetics. In fact the right tuning of process conditions seems to be the key parameter in the control of the final microlens shape because it enables to adjust the kinetics of each mechanism and thus favour the microlens formation with regards to resist crosslinking.

  6. Capillary-assisted fabrication of biconcave polymeric microlenses from microfluidic ternary emulsion droplets.

    PubMed

    Nisisako, Takasi; Ando, Takuya; Hatsuzawa, Takeshi

    2014-12-29

    In this study, a simple capillary-based approach for producing biconcave polymeric microlenses with uniform size and shape from ternary emulsion droplets is presented. Monodisperse ternary emulsion droplets (0.6-4.0 nL) are produced which contain a photocurable segment of an acrylate monomer and two non-curable segments of silicone oil (SO) by using a microfluidic sheath-flowing droplet generator on a glass chip. The curvature radius of the interfaces separating the droplet segments, as well as the droplet size, and production rate can be flexibly varied by changing the flow conditions of the organic and aqueous phases. Subsequently, off-chip suspension photopolymerization yields non-spherical polymeric microparticles with two spherical concave surfaces templated by two SO segments at random positions. By ultraviolet light irradiation of ternary droplets with two SO segments trapped by the interior wall of a cylindrical microcapillary (internal diameter: 130 μm), biconcave microlenses can be produced with two spherical concave surfaces with a common lens axis. The produced lenses are suitable for use as optical diverging lenses.

  7. MOA-2011-BLG-028Lb: A Neptune-mass Microlensing Planet in the Galactic Bulge

    NASA Astrophysics Data System (ADS)

    Skowron, J.; Udalski, A.; Poleski, R.; Kozłowski, S.; Szymański, M. K.; Wyrzykowski, Ł.; Ulaczyk, K.; Pietrukowicz, P.; Pietrzyński, G.; Soszyński, I.; OGLE Collaboration; Abe, F.; Bennett, D. P.; Bhattacharya, A.; Bond, I. A.; Freeman, M.; Fukui, A.; Hirao, Y.; Itow, Y.; Koshimoto, N.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Ohnishi, K.; Rattenbury, N.; Saito, To.; Sullivan, D. J.; Sumi, T.; Suzuki, D.; Tristram, P. J.; Yonehara, A.; MOA Collaboration; Dominik, M.; Jørgensen, U. G.; Bozza, V.; Harpsøe, K.; Hundertmark, M.; Skottfelt, J.; MiNDSTEp Collaboration

    2016-03-01

    We present the discovery of a Neptune-mass planet orbiting a 0.8+/- 0.3{M}⊙ star in the Galactic bulge. The planet manifested itself during the microlensing event MOA-2011-BLG-028/OGLE-2011-BLG-0203 as a low-mass companion to the lens star. The analysis of the light curve provides the measurement of the mass ratio (1.2+/- 0.2)× {10}-4, which indicates that the mass of the planet is 12-60 Earth masses. The lensing system is located at 7.3 ± 0.7 kpc away from the Earth near the direction of Baade’s Window. The projected separation of the planet at the time of the microlensing event was 3.1-5.2 au. Although the microlens parallax effect is not detected in the light curve of this event, preventing the actual mass measurement, the uncertainties of mass and distance estimation are narrowed by the measurement of the source star proper motion on the OGLE-III images spanning eight years, and by the low amount of blended light seen, proving that the host star cannot be too bright and massive. We also discuss the inclusion of undetected parallax and orbital motion effects into the models and their influence onto the final physical parameters estimates. Based on observations obtained with the 1.3 m Warsaw telescope at the Las Campanas Observatory operated by the Carnegie Institution of Washington.

  8. OGLE-2014-BLG-0257L: A Microlensing Brown Dwarf Orbiting a Low-mass M Dwarf

    NASA Astrophysics Data System (ADS)

    Han, C.; Jung, Y. K.; Udalski, A.; Gould, A.; Bozza, V.; Szymański, M. K.; Soszyński, I.; Poleski, R.; Kozłowski, S.; Pietrukowicz, P.; Skowron, J.; Ulaczyk, K.; Wyrzykowski, Ł.; OGLE Collaboration

    2016-05-01

    In this paper, we report the discovery of a binary composed of a brown dwarf (BD) and a low-mass M dwarf from observation of the microlensing event OGLE-2014-BLG-0257. The resolution of the very brief caustic crossing combined with the detection of subtle continuous deviation in the lensing light curve induced by the Earth’s orbital motion enable us to precisely measure both the Einstein radius {θ }{{E}} and the lens parallax {π }{{E}}, which are the two quantities needed to unambiguously determine the mass and distance to the lens. It is found that the companion is a substellar BD with a mass of 0.036+/- 0.005 {M}⊙ (37.7+/- 5.2 {M}{{J}}) and it is orbiting an M dwarf with a mass of 0.19+/- 0.02 {M}⊙ . The binary is located at a distance of 1.25 ± 0.13 kpc toward the Galactic bulge and the projected separation between the binary components is 0.61 ± 0.07 au. The separation scaled by the mass of the host is 3.2 {{au}}/{M}⊙ . Based on the assumption that separations scale with masses, the discovered BD is located in the BD desert. With the growing sample of BDs in various environments, microlensing will provide a powerful probe of BDs in the Galaxy.

  9. Microlensed dual-fiber probe for depth-resolved fluorescence measurements

    NASA Astrophysics Data System (ADS)

    Choi, Hae Young; Ryu, Seon Young; Kim, Jae Young; Kim, Geon Hee; Park, Seong Jun; Lee, Byeong Ha; Chang, Ki Soo

    2011-07-01

    We propose and demonstrate a compact microlensed dual-fiber probe that has a good collection efficiency and a high depth-resolution ability for fluorescence measurements. The probe is formed with a conventional fusion splicer creating a common focusing lens on two fibers placed side by side. The collection efficiency of the fabricated probe was evaluated by measuring the fluorescence signal of a fresh ginkgo leaf. It was shown experimentally that the proposed probe could effectively collect the fluorescence signal with a six-fold increase compared to that of a general flat-tipped probe. The beam propagation method was used to design a probe with an optimized working distance and an improved resolving depth. It was found that the working distance depends mainly on the radius of curvature of the lens, whereas the resolving depth is determined by the core diameters of the illumination and collection fibers. The depth-resolved ability of probes with working distances of ~100 μm and 300 μm was validated by using a two-layer tissue phantom. The experimental results demonstrate that the microlensed dual-fiber probe has the potential to facilitate depth-resolved fluorescence detection of epithelial tissue.

  10. Faint-source-star planetary microlensing: the discovery of the cold gas-giant planet OGLE-2014-BLG-0676Lb

    NASA Astrophysics Data System (ADS)

    Rattenbury, N. J.; Bennett, D. P.; Sumi, T.; Koshimoto, N.; Bond, I. A.; Udalski, A.; Shvartzvald, Y.; Maoz, D.; Jørgensen, U. G.; Dominik, M.; Street, R. A.; Tsapras, Y.; Abe, F.; Asakura, Y.; Barry, R.; Bhattacharya, A.; Donachie, M.; Evans, P.; Freeman, M.; Fukui, A.; Hirao, Y.; Itow, Y.; Li, M. C. A.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Ohnishi, K.; Oyokawa, H.; Saito, To.; Sharan, A.; Sullivan, D. J.; Suzuki, D.; Tristram, P. J.; Yonehara, A.; Poleski, R.; Skowron, J.; Mróz, P.; Szymański, M. K.; Soszyński, I.; Pietrukowicz, P.; Kozłowski, S.; Ulaczyk, K.; Wyrzykowski, Ł.; Friedmann, M.; Kaspi, S.; Alsubai, K.; Browne, P.; Andersen, J. M.; Bozza, V.; Calchi Novati, S.; Damerdji, Y.; Diehl, C.; Dreizler, S.; Elyiv, A.; Giannini, E.; Hardis, S.; Harpsøe, K.; Hinse, T. C.; Liebig, C.; Hundertmark, M.; Juncher, D.; Kains, N.; Kerins, E.; Korhonen, H.; Mancini, L.; Martin, R.; Mathiasen, M.; Rabus, M.; Rahvar, S.; Scarpetta, G.; Skottfelt, J.; Snodgrass, C.; Surdej, J.; Taylor, J.; Tregloan-Reed, J.; Vilela, C.; Wambsganss, J.; Williams, A.; D'Ago, G.; Bachelet, E.; Bramich, D. M.; Figuera Jaimes, R.; Horne, K.; Menzies, J.; Schmidt, R.; Steele, I. A.

    2017-04-01

    We report the discovery of a planet - OGLE-2014-BLG-0676Lb- via gravitational microlensing. Observations for the lensing event were made by the following groups: Microlensing Observations in Astrophysics; Optical Gravitational Lensing Experiment; Wise Observatory; RoboNET/Las Cumbres Observatory Global Telescope; Microlensing Network for the Detection of Small Terrestrial Exoplanets; and μ-FUN. All analyses of the light-curve data favour a lens system comprising a planetary mass orbiting a host star. The most-favoured binary lens model has a mass ratio between the two lens masses of (4.78 ± 0.13) × 10-3. Subject to some important assumptions, a Bayesian probability density analysis suggests the lens system comprises a 3.09_{-1.12}^{+1.02} MJ planet orbiting a 0.62_{-0.22}^{+0.20} M⊙ host star at a deprojected orbital separation of 4.40_{-1.46}^{+2.16} au. The distance to the lens system is 2.22_{-0.83}^{+0.96} kpc. Planet OGLE-2014-BLG-0676Lb provides additional data to the growing number of cool planets discovered using gravitational microlensing against which planetary formation theories may be tested. Most of the light in the baseline of this event is expected to come from the lens and thus high-resolution imaging observations could confirm our planetary model interpretation.

  11. Predictions on the detection of the free-floating planet population with K2 and spitzer microlensing campaigns

    NASA Astrophysics Data System (ADS)

    Hamolli, L.; De Paolis, F.; Hafizi, M.; Nucita, A. A.

    2017-01-01

    The K2's Campaign 9 (K2C9) by the Kepler satellite for microlensing observations towards the Galactic bulge started on April 7, 2016, and is going to last for about three months. It offers the first chance to measure the masses of members of the large population of the isolated dark low-mass objects further away in our Galaxy, free-floating planets (FFPs). Intentionally, this observational period of K2 will overlap with that of the 2016 Spitzer follow-up microlensing project expected to start in June, 2016. Therefore, for the first time it is going to be possible to observe simultaneously the same microlensing events from a ground-based telescope and two satellites. This will help in removing the two-fold degeneracy of the impact parameter and in estimating the FFP mass, provided that the angular Einstein ring radius ΘE is measured. In this paper we calculate the probability that a microlensing event is detectable by two or more telescopes and study how it depends on the mass function index of FFPs and the position of the observers on the orbit.

  12. Highly indistinguishable photons from deterministic quantum-dot microlenses utilizing three-dimensional in situ electron-beam lithography

    PubMed Central

    Gschrey, M.; Thoma, A.; Schnauber, P.; Seifried, M.; Schmidt, R.; Wohlfeil, B.; Krüger, L.; Schulze, J. -H.; Heindel, T.; Burger, S.; Schmidt, F.; Strittmatter, A.; Rodt, S.; Reitzenstein, S.

    2015-01-01

    The success of advanced quantum communication relies crucially on non-classical light sources emitting single indistinguishable photons at high flux rates and purity. We report on deterministically fabricated microlenses with single quantum dots inside which fulfil these requirements in a flexible and robust quantum device approach. In our concept we combine cathodoluminescence spectroscopy with advanced in situ three-dimensional electron-beam lithography at cryogenic temperatures to pattern monolithic microlenses precisely aligned to pre-selected single quantum dots above a distributed Bragg reflector. We demonstrate that the resulting deterministic quantum-dot microlenses enhance the photon-extraction efficiency to (23±3)%. Furthermore we prove that such microlenses assure close to pure emission of triggered single photons with a high degree of photon indistinguishability up to (80±7)% at saturation. As a unique feature, both single-photon purity and photon indistinguishability are preserved at high excitation power and pulsed excitation, even above saturation of the quantum emitter. PMID:26179766

  13. Special relativity corrections for space-based lidars.

    PubMed

    Gudimetla, V S; Kavaya, M J

    1999-10-20

    The theory of special relativity is used to analyze some of the physical phenomena associated with space-based coherent Doppler lidars aimed at Earth and the atmosphere. Two important cases of diffuse scattering and retroreflection by lidar targets are treated. For the case of diffuse scattering, we show that for a coaligned transmitter and receiver on the moving satellite, there is no angle between transmitted and returned radiation. However, the ray that enters the receiver does not correspond to a retroreflected ray by the target. For the retroreflection case there is misalignment between the transmitted ray and the received ray. In addition, the Doppler shift in the frequency and the amount of tip for the receiver aperture when needed are calculated. The error in estimating wind because of the Doppler shift in the frequency due to special relativity effects is examined. The results are then applied to a proposed space-based pulsed coherent Doppler lidar at NASA's Marshall Space Flight Center for wind and aerosol backscatter measurements. The lidar uses an orbiting spacecraft with a pulsed laser source and measures the Doppler shift between the transmitted and the received frequencies to determine the atmospheric wind velocities. We show that the special relativity effects are small for the proposed system.

  14. Special Relativity Corrections for Space-Based Lidars

    NASA Technical Reports Server (NTRS)

    RaoGudimetla, Venkata S.; Kavaya, Michael J.

    1999-01-01

    The theory of special relativity is used to analyze some of the physical phenomena associated with space-based coherent Doppler lidars aimed at Earth and the atmosphere. Two important cases of diffuse scattering and retroreflection by lidar targets are treated. For the case of diffuse scattering, we show that for a coaligned transmitter and receiver on the moving satellite, there is no angle between transmitted and returned radiation. However, the ray that enters the receiver does not correspond to a retroreflected ray by the target. For the retroreflection case there is misalignment between the transmitted ray and the received ray. In addition, the Doppler shift in the frequency and the amount of tip for the receiver aperture when needed are calculated, The error in estimating wind because of the Doppler shift in the frequency due to special relativity effects is examined. The results are then applied to a proposed space-based pulsed coherent Doppler lidar at NASA's Marshall Space Flight Center for wind and aerosol backscatter measurements. The lidar uses an orbiting spacecraft with a pulsed laser source and measures the Doppler shift between the transmitted and the received frequencies to determine the atmospheric wind velocities. We show that the special relativity effects are small for the proposed system.

  15. Quantifying the tracking capability of space-based AIS systems

    NASA Astrophysics Data System (ADS)

    Skauen, Andreas Nordmo

    2016-01-01

    The Norwegian Defence Research Establishment (FFI) has operated three Automatic Identification System (AIS) receivers in space. Two are on dedicated nano-satellites, AISSat-1 and AISSat-2. The third, the NORAIS Receiver, was installed on the International Space Station. A general method for calculating the upper bound on the tracking capability of a space-based AIS system has been developed and the results from the algorithm applied to AISSat-1 and the NORAIS Receiver individually. In addition, a constellation of AISSat-1 and AISSat-2 is presented. The tracking capability is defined as the probability of re-detecting ships as they move around the globe and is explained to represent and upper bound on a space-based AIS system performance. AISSat-1 and AISSat-2 operates on the nominal AIS1 and AIS2 channels, while the NORAIS Receiver data used are from operations on the dedicated space AIS channels, AIS3 and AIS4. The improved tracking capability of operations on the space AIS channels is presented.

  16. Future Prospects for Space-Based Gamma Ray Astronomy

    NASA Astrophysics Data System (ADS)

    McConnell, Mark

    2016-03-01

    The gamma-ray sky offers a unique view into broad range of high energy astrophysical phenomena, from nearby solar flares, to galactic pulsars, to gamma-ray bursts at the furthest reaches of the Universe. In recent years, results from the Fermi mission have further demonstrated the broad range of topics that can be addressed by gamma-ray observations. The full range of gamma-ray energies is quite broad, from about 100 keV up to about 100 TeV. The energy range below several hundred GeV is the domain of space-based gamma-ray observatories, a range that is not completely covered by the Fermi LAT instrument. The gamma ray community has embarked on an effort to define the next steps for space-based gamma ray astronomy. These discussions are being facilitated through the Gamma-ray Science Interest Group (GammaSIG), which exists to provide community input to NASA in regards to current and future needs of the gamma-ray astrophysics community. Through a series of workshops and symposia, the GammaSIG is working to bring the community together with one common vision, a vision that will be expressed in the form of a community roadmap. This talk will summarize some of the latest results from active gamma ray observatories and will summarize the status of the community roadmap effort.

  17. Future Prospects for Space-Based Gamma Ray Astronomy

    NASA Astrophysics Data System (ADS)

    McConnell, Mark

    2015-04-01

    The gamma-ray sky offers a unique view into broad range of astrophysical phenomena, from nearby solar flares, to galactic pulsars, to gamma-ray bursts at the furthest reaches of the Universe. The Fermi mission has dramatically demonstrated the broad range of topics that can be addressed by gamma-ray observations. The full range of gamma-ray energies is quite broad, covering the electromagnetic spectrum at energies above about 100 keV. The energy range below several hundred GeV is the domain of space-based gamma-ray observatories, a range that is not completely covered by the Fermi LAT instrument. The gamma ray community has recently embarked on an effort to define the next steps for space-based gamma ray astronomy. These discussions are being facilitated through the Gamma-ray Science Interest Group (GammaSIG), which exists to provide community input to NASA in regards to current and future needs of the gamma-ray astrophysics community. The GammaSIG, as a part of the Physics of the Cosmos Program Analysis Group, provides a forum open to all members of the gamma-ray community. The GammaSIG is currently working to bring the community together with a common vision that will be expressed in the form of a community roadmap. This talk will summarize some of the latest results from active gamma ray observatories, including both Fermi and INTEGRAL, and will summarize the status of the community roadmap effort.

  18. Concept for lightweight spaced-based deposition technology

    SciTech Connect

    Fulton, Michael; Anders, Andre

    2006-02-28

    In this contribution we will describe a technology path to very high quality coatings fabricated in the vacuum of space. To accomplish the ambitious goals set out in NASA's Lunar-Mars proposal, advanced thin-film deposition technology will be required. The ability to deposit thin-film coatings in the vacuum of lunar-space could be extremely valuable for executing this new space mission. Developing lightweight space-based deposition technology (goal:<300 g, including power supply) will enable the future fabrication and repair of flexible large-area space antennae and fixed telescope mirrors for lunar-station observatories. Filtered Cathodic Arc (FCA) is a proven terrestrial energetic thin-film deposition technology that does not need any processing gas but is well suited for ultra-high vacuum operation. Recently, miniaturized cathodic arcs have already been developed and considered for space propulsion. It is proposed to combine miniaturized pulsed FCA technology and robotics to create a robust, enabling space-based deposition system for the fabrication, improvement, and repair of thin films, especially of silver and aluminum, on telescope mirrors and eventually on large area flexible substrates. Using miniature power supplies with inductive storage, the typical low-voltage supply systems used in space are adequate. It is shown that high-value, small area coatings are within the reach of existing technology, while medium and large area coatings are challenging in terms of lightweight technology and economics.

  19. 76 FR 30202 - National Space-Based Positioning, Navigation, and Timing (PNT) Advisory Board; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-24

    .... Space-Based Positioning, Navigation, and Timing (PNT) Policy, the National Aeronautics and Space... following topics: Update on U.S. Space-Based PNT Policy and Global Positioning System (GPS) modernization... SPACE ADMINISTRATION National Space-Based Positioning, Navigation, and Timing (PNT) Advisory...

  20. Medium Brigade 2003: Can Space-Based Communications Ensure Information Dominance?

    DTIC Science & Technology

    2007-11-02

    MEDIUM BRIGADE 2003: CAN SPACE-BASED COMMUNICATIONS ENSURE INFORMATION DOMINANCE ? A thesis presented to the Faculty of the U.S. Army Command and...Medium Brigade 2003: Can Space-Based Communications Ensure Information Dominance ? Unclassified 5c. PROGRAM ELEMENT NUMBER 5d. PROJECT NUMBER 5e. TASK...Space-Based Communications Ensure Information Dominance ? Approved by: _____________________________________, Thesis Committee Chairman LTC Heather

  1. ISS Space-Based Science Operations Grid for the Ground Systems Architecture Workshop (GSAW)

    NASA Technical Reports Server (NTRS)

    Welch, Clara; Bradford, Bob

    2003-01-01

    Contents include the following:What is grid? Benefits of a grid to space-based science operations. Our approach. Score of prototype grid. The security question. Short term objectives. Long term objectives. Space-based services required for operations. The prototype. Score of prototype grid. Prototype service layout. Space-based science grid service components.

  2. AN EFFICIENT METHOD FOR MODELING HIGH-MAGNIFICATION PLANETARY MICROLENSING EVENTS

    SciTech Connect

    Bennett, David P.

    2010-06-20

    I present a previously unpublished method for calculating and modeling multiple lens microlensing events that is based on the image centered ray-shooting approach of Bennett and Rhie. It has been used to model a wide variety of binary and triple lens systems, but it is designed to efficiently model high-magnification planetary microlensing events, because these high-magnification events are, by far, the most challenging events to model. It is designed to be efficient enough to handle complicated microlensing events, which include more than two lens masses and lens orbital motion. This method uses a polar coordinate integration grid with a smaller grid spacing in the radial direction than in the angular direction, and it employs an integration scheme specifically designed to handle limb-darkened sources. I present tests that show that these features achieve second-order accuracy for the light curves of a number of high-magnification planetary events. They improve the precision of the calculations by a factor of >100 compared to first-order integration schemes with the same grid spacing in both directions (for a fixed number of grid points). This method also includes a {chi}{sup 2} minimization method, based on the Metropolis algorithm, that allows the jump function to vary in a way that allows quick convergence to {chi}{sup 2} minima. Finally, I introduce a global parameter space search strategy that allows a blind search of parameter space for light curve models without requiring {chi}{sup 2} minimization over a large grid of fixed parameters. Instead, the parameter space is explored on a grid of initial conditions for a set of {chi}{sup 2} minimizations using the full parameter space. While this method may be somewhat faster than methods that find the {chi}{sup 2} minima over a large grid of parameters, I argue that the main strength of this method is for events with the signals of multiple planets, where a much higher dimensional parameter space must be explored

  3. Space-based radar array system simulation and validation

    NASA Astrophysics Data System (ADS)

    Schuman, H. K.; Pflug, D. R.; Thompson, L. D.

    1981-08-01

    The present status of the space-based radar phased array lens simulator is discussed. Huge arrays of thin wire radiating elements on either side of a ground screen are modeled by the simulator. Also modeled are amplitude and phase adjust modules connecting radiating elements between arrays, feedline to radiator mismatch, and lens warping. A successive approximation method is employed. The first approximation is based on a plane wave expansion (infinite array) moment method especially suited to large array analysis. the first approximation results then facilitate higher approximation computations that account for effects of nonuniform periodicities (lens edge, lens section interfaces, failed modules, etc.). The programming to date is discussed via flow diagrams. An improved theory is presented in a consolidated development. The use of the simulator is illustrated by computing active impedances and radiating element current distributions for infinite planar arrays of straight and 'swept back' dipoles (arms inclined with respect to the array plane) with feedline scattering taken into account.

  4. One GHz digitizer for space based laser altimeter

    NASA Technical Reports Server (NTRS)

    Staples, Edward J.

    1991-01-01

    This is the final report for the research and development of the one GHz digitizer for space based laser altimeter. A feasibility model was designed, built, and tested. Only partial testing of essential functions of the digitizer was completed. Hybrid technology was incorporated which allows analog storage (memory) of the digitally sampled data. The actual sampling rate is 62.5 MHz, but executed in 16 parallel channels, to provide an effective sampling rate of one GHz. The average power consumption of the one GHz digitizer is not more than 1.5 Watts. A one GHz oscillator is incorporated for timing purposes. This signal is also made available externally for system timing. A software package was also developed for internal use (controls, commands, etc.) and for data communication with the host computer. The digitizer is equipped with an onboard microprocessor for this purpose.

  5. Phytoplankton photocompensation from space-based fluorescence measurements

    NASA Astrophysics Data System (ADS)

    Morrison, J. Ruairidh; Goodwin, Deborah S.

    2010-03-01

    Recent satellite-derived observations linked global scale phytoplankton fluorescence variability with iron stress and hinted at photophysiological responses associated with changing light levels. These photocompensation reactions, the sum of photoacclimation and photoadaptation, were examined with climatological data for the Gulf of Maine. Significant seasonal variability was observed in the fluorescence quantum yield that was unrelated to patterns of biomass. Up to 89% of the variability in the fluorescence quantum yield was explained by a physiology-based photocompensation model. Spatial variability in seasonal patterns was associated with differing hydrodynamic regimes. This variability in the quantum yield demonstrates that satellite-based fluorescence is inappropriate for phytoplankton biomass determinations. More importantly, the work presented here provides the modeling foundation for fluorescence-based investigations of temporal and spatial variability in phytoplankton physiology associated with growth irradiance. These space-based physiological observations have the potential to decrease uncertainties in future ocean color derived primary productivity estimates.

  6. MEMS-Based Communications Systems for Space-Based Applications

    NASA Technical Reports Server (NTRS)

    DeLosSantos, Hector J.; Brunner, Robert A.; Lam, Juan F.; Hackett, Le Roy H.; Lohr, Ross F., Jr.; Larson, Lawrence E.; Loo, Robert Y.; Matloubian, Mehran; Tangonan, Gregory L.

    1995-01-01

    As user demand for higher capacity and flexibility in communications satellites increases, new ways to cope with the inherent limitations posed by the prohibitive mass and power consumption, needed to satisfy those requirements, are under investigation. Recent studies suggest that while new satellite architectures are necessary to enable multi-user, multi-data rate, multi-location satellite links, these new architectures will inevitably increase power consumption, and in turn, spacecraft mass, to such an extent that their successful implementation will demand novel lightweight/low power hardware approaches. In this paper, following a brief introduction to the fundamentals of communications satellites, we address the impact of micro-electro-mechanical systems (MEMS) technology, in particular micro-electro-mechanical (MEM) switches to mitigate the above mentioned problems and show that low-loss/wide bandwidth MEM switches will go a long way towards enabling higher capacity and flexibility space-based communications systems.

  7. Non-Topographic Space-Based Laser Remote Sensing

    NASA Technical Reports Server (NTRS)

    Yu, Anthony W.; Abshire, James B.; Riris, Haris; Purucker, Michael; Janches, Diego; Getty, Stephanie; Krainak, Michael A.; Stephen, Mark A.; Chen, Jeffrey R.; Li, Steve X.; Numata, Kenji; Fahey, Molly E.; Wu, Stewart; Allan, Graham R.; Konoplev, Oleg

    2016-01-01

    In the past 20+ years, NASA Goddard Space Flight Center (GSFC) has successfully developed and flown lidars for mapping of Mars, the Earth, Mercury and the Moon. As laser and electro-optics technologies expand and mature, more sophisticated instruments that once were thought to be too complicated for space are being considered and developed. We will present progress on several new, space-based laser instruments that are being developed at GSFC. These include lidars for remote sensing of carbon dioxide and methane on Earth for carbon cycle and global climate change; sodium resonance fluorescence lidar to measure environmental parameters of the middle and upper atmosphere on Earth and Mars and a wind lidar for Mars orbit; in situ laser instruments include remote and in-situ measurements of the magnetic fields; and a time-of-flight mass spectrometer to study the diversity and structure of nonvolatile organics in solid samples on missions to outer planetary satellites and small bodies.

  8. Dehumidification via membrane separation for space-based applications

    NASA Technical Reports Server (NTRS)

    Gienger, Jane Kucera; Ray, Roderick J.; Chullen, Cinda

    1988-01-01

    The paper describes the development of a membrane-based dehumidification process for space-based applications, such as spacecraft cabins and EVA space suits. Results presented are from: (1) screening tests conducted to determine the efficacy of various membranes to separate water vapor from air, and (2) parametric and long-term tests of membranes operated at conditions that simulate the range of environmental conditions (e.g., temperature and relative humidity) expected in the planned Space Station. Also included in this paper is a discussion of preliminary designs of membrane-based dehumidification processes for the Space Station and EVA space suits. These designs result in compact and energy-efficient systems that offer significant advantages over conventional dehumidification processes.

  9. Infrared Fibers for Use in Space-Based Smart Structures

    NASA Technical Reports Server (NTRS)

    Tucker, Dennis S.; Nettles, Alan T.; Brantley, Lott W. (Technical Monitor)

    2001-01-01

    Infrared optical fibers are finding a number of applications including laser surgery, remote sensing, and nuclear radiation resistant links. Utilizing these fibers in space-based structures is another application, which can be exploited. Acoustic and thermal sensing are two areas in which these fibers could be utilized. In particular, fibers could be embedded in IM7/8552 toughened epoxy and incorporated into space structures both external and internal. ZBLAN optical fibers are a candidate, which have been studied extensively over the past 20 years for terrestrial applications. For the past seven years the effects of gravity on the crystallization behavior of ZBLAN optical fiber has been studied. It has been found that ZBLAN crystallization is suppressed in microgravity. This lack of crystallization leads to a fiber with better transmission characteristics than its terrestrial counterpart.

  10. Space-Based Gravitational-Wave Observatory Mission Concept

    NASA Astrophysics Data System (ADS)

    Livas, Jeffrey C.

    2014-08-01

    Space-based Gravitational-wave Observatories (SGOs) will enable the systematic study of the frequency band from 0.0001 - 1 Hz of gravitational waves, where a rich array of astrophysical sources is expected. ESA has selected “The Gravitational Universe” as the science theme for the L3 mission opportunity with a nominal launch date in 2034. This will be at a minimum 15 years after ground-based detectors and pulsar timing arrays announce their first detections and at least 18 years after the LISA Pathfinder Mission will have demonstrated key technologies in a dedicated space mission. It is therefore important to develop mission concepts that can take advantage of the momentum in the field and the investment in both technology development and a precision measurement community on a more near-term timescale than the L3 opportunity. This talk will discuss a mission concept based on the LISA baseline that resulted from a recent mission architecture study.

  11. Space-Based Information Infrastructure Architecture for Broadband Services

    NASA Technical Reports Server (NTRS)

    Price, Kent M.; Inukai, Tom; Razdan, Rajendev; Lazeav, Yvonne M.

    1996-01-01

    This study addressed four tasks: (1) identify satellite-addressable information infrastructure markets; (2) perform network analysis for space-based information infrastructure; (3) develop conceptual architectures; and (4) economic assessment of architectures. The report concludes that satellites will have a major role in the national and global information infrastructure, requiring seamless integration between terrestrial and satellite networks. The proposed LEO, MEO, and GEO satellite systems have satellite characteristics that vary widely. They include delay, delay variations, poorer link quality and beam/satellite handover. The barriers against seamless interoperability between satellite and terrestrial networks are discussed. These barriers are the lack of compatible parameters, standards and protocols, which are presently being evaluated and reduced.

  12. Characterizing Exoplanets with 2-meter Class Space-based Coronagraphs

    NASA Astrophysics Data System (ADS)

    Robinson, T. D.; Marley, M. S.; Stapelfeldt, K. R.

    2015-12-01

    Several concepts now exist for small, space-based missions to directly characterize exoplanets in reflected light. In this presentation, we explore how instrumental and astrophysical parameters will affect the ability of such missions to obtain spectral and photometric observations that are useful for characterizing their planetary targets. We discuss the development of an instrument noise model suitable for studying the spectral characterization potential of a coronagraph-equipped, space-based telescope. To be consistent with near-future missions and technologies, we assume a baseline set of telescope and instrument parameters that include a 2 meter diameter primary aperture, an operational wavelength range of 0.4-1.0 μm, and an instrument spectral resolution of λ/Δλ=70. We present applications of our baseline noise simulator to a variety of spectral models of different planet types, emphasizing Earth-like planets. With our exoplanet spectral models, we explore wavelength-dependent planet-star flux ratios for main sequence stars of various effective temperatures, and discuss how coronagraph inner and outer working angle constraints will influence the potential to study different types of planets. For planets most favorable to spectroscopic characterization—including nearby Earth twins and super-Earths—we study the integration times required to achieve moderate signal-to-noise ratio spectra. We also explore the sensitivity of the integration times required to detect the base of key absorption bands (for water vapor and molecular oxygen) to coronagraph raw contrast performance, exozodiacal light levels, and the distance to the planetary system. We will also discuss prospects for detecting ocean glint, a habitability signature, from nearby Earth-like planets, as well as the extension of our models to a more distant future Large UV-Optical-InfraRed (LUVOIR) mission.

  13. Space Based Ornithology: On the Wings of Migration and Biophysics

    NASA Technical Reports Server (NTRS)

    Smith, James A.

    2005-01-01

    The study of bird migration on a global scale is one of the compelling and challenging problems of modern biology with major implications for human health and conservation biology. Migration and conservation efforts cross national boundaries and are subject to numerous international agreements and treaties. Space based technology offers new opportunities to shed understanding on the distribution and migration of organisms on the planet and their sensitivity to human disturbances and environmental changes. Migration is an incredibly diverse and complex behavior. A broad outline of space based research must address three fundamental questions: (1) where could birds be, i.e. what is their fundamental niche constrained by their biophysical limits? (2) where do we actually find birds, i.e. what is their realizable niche as modified by local or regional abiotic and biotic factors, and (3) how do they get there (and how do we know?), that is what are their migration patterns and associated mechanisms? Our working hypothesis is that individual organism biophysical models of energy and water balance, driven by satellite measurements of spatio-temporal gradients in climate and habitat, will help us to explain the variability in avian species richness and distribution. Dynamic state variable modeling provides one tool for studying bird migration across multiple scales and can be linked to mechanistic models describing the time and energy budget states of migrating birds. Such models yield an understanding of how a migratory flyway and its component habitats function as a whole and link stop-over ecology with biological conservation and management. Further these models provide an ecological forecasting tool for science and application users to address what are the possible consequences of loss of wetlands, flooding, drought or other natural disasters such as hurricanes on avian biodiversity and bird migration.

  14. Enhanced light extraction from UV LEDs using spin-on glass microlenses

    NASA Astrophysics Data System (ADS)

    Liu, Chi-Min; Su, Guo-Dung J.

    2016-05-01

    In this paper, we present a cost-effective method for fabricating spin-on glass (SOG) microlens arrays (MLAs) on ultra-violet light-emitting diodes. The SOG MLA is formed using thermal reflow molds and multiple replication processes, which can reduce the cost of the solution process. In this paper, we fabricate SOG MLA of different sizes, where the diameter of each microlens is approximately 50, 100, 150, and 200 μm. In each case, the light extraction efficiency is improved by 21.86%, 14.01%, 10.35%, and 7.31%, respectively. We also discuss the effects of different-shaped SOG microlenses, namely circular, square, and hexagonal. The light extraction efficiency is improved by 7.31%, 9.60%, and 13.80% for the circular, square, and hexagonal SOG MLAs, respectively. By applying an optimized lens pattern, an increase in light extraction efficiency of 21.86% is achieved.

  15. The complete catalogue of light curves in equal-mass binary microlensing

    NASA Astrophysics Data System (ADS)

    Liebig, Christine; D'Ago, Giuseppe; Bozza, Valerio; Dominik, Martin

    2015-06-01

    The light curves observed in microlensing events due to binary lenses span an extremely wide variety of forms, characterized by U-shaped caustic crossings and/or additional smoother peaks. However, all peaks of the binary-lens light curve can be traced back to features of caustics of the lens system. Moreover, all peaks can be categorized as one of only four types (cusp-grazing, cusp-crossing, fold-crossing or fold-grazing). This enables us to present the first complete map of the parameter space of the equal-mass case by identifying regions in which light curves feature the same number and nature of peaks. We find that the total number of morphologies that can be obtained is 73 out of 232 different regions. The partition of the parameter space so-obtained provides a new key to optimize modelling of observed events through a clever choice of initial conditions for fitting algorithms.

  16. Search for low-mass exoplanets by gravitational microlensing at high magnification.

    PubMed

    Abe, F; Bennett, D P; Bond, I A; Eguchi, S; Furuta, Y; Hearnshaw, J B; Kamiya, K; Kilmartin, P M; Kurata, Y; Masuda, K; Matsubara, Y; Muraki, Y; Noda, S; Okajima, K; Rakich, A; Rattenbury, N J; Sako, T; Sekiguchi, T; Sullivan, D J; Sumi, T; Tristram, P J; Yanagisawa, T; Yock, P C M; Gal-Yam, A; Lipkin, Y; Maoz, D; Ofek, E O; Udalski, A; Szewczyk, O; Zebrun, K; Soszynski, I; Szymanski, M K; Kubiak, M; Pietrzynski, G; Wyrzykowski, L

    2004-08-27

    Observations of the gravitational microlensing event MOA 2003-BLG-32/OGLE 2003-BLG-219 are presented, for which the peak magnification was over 500, the highest yet reported. Continuous observations around the peak enabled a sensitive search for planets orbiting the lens star. No planets were detected. Planets 1.3 times heavier than Earth were excluded from more than 50% of the projected annular region from approximately 2.3 to 3.6 astronomical units surrounding the lens star, Uranus-mass planets were excluded from 0.9 to 8.7 astronomical units, and planets 1.3 times heavier than Saturn were excluded from 0.2 to 60 astronomical units. These are the largest regions of sensitivity yet achieved in searches for extrasolar planets orbiting any star.

  17. Binary Source Microlensing Event OGLE-2016-BLG-0733: Interpretation of a Long-term Asymmetric Perturbation

    NASA Astrophysics Data System (ADS)

    Jung, Y. K.; Udalski, A.; Yee, J. C.; Sumi, T.; Gould, A.; Han, C.; Albrow, M. D.; Lee, C.-U.; Kim, S.-L.; Chung, S.-J.; Hwang, K.-H.; Ryu, Y.-H.; Shin, I.-G.; Zhu, W.; Cha, S.-M.; Kim, D.-J.; Lee, Y.; Park, B.-G.; Pogge, R. W.; KMTNet Collaboration; Pietrukowicz, P.; Kozłowski, S.; Poleski, R.; Skowron, J.; Mróz, P.; Szymański, M. K.; Soszyński, I.; Pawlak, M.; Ulaczyk, K.; OGLE Collaboration; Abe, F.; Bennett, D. P.; Barry, R.; Bond, I. A.; Asakura, Y.; Bhattacharya, A.; Donachie, M.; Freeman, M.; Fukui, A.; Hirao, Y.; Itow, Y.; Koshimoto, N.; Li, M. C. A.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Oyokawa, H.; Rattenbury, N. J.; Sharan, A.; Sullivan, D. J.; Suzuki, D.; Tristram, P. J.; Yamada, T.; Yamada, T.; Yonehara, A.; MOA Collaboration

    2017-03-01

    In the process of analyzing an observed light curve, one often confronts various scenarios that can mimic the planetary signals causing difficulties in the accurate interpretation of the lens system. In this paper, we present the analysis of the microlensing event OGLE-2016-BLG-0733. The light curve of the event shows a long-term asymmetric perturbation that would appear to be due to a planet. From the detailed modeling of the lensing light curve, however, we find that the perturbation originates from the binarity of the source rather than the lens. This result demonstrates that binary sources with roughly equal-luminosity components can mimic long-term perturbations induced by planets with projected separations near the Einstein ring. The result also represents the importance of the consideration of various interpretations in planet-like perturbations and of high-cadence observations for ensuring the unambiguous detection of the planet.

  18. MOA-2011-BLG-293LB: First microlensing planet possibly in the habitable zone

    SciTech Connect

    Batista, V.; Gould, A.; Yee, J. C.; Gaudi, B. S.; Beaulieu, J.-P.; Bennett, D. P.; Fukui, A.; Sumi, T.; Udalski, A. E-mail: gould@astronomy.ohio-state.edu E-mail: beaulieu@iap.fr E-mail: afukui@oao.nao.ac.jp E-mail: udalski@astrouw.edu.pl

    2014-01-01

    We used Keck adaptive optics observations to identify the first planet discovered by microlensing to lie in or near the habitable zone, i.e., at projected separation r = 1.1 ± 0.1 AU from its M{sub L} = 0.86 ± 0.06 M {sub ☉} host, being the highest microlensing mass definitely identified. The planet has a mass m{sub p} = 4.8 ± 0.3 M {sub Jup}, and could in principle have habitable moons. This is also the first planet to be identified as being in the Galactic bulge with good confidence: D{sub L} = 7.72 ± 0.44 kpc. The planet/host masses and distance were previously not known, but only estimated using Bayesian priors based on a Galactic model. These estimates had suggested that the planet might be a super-Jupiter orbiting an M dwarf, a very rare class of planets. We obtained high-resolution JHK images using Keck adaptive optics to detect the lens and so test this hypothesis. We clearly detect light from a G dwarf at the position of the event, and exclude all interpretations other than that this is the lens with high confidence (95%), using a new astrometric technique. The calibrated magnitude of the planet host star is H{sub L} = 19.16 ± 0.13. We infer the following probabilities for the three possible orbital configurations of the gas giant planet: 53% to be in the habitable zone, 35% to be near the habitable zone, and 12% to be beyond the snow line, depending on the atmospherical conditions and the uncertainties on the semimajor axis.

  19. Microlensing Constraints on Broad Absorption and Emission Line Flows in the Quasar H1413+117

    NASA Astrophysics Data System (ADS)

    O'Dowd, Matthew J.; Bate, Nicholas F.; Webster, Rachel L.; Labrie, Kathleen; Rogers, Joshua

    2015-11-01

    We present new integral field spectroscopy of the gravitationally lensed broad absorption line (BAL) quasar H1413+117, covering the ultraviolet restframe spectral range. We observe strong microlensing signatures in lensed image D, and we use this microlensing to simultaneously constrain both the broad emission and broad absorption line gas. The wavelength independence of image D magnifications across the broad emission lines (BELs) indicates a lower limit on the broad emission line region (BELR) size equal to the Einstein radius (ER) of the system: ≳11 {(< M> /{M}⊙ )}0.5 lt-day for a lens redshift of 1.4 and ≳15 {(< M> /{M}⊙ )}0.5 lt-day for zL = 0.94. Lensing simulations verify that the observed wavelength independence is very unlikely for BELRs with significant velocity stratification at size scales below an ER. We perform spectral decomposition to derive the intrinsic BEL and continuum spectrum, subject to BAL absorption. We reconstruct the intrinsic BAL absorption profile, whose features allow us to constrain outflow kinematics in the context of a disk-wind model. We find a very sharp, blueshifted onset of absorption of 1500 km s-1 in both C iv and N v, which may correspond to an inner edge of a disk-wind’s radial outflow. The lower ionization Si iv and Al iii have higher-velocity absorption onsets, consistent with a decreasing ionization parameter with radius in an accelerating outflow. There is evidence of strong absorption in the BEL component, which indicates a high covering factor for absorption over two orders of magnitude in outflow radius.

  20. The First Circumbinary Planet Found by Microlensing: OGLE-2007-BLG-349L(AB)c

    NASA Technical Reports Server (NTRS)

    Bennett, D. P.; Rhie, S. H.; Udalski, A.; Gould, A.; Tsapras, Y.; Kubas, D.; Bond, I. A.; Greenhill, J.; Cassan, A.; Rattenbury, N. J.; Boyajian, T. S.; Luhn, J.; Penny, M. T.; Anderson, J.; Abe, F.; Bhattacharya, A.; Botzler, C. S.; Donachie, M.; Freeman, M.; Fukui, A.; Hirao, Y.; Itow, Y.; Koshimoto, N.; Li, M. C. A.; Suzuki, Daisuke

    2016-01-01

    We present the analysis of the first circumbinary planet microlensing event, OGLE-2007-BLG-349. This event has a strong planetary signal that is best fit with a mass ratio of q approx. = 3.4×10(exp -4), but there is an additional signal due to an additional lens mass, either another planet or another star. We find acceptable light-curve fits with two classes of models: two-planet models (with a single host star) and circumbinary planet models. The light curve also reveals a significant microlensing parallax effect, which constrains the mass of the lens system to be M(sub L) approx. = 0.7 Stellar Mass. Hubble Space Telescope (HST) images resolve the lens and source stars from their neighbors and indicate excess flux due to the star(s) in the lens system. This is consistent with the predicted flux from the circumbinary models, where the lens mass is shared between two stars, but there is not enough flux to be consistent with the two-planet, one-star models. So, only the circumbinary models are consistent with the HST data. They indicate a planet of mass m(sub c) = 80 +/- 13 Stellar Mass, orbiting a pair of M dwarfs with masses of M(sub A) = 0.41+/- 0.07 and M(sub B) = 0.30 +/- 0.07, which makes this the lowest-mass circumbinary planet system known. The ratio of the separation between the planet and the center of mass to the separation of the two stars is approx.40, so unlike most of the circumbinary planets found by Kepler, the planet does not orbit near the stability limit.

  1. The First Circumbinary Planet Found by Microlensing: OGLE-2007-BLG-349L(AB)c

    NASA Astrophysics Data System (ADS)

    Bennett, D. P.; Rhie, S. H.; Udalski, A.; Gould, A.; Tsapras, Y.; Kubas, D.; Bond, I. A.; Greenhill, J.; Cassan, A.; Rattenbury, N. J.; Boyajian, T. S.; Luhn, J.; Penny, M. T.; Anderson, J.; Abe, F.; Bhattacharya, A.; Botzler, C. S.; Donachie, M.; Freeman, M.; Fukui, A.; Hirao, Y.; Itow, Y.; Koshimoto, N.; Li, M. C. A.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Ohnishi, K.; Oyokawa, H.; Perrott, Y. C.; Saito, To.; Sharan, A.; Sullivan, D. J.; Sumi, T.; Suzuki, D.; Tristram, P. J.; Yonehara, A.; Yock, P. C. M.; MOA Collaboration; Szymański, M. K.; Soszyński, I.; Ulaczyk, K.; Wyrzykowski, Ł.; OGLE Collaboration; Allen, W.; DePoy, D.; Gal-Yam, A.; Gaudi, B. S.; Han, C.; Monard, I. A. G.; Ofek, E.; Pogge, R. W.; μFUN Collaboration; Street, R. A.; Bramich, D. M.; Dominik, M.; Horne, K.; Snodgrass, C.; Steele, I. A.; Robonet Collaboration; Albrow, M. D.; Bachelet, E.; Batista, V.; Beaulieu, J.-P.; Brillant, S.; Caldwell, J. A. R.; Cole, A.; Coutures, C.; Dieters, S.; Dominis Prester, D.; Donatowicz, J.; Fouqué, P.; Hundertmark, M.; Jørgensen, U. G.; Kains, N.; Kane, S. R.; Marquette, J.-B.; Menzies, J.; Pollard, K. R.; Ranc, C.; Sahu, K. C.; Wambsganss, J.; Williams, A.; Zub, M.; PLANET Collaboration

    2016-11-01

    We present the analysis of the first circumbinary planet microlensing event, OGLE-2007-BLG-349. This event has a strong planetary signal that is best fit with a mass ratio of q ≈ 3.4 × 10-4, but there is an additional signal due to an additional lens mass, either another planet or another star. We find acceptable light-curve fits with two classes of models: two-planet models (with a single host star) and circumbinary planet models. The light curve also reveals a significant microlensing parallax effect, which constrains the mass of the lens system to be M L ≈ 0.7 {M}⊙ . Hubble Space Telescope (HST) images resolve the lens and source stars from their neighbors and indicate excess flux due to the star(s) in the lens system. This is consistent with the predicted flux from the circumbinary models, where the lens mass is shared between two stars, but there is not enough flux to be consistent with the two-planet, one-star models. So, only the circumbinary models are consistent with the HST data. They indicate a planet of mass m c = 80 ± 13 {M}\\oplus , orbiting a pair of M dwarfs with masses of M A = 0.41 ± 0.07 and M B = 0.30 ± 0.07, which makes this the lowest-mass circumbinary planet system known. The ratio of the separation between the planet and the center of mass to the separation of the two stars is ˜40, so unlike most of the circumbinary planets found by Kepler, the planet does not orbit near the stability limit.

  2. OGLE-2011-BLG-0265Lb: A Jovian Microlensing Planet Orbiting an M Dwarf

    NASA Astrophysics Data System (ADS)

    Skowron, J.; Shin, I.-G.; Udalski, A.; Han, C.; Sumi, T.; Shvartzvald, Y.; Gould, A.; Dominis Prester, D.; Street, R. A.; Jørgensen, U. G.; Bennett, D. P.; Bozza, V.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Poleski, R.; Kozłowski, S.; Pietrukowicz, P.; Ulaczyk, K.; Wyrzykowski, Ł.; OGLE Collaboration; Abe, F.; Bhattacharya, A.; Bond, I. A.; Botzler, C. S.; Freeman, M.; Fukui, A.; Fukunaga, D.; Itow, Y.; Ling, C. H.; Koshimoto, N.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Namba, S.; Ohnishi, K.; Philpott, L. C.; Rattenbury, N.; Saito, T.; Sullivan, D. J.; Suzuki, D.; Tristram, P. J.; Yock, P. C. M.; MOA Collaboration; Maoz, D.; Kaspi, S.; Friedmann, M.; Wise Group; Almeida, L. A.; Batista, V.; Christie, G.; Choi, J.-Y.; DePoy, D. L.; Gaudi, B. S.; Henderson, C.; Hwang, K.-H.; Jablonski, F.; Jung, Y. K.; Lee, C.-U.; McCormick, J.; Natusch, T.; Ngan, H.; Park, H.; Pogge, R. W.; Yee, J. C.; μFUN Collaboration; Albrow, M. D.; Bachelet, E.; Beaulieu, J.-P.; Brillant, S.; Caldwell, J. A. R.; Cassan, A.; Cole, A.; Corrales, E.; Coutures, Ch.; Dieters, S.; Donatowicz, J.; Fouqué, P.; Greenhill, J.; Kains, N.; Kane, S. R.; Kubas, D.; Marquette, J.-B.; Martin, R.; Menzies, J.; Pollard, K. R.; Ranc, C.; Sahu, K. C.; Wambsganss, J.; Williams, A.; Wouters, D.; PLANET Collaboration; Tsapras, Y.; Bramich, D. M.; Horne, K.; Hundertmark, M.; Snodgrass, C.; Steele, I. A.; RoboNet Collaboration; Alsubai, K. A.; Browne, P.; Burgdorf, M. J.; Calchi Novati, S.; Dodds, P.; Dominik, M.; Dreizler, S.; Fang, X.-S.; Gu, C.-H.; Hardis; Harpsøe, K.; Hessman, F. V.; Hinse, T. C.; Hornstrup, A.; Jessen-Hansen, J.; Kerins, E.; Liebig, C.; Lund, M.; Lundkvist, M.; Mancini, L.; Mathiasen, M.; Penny, M. T.; Rahvar, S.; Ricci, D.; Scarpetta, G.; Skottfelt, J.; Southworth, J.; Surdej, J.; Tregloan-Reed, J.; Wertz, O.; MiNDSTEp Consortium

    2015-05-01

    We report the discovery of a Jupiter-mass planet orbiting an M-dwarf star that gave rise to the microlensing event OGLE-2011-BLG-0265. Such a system is very rare among known planetary systems and thus the discovery is important for theoretical studies of planetary formation and evolution. High-cadence temporal coverage of the planetary signal, combined with extended observations throughout the event, allows us to accurately model the observed light curve. However, the final microlensing solution remains degenerate, yielding two possible configurations of the planet and the host star. In the case of the preferred solution, the mass of the planet is {{M}p}=0.9+/- 0.3 {{M}J}, and the planet is orbiting a star with a mass M=0.22+/- 0.06 {{M}⊙ }. The second possible configuration (2σ away) consists of a planet with {{M}p}=0.6+/- 0.3 {{M}J} and host star with M=0.14+/- 0.06 {{M}⊙ }. The system is located in the Galactic disk 3-4 kpc toward the Galactic bulge. In both cases, with an orbit size of 1.5-2.0 AU, the planet is a “cold Jupiter”—located well beyond the “snow line” of the host star. Currently available data make the secure selection of the correct solution difficult, but there are prospects for lifting the degeneracy with additional follow-up observations in the future, when the lens and source star separate.

  3. Single Crystal DMs for Space-Based Observatories

    NASA Astrophysics Data System (ADS)

    Bierden, Paul

    We propose to demonstrate the feasibility of a new manufacturing process for large aperture, high-actuator count microelectromechanical deformable mirrors (MEMS-DMs). These DMs are designed to fill a critical technology gap in NASA s plan for high- contrast space-based exoplanet observatories. We will manufacture a prototype DM with a continuous mirror facesheet, having an active aperture of 50mm diameter, supported by 2040 electrostatic actuators (50 across the diameter of the active aperture), spaced at a pitch of 1mm. The DM will be manufactured using silicon microfabrication tools. The strategic motivation for the proposed project is to advance MEMS DMs as an enabling technology in NASA s rapidly emerging program for extrasolar planet exploration. That goal is supported by an Astro2010 white paper on Technologies for Direct Optical Imaging of Exoplanets, which concluded that DMs are a critical component for all proposed internal coronagraph instrument concepts. That white paper pointed to great strides made by DM developers in the past decade, and acknowledged the components made by Boston Micromachines Corporation to be the most notable MEMS-based technology option. The principal manufacturing innovation in this project will be assembly of the DM through fusion bonding of three separate single crystal silicon wafers comprising the device s substrate, actuator array, and facesheet. The most significant challenge of this project will be to develop processes that allow reliable fusion bonds between multiple compliant silicon layers while yielding an optically flat surface and a robust electromechanical system. The compliance of the DM, which is required for its electromechanical function, will make it challenging to achieve the intimate, planar contact that is generally needed for success in fusion bonding. The manufacturing approach will use photolithography and reactive ion etching to pattern structural layers. Three wafer-scale devices will be patterned and

  4. Orbits design for LEO space based solar power satellite system

    NASA Astrophysics Data System (ADS)

    Addanki, Neelima Krishna Murthy

    2011-12-01

    Space Based Solar Power satellites use solar arrays to generate clean, green, and renewable electricity in space and transmit it to earth via microwave, radiowave or laser beams to corresponding receivers (ground stations). These traditionally are large structures orbiting around earth at the geo-synchronous altitude. This thesis introduces a new architecture for a Space Based Solar Power satellite constellation. The proposed concept reduces the high cost involved in the construction of the space satellite and in the multiple launches to the geo-synchronous altitude. The proposed concept is a constellation of Low Earth Orbit satellites that are smaller in size than the conventional system. 7For this application a Repeated Sun-Synchronous Track Circular Orbit is considered (RSSTO). In these orbits, the spacecraft re-visits the same locations on earth periodically every given desired number of days with the line of nodes of the spacecraft's orbit fixed relative to the Sun. A wide range of solutions are studied, and, in this thesis, a two-orbit constellation design is chosen and simulated. The number of satellites is chosen based on the electric power demands in a given set of global cities. The orbits of the satellites are designed such that their ground tracks visit a maximum number of ground stations during the revisit period. In the simulation, the locations of the ground stations are chosen close to big cities, in USA and worldwide, so that the space power constellation beams down power directly to locations of high electric power demands. The j2 perturbations are included in the mathematical model used in orbit design. The Coverage time of each spacecraft over a ground site and the gap time between two consecutive spacecrafts visiting a ground site are simulated in order to evaluate the coverage continuity of the proposed solar power constellation. It has been observed from simulations that there always periods in which s spacecraft does not communicate with any

  5. 21St Century Atmospheric Forecasting for Space Based Applications

    NASA Astrophysics Data System (ADS)

    Alliss, R.; Felton, B.; Craddock, M.; Kiley, H.; Mason, M.

    2016-09-01

    Many space based applications from imaging to communications are impacted by the atmosphere. Atmospheric impacts such as optical turbulence and clouds are the main drivers for these types of systems. For example, in space based optical communications, clouds will produce channel fades on the order of many hundreds of decibels (dB) thereby breaking the communication link. Optical turbulence can also produce fades but these can be compensated for by adaptive optics. The ability to forecast the current and future location and optical thickness of clouds for space to ground Electro Optical or optical communications is therefore critical in order to achieve a highly reliable system. We have developed an innovative method for producing such forecasts. These forecasts are intended to provide lead times on the order of several hours to days so that communication links can be transferred from a currently loudy ground location to another more desirable ground site. The system uses high resolution Numerical Weather Prediction (NWP) along with a variational data assimilation (DA) scheme to improve the initial conditions and forecasts. DA is used to provide an improved estimate of the atmospheric state by combining meteorological observations with NWP products and their respective error statistics. Variational DA accomplishes this through the minimization of a prescribed cost function, whereby differences between the observations and analysis are damped according to their perceived error. The NWP model is a fully three-dimensional (3D) physics-based model of the atmosphere initialized with gridded atmospheric data obtained from a global scale model. The global model input data has a horizontal resolution of approximately 25km, which is insufficient for the desired atmospheric forecasts required at near 1km resolution. Therefore, a variational DA system is used to improve the quality and resolution of the initial conditions first prescribed by the global model. Data used by the

  6. Special relativity effects for space-based coherent lidar experiments

    NASA Technical Reports Server (NTRS)

    Raogudimetla, V. S.

    1994-01-01

    There is a great need to develop a system that can measure accurately atmospheric wind profiles because an accurate data of wind profiles in the atmosphere constitutes single most input for reliable simulations of global climate numerical methods. Also such data helps us understand atmospheric circulation and climate dynamics better. Because of this need for accurate wind measurements, a space-based Laser Atmospheric Winds Sounder (LAWS) is being designed at MSFC to measure wind profiles in the lower atmosphere of the earth with an accuracy of 1 m/s at lower altitudes to 5m/s at higher altitudes. This system uses an orbiting spacecraft with a pulsed laser source and measures the Doppler shift between the transmitted and received frequencies to estimate the atmospheric wind velocities. If a significant return from the ground (sea) is possible, the spacecraft speed and height are estimated from it and these results and the Doppler shift are then used to estimate the wind velocities in the atmosphere. It is expected that at the proposed wavelengths, there will be enough backscatter from the aerosols but there may no be significant return from the ground. So a coherent (heterodyne) detection system is being proposed for signal processing because it can provide high signal to noise ratio and sensitivity and thus make the best use of low ground return. However, for a heterodyne detection scheme to provide the best results, it is important that the receiving aperture be aligned properly for the proposed wind sounder, this amounts to only a few microradians tolerance in alignment. It is suspected that the satellite motion relative to the ground may introduce errors in the order of a few microradians because of special relativity. Hence, the problem of laser scattering off a moving fixed target when the source and receiver are moving, which was not treated in the past in the literature, was analyzed in the following, using relativistic electrodynamics and applied to the

  7. Measurement and modeling of microlenses fabricated on single-photon avalanche diode arrays for fill factor recovery.

    PubMed

    Pavia, Juan Mata; Wolf, Martin; Charbon, Edoardo

    2014-02-24

    Single-photon avalanche diode (SPAD) imagers typically have a relatively low fill factor, i.e. a low proportion of the pixel's surface is light sensitive, due to in-pixel circuitry. We present a microlens array fabricated on a 128×128 single-photon avalanche diode (SPAD) imager to enhance its sensitivity. The benefits and limitations of these light concentrators are studied for low light imaging applications. We present a new simulation software that can be used to simulate microlenses' performance under different conditions and a new non-destructive contact-less method to estimate the height of the microlenses. Results of experiments and simulations are in good agreement, indicating that a gain >10 can be achieved for this particular sensor.

  8. Using graphical and pictorial representations to teach introductory astronomy students about the detection of extrasolar planets via gravitational microlensing

    NASA Astrophysics Data System (ADS)

    Wallace, Colin S.; Chambers, Timothy G.; Prather, Edward E.; Brissenden, Gina

    2016-05-01

    The detection and study of extrasolar planets is an exciting and thriving field in modern astrophysics and an increasingly popular topic in introductory astronomy courses. One detection method relies on searching for stars whose light has been gravitationally microlensed by an extrasolar planet. In order to facilitate instructors' abilities to bring this interesting mix of general relativity and extrasolar planet detection into the introductory astronomy classroom, we have developed a new Lecture-Tutorial called "Detecting Exoplanets with Gravitational Microlensing." In this paper, we describe how this new Lecture-Tutorial's representations of astrophysical phenomena, which we selected and created based on theoretically motivated considerations of their pedagogical affordances, are used to help introductory astronomy students develop more expert-like reasoning abilities.

  9. Space-based solar power conversion and delivery systems study

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Even at reduced rates of growth, the demand for electric power is expected to more than triple between now and 1995, and to triple again over the period 1995-2020. Without the development of new power sources and advanced transmission technologies, it may not be possible to supply electric energy at prices that are conductive to generalized economic welfare. Solar power is renewable and its conversion and transmission from space may be advantageous. The goal of this study is to assess the economic merit of space-based photovoltaic systems for power generation and a power relay satellite for power transmission. In this study, satellite solar power generation and transmission systems, as represented by current configurations of the Satellite Solar Station (SSPS) and the Power Relay Satellite (PRS), are compared with current and future terrestrial power generation and transmission systems to determine their technical and economic suitability for meeting power demands in the period of 1990 and beyond while meeting ever-increasing environmental and social constraints.

  10. Planet Diversity Yields with Space-based Direct Imaging Telescopes

    NASA Astrophysics Data System (ADS)

    Domagal-Goldman, Shawn; Kopparapu, Ravi Kumar; Hébrard, Eric; Stark, Chris; Robinson, Tyler D.; Roberge, Aki; Mandell, Avi; McElwain, Michael W.; Clampin, Mark; Meadows, Victoria; Arney, Giada; Advanced Technology Large Aperture Space Telescope Science Team, Exoplanet Climate Group

    2016-01-01

    In this presentation, we will estimate the yield for a diversity of planets from future space-based flagship telescopes. We first divvy up planets into categories that are based on current observables, and that should impact the spectra we hope to observe in the future. The two main classification parameters we use here are the size of a planet and the energy flux into the planet's atmosphere. These two parameters are measureable or inferable from present-day observations, and should have a strong influence on future spectroscopy observations from JWST, WFIRST (with a coronagraph and/or starshade), and concept flagship missions that would fly some time after WFIRST. This allows us to calculate "ηplanet" values for each kind of planet. These η values then allow calculations of the expected yields from direct imaging missions, by leveraging the models and prior work by Stark and colleagues (2014, 2015). That work estimated the yields for potentially Earth-like worlds (i.e. of a size and stellar irradiation consistent with definitions of the habitable zone) for telescopes with a variety of observational parameters. We will do the same thing here, but for a wider variety of planets. This will allow us to discuss the implications of architecture and instrument properties on the diversity of worlds that future direct imaging missions would observe.

  11. Telescopes for a Space-Based Gravitational Wave Observatory

    NASA Astrophysics Data System (ADS)

    Sankar, Shannon; Livas, Jeffrey

    2017-01-01

    Telescopes are an important part of the science measurement for a space-based gravitational wave observatory. The telescopes should not introduce excess phase noise which might lower the signal-to-noise of the gravitational wave signal. This requirement constrains both the telescope stability and the phase noise due to scattered light. The photoreceiver senses a combination of a local beam, the received beam and scattered light. If the scattered light has significant spatial overlap, and if there is displacement noise in the scatter path, the signal-to-noise of the main measurement can be impacted. We will discuss our approach to addressing this concern. We model the scattered power from the telescope under expected conditions and use these models for evaluating potential telescope designs. We also determine allowable mirror surface roughness and contamination levels from the scattered light models. We implement the best designs by fabricating a series of prototype telescopes of increasing flight readiness, using eLISA as a reference mission for design specifications. Finally, we perform laboratory tests of the fabricated prototype telescope to validate the models and inform our understanding of the eventual flight telescopes.

  12. Design optimization for a space based, reusable orbit transfer vehicle

    NASA Technical Reports Server (NTRS)

    Redd, L.

    1985-01-01

    Future NASA and DOD missions will benefit from high performance, reusable orbit transfer vehicles. With the advent of a space station, advanced engine technology, and various new vehicle concepts, reusable orbit transfer vehicles that provide significant economic benefits and mission capability improvements will be realized. Engine and vehicle design criteria previously have lacked definition with regard to issues such as space basing and servicing, man-rating and reliability, performance, mission flexibility, and life cycle cost for a reusable vehicle. The design study described here has resulted in the definition of a reusable orbit transfer vehicle concept and subsequent recommendations for the design criteria of an advanced LO2/LH2 engine. These design criteria include number of engines per vehicle, nozzle design, etc. The major characteristics of the vehicle preliminary design include low lift to drag aerocapture capability, a main propulsion system failure criteria of fail operational/fail safe, and either two main engines with a high performance attitude control system for back-up or three main engines with which to meet this failure criteria. In addition, a maintenance approach has been established for the advanced vehicle concept.

  13. Space-based observation of the extensive airshowers

    NASA Astrophysics Data System (ADS)

    Ebisuzaki, T.

    2013-06-01

    Space based observations of extensive air showers constitute the next experimental challenge for the study of the universe at extreme energy. Space observation will allow a "quantum jump" in the observational area available to detect the UV light tracks produced by particles with energies higher than 1020 eV. These are thought to reach the Earth almost undeflected by the cosmic magnetic field. This new technique will contribute to establish the new field of astronomy and astrophysics performed with charged particles and neutrinos at the highest energies. This idea was created by the incredible efforts of three outstanding comic ray physicists: John Linsley, Livio Scarsi, and Yoshiyuki Takahashi. This challenging technique has four significant merits in comparison with ground-based observations: 1) Very large observational area, 2) Well constrained distances of the showers, 3) Clear and stable atmospheric transmission in the above half troposphere, 4) Uniform Exposure across both the north and south skies. Four proposed and planned missions constitute the roadmap of the community: TUS, JEM-EUSO, KLPVE, and Super-EUSO will contribute step-by-step to establish this challenging field of research.

  14. Possible Space-Based Gravitational-Wave Observatory Mission Concept

    NASA Technical Reports Server (NTRS)

    Livas, Jeffrey C.

    2015-01-01

    The existence of gravitational waves was established by the discovery of the Binary Pulsar PSR 1913+16 by Hulse and Taylor in 1974, for which they were awarded the 1983 Nobel Prize. However, it is the exploitation of these gravitational waves for the extraction of the astrophysical parameters of the sources that will open the first new astronomical window since the development of gamma ray telescopes in the 1970's and enable a new era of discovery and understanding of the Universe. Direct detection is expected in at least two frequency bands from the ground before the end of the decade with Advanced LIGO and Pulsar Timing Arrays. However, many of the most exciting sources will be continuously observable in the band from 0.1-100 mHz, accessible only from space due to seismic noise and gravity gradients in that band that disturb ground-based observatories. This poster will discuss a possible mission concept, Space-based Gravitational-wave Observatory (SGO-Mid) developed from the original Laser Interferometer Space Antenna (LISA) reference mission but updated to reduce risk and cost.

  15. Space-Based Chemical Lasers in strategic defense

    SciTech Connect

    Wildt, D. )

    1992-07-01

    The Strategic Defense Initiative Organization (SDIO) has made significant progress in developing Space-Based chemical Laser (SBL) technologies and in studying the SBLs global defense capability. In this mission, a constellation of several orbiting laser platforms provides continuous global defense by intercepting threatening missiles in their boost phase, including short range ballistic missiles (SRBMs). An optional smaller constellation provides defense against launches from the low and midlatitude regions. In addition, SBLs have utility in other important related missions such as surveillance, air defense and discrimination. The hardware necessary to build such a system has been developed to the point where it is mature and ready for demonstration in space. Advances have been made in each of the following major areas of the SBL: laser device; optics/beam control; beam pointing; ATP (acquisition, tracking and pointing); uncooled optics; and laser lethality. Integration of the key laser and beam control technologies is now occurring in the ground-based ALI experiment, and a space demonstration experiment, Star LITE, is in the planning and concept development phase.

  16. Space-based lidar measurements of global ocean carbon stocks

    NASA Astrophysics Data System (ADS)

    Behrenfeld, Michael J.; Hu, Yongxiang; Hostetler, Chris A.; Dall'Olmo, Giorgio; Rodier, Sharon D.; Hair, John W.; Trepte, Charles R.

    2013-08-01

    Global ocean phytoplankton biomass (Cphyto) and total particulate organic carbon (POC) stocks have largely been characterized from space using passive ocean color measurements. A space-based light detection and ranging (lidar) system can provide valuable complementary observations for Cphyto and POC assessments, with benefits including day-night sampling, observations through absorbing aerosols and thin cloud layers, and capabilities for vertical profiling through the water column. Here we use measurements from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) to quantify global Cphyto and POC from retrievals of subsurface particulate backscatter coefficients (bbp). CALIOP bbp data compare favorably with airborne, ship-based, and passive ocean data and yield global average mixed-layer standing stocks of 0.44 Pg C for Cphyto and 1.9 Pg for POC. CALIOP-based Cphyto and POC data exhibit global distributions and seasonal variations consistent with ocean plankton ecology. Our findings support the use of spaceborne lidar measurements for advancing understanding of global plankton systems.

  17. UV lifetime laser demonstrator for space-based applications

    NASA Astrophysics Data System (ADS)

    Albert, Michael; Puffenburger, Kent; Schum, Tom; Fitzpatrick, Fran; Litvinovitch, Slava; Jones, Darrell; Rudd, Joseph; Hovis, Floyd

    2015-09-01

    A long-lived UV laser is an enabling technology for a number of high-priority, space-based lidar instruments. These include next generation cloud and aerosol lidars that incorporates a UV channel, direct detection 3-D wind lidars, and ozone DIAL (differential absorption lidar) system. In previous SBIR funded work we developed techniques for increasing the survivability of components in high power UV lasers and demonstrated improved operational lifetimes. In this Phase III ESTO funded effort we are designing and building a TRL (Technology Readiness Level) 6 demonstrator that will have increased output power and a space-qualifiable package that is mechanically robust and thermally-stable. For full space compatibility, thermal control will be through pure conductive cooling. Contamination control processes and optical coatings will be chosen that are compatible with lifetimes in excess of 1 billion shots. The 1064nm output will be frequency tripled to provide greater than 100mJ pulses of 355nm light at 150 Hz. After completing the laser module build in the third quarter of 2015 we will initiate lifetime testing, followed by thermal/vacuum (TVAC) and vibration testing to demonstrate that the design is at TRL 6.

  18. Architectures for a Space-based Gravitational-Wave Observatory

    NASA Astrophysics Data System (ADS)

    Stebbins, Robin

    2015-04-01

    The European Space Agency (ESA) selected the science theme, the ``Gravitational Universe,'' for the third large mission opportunity, known as L3, under its Cosmic Vision Programme. The planned launch date is 2034. ESA is considering a 20% participation by an international partner, and NASA's Astrophysics Division has begun negotiating a NASA role. We have studied the design consequences of a NASA contribution, evaluated the science benefits and identified the technology requirements for hardware that could be delivered by NASA. The European community proposed a strawman mission concept, called eLISA, having two measurement arms, derived from the well studied LISA (Laser Interferometer Space Antenna) concept. The US community is promoting a mission concept known as SGO Mid (Space-based Gravitational-wave Observatory Mid-sized), a three arm LISA-like concept. If NASA were to partner with ESA, the eLISA concept could be transformed to SGO Mid by the addition of a third arm, thereby augmenting science, reducing risk and reducing non-recurring engineering costs. The characteristics of the mission concepts and the relative science performance of eLISA, SGO Mid and LISA are described.

  19. A space-based radio frequency transient event classifier

    SciTech Connect

    Moore, K.R.; Blain, C.P.; Caffrey, M.P.; Franz, R.C.; Henneke, K.M.; Jones, R.G.

    1998-03-01

    The Department of Energy is currently investigating economical and reliable techniques for space-based nuclear weapon treaty verification. Nuclear weapon detonations produce RF transients that are signatures of illegal nuclear weapons tests. However, there are many other sources of RF signals, both natural and man-made. Direct digitization of RF signals requires rates of 300 MSamples per second and produces 10{sup 13} samples per day of data to analyze. it is impractical to store and downlink all digitized RF data from such a satellite without a prohibitively expensive increase in the number and capacities of ground stations. Reliable and robust data processing and information extraction must be performed onboard the spacecraft in order to reduce downlinked data to a reasonable volume. The FORTE (Fast On-Orbit Recording of Transient Events) satellite records RF transients in space. These transients will be classified onboard the spacecraft with an Event Classifier specialized hardware that performs signal preprocessing and neural network classification. The authors describe the Event Classifier requirements, scientific constraints, design and implementation.

  20. Space-based laser-driven MHD generator: Feasibility study

    NASA Technical Reports Server (NTRS)

    Choi, S. H.

    1986-01-01

    The feasibility of a laser-driven MHD generator, as a candidate receiver for a space-based laser power transmission system, was investigated. On the basis of reasonable parameters obtained in the literature, a model of the laser-driven MHD generator was developed with the assumptions of a steady, turbulent, two-dimensional flow. These assumptions were based on the continuous and steady generation of plasmas by the exposure of the continuous wave laser beam thus inducing a steady back pressure that enables the medium to flow steadily. The model considered here took the turbulent nature of plasmas into account in the two-dimensional geometry of the generator. For these conditions with the plasma parameters defining the thermal conductivity, viscosity, electrical conductivity for the plasma flow, a generator efficiency of 53.3% was calculated. If turbulent effects and nonequilibrium ionization are taken into account, the efficiency is 43.2%. The study shows that the laser-driven MHD system has potential as a laser power receiver for space applications because of its high energy conversion efficiency, high energy density and relatively simple mechanism as compared to other energy conversion cycles.

  1. Elastomeric inverse moulding and vacuum casting process characterization for the fabrication of arrays of concave refractive microlenses

    NASA Astrophysics Data System (ADS)

    Desmet, L.; Van Overmeire, S.; Van Erps, J.; Ottevaere, H.; Debaes, C.; Thienpont, H.

    2007-01-01

    We present a complete and precise quantitative characterization of the different process steps used in an elastomeric inverse moulding and vacuum casting technique. We use the latter replication technique to fabricate concave replicas from an array of convex thermal reflow microlenses. During the inverse elastomeric moulding we obtain a secondary silicone mould of the original silicone mould in which the master component is embedded. Using vacuum casting, we are then able to cast out of the second mould several optical transparent poly-urethane arrays of concave refractive microlenses. We select ten particular representative microlenses on the original, the silicone moulds and replica sample and quantitatively characterize and statistically compare them during the various fabrication steps. For this purpose, we use several state-of-the-art and ultra-precise characterization tools such as a stereo microscope, a stylus surface profilometer, a non-contact optical profilometer, a Mach-Zehnder interferometer, a Twyman-Green interferometer and an atomic force microscope to compare various microlens parameters such as the lens height, the diameter, the paraxial focal length, the radius of curvature, the Strehl ratio, the peak-to-valley and the root-mean-square wave aberrations and the surface roughness. When appropriate, the microlens parameter under test is measured with several different measuring tools to check for consistency in the measurement data. Although none of the lens samples shows diffraction-limited performance, we prove that the obtained replicated arrays of concave microlenses exhibit sufficiently low surface roughness and sufficiently high lens quality for various imaging applications.

  2. Structure of Quasar Continuum Emission Regions and Cosmology from Optical and X-Ray Microlensing in Gravitationally Lensed Quasars

    DTIC Science & Technology

    2008-05-02

    available. The flux of each component of the multiply-imaged quasars was measured in many seasons of ground-based optical imagery. Lightcurves were...constructed from the flux measurements, and Monte Carlo methods were used to analyze the microlensing variability in the lightcurves . The results of...available. The flux of each component of the multiply-imaged quasars was measured in many seasons of ground-based optical imagery. Lightcurves were

  3. Interpreting the Strongly Lensed Supernova iPTF16geu: Time Delay Predictions, Microlensing, and Lensing Rates

    NASA Astrophysics Data System (ADS)

    More, Anupreeta; Suyu, Sherry H.; Oguri, Masamune; More, Surhud; Lee, Chien-Hsiu

    2017-02-01

    We present predictions for time delays between multiple images of the gravitationally lensed supernova, iPTF16geu, which was recently discovered from the intermediate Palomar Transient Factory (iPTF). As the supernova is of Type Ia where the intrinsic luminosity is usually well known, accurately measured time delays of the multiple images could provide tight constraints on the Hubble constant. According to our lens mass models constrained by the Hubble Space Telescope F814W image, we expect the maximum relative time delay to be less than a day, which is consistent with the maximum of 100 hr reported by Goobar et al. but places a stringent upper limit. Furthermore, the fluxes of most of the supernova images depart from expected values suggesting that they are affected by microlensing. The microlensing timescales are small enough that they may pose significant problems to measure the time delays reliably. Our lensing rate calculation indicates that the occurrence of a lensed SN in iPTF is likely. However, the observed total magnification of iPTF16geu is larger than expected, given its redshift. This may be a further indication of ongoing microlensing in this system.

  4. Grayscale lithography process study applied to zero-gap microlenses for sub-2μm CMOS image sensors

    NASA Astrophysics Data System (ADS)

    Audran, S.; Vaillant, J.; Farys, V.; Hirigoyen, F.; Huss, E.; Mortini, B.; Cowache, C.; Berthier, L.; Mortini, E.; Fantuz, J.; Arnaud, O.; Depoyan, L.; Sundermann, F.; Baron, C.; Reynard, J.-P.

    2010-04-01

    Microlens arrays are used on CMOS image sensors to focus incident light onto the appropriate photodiode and thus improve the device quantum efficiency. As the pixel size shrinks, the fill factor of the sensor (i.e. ratio of the photosensitive area to the total pixel area) decreases and one way to compensate this loss of sensibility is to improve the microlens photon collection efficiency. This can be achieved by developing zero-gap microlens processes. One elegant solution to pattern zero-gap microlenses is to use a grayscale reticle with varying optical densities which locally modulate the UV light intensity, allowing the creation of continuous relief structure in the resist layer after development. Contrary to conventional lithography for which high resist contrast is appreciated to achieve straight resist pattern profiles, grayscale lithography requires smooth resist contrast curve. In this study we demonstrate the efficiency of grayscale lithography to generate sub-2μm diameter microlens with a positive-tone photoresist. We also show that this technique is resist and process (film thickness, development normality and exposure conditions) dependent. Under the best conditions, spherical zero-gap microlenses as well as aspherical and off-axis microlenses, which are impossible to obtain with the conventional reflow method, were obtained with satisfying process latitude.

  5. Confirmation of the Planetary Microlensing Signal and Star and Planet Mass Determinations for Event OGLE-2005-BLG-169

    NASA Astrophysics Data System (ADS)

    Bennett, D. P.; Bhattacharya, A.; Anderson, J.; Bond, I. A.; Anderson, N.; Barry, R.; Batista, V.; Beaulieu, J.-P.; DePoy, D. L.; Dong, Subo; Gaudi, B. S.; Gilbert, E.; Gould, A.; Pfeifle, R.; Pogge, R. W.; Suzuki, D.; Terry, S.; Udalski, A.

    2015-08-01

    We present Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) observations of the source and lens stars for planetary microlensing event OGLE-2005-BLG-169, which confirm the relative proper motion prediction due to the planetary light curve signal observed for this event. This (and the companion Keck result) provide the first confirmation of a planetary microlensing signal, for which the deviation was only 2%. The follow-up observations determine the flux of the planetary host star in multiple passbands and remove light curve model ambiguity caused by sparse sampling of part of the light curve. This leads to a precise determination of the properties of the OGLE-2005-BLG-169Lb planetary system. Combining the constraints from the microlensing light curve with the photometry and astrometry of the HST/WFC3 data, we find star and planet masses of {M}*=0.69+/- 0.02{M}⊙ and {m}{{p}}=14.1+/- 0.9{M}\\oplus . The planetary microlens system is located toward the Galactic bulge at a distance of {D}L=4.1+/- 0.4 kpc and the projected star-planet separation is {a}\\perp =3.5+/- 0.3 AU, corresponding to a semimajor axis of a={4.0}-0.6+2.2 AU.

  6. OGLE-2015-BLG-0479LA,B: Binary Gravitational Microlens Characterized by Simultaneous Ground-based and Space-based Observations

    NASA Astrophysics Data System (ADS)

    Han, C.; Udalski, A.; Gould, A.; Zhu, Wei; Street, R. A.; Yee, J. C.; Beichman, C.; Bryden, C.; Calchi Novati, S.; Carey, S.; Fausnaugh, M.; Gaudi, B. S.; Henderson, Calen B.; Shvartzvald, Y.; Wibking, B.; Spitzer Microlensing Team; Szymański, M. K.; Soszyński, I.; Skowron, J.; Mróz, P.; Poleski, R.; Pietrukowicz, P.; Kozłowski, S.; Ulaczyk, K.; Wyrzykowski, Ł.; Pawlak, M.; OGLE Collaboration; Tsapras, Y.; Hundertmark, M.; Bachelet, E.; Dominik, M.; Bramich, D. M.; Cassan, A.; Figuera Jaimes, R.; Horne, K.; Ranc, C.; Schmidt, R.; Snodgrass, C.; Wambsganss, J.; Steele, I. A.; Menzies, J.; Mao, S.; RoboNet Collaboration; Bozza, V.; Jørgensen, U. G.; Alsubai, K. A.; Ciceri, S.; D'Ago, G.; Haugbølle, T.; Hessman, F. V.; Hinse, T. C.; Juncher, D.; Korhonen, H.; Mancini, L.; Popovas, A.; Rabus, M.; Rahvar, S.; Scarpetta, G.; Skottfelt, J.; Southworth, J.; Starkey, D.; Surdej, J.; Wertz, O.; Zarucki, M.; MiNDSTEp Consortium; Pogge, R. W.; DePoy, D. L.; μFUN Collaboration

    2016-09-01

    We present a combined analysis of the observations of the gravitational microlensing event OGLE-2015-BLG-0479 taken both from the ground and by the Spitzer Space Telescope. The light curves seen from the ground and from space exhibit a time offset of ˜13 days between the caustic spikes, indicating that the relative lens-source positions seen from the two places are displaced by parallax effects. From modeling the light curves, we measure the space-based microlens parallax. Combined with the angular Einstein radius measured by analyzing the caustic crossings, we determine the mass and distance of the lens. We find that the lens is a binary composed of two G-type stars with masses of ˜1.0 M ⊙ and ˜0.9 M ⊙ located at a distance of ˜3 kpc. In addition, we are able to constrain the complete orbital parameters of the lens thanks to the precise measurement of the microlens parallax derived from the joint analysis. In contrast to the binary event OGLE-2014-BLG-1050, which was also observed by Spitzer, we find that the interpretation of OGLE-2015-BLG-0479 does not suffer from the degeneracy between (±, ±) and (±, ∓) solutions, confirming that the four-fold parallax degeneracy in single-lens events collapses into the two-fold degeneracy for the general case of binary-lens events. The location of the blend in the color-magnitude diagram is consistent with the lens properties, suggesting that the blend is the lens itself. The blend is bright enough for spectroscopy and thus this possibility can be checked from future follow-up observations.

  7. Just in Time in Space or Space Based JIT

    NASA Technical Reports Server (NTRS)

    VanOrsdel, Kathleen G.

    1995-01-01

    Our satellite systems are mega-buck items. In today's cost conscious world, we need to reduce the overall costs of satellites if our space program is to survive. One way to accomplish this would be through on-orbit maintenance of parts on the orbiting craft. In order to accomplish maintenance at a low cost I advance the hypothesis of having parts and pieces (spares) waiting. Waiting in the sense of having something when you need it, or just-in-time. The JIT concept can actually be applied to space processes. Its definition has to be changed just enough to encompass the needs of space. Our space engineers tell us which parts and pieces the satellite systems might be needing once in orbit. These items are stored in space for the time of need and can be ready when they are needed -- or Space Based JIT. When a system has a problem, the repair facility is near by and through human or robotics intervention, it can be brought back into service. Through a JIT process, overall system costs could be reduced as standardization of parts is built into satellite systems to facilitate reduced numbers of parts being stored. Launch costs will be contained as fewer spare pieces need to be included in the launch vehicle and the space program will continue to thrive even in this era of reduced budgets. The concept of using an orbiting parts servicer and human or robotics maintenance/repair capabilities would extend satellite life-cycle and reduce system replacement launches. Reductions of this nature throughout the satellite program result in cost savings.

  8. Project SPARC: Space-Based Aeroassisted Reusable Craft

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Future United States' space facilities include a Space Station in low Earth orbit (LEO) and a Geosynchronous Operations Support Center, or GeoShack, in geosynchronous orbit (GEO). One possible mode of transfer between the two orbits is an aerobraking vehicle. When traveling from GEO to LEO, the Earth's atmosphere can be used to aerodynamically reduce the velocity of the vehicle, which reduces the amount of propulsive change in velocity required for the mission. An aerobrake is added to the vehicle for this purpose, but the additional mass increases propellant requirements. This increase must not exceed the amount of propellant saved during the aeropass. The design and development of an aerobraking vehicle that will transfer crew and cargo between the Space Station and GeoShack is examined. The vehicle is referred to as Project SPARC, a SPace-based Aeroassisted Reusable Craft. SPARC consists of a removable 45 ft diameter aerobrake, two modified Pratt and Whitney Advanced Expander Engines with a liquid oxygen/liquid hydrogen propellant, a removable crew module with a maximum capacity of five, and standard sized payload bays providing a maximum payload capacity of 28,000 lbm. The aerobrake, a rigid, ellipsoidally blunted elliptical cone, provides lift at zero angle-of-attack due to a 73 deg rake angle, and is covered with a flexible multi-layer thermal protection system. Maximum dry mass of the vehicle without payload is 20,535 lbm, and the maximum propellant requirement is 79,753 lbm at an oxidizer to fuel ratio of 6/1. Key advantages of SPARC include its capability to meet mission changes, and its removable aerobrake and crew module.

  9. UV lifetime demonstrator for space-based applications

    NASA Astrophysics Data System (ADS)

    Albert, Michael; Puffenburger, Kent; Schum, Tom; Fitzpatrick, Fran; Litvinovitch, Slava; Jones, Darrell; Rudd, Joseph; Hovis, Floyd

    2016-05-01

    A long-lived UV laser is an enabling technology for a number of high-priority, space-based lidar instruments. These include next generation cloud and aerosol lidars that incorporates a UV channel, direct detection 3-D wind lidars, and ozone DIAL (differential absorption lidar) systems. In previous SBIR funded work we developed techniques for increasing the survivability of components in high power UV lasers and demonstrated improved operational lifetimes. In this Phase III ESTO funded effort we are designing and building a TRL (Technology Readiness Level) 6 demonstrator that will have increased output power and a space-qualifiable package that is mechanically robust and thermally-stable. For full space compatibility, thermal control will be through pure conductive cooling. Contamination control processes and optical coatings will be chosen that are compatible with lifetimes in excess of 1 billion shots. The 1064nm output will be frequency tripled to provide greater than 100 mJ pulses of 355 nm light at 150 Hz. The laser module build was completed in the third quarter of 2015 at which time a series of life tests were initiated. The first phase of the lifetime testing is a 532 nm only test that is expected to complete in April 2016. The 532 nm lifetest will be followed by a 4 month half power UV life test and then a four month full power UV life test. The lifetime tests will be followed by thermal/vacuum (TVAC) and vibration testing to demonstrate that the laser optics module design is at TRL 6.

  10. Cost of space-based laser ballistic missile defense

    SciTech Connect

    Field, G.; Spergel, D.

    1986-03-21

    Orbiting platforms carrying infrared lasers have been proposed as weapons forming the first tier of a ballistic missile defense system under the President's Strategic Defense Initiative. As each laser platform can destroy a limited number of missiles, one of several methods of countering such a system is to increase the number of offensive missiles. Hence it is important to know whether the cost-exchange ratio, defined as the ratio of the cost to the defense of destroying a missile to the cost to the offense of deploying an additional missile, is greater or less than 1. Although the technology to be used in a ballistic missile defense system is still extremely uncertain, it is useful to examine methods for calculating the cost-exchange ration. As an example, the cost of an orbiting infrared laser ballistic missile defense system employed against intercontinental ballistic missiles launched simultaneously from a small area is compared to the cost of additional offensive missiles. If one adopts lower limits to the costs for the defense and upper limits to the costs for the offense, the cost-exchange ratio comes out substantially greater than 1. If these estimates are confirmed, such a ballistic missile defense system would be unable to maintain its effectiveness at less cost than it would take to proliferate the ballistic missiles necessary to overcome it and would therefore not satisfy the President's requirements for an effective strategic defense. Although the method is illustrated by applying it to a space-based infrared laser system, it should be straightforward to apply it to other proposed systems. 28 references, 2 tables.

  11. Cost of space-based laser ballistic missile defense.

    PubMed

    Field, G; Spergel, D

    1986-03-21

    Orbiting platforms carrying infrared lasers have been proposed as weapons forming the first tier of a ballistic missile defense system under the President's Strategic Defense Initiative. As each laser platform can destroy a limited number of missiles, one of several methods of countering such a system is to increase the number of offensive missiles. Hence it is important to know whether the cost-exchange ratio, defined as the ratio of the cost to the defense of destroying a missile to the cost to the offense of deploying an additional missile, is greater or less than 1. Although the technology to be used in a ballistic missile defense system is still extremely uncertain, it is useful to examine methods for calculating the cost-exchange ratio. As an example, the cost of an orbiting infrared laser ballistic missile defense system employed against intercontinental ballistic missiles launched simultaneously from a small area is compared to the cost of additional offensive missiles. If one adopts lower limits to the costs for the defense and upper limits to the costs for the offense, the cost-exchange ratio comes out substantially greater than 1. If these estimates are confirmed, such a ballistic missile defense system would be unable to maintain its effectiveness at less cost than it would take to proliferate the ballistic missiles necessary to overcome it and would therefore not satisfy the President's requirements for an effective strategic defense. Although the method is illustrated by applying it to a space-based infrared laser system, it should be straightforward to apply it to other proposed systems.

  12. Concept for a Space-Based Transfer Standard Spectroradiometer (SCATS)

    NASA Astrophysics Data System (ADS)

    Heath, D.; Valle, T.; Tarde, R.; Leitch, J.

    2008-12-01

    Future Earth science missions will require instrument calibration traceable to SI units and stable to 0.5% over 10 year operational lifetimes. A strategy consistent with those objectives is the direct measurement of the Earth radiance, solar irradiance, and lunar irradiance through a scanning un-obstructed collector; the Earth albedo follows directly. We describe a Space-based Transfer Standard Spectroradiometer (SCATS) that directly transfers the solar (or lunar) disc spectral irradiance to measurements of the Earth's disc spectral radiance. SCATS is a low cost, compact, light weight instrument capable of accurate ratio measurements that are temporally invariant over measurement time scales. SCATS provides albedo measurements in the solar reflective region and thermal emission bands of the Earth and its atmosphere relative to the solar irradiance. We expect the SCATS calibration to be stable to 0.1% being tied to solar irradiance. This SI traceable concept eliminates the long term stability concerns associated with solar diffusers. SCATS is a simple geometrically baffled spectroradiometer calibrated against NIST radiometric standards on the ground for spectral radiance and irradiance measurements. The instrument consists of multiple detectors utilizing radiometrically stable narrow band interference filters: 300 nm to 15 um in 19 simultaneously measured channels. Thermally, the sun is used as a blackbody calibration source for the earth radiance. Un-cooled Si photodiodes measure in the solar reflective band, and thermoelectrically cooled InGaAs photodiodes, and high sensitivity thermopiles are used in the thermal infrared. An orthogonal 2-mirror system eliminates polarization effects and allows viewing the Sun, Earth, Moon, or space from GEO or LEO. This report details the concept, provides a status, and describes future directions for our laboratory demonstration.

  13. OGLE-2012-BLG-0455/MOA-2012-BLG-206: Microlensing event with ambiguity in planetary interpretations caused by incomplete coverage of planetary signal

    SciTech Connect

    Park, H.; Han, C.; Choi, J.-Y.; Hwang, K.-H.; Jung, Y. K.; Shin, I.-G.; Gould, A.; Gaudi, B. S.; Kavka, A.; Pogge, R. W.; Udalski, A.; Sumi, T.; Fouqué, P.; Christie, G.; Natusch, T.; Ngan, H.; Depoy, D. L.; Dong, Subo; Lee, C.-U.; Monard, L. A. G.; Collaboration: μFUN Collaboration; OGLE Collaboration; MOA Collaboration; and others

    2014-05-20

    Characterizing a microlensing planet is done by modeling an observed lensing light curve. In this process, it is often confronted that solutions of different lensing parameters result in similar light curves, causing difficulties in uniquely interpreting the lens system, and thus understanding the causes of different types of degeneracy is important. In this work, we show that incomplete coverage of a planetary perturbation can result in degenerate solutions even for events where the planetary signal is detected with a high level of statistical significance. We demonstrate the degeneracy for an actually observed event OGLE-2012-BLG-0455/MOA-2012-BLG-206. The peak of this high-magnification event (A {sub max} ∼ 400) exhibits very strong deviation from a point-lens model with Δχ{sup 2} ≳ 4000 for data sets with a total of 6963 measurements. From detailed modeling of the light curve, we find that the deviation can be explained by four distinct solutions, i.e., two very different sets of solutions, each with a twofold degeneracy. While the twofold (so-called close/wide) degeneracy is well understood, the degeneracy between the radically different solutions is not previously known. The model light curves of this degeneracy differ substantially in the parts that were not covered by observation, indicating that the degeneracy is caused by the incomplete coverage of the perturbation. It is expected that the frequency of the degeneracy introduced in this work will be greatly reduced with the improvement of the current lensing survey and follow-up experiments and the advent of new surveys.

  14. Space-based societal applications—Relevance in developing countries

    NASA Astrophysics Data System (ADS)

    Bhaskaranarayana, A.; Varadarajan, C.; Hegde, V. S.

    2009-11-01

    (ISRO) is already a part of the International initiative called Satellite Aided Search and Rescue System. The programme to set up satellite-based Village Resource Centres (VRCs) across India, for providing a variety of services relevant to the rural communities, is also a unique societal application of space technology. The VRCs are envisaged as single window delivery mechanism for a variety of space-based products and services, such as tele-education; telemedicine; information on natural resources for planning and development at local level; interactive advisories on agriculture, fisheries, land and water resources management, livestock management, etc.; interactive vocational training towards alternative livelihood; e-governance; weather information; etc. This paper describes the various possibilities and potentials of Satcom and Remote Sensing technologies for societal applications. The initiatives taken by Indian Space Research Organisation in this direction are highlighted.

  15. The proposal for new space-based gravitational experiments

    NASA Astrophysics Data System (ADS)

    Milyukov, Vadim; Sazhin, Mikhail; Zharov, Vladimir

    The development of space technologies opens new perspectives in solving the fundamental problems of gravity. We propose the experimental investigation of General Relativity (GR) in space experiments in following: a) measurement of post-Newtonian parameters (PPN), b) gravity wave detection in the low frequency band. The accuracy, with which GR is currently confirmed, is fractions of percent: 2.3× 10(-5) . However, in spite of the remarkable success of GR in the weak-field approximation, there are many reasons to consider alternative relativistic theories of gravity that predict the existence of effects other than GR, thus motivating new fundamental gravitational experiments. In this connection, the experimental measurements of PPN of parameters play a special role. To improve the accuracy of measurement of geodetic effects in the gravitational field of the Earth the clusters of spacecrafts, connected by microwave radio links and optical links, are widely used. Such a scheme allows to suppress effectively a coherent noise acting on the spacecraft, and to measure the distance between the satellites within a fraction of a millimeter. This technology was already tested for GRACE and GRAIL NASA missions. Furthermore, there are technologies allowing to effectively compensate non-gravitational noise to the level of 10(-10) - 10(-12) \\ m/s(2/sqrt{Hz}) . The project, which assume the lunch of cluster of the spacecrafts intended to study fundamental processes in the Universe, including the measurement of the PPN parameters and low frequency gravitational waves, is proposed in this report. We study the space-based systems in a configuration of few spacecrafts on different orbits in the gravitational field of the Earth for measuring these effects. Measurements of distances between spacecrafts are performed using microwave radio links, laser interferometry and ultra stable frequency standards. Developed modern technologies for distant measurements allow to reach the accuracy

  16. Performance of a Space-based Methane Lidar

    NASA Astrophysics Data System (ADS)

    Kiemle, Christoph; Ehret, Gerhard; Flamant, Pierre; Kawa, Randy; Browell, Ed

    2014-05-01

    Future space-based lidar measurements of anthropogenic greenhouse gases are expected to close observational gaps particularly over remote, polar, and aerosol-contaminated regions where in-situ and passive remote sensing observation techniques have difficulties. Recently, a "Methane Remote Lidar Mission" (MERLIN) was proposed by DLR and CNES in the frame of a German-French climate monitoring initiative. The goal is to measure atmospheric methane at high precision and unprecedented accuracy sufficient to constrain the various surface sources significantly better than with the current observational network. The MERLIN mission will have a minimum operational lifetime of 3 years. It is currently in Phase B, in which all mission components are planned in detail. Launch is foreseen in 2017. The MERLIN data will primarily be supplied to inverse numerical models that use the globally observed concentration gradients to infer methane surface fluxes. Simulations with an instrument model are used to assess the performance of this mission in terms of random error (measurement precision) with the help of MODIS and CALIPSO satellite observations of earth surface albedo and atmospheric optical depth, respectively. These are key environmental state parameters for integrated path differential absorption (IPDA) lidar which uses the surface backscatter to measure the atmospheric methane column beneath the satellite. Our results show that a lidar with an average optical power of 0.45 W at 1.6 µm wavelength and a telescope diameter of 0.55 m, installed on a low earth orbit platform (506 km), will measure methane columns at precisions of 1.2 %, 1.7 % and 2.1 % over land, water, and snow or ice surfaces, respectively. This applies to monthly aggregated measurement samples within areas of 50x50 km², and approaches the requirements that had been formulated by future users of the data in order to meet the abovementioned goal. Globally, the mean precision for the simulated year 2007 is 1

  17. Validation Issues of a Space-based Methane Lidar

    NASA Astrophysics Data System (ADS)

    Kiemle, C.; Fix, A.; Ehret, G.; Flamant, P.

    2014-12-01

    Space-based lidar missions targeting greenhouse gases are expected to close observational gaps, e.g., over subarctic permafrost and tropical wetlands, where in-situ and passive remote sensing techniques have difficulties. In the frame of a joint climate monitoring initiative, a "Methane Remote Lidar Mission" (MERLIN) was proposed by the German and French space agencies DLR and CNES. MERLIN is now in Phase B, in which all mission components are planned in detail. Launch is foreseen in 2019. The instrument is an integrated path differential absorption (IPDA) lidar which, installed on a low earth orbit platform provided by CNES, uses the surface backscatter to measure the atmospheric methane column. The globally observed concentration gradients will primarily help inverse numerical models to better infer regional methane fluxes. The lidar signals are able to travel through optically thin cloud and aerosol layers without producing a bias, and MERLIN's small field of view, of order 100 m, is expected to provide observations in broken cloud environments, often encountered in the tropics. As IPDA is a novel technique, calibration and validation will be essential. It is foreseen to validate MERLIN by under-flying the satellite with another IPDA lidar, CHARM-F, and a passive remote sensor, both airborne. However, active and passive remote sensors have different, pressure and temperature dependent measurements sensitivities (weighting functions), different fields of view, and do not sample the total methane column on-board an aircraft. Furthermore, since the methane profile is not constant, its column depends on the height of the boundary layer and of the tropopause. We investigate the impact of these issues on the expected validation accuracy, and we examine whether the ground-based Total Carbon Column Observing Network (TCCON) may be useful for validation, too. Finally, validation opportunities are dependent on the location and size of cloud-free regions, since clouds with

  18. Commercial off the Shelf Ground Control Supports Calibration and Conflation from Ground to Space Based Sensors

    NASA Astrophysics Data System (ADS)

    Danielová, M.; Hummel, P.

    2016-06-01

    The need for rapid deployment of aerial and satellite imagery in support of GIS and engineering integration projects require new sources of geodetic control to ensure the accuracy for geospatial projects. In the past, teams of surveyors would need to deploy to project areas to provide targeted or photo identifiable points that are used to provide data for orthorecificaion, QA/QC and calibration for multi-platform sensors. The challenge of integrating street view, UAS, airborne and Space based sensors to produce the common operational picture requires control to tie multiple sources together. Today commercial off the shelf delivery of existing photo identifiable control is increasing the speed of deployment of this data without having to revisit sites over and over again. The presentation will discuss the processes developed by CompassData to build a global library of 40,000 control points available today. International Organization for Standardization (ISO) based processes and initiatives ensure consistent quality of survey data, photo identifiable features selected and meta data to support photogrammetrist, engineers and GIS professionals to quickly deliver projects with better accuracy.

  19. 76 FR 65540 - National Space-Based Positioning, Navigation, and Timing (PNT) Advisory Board; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-21

    ... SPACE ADMINISTRATION National Space-Based Positioning, Navigation, and Timing (PNT) Advisory Board; Meeting AGENCY: National Aeronautics and Space Administration (NASA). ACTION: Notice of meeting. SUMMARY...'s 2004 U.S. Space-Based Positioning, Navigation, and Timing Policy, the National Aeronautics...

  20. 78 FR 23598 - National Space-Based Positioning, Navigation, and Timing (PNT) Advisory Board; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-19

    ... SPACE ADMINISTRATION National Space-Based Positioning, Navigation, and Timing (PNT) Advisory Board; Meeting AGENCY: National Aeronautics and Space Administration (NASA). ACTION: Notice of Meeting. SUMMARY... President's 2004 U.S. Space-Based Positioning, Navigation, and Timing (PNT) Policy, the National...

  1. 78 FR 65006 - National Space-Based Positioning, Navigation, and Timing (PNT) Advisory Board; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-30

    ... SPACE ADMINISTRATION National Space-Based Positioning, Navigation, and Timing (PNT) Advisory Board; Meeting AGENCY: National Aeronautics and Space Administration (NASA). ACTION: Notice of meeting. SUMMARY... President's 2004 U.S. Space-Based Positioning, Navigation, and Timing (PNT) Policy, the National...

  2. A MICROLENSING MEASUREMENT OF DARK MATTER FRACTIONS IN THREE LENSING GALAXIES

    SciTech Connect

    Bate, N. F.; Webster, R. L.; Wyithe, J. S. B.; Floyd, D. J. E.

    2011-04-10

    Direct measurements of dark matter distributions in galaxies are currently only possible through the use of gravitational lensing observations. Combinations of lens modeling and stellar velocity dispersion measurements provide the best constraints on dark matter distributions in individual galaxies, however they can be quite complex. In this paper, we use observations and simulations of gravitational microlensing to measure the smooth (dark) matter mass fraction at the position of lensed images in three lens galaxies: MG 0414+0534, SDSS J0924+0219, and Q2237+0305. The first two systems consist of early-type lens galaxies, and both display a flux ratio anomaly in their close image pair. Anomalies such as these suggest that a high smooth matter percentage is likely, and indeed we prefer {approx}50% smooth matter in MG 0414+0534 and {approx}80% in SDSS J0924+0219 at the projected locations of the lensed images. Q2237+0305 differs somewhat in that its lensed images lie in the central kiloparsec of the barred spiral lens galaxy, where we expect stars to dominate the mass distribution. In this system, we find a smooth matter percentage that is consistent with zero.

  3. Gravitational microlensing - Powerful combination of ray-shooting and parametric representation of caustics

    NASA Technical Reports Server (NTRS)

    Wambsganss, J.; Witt, H. J.; Schneider, P.

    1992-01-01

    We present a combination of two very different methods for numerically calculating the effects of gravitational microlensing: the backward-ray-tracing that results in two-dimensional magnification patterns, and the parametric representation of caustic lines; they are in a way complementary to each other. The combination of these methods is much more powerful than the sum of its parts. It allows to determine the total magnification and the number of microimages as a function of source position. The mean number of microimages is calculated analytically and compared to the numerical results. The peaks in the lightcurves, as obtained from one-dimensional tracks through the magnification pattern, can now be divided into two groups: those which correspond to a source crossing a caustic, and those which are due to sources passing outside cusps. We determine the frequencies of those two types of events as a function of the surface mass density, and the probability distributions of their magnitudes. We find that for low surface mass density as many as 40 percent of all events in a lightcurve are not due to caustic crossings, but rather due to passings outside cusps.

  4. Mechanics and optics of stretchable microlenses for artificial compound eye camera

    NASA Astrophysics Data System (ADS)

    Li, Zhengwei; Xiao, Jianliang

    2014-03-01

    Due to the wide-angle field of view, low aberrations, high acuity to motion and infinite depth of field, insect eye-inspired imaging devices have attracted more and more interest. Recently, researchers have developed an imaging device that resembles the structure and functions of insects' apposition eyes. Elastomeric microlens array that can be mechanically stretched to very large extent without deteriorating the optics is critical to this development. The stretchable microlens array is composed of a number of hemispherical microlenses each sitting on top of a pedestal and connected through a continuous elastomeric film. Here we present our study on mechanical and optical aspects of stretchable microlens. Our results show that proper designs of the hemispherical microlens, pedestal and film are critically important to meet both mechanical and optical requirements simultaneously. Our study can have important implications in not only the design of artificial compound eye cameras, but also other developments that require stretchable optical elements. PhD candidate from Department of Mechanical Enginering, at University of Colorado Boulder.

  5. Beyond the Wobbles: Teaching Students About Detecting Planets with the Transit and Gravitational Microlensing Methods

    NASA Astrophysics Data System (ADS)

    Prather, Edward E.; Wallace, Colin Scott; Chambers, Timothy G.; Brissenden, Gina; Traub, Wesley A.; Greene, W. M.; Biferno, Anya A.; Rodriguez, Joshua

    2015-01-01

    Members of the Center for Astronomy Education (CAE) at the University of Arizona's Steward Observatory in collaboration with JPL scientists, visualization experts, and education and public outreach professionals with the Exoplanet Exploration Program (ExEP) have recently completed classroom field-testing of a new suite of educational materials to help learners better understand how extrasolar planets are detected using the transit and gravitational microlensing techniques. This collaboration has created a set of evidence-based Think-Pair-Share questions, Lecture-Tutorials, animations, presentation slides, and instrucotrs guide that can be used together or separately to actively engage learners in reasoning about the data and scientific representations associated with these exciting new extrasolar planet detection methods. In this talk we present several of the conceptually challenging collaborative learning tasks that students encounter with this new suite of educational materials and some of the assessment questions we are using to assess the efficacy of their use in general education, college-level astronomy courses.

  6. Gravitational microlensing - The effect of random motion of individual stars in the lensing galaxy

    NASA Technical Reports Server (NTRS)

    Kundic, Tomislav; Wambsganss, Joachim

    1993-01-01

    We investigate the influence of random motion of individual stars in the lensing galaxy on the light curve of a gravitationally lensed background quasar. We compare this with the effects of the transverse motion of the galaxy. We find that three-dimensional random motion of stars with a velocity dispersion sigma in each dimension is more effective in producing 'peaks' in a microlensed light curve by a factor a about 1.3 than motion of the galaxy with a transverse velocity v(t) = sigma. This effectiveness parameter a seems to depend only weakly on the surface mass density. With an assumed transverse velocity of v(t) = 600 km/s of the galaxy lensing the QSO 2237+0305 and a measured velocity dispersion of sigma = 215 km/s, the expected rate of maxima in the light curves calculated for bulk motion alone has to be increased by about 10 percent due to the random motion of stars. As a consequence, the average time interval Delta t between two high-magnification events is smaller than the time interval Delta(t) bulk, calculated for bulk motion alone, Delta t about 0.9 Delta(t) bulk.

  7. Focal performance analysis of closed-boundary cylindrical microlenses made of uniaxial crystal

    NASA Astrophysics Data System (ADS)

    Lin, Jie; Ye, Jiasheng; Liu, Jianlong; Liu, Shutian

    2007-11-01

    In this paper, we investigate the focal performance of closed-boundary cylindrical microlenses (CBCMs) made of anisotropic uniaxial crystal based on rigorous electromagnetic theory and the boundary element method (BEM). For both TE and TM polarizations, focal performances of the anisotropic CBCMs with different f-numbers are studied in detail. The influence of illumination type on focal performances of CBCMs are also considered. Several focal performance quantities, such as the real focal position, the focal spot size, the diffraction efficiency and the normalized transmitted power, are presented. Numerical results indicate that the focal performance of anisotropic CBCMs made of uniaxial crystal differs greatly in the case of different polarizations. Especially, there exists a large focal shift, which is due to the birefringence effect of a uniaxial crystal. In contrast, for conventional isotropic CBCMs, the focal characteristics for different polarizations are similar. Meanwhile, our analysis indicates that the focal performances of CBCMs with small f-number are sensitive to illumination type. It is expected that the CBCMs made of uniaxial crystal should be used as a micropolarization optical filter in micro-optical systems and also offer useful help in application of CBCMs with small f-number.

  8. A New Nonplanetary Interpretation of the Microlensing Event OGLE-2013-BLG-0723

    NASA Astrophysics Data System (ADS)

    Han, Cheongho; Bennett, David P.; Udalski, Andrzej; Jung, Youn Kil

    2016-07-01

    Recently, the discovery of a Venus-mass planet orbiting a brown-dwarf host in a binary system was reported from the analysis of the microlensing event OGLE-2013-BLG-0723. We reanalyze the event considering the possibility of other interpretations. From this, we find a new solution where the lens is composed of two bodies, in contrast to the three-body solution of the previous analysis. The new solution better explains the observed light curve than the previous solution with Δχ 2 ˜ 202, suggesting that the new solution is a correct model for the event. From the estimation of the physical parameters based on the new interpretation, we find that the lens system is composed of two low-mass stars with ˜0.2 M ⊙ and ˜0.1 M ⊙ and located at a distance of ˜3 kpc. The fact that the physical parameters correspond to those of the most common lens population located at a distance with a large lensing probability further supports the likelihood of the new interpretation. Considering that two dramatically different solutions can approximately explain the observed light curve, the event suggests the need for carefully testing all possible lens-system geometries.

  9. Study by MOA of extrasolar planets in gravitational microlensing events of high magnification

    NASA Astrophysics Data System (ADS)

    Bond, I. A.; Rattenbury, N. J.; Skuljan, J.; Abe, F.; Dodd, R. J.; Hearnshaw, J. B.; Honda, M.; Jugaku, J.; Kilmartin, P. M.; Marles, A.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nakamura, T.; Nankivell, G.; Noda, S.; Noguchi, C.; Ohnishi, K.; Reid, M.; Saito, To.; Sato, H.; Sekiguchi, M.; Sullivan, D. J.; Sumi, T.; Takeuti, M.; Watase, Y.; Wilkinson, S.; Yamada, R.; Yanagisawa, T.; Yock, P. C. M.

    2002-06-01

    A search for extrasolar planets was carried out in three gravitational microlensing events of high magnification, MACHO 98-BLG-35, MACHO 99-LMC-2 and OGLE 00-BUL-12. Photometry was derived from observational images by the MOA and OGLE groups using an image subtraction technique. For MACHO 98-BLG-35, additional photometry derived from the MPS and PLANET groups was included. Planetary modelling of the three events was carried out in a supercluster computing environment. The estimated probability for explaining the data on MACHO 98-BLG-35 without a planet is <1 per cent. The best planetary model has a planet of mass ~(0.4-1.5)×MEarth at a projected radius of either ~1.5 or ~2.3au. We show how multiplanet models can be applied to the data. We calculate exclusion regions for the three events and find that Jupiter-mass planets can be excluded with projected radii from as wide as about 30au to as close as around 0.5au for MACHO 98-BLG-35 and OGLE 00-BUL-12. For MACHO 99-LMC-2, the exclusion region extends out to around 10au and constitutes the first limit placed on a planetary companion to an extragalactic star. We derive a particularly high peak magnification of ~160 for OGLE 00-BUL-12. We discuss the detectability of planets with masses as low as Mercury in this and similar events.

  10. Non Radiation Hardened Microprocessors in Spaced Based Remote Sensing Systems

    NASA Technical Reports Server (NTRS)

    Decoursey, Robert J.; Estes, Robert F.; Melton, Ryan

    2006-01-01

    The CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) mission is a comprehensive suite of active and passive sensors including a 20Hz 230mj Nd:YAG lidar, a visible wavelength Earth-looking camera and an imaging infrared radiometer. CALIPSO flies in formation with the Earth Observing System Post-Meridian (EOS PM) train, provides continuous, near-simultaneous measurements and is a planned 3 year mission. CALIPSO was launched into a 98 degree sun synchronous Earth orbit in April of 2006 to study clouds and aerosols and acquires over 5 gigabytes of data every 24 hours. The ground track of one CALIPSO orbit as well as high and low intensity South Atlantic Anomaly outlines is shown. CALIPSO passes through the SAA several times each day. Spaced based remote sensing systems that include multiple instruments and/or instruments such as lidar generate large volumes of data and require robust real-time hardware and software mechanisms and high throughput processors. Due to onboard storage restrictions and telemetry downlink limitations these systems must pre-process and reduce the data before sending it to the ground. This onboard processing and realtime requirement load may mean that newer more powerful processors are needed even though acceptable radiation-hardened versions have not yet been released. CALIPSO's single board computer payload controller processor is actually a set of four (4) voting non-radiation hardened COTS Power PC 603r's built on a single width VME card by General Dynamics Advanced Information Systems (GDAIS). Significant radiation concerns for CALIPSO and other Low Earth Orbit (LEO) satellites include the South Atlantic Anomaly (SAA), the north and south poles and strong solar events. Over much of South America and extending into the South Atlantic Ocean the Van Allen radiation belts dip to just 200-800km and spacecraft entering this area are subjected to high energy protons and experience higher than normal Single Event Upset

  11. Low-cost, high-precision micro-lensed optical fiber providing deep-micrometer to deep-nanometer-level light focusing.

    PubMed

    Wen, Sy-Bor; Sundaram, Vijay M; McBride, Daniel; Yang, Yu

    2016-04-15

    A new type of micro-lensed optical fiber through stacking appropriate high-refractive microspheres at designed locations with respect to the cleaved end of an optical fiber is numerically and experimentally demonstrated. This new type of micro-lensed optical fiber can be precisely constructed with low cost and high speed. Deep micrometer-scale and submicrometer-scale far-field light spots can be achieved when the optical fibers are multimode and single mode, respectively. By placing an appropriate teardrop dielectric nanoscale scatterer at the far-field spot of this new type of micro-lensed optical fiber, a deep-nanometer near-field spot can also be generated with high intensity and minimum joule heating, which is valuable in high-speed, high-resolution, and high-power nanoscale detection compared with traditional near-field optical fibers containing a significant portion of metallic material.

  12. Fabrication of micro-lenses using excimer laser ablation by means of laser-generated grey-tone-masks

    NASA Astrophysics Data System (ADS)

    Klotzbuecher, T.; Dadic, D.

    2010-02-01

    Micro-lenses, including Fresnel-Lenses, were fabricated by excimer laser ablation of polymers by means of lasergenerated grey-tone-masks. The smallest reproducible holes that could be fabricated by excimer laser ablation (193 nm, 1 J/cm2) of chromium-on-quartz (thickness 50-100 nm) were around 3 μm, the pitch of which should be at least at the same value to ensure a reproducibility of hole-arrays. To achieve acceptable ablation times during the fabrication of the grey-tone-masks, on-the-fly ablation instead of step-and-repeat technique was used, operating the laser at a constant pulse repetition rate <30 Hz with a continuously moving quartz-substrate. In this way and using different encoding techniques it was possible to generate at least 11 different grey-tones. The available grey-tones were used to generate grey-tone-masks for ablation of Polymethylmethacrylate (PMMA) and Polycarbonate (PC). For that, fluences in the range of 0.07-0.14 J/cm2 could be applied, corresponding to a value of 1.25 J/cm2 on the workpiece without grey-tonemask and a value lying well below the damage threshold of the chromium mask. Refractive micro-lenses fabricated in this way did not show a good imaging quality, since 11 grey-tones is less than required to generate a continuous surface profile over the full diameter of the lens during ablation and the achievable aspect ratio is limited with the small fluences. However, flat diffractive micro-lenses of the Fresenel type with a quasi-continuously surface profile could be fabricated in a sufficient manner. This can be attributed to the fact that each segment of the Fresenel-lenses can be encoded by 11 grey-tones, leading to much smoother surface reliefs and to a sufficient imaging quality.

  13. PROSPECTS FOR CHARACTERIZING HOST STARS OF THE PLANETARY SYSTEM DETECTIONS PREDICTED FOR THE KOREAN MICROLENSING TELESCOPE NETWORK

    SciTech Connect

    Henderson, Calen B.

    2015-02-10

    I investigate the possibility of constraining the flux of the lens (i.e., host star) for the types of planetary systems the Korean Microlensing Telescope Network is predicted to find. I examine the potential to obtain lens flux measurements by (1) imaging the lens once it is spatially resolved from the source, (2) measuring the elongation of the point-spread function of the microlensing target (lens+source) when the lens and source are still unresolved, and (3) taking prompt follow-up photometry. In each case I simulate the observing programs for a representative example of current ground-based adaptive optics (AO) facilities (specifically NACO on the Very Large Telescope), future ground-based AO facilities (GMTIFS on the Giant Magellan Telescope, GMT), and future space telescopes (NIRCAM on the James Webb Space Telescope, JWST). Given the predicted distribution of relative lens-source proper motions, I find that the lens flux could be measured to a precision of σ{sub H{sub ℓ}}≤0.1 for ≳60% of planet detections ≥5 yr after each microlensing event for a simulated observing program using GMT, which images resolved lenses. NIRCAM on JWST would be able to carry out equivalently high-precision measurements for ∼28% of events Δt = 10 yr after each event by imaging resolved lenses. I also explore the effects various blend components would have on the mass derived from prompt follow-up photometry, including companions to the lens, companions to the source, and unassociated interloping stars. I find that undetected blend stars would cause catastrophic failures (i.e., >50% fractional uncertainty in the inferred lens mass) for ≲ (16 · f {sub bin})% of planet detections, where f {sub bin} is the binary fraction, with the majority of these failures occurring for host stars with mass ≲0.3 M {sub ☉}.

  14. Resolving the Innermost Region of the Accretion Disk of the Lensed Quasar Q2237+0305 through Gravitational Microlensing

    NASA Astrophysics Data System (ADS)

    Mediavilla, E.; Jiménez-vicente, J.; Muñoz, J. A.; Mediavilla, T.

    2015-12-01

    We study three high magnification microlensing events, generally recognized as probable caustic crossings, in the optical light curves of the multiply imaged quasar Q2237+0305. We model the light curve of each event as the convolution of a standard thin disk luminosity profile with a straight fold caustic. We also allow for a linear gradient that can account for an additional varying background effect of microlensing. This model not only matches noticeably well the global shape of each of the three independent microlensing events but also gives remarkably similar estimates for the disk size parameter. The measured average half-light radius, {R}1/2=(3.0+/- 1.5)\\sqrt{M/0.3M⊙ } light-days, agrees with previous estimates. In the three events, the core of the magnification profile exhibits “fine structure” related to the innermost region of the accretion disk (located at a radial distance of 2.7 ± 1.4 Schwarzschild radii according to our measurement). Relativistic beaming at the internal rim of the accretion disk can explain the shape and size of the fine structure, although alternative explanations are also possible. This is the first direct measurement of the size of a structure, likely the innermost stable circular orbit, at ˜3 Schwarzschild radii in a quasar accretion disk. The monitoring of thousands of lensed quasars with future telescopes will allow the study of the event horizon environment of black holes in hundreds of quasars in a wide range of redshifts (0.5 < z < 5).

  15. Long-term monitoring, time delay, and microlensing in the gravitational lens system Q0142-100

    SciTech Connect

    Oscoz, A.; Serra-Ricart, M.; Mediavilla, E.

    2013-12-20

    We present 12 yr of monitoring of the gravitational lens Q0142-100 from the Teide Observatory. The data, taken from 1999 to 2010, comprise 105 observing nights with the IAC80 Telescope. The application of the δ{sup 2} method to the dataset leads to a value for the time delay between both components of the system of 72 ± 22 days (68% confidence level), consistent within uncertainties with the most recent results. With this value in mind a possible microlensing event is detected in Q0142-100.

  16. Single nucleotide polymorphism detection using gold nanoprobes and bio-microfluidic platform with embedded microlenses.

    PubMed

    Bernacka-Wojcik, Iwona; Águas, Hugo; Carlos, Fabio Ferreira; Lopes, Paulo; Wojcik, Pawel Jerzy; Costa, Mafalda Nascimento; Veigas, Bruno; Igreja, Rui; Fortunato, Elvira; Baptista, Pedro Viana; Martins, Rodrigo

    2015-06-01

    The use of microfluidics platforms combined with the optimal optical properties of gold nanoparticles has found plenty of application in molecular biosensing. This paper describes a bio-microfluidic platform coupled to a non-cross-linking colorimetric gold nanoprobe assay to detect a single nucleotide polymorphism associated with increased risk of obesity fat-mass and obesity-associated (FTO) rs9939609 (Carlos et al., 2014). The system enabled significant discrimination between positive and negative assays using a target DNA concentration of 5 ng/µL below the limit of detection of the conventionally used microplate reader (i.e., 15 ng/µL) with 10 times lower solution volume (i.e., 3 µL). A set of optimization of our previously reported bio-microfluidic platform (Bernacka-Wojcik et al., 2013) resulted in a 160% improvement of colorimetric analysis results. Incorporation of planar microlenses increased 6 times signal-to-loss ratio reaching the output optical fiber improving by 34% the colorimetric analysis of gold nanoparticles, while the implementation of an optoelectronic acquisition system yielded increased accuracy and reduced noise. The microfluidic chip was also integrated with a miniature fiber spectrometer to analyze the assays' colorimetric changes and also the LEDs transmission spectra when illuminating through various solutions. Furthermore, by coupling an optical microscope to a digital camera with a long exposure time (30 s), we could visualise the different scatter intensities of gold nanoparticles within channels following salt addition. These intensities correlate well to the expected difference in aggregation between FTO positive (none to small aggregates) and negative samples (large aggregates).

  17. Accurate Mass Determination of the Ancient White Dwarf ER 8 Through Astrometric Microlensing

    NASA Astrophysics Data System (ADS)

    Sahu, Kailash

    2005-07-01

    We propose to determine the mass of the very cool white dwarf ER 8 through astrometric microlensing. We have predicted that ER 8 will pass very close to a 15th-mag background star in January 2006, with an impact parameter of less than 0.05 arcsec. As it passes in front, it will cause a deflection of the background star's image by >8 milliarcsec, an amount easily detectable with HST/FGS. The gravitational deflection angle depends only on the distances and relative positions of the stars, and on the mass of the white dwarf. Since the distances and positions can be determined precisely before the event, the astrometric measurement offers a unique and direct method to measure the mass of the white dwarf to high accuracy {<5%}. Unlike all other stellar mass determinations, this technique works for single stars {but only if they are nearby and of sufficient mass}. The mass of ER 8 is of special interest because it is a member of the Galactic halo, and appears to be the oldest known field white dwarf. This object can thus set a lower limit on the age of the Galactic halo, but since white-dwarf cooling rates depend on their masses, the mass is a necessary ingredient in the age determination. As a byproduct, we will obtain an accurate parallax for ER 8, and thus its luminosity and {from its effective temperature} its radius. Such quantities are at present rather poorly known for the coolest white dwarfs, and will provide strong constraints on white-dwarf physics.

  18. Accurate Mass Determination of the Ancient White Dwarf ER 8 Through Astrometric Microlensing

    NASA Astrophysics Data System (ADS)

    Sahu, Kailash

    2004-07-01

    We propose to determine the mass of the very cool white dwarf ER 8 through astrometric microlensing. We have predicted that ER 8 will pass very close to a 15th-mag background star in January 2006, with an impact parameter of less than 0.05 arcsec. As it passes in front, it will cause a deflection of the background star's image by >8 milliarcsec, an amount easily detectable with HST/FGS. The gravitational deflection angle depends only on the distances and relative positions of the stars, and on the mass of the white dwarf. Since the distances and positions can be determined precisely before the event, the astrometric measurement offers a unique and direct method to measure the mass of the white dwarf to high accuracy {<5%}. Unlike all other stellar mass determinations, this technique works for single stars {but only if they are nearby and of sufficient mass}. The mass of ER 8 is of special interest because it is a member of the Galactic halo, and appears to be the oldest known field white dwarf. This object can thus set a lower limit on the age of the Galactic halo, but since white-dwarf cooling rates depend on their masses, the mass is a necessary ingredient in the age determination. As a byproduct, we will obtain an accurate parallax for ER 8, and thus its luminosity and {from its effective temperature} its radius. Such quantities are at present rather poorly known for the coolest white dwarfs, and will provide strong constraints on white-dwarf physics.

  19. The Microlensing Planet Finder: A Census Of Planetary Systems Like Our Own.

    NASA Astrophysics Data System (ADS)

    Bennett, David P.; Cheng, E.; Kimble, R.; Mather, J.; Gould, A.; Brown, M.; Anderson, J.; Beaulieu, J.; Bond, I.; Cook, K.; Friedman, S.; Gaudi, S.; Gilliland, R.; Griest, K.; Jenkins, J.; Lunine, J.; Minniti, D.; Paczynski, B.; Peale, S.; Rich, M.; Sahu, K.; Shao, M.; Tenerelli, D.; Udalski, A.; Yock, P.

    2006-09-01

    The Microlensing Planet Finder (MPF) will complete the first census of extrasolar planets with sensitivity to planets like those in our own Solar System. MPF uses a proven low-mass planet detection method to detect planets with masses of 0.1 Earth masses or more at all separations of 0.5 AU or larger from their host stars. MPF's planetary census provides critical data for understanding planet formation and habitability that cannot be obtained by other means. MPF's results complement those of the Kepler mission, which detects Earth-like planets at separations of 1 AU or less. MPF and Kepler overlap at a 1 AU, in the habitable zone for Solar type stars. MPF's employs a 1.1m telescope with a 0.65 square degree FOV that images in the near IR (600-1700nm). MPF's inclined geosynchronous orbit allows continuous data transmission to a dedicated ground station while maintaining continuous, high angular resolution observations of 2.5 square degrees of the central Galactic bulge. This is necessary to discovery terrestrial extrasolar planets at a wide range of orbital separations. If every planetary system has the same planet-star mass ratios and separations as our own Solar System, then MPF detects 150 terrestrial planets, 6000 gas giants, and 130 ice giants. MPF also detects 60 free-floating Earths if there is one such planet per Galactic star. During the 3 months per year when the Galactic bulge cannot be observed, addresses other science goals, such as the follow-up of Kepler planet candidates observations to exclude "false positive” Kepler planet detections. MPF also searches beyond the Kuiper Belt for objects like Sedna to test theories of the Solar System's formation and runs a General Observer program.

  20. Discovery of a Gas Giant Planet in Microlensing Event Ogle-2014-BLG-1760

    NASA Technical Reports Server (NTRS)

    Bhattacharya, A.; Bennett, D. P.; Bond, I. A.; Sumi, T.; Udalski, A.; Street, R.; Tsapras, Y.; Abe, F.; Freeman, M.; Fukui, A.

    2016-01-01

    We present the analysis of the planetary microlensing event OGLE-2014-BLG-1760, which shows a strong light-curve signal due to the presence of a Jupiter mass ratio planet. One unusual feature of this event is that the source star is quite blue, with V-I = 1.48 +/- 0.08. This is marginally consistent with a source star in the Galactic bulge, but it could possibly indicate a young source star on the far side of the disk. Assuming a bulge source, we perform a Bayesian analysis assuming a standard Galactic model, and this indicates that the planetary system resides in or near the Galactic bulge at D(sub L) = 6.9 +/- 1.1 kpc. It also indicates a host-star mass of M(sub *) = 0.51(sup + 0.44/sub -0.28) M(sub theta), a planet mass of m(sub p ) = 0.56(sup +0.34/sub -0.26) M(sub J), and a projected star-planet separation of a(perpendicular) = 1.75(sup +0.33/sub -0.34) au. The lens-source relative proper motion is micro(sub rel) = 6.5 +/- 1.1mas per yr. The lens (and stellar host star) is estimated to be very faint compared to the source star, so it is most likely that it can be detected only when the lens and source stars start to separate. Due to the relatively high relative proper motion, the lens and source will be resolved to about approximately 46 mas in 6-8 yr after the peak magnification. So, by 2020-2022, we can hope to detect the lens star with deep, high-resolution images.

  1. Properties of Microlensing Events by Wide-separation Planets with a Moon

    NASA Astrophysics Data System (ADS)

    Chung, Sun-Ju; Ryu, Yoon-Hyun

    2016-07-01

    We investigate the properties of microlensing events caused by planetary systems where planets with a moon are widely separated from their host stars. From this investigation, we find that the moon feature generally appears as a very short-duration perturbation on the smooth asymmetric light curve of the lensing event induced by the wide-separation planet; thus it can be easily discriminated from the planet feature responsible for the overall asymmetric light curve. For typical Galactic lensing events with an Einstein radius of ˜2 au, the asymmetry of the light curves due to bound planets can be noticed up to ˜20 au. We also find that the perturbations of wide planetary systems become dominated by the moon as the projected star-planet separation increases, and eventually the light curves of events produced by such systems appear as the single lensing light curve of the planet itself with a very short-duration perturbation induced by the moon, which is a representative light curve of the event induced by a star and a planet, except on the Einstein timescale of the planet. We also study the effect of a finite source star on the moon feature in wide planetary lensing events. From this study, we find that when the lunar caustic is sufficiently separated from the planetary caustic, the lower limit on the ratio of the size of the lunar caustic to the source radius causing a ≥5% lunar deviation depends mostly on the projected planet-moon separation regardless of the moon/star mass ratio, and it decreases as the planet-moon separation becomes smaller or larger than the planetary Einstein radius.

  2. A PLANETARY LENSING FEATURE IN CAUSTIC-CROSSING HIGH-MAGNIFICATION MICROLENSING EVENTS

    SciTech Connect

    Chung, Sun-Ju; Hwang, Kyu-Ha; Ryu, Yoon-Hyun; Lee, Chung-Uk E-mail: kyuha@kasi.re.kr E-mail: leecu@kasi.re.kr

    2012-05-20

    Current microlensing follow-up observations focus on high-magnification events because of the high efficiency of planet detection. However, central perturbations of high-magnification events caused by a planet can also be produced by a very close or a very wide binary companion, and the two kinds of central perturbations are not generally distinguished without time consuming detailed modeling (a planet-binary degeneracy). Hence, it is important to resolve the planet-binary degeneracy that occurs in high-magnification events. In this paper, we investigate caustic-crossing high-magnification events caused by a planet and a wide binary companion. From this investigation, we find that because of the different magnification excess patterns inside the central caustics induced by the planet and the binary companion, the light curves of the caustic-crossing planetary-lensing events exhibit a feature that is discriminated from those of the caustic-crossing binary-lensing events, and the feature can be used to immediately distinguish between the planetary and binary companions. The planetary-lensing feature appears in the interpeak region between the two peaks of the caustic-crossings. The structure of the interpeak region for the planetary-lensing events is smooth and convex or boxy, whereas the structure for the binary-lensing events is smooth and concave. We also investigate the effect of a finite background source star on the planetary-lensing feature in the caustic-crossing high-magnification events. From this, we find that the convex-shaped interpeak structure appears in a certain range that changes with the mass ratio of the planet to the planet-hosting star.

  3. Discovery of a Gas Giant Planet in Microlensing Event OGLE-2014-BLG-1760

    NASA Astrophysics Data System (ADS)

    Bhattacharya, A.; Bennett, D. P.; Bond, I. A.; Sumi, T.; Udalski, A.; Street, R.; Tsapras, Y.; Abe, F.; Freeman, M.; Fukui, A.; Hirao, Y.; Itow, Y.; Koshimoto, N.; Li, M. C. A.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Ohnishi, K.; Rattenbury, N.; Saito, T.; Sharan, A.; Sullivan, D. J.; Suzuki, D.; Tristram, P. J.; MOA Collaboration; Skowron, J.; Szymański, M. K.; Soszyński, I.; Poleski, R.; Mróz, P.; Kozlowski, S.; Pietrukowicz, P.; Ulaczyk, K.; Wyrzykowski, L.; OGLE Collaboration; Bachelet, E.; Bramich, D. M.; D'Ago, G.; Dominik, M.; Figuera Jaimes, R.; Horne, K.; Hundertmark, M.; Kains, N.; Menzies, J.; Schmidt, R.; Snodgrass, C.; Steele, I. A.; Wambsganss, J.; ROBONET Collaboration

    2016-11-01

    We present the analysis of the planetary microlensing event OGLE-2014-BLG-1760, which shows a strong light-curve signal due to the presence of a Jupiter mass ratio planet. One unusual feature of this event is that the source star is quite blue, with V-I=1.48+/- 0.08. This is marginally consistent with a source star in the Galactic bulge, but it could possibly indicate a young source star on the far side of the disk. Assuming a bulge source, we perform a Bayesian analysis assuming a standard Galactic model, and this indicates that the planetary system resides in or near the Galactic bulge at {D}L=6.9+/- 1.1 {kpc}. It also indicates a host-star mass of {M}* ={0.51}-0.28+0.44{M}⊙ , a planet mass of {m}{{p}}={0.56}-0.26+0.34{M}J, and a projected star-planet separation of {a}\\perp ={1.75}-0.33+0.34 au. The lens-source relative proper motion is {μ }{rel}=6.5+/- 1.1 mas yr-1. The lens (and stellar host star) is estimated to be very faint compared to the source star, so it is most likely that it can be detected only when the lens and source stars start to separate. Due to the relatively high relative proper motion, the lens and source will be resolved to about ˜46 mas in 6-8 yr after the peak magnification. So, by 2020-2022, we can hope to detect the lens star with deep, high-resolution images.

  4. A Search For Stellar-mass Black Holes Via Astrometric Microlensing

    NASA Astrophysics Data System (ADS)

    Lu, J. R.; Sinukoff, E.; Ofek, E. O.; Udalski, A.; Kozlowski, S.

    2016-10-01

    While dozens of stellar-mass black holes (BHs) have been discovered in binary systems, isolated BHs have eluded detection. Their presence can be inferred when they lens light from a background star. We attempt to detect the astrometric lensing signatures of three photometrically identified microlensing events, OGLE-2011-BLG-0022, OGLE-2011-BLG-0125, and OGLE-2012-BLG-0169 (OB110022, OB110125, and OB120169), located toward the Galactic Bulge. These events were selected because of their long durations, which statistically favors more massive lenses. Astrometric measurements were made over one to two years using laser-guided adaptive optics observations from the W. M. Keck Observatory. Lens model parameters were first constrained by the photometric light curves. The OB120169 light curve is well fit by a single-lens model, while both OB110022 and OB110125 light curves favor binary lens models. Using the photometric fits as prior information, no significant astrometric lensing signal was detected and all targets were consistent with linear motion. The significant lack of astrometric signal constrains the lens mass of OB110022 to 0.05-1.79 M ⊙ in a 99.7% confidence interval, which disfavors a BH lens. Fits to OB110125 yielded a reduced Einstein crossing time and insufficient observations during the peak, so no mass limits were obtained. Two degenerate solutions exist for OB120169, which have a lens mass between 0.2-38.8 M ⊙ and 0.4-39.8 M ⊙ for a 99.7% confidence interval. Follow-up observations of OB120169 will further constrain the lens mass. Based on our experience, we use simulations to design optimal astrometric observing strategies and show that with more typical observing conditions the detection of BHs is feasible.

  5. Alaska at the Crossroads of Migration: Space Based Ornithology

    NASA Technical Reports Server (NTRS)

    Deppe, Jill; Wessels, Konrad; Smith, James A.

    2007-01-01

    Understanding bird migration on a global scale is one of the most compelling and challenging problems of modern biology with major implications for human health and conservation biology. Revolutionary advances in remote sensing now provide us with near real-time measurements of atmospheric and land surface conditions at high spatial resolution over entire continents. We use spatially-explicit, individual based bird migration models driven by numerical weather prediction models of atmospheric conditions, dynamic habitat suitability maps derived from remotely sensed land surface conditions, biophysiological models, and biological field data to simulate migration routes, timing, energy budgets, and survival of individual birds and populations. Long-distance migratory birds travel annually between breeding grounds in Alaska and wintering grounds in Latin Amierica. Approximately 25% of these species are potential vectors of Avian Influenza. Alaska is at the crossroads of Asian and New World migratory flyways and is likely to be a point of introduction of Asian H5N1 AI into the western hemisphere. If/when an infected bird is detected, a pressing question will be where was this bird several days ago, and where is it likely to go after it was released from the survey site? Answers to such questions will increase effectiveness of AI surveillance and mitigation measures. From a conservation perspective, Alaska's diverse landscape provides breeding sites for many migrants, and climatic and land surface changes along migratory flyways in the western hemisphere may reduce bird survival and physical condition upon arrival at Alaskan breeding territories, success and migrant populations.

  6. FREQUENCY OF SOLAR-LIKE SYSTEMS AND OF ICE AND GAS GIANTS BEYOND THE SNOW LINE FROM HIGH-MAGNIFICATION MICROLENSING EVENTS IN 2005-2008

    SciTech Connect

    Gould, A.; Dong, Subo; Gaudi, B. S.; Han, C. E-mail: gaudi@astronomy.ohio-state.ed

    2010-09-10

    We present the first measurement of the planet frequency beyond the 'snow line', for the planet-to-star mass-ratio interval -4.5 < log q < -2, corresponding to the range of ice giants to gas giants. We find (d{sup 2}N{sub pl})/(d log q d log s) = (0.36{+-}0.15) dex{sup -2} at the mean mass ratio q = 5 x 10{sup -4} with no discernible deviation from a flat (Oepik's law) distribution in log-projected separation s. The determination is based on a sample of six planets detected from intensive follow-up observations of high-magnification (A>200) microlensing events during 2005-2008. The sampled host stars have a typical mass M{sub host} {approx} 0.5 M {sub sun}, and detection is sensitive to planets over a range of planet-star-projected separations (s {sup -1}{sub max} R {sub E}, s{sub max} R {sub E}), where R {sub E} {approx} 3.5 AU(M{sub host}/M{sub sun}){sup 1/2} is the Einstein radius and s {sub max} {approx} (q/10{sup -4.3}){sup 1/3}. This corresponds to deprojected separations roughly three times the 'snow line'. We show that the observations of these events have the properties of a 'controlled experiment', which is what permits measurement of absolute planet frequency. High-magnification events are rare, but the survey-plus-follow-up high-magnification channel is very efficient: half of all high-mag events were successfully monitored and half of these yielded planet detections. The extremely high sensitivity of high-mag events leads to a policy of monitoring them as intensively as possible, independent of whether they show evidence of planets. This is what allows us to construct an unbiased sample. The planet frequency derived from microlensing is a factor 8 larger than the one derived from Doppler studies at factor {approx}25 smaller star-planet separations (i.e., periods 2-2000 days). However, this difference is basically consistent with the gradient derived from Doppler studies (when extrapolated well beyond the separations from which it is measured). This

  7. Space Acquisitions: Space Based Infrared System Could Benefit from Technology Insertion Planning

    DTIC Science & Technology

    2015-04-01

    insertion—in the Space Based Infrared System (SBIRS) geosynchronous earth orbit (GEO) satellites 5 and 6. However, the assessment was limited in the number...GAO Contact and Staff Acknowledgments 20 Figures Figure 1: Example of a Single Geosynchronous Earth Orbit (GEO) Satellite Field of View 4 Figure 2...System Geosynchronous Earth Orbit Satellite Components 7 Figure 4: Timeline of Space Based Infrared System (SBIRS) Program Events and Efforts to

  8. Application of sunlight and lamps for plant irradiation in space bases

    NASA Astrophysics Data System (ADS)

    Sager, J. C.; Wheeler, R. M.

    The radiation sources used for plant growth on a space base must meet the biological requirements for photosynthesis and photomorphogensis. In addition the sources must be energy and volume efficient, while maintaining the required irradiance levels, spectral, spatial and temporal distribution. These requirements are not easily met, but as the biological and mission requirements are better defined, then specific facility designs can begin to accommodate both the biological requirements and the physical limitations of a space based plant growth system.

  9. Application of sunlight and lamps for plant irradiation in space bases

    NASA Technical Reports Server (NTRS)

    Sager, J. C.; Wheeler, R. M.

    1992-01-01

    The radiation sources used for plant growth on a space base must meet the biological requirements for photosynthesis and photomorphogenesis. In addition, the sources must be energy and volume efficient, while maintaining the required irradiance levels, spectral, spatial and temporal distribution. These requirements are not easily met, but as the biological and mission requirements are better defined, then specific facility designs can begin to accommodate both the biological requirements and the physical limitations of a space-based plant growth system.

  10. Autonomous Sub-Pixel Satellite Track Endpoint Determination for Space Based Images

    SciTech Connect

    Simms, L M

    2011-03-07

    An algorithm for determining satellite track endpoints with sub-pixel resolution in spaced-based images is presented. The algorithm allows for significant curvature in the imaged track due to rotation of the spacecraft capturing the image. The motivation behind the subpixel endpoint determination is first presented, followed by a description of the methodology used. Results from running the algorithm on real ground-based and simulated spaced-based images are shown to highlight its effectiveness.

  11. Applications of improved first Rayleigh-Sommerfeld method to analyze the performance of cylindrical microlenses with different f-numbers.

    PubMed

    Ye, Jia-Sheng; Gu, Ben-Yuan; Dong, Bi-Zhen; Liu, Shu-Tian

    2005-05-01

    Based on the previous Letter [Opt. Lett. 29, 2345 (2004)], we significantly extend the applications of the improved first Rayleigh-Sommerfeld method (IRSM1) to analyze the focusing performance of cylindrical micro-lenses for different types of profile (continuous or stepwise), different f-numbers (from f/1.5 to f/0.75), and different polarizations (the TE or TM). A number of performance measures of the cylindrical microlenses, such as the focal spot size, the diffraction efficiency, the real focal position, and the normalized sidelobe power, are studied in detail. We compare numerical results obtained by the IRSM1, by the original first Rayleigh-Sommerfeld method (ORSM1), and by the rigorous boundary element method (BEM). For continuously refractive lenses, the results calculated by the IRSM1 are quite close to those obtained by the BEM; in contrast, the results calculated by the ORSM1 significantly deviate from those obtained from the rigorous BEM. For multilevel diffractive lenses, the IRSM1 also provides much more accurate results than the ORSM1. In addition, compared with the BEM, a notable advantage of the IRSM1 is much lower computer memory and time consumption in computations.

  12. Constraint on Additional Planets in Planetary Systems Discovered Through the Channel of High-magnification Gravitational Microlensing Events

    NASA Astrophysics Data System (ADS)

    Shin, I.-G.; Han, C.; Choi, J.-Y.; Hwang, K.-H.; Jung, Y.-K.; Park, H.

    2015-04-01

    High-magnification gravitational microlensing events provide an important channel of detecting planetary systems with multiple giants located at their birth places. In order to investigate the potential existence of additional planets, we reanalyze the light curves of the eight high-magnification microlensing events, for each of which a single planet was previously detected. The analyzed events include OGLE-2005-BLG-071, OGLE-2005-BLG-169, MOA-2007-BLG-400, MOA-2008-BLG-310, MOA-2009-BLG-319, MOA-2009-BLG-387, MOA-2010-BLG-477, and MOA-2011-BLG-293. We find that including an additional planet improves fits with {Δ }{{χ }2}\\lt 80 for seven out of eight analyzed events. For MOA-2009-BLG-319, the improvement is relatively big with {Δ }{{χ }2}∼ 143. From inspection of the fits, we find that the improvement of the fits is attributed to systematics in data. Although no clear evidence of additional planets is found, it is still possible to constrain the existence of additional planets in the parameter space. For this purpose, we construct exclusion diagrams showing the confidence levels excluding the existence of an additional planet as a function of its separation and mass ratio. We also present the exclusion ranges of additional planets with 90% confidence level for Jupiter-, Saturn-, and Uranus-mass planets.

  13. Variability of GeV gamma-ray emission in QSO B0218+357 due to microlensing on intermediate size structures

    NASA Astrophysics Data System (ADS)

    Sitarek, J.; Bednarek, W.

    2016-06-01

    Strong gravitational lensing leads to an occurrence of multiple images, with different magnifications, of a lensed source. Those magnifications can in turn be modified by microlensing on smaller mass scales within the lens. Recently, measurements of the changes in the magnification ratio of the individual images have been proposed as a powerful tool for estimation of the size and velocity of the emission region in the lensed source. The changes of the magnification ratios in blazars PKS1830-211 and QSO B0218+357, if interpreted as caused by a microlensing on individual stars, put strong constraints on those two variables. These constraints are difficult to accommodate with the current models of gamma-ray emission in blazars. In this paper we study if similar changes in the magnification ratio can be caused by microlensing on intermediate size structures in the lensing galaxy. We investigate in details three classes of possible lenses: globular clusters (GCs), open clusters (OCs) and giant molecular clouds (GMCs). We apply this scenario to the case of QSO B0218+357. Our numerical simulations show that changes in magnifications with similar time-scales can be obtained for relativistically moving emission regions with sizes up to 0.01 pc in the case of microlensing on the cores of GCs or clumps in GMCs. From the density of such structures in spiral galaxies we estimate however that lensing in GMCs would be more common.

  14. The First Simultaneous Microlensing Observations by Two Space Telescopes: Spitzer and Swift Reveal a Brown Dwarf in Event OGLE-2015-BLG-1319

    NASA Astrophysics Data System (ADS)

    Shvartzvald, Y.; Li, Z.; Udalski, A.; Gould, A.; Sumi, T.; Street, R. A.; Calchi Novati, S.; Hundertmark, M.; Bozza, V.; Beichman, C.; Bryden, G.; Carey, S.; Drummond, J.; Fausnaugh, M.; Gaudi, B. S.; Henderson, C. B.; Tan, T. G.; Wibking, B.; Pogge, R. W.; Yee, J. C.; Zhu, W.; (Spitzer Team; Tsapras, Y.; Bachelet, E.; Dominik, M.; Bramich, D. M.; Cassan, A.; Figuera Jaimes, R.; Horne, K.; Ranc, C.; Schmidt, R.; Snodgrass, C.; Wambsganss, J.; Steele, I. A.; Menzies, J.; Mao, S.; (RoboNet; Poleski, R.; Pawlak, M.; Szymański, M. K.; Skowron, J.; Mróz, P.; Kozłowski, S.; Wyrzykowski, Ł.; Pietrukowicz, P.; Soszyński, I.; Ulaczyk, K.; (OGLE Group; Abe, F.; Asakura, Y.; Barry, R. K.; Bennett, D. P.; Bhattacharya, A.; Bond, I. A.; Freeman, M.; Hirao, Y.; Itow, Y.; Koshimoto, N.; Li, M. C. A.; Ling, C. H.; Masuda, K.; Fukui, A.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Nishioka, T.; Ohnishi, K.; Oyokawa, H.; Rattenbury, N. J.; Saito, To.; Sharan, A.; Sullivan, D. J.; Suzuki, D.; Tristram, P. J.; Yonehara, A.; (MOA Group; Jørgensen, U. G.; Burgdorf, M. J.; Ciceri, S.; D'Ago, G.; Evans, D. F.; Hinse, T. C.; Kains, N.; Kerins, E.; Korhonen, H.; Mancini, L.; Popovas, A.; Rabus, M.; Rahvar, S.; Scarpetta, G.; Skottfelt, J.; Southworth, J.; Peixinho, N.; Verma, P.; (MiNDSTEp; Sbarufatti, B.; Kennea, J. A.; Gehrels, N.; (Swift

    2016-11-01

    Simultaneous observations of microlensing events from multiple locations allow for the breaking of degeneracies between the physical properties of the lensing system, specifically by exploring different regions of the lens plane and by directly measuring the “microlens parallax.” We report the discovery of a 30-65M J brown dwarf orbiting a K dwarf in the microlensing event OGLE-2015-BLG-1319. The system is located at a distance of ˜5 kpc toward the Galactic Bulge. The event was observed by several ground-based groups as well as by Spitzer and Swift, allowing a measurement of the physical properties. However, the event is still subject to an eight-fold degeneracy, in particular the well-known close-wide degeneracy, and thus the projected separation between the two lens components is either ˜0.25 au or ˜45 au. This is the first microlensing event observed by Swift, with the UVOT camera. We study the region of microlensing parameter space to which Swift is sensitive, finding that though Swift could not measure the microlens parallax with respect to ground-based observations for this event, it can be important for other events. Specifically, it is important for detecting nearby brown dwarfs and free-floating planets in high magnification events.

  15. Feasibility of performing space surveillance tasks with a proposed space-based optical architecture

    NASA Astrophysics Data System (ADS)

    Flohrer, Tim; Krag, Holger; Klinkrad, Heiner; Schildknecht, Thomas

    Under ESA contract an industrial consortium including Aboa Space Research Oy (ASRO), the Astronomical Institute of the University of Bern (AIUB), and the Dutch National Aerospace Laboratory (NLR), proposed the observation concept, developed a suitable sensor architecture, and assessed the performance of a space-based optical (SBO) telescope in 2005. The goal of the SBO instrumentation was to analyse how the existing knowledge gap in the space debris population in the millimetre and centimetre regime may be closed by means of a passive op-tical instrument. SBO was requested to provide statistical information on the space debris population, in terms of number of objects and size distribution. The SBO was considered to be a cost-efficient instrumentation of 20 cm aperture and 6 deg field-of-view with flexible integration requirements. It should be possible to integrate the SBO easily as a secondary payload on satellites launched into low-Earth orbits (LEO), or into geostationary orbit (GEO). Thus the selected mission concept only allowed for fix-mounted telescopes, and the pointing direction could be requested freely. It was shown in the performance analysis that the statistical information on small-sized space debris can only be collected if the observation ranges are comparatively small. Two of the most promising concepts were to observe objects in LEO from a sensor placed into a sun-synchronous LEO, while objects in GEO should be observed from a GEO satellite. Since 2007 ESA focuses space surveillance and tracking activities in the Space Situational Awareness (SSA) preparatory program. Ground-based radars and optical telescopes are stud-ied for the build-up and to maintenance of a catalogue of objects. In this paper we analyse how the SBO architecture could contribute to the space surveillance tasks survey and tracking. We assume that the SBO instrumentation is placed into a circular sun-synchronous orbit at 800 km altitude. We discuss the observation conditions of

  16. The GSC2 Survey of Cool White Dwarfs

    NASA Astrophysics Data System (ADS)

    Carollo, D.; Spagna, A.; Lattanzi, M. G.; Smart, R. L.; Bucciarelli, B.; Terranegra, L.; Hodgkin, S. T.; McLean, B.

    2005-07-01

    Microlensing experiments (Alcock et al. 2000) have suggested that a significant part of the dark halo of the Milky Way could be composed of matter in the form of massive compact halo objects (MACHOs). Cool ancient white dwarfs (WDs) are the natural candidates. Here we present a new survey of halo WDs and evaluate the local space density using an accurate kinematic analysis. A comparison to a re-derivation of the Oppenheimer et al. (2001) results is also provided. The local space density estimated from the two independent samples is only about ˜ 10-5M⊙pc-3 corresponding to 0.1%-0.2% of the local dark matter.

  17. A neuroanatomical model of space-based and object-centered processing in spatial neglect.

    PubMed

    Pedrazzini, Elena; Schnider, Armin; Ptak, Radek

    2017-04-05

    Visual attention can be deployed in space-based or object-centered reference frames. Right-hemisphere damage may lead to distinct deficits of space- or object-based processing, and such dissociations are thought to underlie the heterogeneous nature of spatial neglect. Previous studies have suggested that object-centered processing deficits (such as in copying, reading or line bisection) result from damage to retro-rolandic regions while impaired spatial exploration reflects damage to more anterior regions. However, this evidence is based on small samples and heterogeneous tasks. Here, we tested a theoretical model of neglect that takes in account the space- and object-based processing and relates them to neuroanatomical predictors. One hundred and one right-hemisphere-damaged patients were examined with classic neuropsychological tests and structural brain imaging. Relations between neglect measures and damage to the temporal-parietal junction, intraparietal cortex, insula and middle frontal gyrus were examined with two structural equation models by assuming that object-centered processing (involved in line bisection and single-word reading) and space-based processing (involved in cancelation tasks) either represented a unique latent variable or two distinct variables. Of these two models the latter had better explanatory power. Damage to the intraparietal sulcus was a significant predictor of object-centered, but not space-based processing, while damage to the temporal-parietal junction predicted space-based, but not object-centered processing. Space-based processing and object-centered processing were strongly intercorrelated, indicating that they rely on similar, albeit partly dissociated processes. These findings indicate that object-centered and space-based deficits in neglect are partly independent and result from superior parietal and inferior parietal damage, respectively.

  18. The Spitzer Microlensing Program as a Probe for Globular Cluster Planets: Analysis of OGLE-2015-BLG-0448

    NASA Astrophysics Data System (ADS)

    Poleski, Radosław; Zhu, Wei; Christie, Grant W.; Udalski, Andrzej; Gould, Andrew; Bachelet, Etienne; Skottfelt, Jesper; Calchi Novati, Sebastiano; Szymański, M. K.; Soszyński, I.; Pietrzyński, G.; Wyrzykowski, Ł.; Ulaczyk, K.; Pietrukowicz, P.; Kozłowski, Szymon; Skowron, J.; Mróz, P.; Pawlak, M.; OGLE Group; Beichman, C.; Bryden, G.; Carey, S.; Fausnaugh, M.; Gaudi, B. S.; Henderson, C. B.; Pogge, R. W.; Shvartzvald, Y.; Wibking, B.; Yee, J. C.; Spitzer Team; Beatty, T. G.; Eastman, J. D.; Drummond, J.; Friedmann, M.; Henderson, M.; Johnson, J. A.; Kaspi, S.; Maoz, D.; McCormick, J.; McCrady, N.; Natusch, T.; Ngan, H.; Porritt, I.; Relles, H. M.; Sliski, D. H.; Tan, T.-G.; Wittenmyer, R. A.; Wright, J. T.; μFUN Group; Street, R. A.; Tsapras, Y.; Bramich, D. M.; Horne, K.; Snodgrass, C.; Steele, I. A.; Menzies, J.; Figuera Jaimes, R.; Wambsganss, J.; Schmidt, R.; Cassan, A.; Ranc, C.; Mao, S.; project, RoboNet; Bozza, V.; Dominik, M.; Hundertmark, M. P. G.; Jørgensen, U. G.; Andersen, M. I.; Burgdorf, M. J.; Ciceri, S.; D'Ago, G.; Evans, D. F.; Gu, S.-H.; Hinse, T. C.; Kains, N.; Kerins, E.; Korhonen, H.; Kuffmeier, M.; Mancini, L.; Popovas, A.; Rabus, M.; Rahvar, S.; Rasmussen, R. T.; Scarpetta, G.; Southworth, J.; Surdej, J.; Unda-Sanzana, E.; Verma, P.; von Essen, C.; Wang, Y.-B.; Wertz, O.; MiNDSTEp Group

    2016-05-01

    The microlensing event OGLE-2015-BLG-0448 was observed by Spitzer and lay within the tidal radius of the globular cluster NGC 6558. The event had moderate magnification and was intensively observed, hence it had the potential to probe the distribution of planets in globular clusters. We measure the proper motion of NGC 6558 ({{\\boldsymbol{μ }}}{cl}(N,E)=(+0.36+/- 0.10,+1.42+/- 0.10) {{mas}} {{{yr}}}-1) as well as the source and show that the lens is not a cluster member. Even though this particular event does not probe the distribution of planets in globular clusters, other potential cluster lens events can be verified using our methodology. Additionally, we find that microlens parallax measured using Optical Gravitational Lens Experiment (OGLE) photometry is consistent with the value found based on the light curve displacement between the Earth and Spitzer.

  19. Conceptual Design of a Space-Based Multimegawatt MHD Power System

    DTIC Science & Technology

    1988-01-01

    WAESD-TR-88-0002 Conceptual Design Of A Space-Based Multimegawatt MHD Power System Task 1 Topical Report Volume II: Requirements Document fe...26452 WAESD-TR-88-0002 CONCEPTUAL DESIGN OF A SPACE-BASED MULTIMEGAWATT MHD POWER SYSTEM TASK 1 TOPICAL REPORT VOLUME II: REQUIREMENTS DOCUMENT...System Conceptual Design Scope 1 -9 2- 1 System Schematic and Statepoint Data 2-2 2-2 Reactor Separation Distances 2-15 2-3 MHD Power System to

  20. Wavefront sensing for deformable space-based optics exploiting natural and synthetic guide stars

    NASA Astrophysics Data System (ADS)

    McComas, Brian K.; Friedman, Edward J.

    2002-08-01

    Natural and synthetic guide stars can serve as beacons for Shack-Hartmann wavefront sensors in space-based applications. In this paper, the authors determine the key equations that govern the optimization of the wavefront sensor employed on a space- based imaging system. There are two major products of this analysis. First, the number of subapertures can be optimized. Second, the number of modes used in the wavefront recovery can be optimized. Finally, the process for optimizing these values is explained. For the examples shown, the optimal number of retrieved modes and the optimal number of subapertures are determined.

  1. Ground Support for the Space-Based Range Flight Demonstration 2

    NASA Technical Reports Server (NTRS)

    Burkes, Darryl A.

    2007-01-01

    The primary objective of the NASA Space-Based Range Demonstration and Certification program was to develop and demonstrate space-based range capabilities. The Flight Demonstration 2 flights at NASA Dryden Flight Research Center were conducted to support Range Safety (commanding and position reporting) and high-rate (5 Mbps) Range User (video and data) requirements. Required ground support infrastructure included a flight termination system computer, the ground-data distribution network to send range safety commands and receive range safety and range user telemetry data and video, and the ground processing systems at the Dryden Mission Control Center to process range safety and range user telemetry data and video.

  2. Retrieving the aerosol lidar ratio profile by combining ground- and space-based elastic lidars.

    PubMed

    Feiyue, Mao; Wei, Gong; Yingying, Ma

    2012-02-15

    The aerosol lidar ratio is a key parameter for the retrieval of aerosol optical properties from elastic lidar, which changes largely for aerosols with different chemical and physical properties. We proposed a method for retrieving the aerosol lidar ratio profile by combining simultaneous ground- and space-based elastic lidars. The method was tested by a simulated case and a real case at 532 nm wavelength. The results demonstrated that our method is robust and can obtain accurate lidar ratio and extinction coefficient profiles. Our method can be useful for determining the local and global lidar ratio and validating space-based lidar datasets.

  3. Wide-Field Infrared Survey Telescope (WFIRST) Interim Report

    NASA Technical Reports Server (NTRS)

    Green, J.; Schechter, P.; Baltay, C.; Bean, R.; Bennett, D.; Brown, R.; Conselice, C.; Donahue, M.; Gaudi, S.; Lauer, T.; Perlmutter, S.; Rauscher, B.; Rhodes, J.; Roellig, T.; Stern, D.; Sumi, T.; Gerhels, N.; Sambruna, R.; Barry, R. K.; Content, D.; Grady, K; Jackson, C.; Kruk, J.; Melton, M.; Rioux, N.

    2011-01-01

    The New Worlds, New Horizons (NWNH) in Astronomy and Astrophysics 2010 Decadal Survey prioritized the community consensus for ground-based and space-based observatories. Recognizing that many of the community s key questions could be answered with a wide-field infrared survey telescope in space, and that the decade would be one of budget austerity, WFIRST was top ranked in the large space mission category. In addition to the powerful new science that could be accomplished with a wide-field infrared telescope, the WFIRST mission was determined to be both technologically ready and only a small fraction of the cost of previous flagship missions, such as HST or JWST. In response to the top ranking by the community, NASA formed the WFIRST Science Definition Team (SDT) and Project Office. The SDT was charged with fleshing out the NWNH scientific requirements to a greater level of detail. NWNH evaluated the risk and cost of the JDEM-Omega mission design, as submitted by NASA, and stated that it should serve as the basis for the WFIRST mission. The SDT and Project Office were charged with developing a mission optimized for achieving the science goals laid out by the NWNH re-port. The SDT and Project Office opted to use the JDEM-Omega hardware configuration as an initial start-ing point for the hardware implementation. JDEM-Omega and WFIRST both have an infrared imager with a filter wheel, as well as counter-dispersed moderate resolution spectrometers. The primary advantage of space observations is being above the Earth's atmosphere, which absorbs, scatters, warps and emits light. Observing from above the atmosphere enables WFIRST to obtain precision infrared measurements of the shapes of galaxies for weak lensing, infrared light-curves of supernovae and exoplanet microlensing events with low systematic errors, and infrared measurements of the H hydrogen line to be cleanly detected in the 1

  4. Infrared Sky Surveys

    NASA Astrophysics Data System (ADS)

    Price, Stephan D.

    2009-02-01

    A retrospective is given on infrared sky surveys from Thomas Edison’s proposal in the late 1870s to IRAS, the first sensitive mid- to far-infrared all-sky survey, and the mid-1990s experiments that filled in the IRAS deficiencies. The emerging technology for space-based surveys is highlighted, as is the prominent role the US Defense Department, particularly the Air Force, played in developing and applying detector and cryogenic sensor advances to early mid-infrared probe-rocket and satellite-based surveys. This technology was transitioned to the infrared astronomical community in relatively short order and was essential to the success of IRAS, COBE and ISO. Mention is made of several of the little known early observational programs that were superseded by more successful efforts.

  5. 77 FR 44288 - National Space-Based Positioning, Navigation, and Timing (PNT) Advisory Board; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-27

    ...; Meeting AGENCY: National Aeronautics and Space Administration (NASA). ACTION: Notice of meeting. SUMMARY... and Space Administration (NASA) announces a meeting of the National Space-Based Positioning... Operations Mission Directorate, NASA Headquarters, Washington, DC 20546, (202) 358-4417, fax (202)...

  6. Quantifying Spatial and Seasonal Variability in Atmospheric Ammonia with In Situ and Space-Based Observations

    EPA Science Inventory

    Ammonia plays an important role in many biogeochemical processes, yet atmospheric mixing ratios arc not well known. Recently, methods have been developed for retrieving NH3 from space-based observations, but they have not been compared to in situ measurements. We have ...

  7. Nuclear reactor power as applied to a space-based radar mission

    NASA Technical Reports Server (NTRS)

    Jaffe, L.; Beatty, R.; Bhandari, P.; Chow, E.; Deininger, W.; Ewell, R.; Fujita, T.; Grossman, M.; Bloomfield, H.; Heller, J.

    1988-01-01

    A space-based radar mission and spacecraft are examined to determine system requirements for a 300 kWe space nuclear reactor power system. The spacecraft configuration and its orbit, launch vehicle, and propulsion are described. Mission profiles are addressed, and storage in assembly orbit is considered. Dynamics and attitude control and the problems of nuclear and thermal radiation are examined.

  8. Space Acquisitions: DOD’s Goals for Resolving Space Based Infrared System Software Problems are Ambitious

    DTIC Science & Technology

    2008-09-01

    Resolving Space Based Infrared System Software Problems Are Ambitious September 2008 GAO-08- 1073 Report Documentation Page Form...click on GAO-08- 1073 . For more information, contact Cristina T. Chaplain at (202) 512-4841 or chaplainc@gao.gov. Highlights of GAO-08- 1073 , a... 1073 SBIRS Software Abbreviations DOD Department of Defense FFRDC

  9. Ground-Based and Space-Based Laser Beam Power Applications

    NASA Technical Reports Server (NTRS)

    Bozek, John M.

    1995-01-01

    A space power system based on laser beam power is sized to reduce mass, increase operational capabilities, and reduce complexity. The advantages of laser systems over solar-based systems are compared as a function of application. Power produced from the conversion of a laser beam that has been generated on the Earth's surface and beamed into cislunar space resulted in decreased round-trip time for Earth satellite electric propulsion tugs and a substantial landed mass savings for a lunar surface mission. The mass of a space-based laser system (generator in space and receiver near user) that beams down to an extraterrestrial airplane, orbiting spacecraft, surface outpost, or rover is calculated and compared to a solar system. In general, the advantage of low mass for these space-based laser systems is limited to high solar eclipse time missions at distances inside Jupiter. The power system mass is less in a continuously moving Mars rover or surface outpost using space-based laser technology than in a comparable solar-based power system, but only during dust storm conditions. Even at large distances for the Sun, the user-site portion of a space-based laser power system (e.g., the laser receiver component) is substantially less massive than a solar-based system with requisite on-board electrochemical energy storage.

  10. Phase Diversity Wavefront Sensing for Control of Space Based Adaptive Optics Systems

    DTIC Science & Technology

    2007-12-01

    WAVEFRONT SENSING FOR CONTROL OF SPACE BASED ADAPTIVE OPTICS SYSTEMS by Richard J Schgallis December 2007 Thesis Advisor: Brij Agrawal...J Schgallis Approved by: Dr. Brij Agrawal Thesis Advisor Dr. Andres Larraza Co-Advisor Dr. Jae-Jun Kim Second Reader Dr...Control ..................................................................................... 35 B. EXPERIMENTS AND RESULTS

  11. Overview of Mirror Technology Development for Large Lightweight Space-Based Optical Systems

    NASA Technical Reports Server (NTRS)

    Smith, W. Scott; Stahl, H. P.; Rose, M. Frank (Technical Monitor)

    2000-01-01

    The Space Optics Manufacturing Technology Center of Marshall Space Flight Center is involved in the development of lightweight optics for spacebased'systems. The NGST and other future NASA programs require large aperture space-based instruments. This paper reviews the technologies under development for NGST including discussions of the environmental testing of candidate segment for the NGST primary mirror.

  12. A prototype ground support system security monitor for space based power system health monitoring

    NASA Astrophysics Data System (ADS)

    Janik, Donald F.; Gholdston, Edward W.

    This paper reports on the work Rocketdyne is performing in the area of power system security monitoring for space-based system health monitoring. The Integrated Power Advisory Controller, which represents a portion of a ground-based system security monitor and uses an object-oriented knowledge design, is discussed. The simulation environment used to develop and test the system is described.

  13. A digital beamforming processor for the joint DoD/NASA space based radar mission

    NASA Technical Reports Server (NTRS)

    Fischman, Mark A.; Le, Charles; Rosen, Paul A.

    2004-01-01

    The Space Based Radar (SBR) program includes a joint technology demonstration between NASA and the Air Force to design a low-earth orbiting, 2x50 m L-band radar system for both Earth science and intelligence related observations.

  14. Space-based infrared scanning sensor LOS determination and calibration using star observation

    NASA Astrophysics Data System (ADS)

    Chen, Jun; Xu, Zhan; An, Wei; Deng, Xin-Pu; Yang, Jun-Gang

    2015-10-01

    This paper provides a novel methodology for removing sensor bias from a space based infrared (IR) system (SBIRS) through the use of stars detected in the background field of the sensor. Space based IR system uses the LOS (line of sight) of target for target location. LOS determination and calibration is the key precondition of accurate location and tracking of targets in Space based IR system and the LOS calibration of scanning sensor is one of the difficulties. The subsequent changes of sensor bias are not been taking into account in the conventional LOS determination and calibration process. Based on the analysis of the imaging process of scanning sensor, a theoretical model based on the estimation of bias angles using star observation is proposed. By establishing the process model of the bias angles and the observation model of stars, using an extended Kalman filter (EKF) to estimate the bias angles, and then calibrating the sensor LOS. Time domain simulations results indicate that the proposed method has a high precision and smooth performance for sensor LOS determination and calibration. The timeliness and precision of target tracking process in the space based infrared (IR) tracking system could be met with the proposed algorithm.

  15. Antenna Autocalibration and Metrology Approach for the AFR/JPL Space-Based Radar

    NASA Technical Reports Server (NTRS)

    McWatters, Dalia; Michel, Thierry; Freedman, Adam; Cable, Vaughn

    2003-01-01

    The Air Force Research Laboratory (AFRL) and the Jet Propulsion Laboratory (JPL) are collaborating in the technology development for a space based radar (SBR) system that would feature a large aperture lightweight antenna for a joint mission later in this decade.

  16. Adaptive PSF fitting - a highly performing photometric method and light curves of the GLS H1413+117: time delays and micro-lensing effects

    NASA Astrophysics Data System (ADS)

    Akhunov, T. A.; Wertz, O.; Elyiv, A.; Gaisin, R.; Artamonov, B. P.; Dudinov, V. N.; Nuritdinov, S. N.; Delvaux, C.; Sergeyev, A. V.; Gusev, A. S.; Bruevich, V. V.; Burkhonov, O.; Zheleznyak, A. P.; Ezhkova, O.; Surdej, J.

    2017-03-01

    We present new photometric observations of H1413+117 acquired during seasons between 2001 and 2008 in order to estimate the time delays between the lensed quasar images and to characterize at best the on-going micro-lensing events. We propose a highly performing photometric method called the adaptive point spread function fitting and have successfully tested this method on a large number of simulated frames. This has enabled us to estimate the photometric error bars affecting our observational results. We analysed the V- and R-band light curves and V-R colour variations of the A-D components which show short- and long-term brightness variations correlated with colour variations. Using the χ2 and dispersion methods, we estimated the time delays on the basis of the R-band light curves over the seasons between 2003 and 2006. We have derived the new values: ΔtAB = -17.4 ± 2.1, ΔtAC = -18.9 ± 2.8 and ΔtAD = 28.8 ± 0.7 d using the χ2 method (B and C are leading, D is trailing) with 1σ confidence intervals. We also used available observational constraints (resp. the lensed image positions, the flux ratios in mid-IR and two sets of time delays derived in the present work) to update the lens redshift estimation. We obtained z_l = 1.95^{+0.06}_{-0.10} which is in good agreement with previous estimations. We propose to characterize two kinds of micro-lensing events: micro-lensing for the A, B, C components corresponds to typical variations of ∼10-4 mag d-1 during all the seasons, while the D component shows an unusually strong micro-lensing effect with variations of up to ∼10-3 mag d-1 during 2004 and 2005.

  17. Feasibility of performing space surveillance tasks with a proposed space-based optical architecture

    NASA Astrophysics Data System (ADS)

    Flohrer, T.; Krag, H.; Klinkrad, H.; Schildknecht, T.

    2011-03-01

    Under ESA contract an industrial consortium including Aboa Space Research Oy (ASRO), the Astronomical Institute of the University of Bern (AIUB), and the Dutch National Aerospace Laboratory (NLR), proposed the observation concept, developed a suitable sensor architecture, and assessed the performance of a space-based optical (SBO) telescope in 2005. The goal of the SBO study was to analyse how the existing knowledge gap in the space debris population in the millimetre and centimetre regime may be closed by means of a passive optical instrument. The SBO instrument was requested to provide statistical information on the space debris population in terms of number of objects and size distribution. The SBO instrument was considered to be a cost-efficient with 20 cm aperture and 6° field-of-view and having flexible integration requirements. It should be possible to integrate the SBO instrument easily as a secondary payload on satellites launched into low-Earth orbits (LEO), or into geostationary orbit (GEO). Thus the selected mission concept only allowed for fix-mounted telescopes, and the pointing direction could be requested freely. Since 2007 ESA focuses space surveillance and tracking activities in the Space Situational Awareness (SSA) preparatory program. Ground-based radars and optical telescopes are studied for the build-up and maintenance of a catalogue of objects. In this paper we analyse how the proposed SBO architecture could contribute to the space surveillance tasks survey and tracking. We assume that the SBO instrumentation is placed into a circular sun-synchronous orbit at 800 km altitude. We discuss the observation conditions of objects at higher altitude, and select an orbit close to the terminator plane. A pointing of the sensor orthogonal to the orbital plane with optimal elevation slightly in positive direction (0° and +5°) is found optimal for accessing the entire GEO regime within one day, implying a very good coverage of controlled objects in

  18. Space-based solar power conversion and delivery systems study. Volume 3: Economic analysis of space-based solar power systems

    NASA Technical Reports Server (NTRS)

    Hazelrigg, G. A., Jr.

    1976-01-01

    A variety of economic and programmatic issues are discussed concerning the development and deployment of a fleet of space-based solar power satellites (SSPS). The costs, uncertainties and risks associated with the current photovoltaic SSPS configuration, and with issues affecting the development of an economically viable SSPS development program are analyzed. The desirability of a low earth orbit (LEO) demonstration satellite and a geosynchronous (GEO) pilot satellite is examined and critical technology areas are identified. In addition, a preliminary examination of utility interface issues is reported. The main focus of the effort reported is the development of SSPS unit production, and operation and maintenance cost models suitable for incorporation into a risk assessment (Monte Carlo) model (RAM). It is shown that the key technology area deals with the productivity of man in space, not, as might be expected, with some hardware component technology.

  19. The space exploration initiative. Operational efficiency panel space-basing technology requirements

    NASA Technical Reports Server (NTRS)

    Pena, Luis R.

    1991-01-01

    The topics covered include the following: (1) space basing technology requirements sources; (2) orbit transfer vehicle (OTV) processing heritage; (3) ground processing progression to space processing; (4) technology requirements for space based OTV servicing and maintenance; (5) design and development schedule for OTV's and OTV accommodations/ support hardware; (6) cryogenic technology test program development; (7) cryogenic propellant transfer, storage, and reliquefaction management summary; (8) propellant transfer technology analysis and ground testing; (8) OTV propellant storage depot development critical scaling relationships; (9) flight experiment options; (10) OTV maintenance; (11) automated fault detection/ isolation and system checkout summary; (12) engine replacement; (13) alternative docking operation; (14) OTV/payload integration; and (15) technology criticality and capability assessment. This document is presented in viewgraph form.

  20. Invited Article: Advanced drag-free concepts for future space-based interferometers: acceleration noise performance

    NASA Astrophysics Data System (ADS)

    Gerardi, D.; Allen, G.; Conklin, J. W.; Sun, K.-X.; DeBra, D.; Buchman, S.; Gath, P.; Fichter, W.; Byer, R. L.; Johann, U.

    2014-01-01

    Future drag-free missions for space-based experiments in gravitational physics require a Gravitational Reference Sensor with extremely demanding sensing and disturbance reduction requirements. A configuration with two cubical sensors is the current baseline for the Laser Interferometer Space Antenna (LISA) and has reached a high level of maturity. Nevertheless, several promising concepts have been proposed with potential applications beyond LISA and are currently investigated at HEPL, Stanford, and EADS Astrium, Germany. The general motivation is to exploit the possibility of achieving improved disturbance reduction, and ultimately understand how low acceleration noise can be pushed with a realistic design for future mission. In this paper, we discuss disturbance reduction requirements for LISA and beyond, describe four different payload concepts, compare expected strain sensitivities in the "low-frequency" region of the frequency spectrum, dominated by acceleration noise, and ultimately discuss advantages and disadvantages of each of those concepts in achieving disturbance reduction for space-based detectors beyond LISA.

  1. Invited article: advanced drag-free concepts for future space-based interferometers: acceleration noise performance.

    PubMed

    Gerardi, D; Allen, G; Conklin, J W; Sun, K-X; DeBra, D; Buchman, S; Gath, P; Fichter, W; Byer, R L; Johann, U

    2014-01-01

    Future drag-free missions for space-based experiments in gravitational physics require a Gravitational Reference Sensor with extremely demanding sensing and disturbance reduction requirements. A configuration with two cubical sensors is the current baseline for the Laser Interferometer Space Antenna (LISA) and has reached a high level of maturity. Nevertheless, several promising concepts have been proposed with potential applications beyond LISA and are currently investigated at HEPL, Stanford, and EADS Astrium, Germany. The general motivation is to exploit the possibility of achieving improved disturbance reduction, and ultimately understand how low acceleration noise can be pushed with a realistic design for future mission. In this paper, we discuss disturbance reduction requirements for LISA and beyond, describe four different payload concepts, compare expected strain sensitivities in the "low-frequency" region of the frequency spectrum, dominated by acceleration noise, and ultimately discuss advantages and disadvantages of each of those concepts in achieving disturbance reduction for space-based detectors beyond LISA.

  2. Large space-based systems for dealing with global environment change

    NASA Technical Reports Server (NTRS)

    Jenkins, Lyle M.

    1992-01-01

    Increased concern over the effects of global climate change and depletion of the ozone layer has resulted in support for the Global Change Research Program and the Mission to Planet Earth. Research to understand Earth system processes is critical, but it falls short of providing ways of mitigating the effects of change. Geoengineering options and alternatives to interactively manage change need to be developed. Space-based concepts for dealing with changes to the environment should be considered in addition to Earth-based actions. 'Mission for Planet Earth' describes those space-based geoengineering solutions that may combine with an international global change program to stabilize the Global environment. Large space systems that may be needed for this response challenge guidance and control engineering and technology. Definition, analysis, demonstration, and preparation of geoengineering technology will provide a basis for policy response if global change consequences are severe.

  3. Space-based visual attention: a marker of immature selective attention in toddlers?

    PubMed

    Rivière, James; Brisson, Julie

    2014-11-01

    Various studies suggested that attentional difficulties cause toddlers' failure in some spatial search tasks. However, attention is not a unitary construct and this study investigated two attentional mechanisms: location selection (space-based attention) and object selection (object-based attention). We investigated how toddlers' attention is distributed in the visual field during a manual search task for objects moving out of sight, namely the moving boxes task. Results show that 2.5-year-olds who failed this task allocated more attention to the location of the relevant object than to the object itself. These findings suggest that in some manual search tasks the primacy of space-based attention over object-based attention could be a marker of immature selective attention in toddlers.

  4. The Platform Design of Space-based Optical Observations of Space Debris

    NASA Astrophysics Data System (ADS)

    Chen, B. R.; Xiong, J. N.

    2016-03-01

    The basic design method of the platform for the space-based optical observations of space debris is introduced. The observation schemes of GEO (geosynchronous equatorial orbit) and LEO (low Earth orbit) debris are given respectively, including orbital parameters of platforms and pointing of telescopes, etc. Debris studied here is all from foreign catalog. According to the real orbit of space debris, the observational results of different schemes are simulated. By studying single platform, the optimal observing altitude for GEO debris and the optimal telescope's deflection angles at different altitudes for LEO debris are given. According to these, multi-platforms observation networks are designed. By analyzing the advantages and disadvantages of each scheme, it can provide reference for the application of space-based optical debris observation.

  5. Space-based application of the CAN laser to LIDAR and orbital debris remediation

    NASA Astrophysics Data System (ADS)

    Quinn, M. N.; Jukna, V.; Ebisuzaki, T.; Dicaire, I.; Soulard, R.; Summerer, L.; Couairon, A.; Mourou, G.

    2015-10-01

    Development of pulsed lasers for space-based science missions entail many additional challenges compared to terrestrial experiments. For systems requiring short pulses ≪1 ns with energies >100 mJ and fast repetition rates >10 kHz there are currently few if no laser architectures capable of operating with high electrical efficiency >20% and have good system stability. The emergence of a mulit-channel fiber-based Coherent-Amplifying-Network or CAN laser potentially enables such capability for space based missions. Here in this article we present an analysis of two such missions scaling up in pulse energy from ≈100 mJ for a supercontinuum LIDAR application utilising atmospheric filamentation to the higher energy demands needed for space debris remediation requiring ≈10 J pulses. This scalability of the CAN laser provides pathways for development of the core science and technology where many new novel space applications can be made possible.

  6. The Platform Design of Space-based Optical Observations of Space Debris

    NASA Astrophysics Data System (ADS)

    Bing-er, Chen; Jian-ning, Xiong

    2017-01-01

    The basic method to design a platform for the space-based optical observations of space debris is introduced. The observation schemes of GEO (geosynchronous equatorial orbit) and LEO (low Earth orbit) debris are given respectively, including the orbital parameters of platforms and the pointing of telescopes, etc. The debris studied here are all taken from the foreign catalog. According to the real orbits of space debris, the observational results of different schemes are simulated. By studying the single platform, the optimal observing altitude for the GEO debris and the optimal telescope's deflection angles at different altitudes for the LEO debris are given. According to these, the multi-platform observation networks are designed. By analyzing the advantages and disadvantages of different schemes, it can provide a reference for the application of space-based optical observations of space debris

  7. Testing General Relativity with Low-Frequency, Space-Based Gravitational-Wave Detectors.

    PubMed

    Gair, Jonathan R; Vallisneri, Michele; Larson, Shane L; Baker, John G

    2013-01-01

    We review the tests of general relativity that will become possible with space-based gravitational-wave detectors operating in the ∼ 10(-5) - 1 Hz low-frequency band. The fundamental aspects of gravitation that can be tested include the presence of additional gravitational fields other than the metric; the number and tensorial nature of gravitational-wave polarization states; the velocity of propagation of gravitational waves; the binding energy and gravitational-wave radiation of binaries, and therefore the time evolution of binary inspirals; the strength and shape of the waves emitted from binary mergers and ringdowns; the true nature of astrophysical black holes; and much more. The strength of this science alone calls for the swift implementation of a space-based detector; the remarkable richness of astrophysics, astronomy, and cosmology in the low-frequency gravitational-wave band make the case even stronger.

  8. Space-Based Gravitational-Wave Observations as Tools for Testing General Relativity

    NASA Technical Reports Server (NTRS)

    Will, Clifford M.

    2004-01-01

    We continued a project, to analyse the ways in which detection and study of gravitational waves could provide quantitative tests of general relativity, with particular emphasis on waves that would be detectable by space-based observatories, such as LISA. This work had three foci: 1) Tests of scalar-tensor theories of gravity that, could be done by analyzing gravitational waves from neutron stars inspiralling into massive black holes, as detectable by LISA; 2) Study of alternative theories of gravity in which the graviton could be massive, and of how gravitational-wave observations by space-based detectors, solar-system tests, and cosmological observations could constrain such theories; and 3) Study of gravitational-radiation back reaction of particles orbiting black holes in general relativity, with emphasis on the effects of spin.

  9. Enabling technologies for transition to utilization of space-based resources and operations

    NASA Technical Reports Server (NTRS)

    Sadin, S. R.; Litty, J. D.

    1985-01-01

    This article explores a potential scenario for the further development of space infrastructure resources and operations management. It is a scenario that transitions from the current ground-based system to an architecture that is predominantly space-based by exploiting key mission systems in an operational support role. If this view is accurate, an examination of the range of potential infrastructure elements and how they might interact in a maximally productive space-based operations complex is needed, innovative technologies beyond the current Shuttle and Space Station legacy need to be identified, and research programs pursued. Development of technologies within the areas of telerobotics, machine autonomy, human autonomy, in-space manufacturing and construction, propulsion and energy is discussed.

  10. Measurements of strain at plate boundaries using space based geodetic techniques

    NASA Technical Reports Server (NTRS)

    Robaudo, Stefano; Harrison, Christopher G. A.

    1993-01-01

    We have used the space based geodetic techniques of Satellite Laser Ranging (SLR) and VLBI to study strain along subduction and transform plate boundaries and have interpreted the results using a simple elastic dislocation model. Six stations located behind island arcs were analyzed as representative of subduction zones while 13 sites located on either side of the San Andreas fault were used for the transcurrent zones. The length deformation scale was then calculated for both tectonic margins by fitting the relative strain to an exponentially decreasing function of distance from the plate boundary. Results show that space-based data for the transcurrent boundary along the San Andreas fault help to define better the deformation length scale in the area while fitting nicely the elastic half-space earth model. For subduction type bonndaries the analysis indicates that there is no single scale length which uniquely describes the deformation. This is mainly due to the difference in subduction characteristics for the different areas.

  11. Issues, concerns, and initial implementation results for space based telerobotic control

    NASA Technical Reports Server (NTRS)

    Lawrence, D. A.; Chapel, J. D.; Depkovich, T. M.

    1987-01-01

    Telerobotic control for space based assembly and servicing tasks presents many problems in system design. Traditional force reflection teleoperation schemes are not well suited to this application, and the approaches to compliance control via computer algorithms have yet to see significant testing and comparison. These observations are discussed in detail, as well as the concerns they raise for imminent design and testing of space robotic systems. As an example of the detailed technical work yet to be done before such systems can be specified, a particular approach to providing manipulator compliance is examined experimentally and through modeling and analysis. This yields some initial insight into the limitations and design trade-offs for this class of manipulator control schemes. Implications of this investigation for space based telerobots are discussed in detail.

  12. Space Based Observations of Coronal Cavities in Conjunction with the Total Solar Eclipse of July 2010

    NASA Technical Reports Server (NTRS)

    Kucera, T. A.; Berger, T. E.; Druckmuller, M.; Dietzel, M.; Gibson, S. E.; Habbal, S. R.; Morgan, H.; Reeves, K. K.; Schmit, D. J.; Seaton, D. B.

    2010-01-01

    In conjunction with the total solar eclipse on July 11, 2010 we coordinated a campaign between ground and space based observations. Our specific goal was to augment the ground based measurement of corona) prominence cavity temperatures made using iron lines in the IR (Habbal et al. 2010 ApJ 719 1362) with measurements performed by space based instruments. Included in the campaign were Hinode/EIS, XRT and SOT, PROBA2/SWAP, SDO/AIA, SOHO/CDS and STEREO/SECCHI/EUVI, in addition to the ground based IR measurements. We plan to use a combination of line ratio and forward modeling techniques to investigate the density and temperature structure of the cavities at that time.

  13. Microlensing results toward the galactic bulge, theory of fitting blended light curves, and discussion of weak lensing corrections

    NASA Astrophysics Data System (ADS)

    Thomas, Christian L.

    2006-06-01

    Analysis and results (Chapters 2-5) of the full 7 year Macho Project dataset toward the Galactic bulge are presented. A total of 450 high quality, relatively large signal-to-noise ratio, events are found, including several events exhibiting exotic effects, and lensing events on possible Sagittarius dwarf galaxy stars. We examine the problem of blending in our sample and conclude that the subset of red clump giants are minimally blended. Using 42 red clump giant events near the Galactic center we calculate the optical depth toward the Galactic bulge to be t = [Special characters omitted.] × 10 -6 at ( l, b ) = ([Special characters omitted.] ) with a gradient of (1.06 ± 0.71) × 10 -6 deg -1 in latitude, and (0.29±0.43) × 10 -6 deg -1 in longitude, bringing measurements into consistency with the models for the first time. In Chapter 6 we reexamine the usefulness of fitting blended light-curve models to microlensing photometric data. We find agreement with previous workers (e.g. Wozniak & Paczynski) that this is a difficult proposition because of the degeneracy of blend fraction with other fit parameters. We show that follow-up observations at specific points along the light curve (peak region and wings) of high magnification events are the most helpful in removing degeneracies. We also show that very small errors in the baseline magnitude can result in problems in measuring the blend fraction, and study the importance of non- Gaussian errors in the fit results. The biases and skewness in the distribution of the recovered blend fraction is discussed. We also find a new approximation formula relating the blend fraction and the unblended fit parameters to the underlying event duration needed to estimate microlensing optical depth. In Chapter 7 we present work-in-progress on the possibility of correcting standard candle luminosities for the magnification due to weak lensing. We consider the importance of lenses in different mass ranges and look at the contribution

  14. Space-to-Space Based Relative Motion Estimation Using Direct Relative Orbit Parameters

    NASA Astrophysics Data System (ADS)

    Bennett, T.; Schaub, H.

    There has been an increasing interest in space-based space situational awareness around satellite assets and the tracking of orbital debris. Of particular interest is the space-based tracking of objects near critical circular orbit regimes, for example near the Geostationary belt or the International Space Station. Relative orbit descriptions such as the Clohessy-Wiltshire equations describe the motion using time-varying Cartesian or curvilinear coordinates. Orbit element differences describe the unperturbed motion using constant variations of inertial orbit elements. With perturbations these only vary slowly, but can be challenging to estimate. Linearized Relative Orbit Elements (LROEs) employ invariants of the linearized relative motion, are thus constant for the unperturbed linear case, and share the benefit of the CW equations in that they directly related to space-based relative motion measurements. The variational LROE equations enable the relative orbit to be directly propagated including perturbation forces. Utilization of the invariant-inspired relative motion parameters exhibits exciting applications in relative motion sensing and control. Many methods of relative motion estimation involve the direct estimation of time-evolving position and velocity variables. Developed is an angles-only relative orbit Extended Kalman filter (EKF) navigation approach that directly estimates these nominally constant LROEs. The proposed variational equations and filtering scheme enables direct estimation of geometric parameters with clear geometric insight. Preliminary numerical simulation results demonstrate the relative orbit insight gained and speed of convergence. EKF implementations often exhibit significant sensitivity to initial conditions, however, initial results show that the LROE filter converges within fractions of an orbit with initialization errors that exceed 100 percent. The manuscript presents the invariants of motion, develops the variational equations for

  15. Unmanned, space-based, reusable orbital transfer vehicle, DARVES. Volume 1: Trade analysis and design

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The design of an unmanned, space-based, reusable Orbital Transfer Vehicle (OTV) is presented. This OTV will be utilized for the delivery and retrieval of satellites from geosynchronous Earth orbit (GEO) in conjunction with a space station assumed to be in existence in low Earth orbit (LEO). The trade analysis used to determine the vehicle design is presented, and from this study a vehicle definition is given.

  16. Space-Based Solar Power: A Technical, Economic, and Operational Assessment

    DTIC Science & Technology

    2015-04-01

    considerably more energy is wasted in the form of heat than with microwave systems , and this heat must be managed as part of the satellite operation.42 One...space-based solar power systems will provide the best energy solution? How does the Army’s current approach to incorporating a diverse portfolio of...serious studies often conclude that such systems remain on the future horizon, usually at least 10 years away from practical application. This

  17. 76 FR 22924 - Re-Establishment of the National Space-Based Positioning, Navigation, and Timing (PNT) Advisory...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-25

    ...'s 2004 U.S. Space-Based PNT Policy established on December 8, 2004, and continuing and consistent...-Based PNT Advisory Board will provide advice on U.S. space-based PNT policy, planning, program management, and funding profiles in relation to the current state of national and international...

  18. A preliminary structural analysis of space-base living quarters modules to verify a weight-estimating technique

    NASA Technical Reports Server (NTRS)

    Grissom, D. S.; Schneider, W. C.

    1971-01-01

    The determination of a base line (minimum weight) design for the primary structure of the living quarters modules in an earth-orbiting space base was investigated. Although the design is preliminary in nature, the supporting analysis is sufficiently thorough to provide a reasonably accurate weight estimate of the major components that are considered to comprise the structural weight of the space base.

  19. Resolved rate and torque control schemes for large scale space based kinematically redundant manipulators

    NASA Technical Reports Server (NTRS)

    Bailey, Robert W.; Quiocho, Leslie J.

    1991-01-01

    Resolved rate control of kinematically redundant ground based manipulators is a challenging problem. The structural, actuator, and control loop frequency characteristics of industrial grade robots generally allow operation with resolved rate control; a rate command is achievable with good accuracy. However, space based manipulators are different, typically have less structural stiffness, more motor and joint friction, and lower control loop cycle frequencies. These undesirable characteristics present a considerable Point of Resolution (POR) control problem for space based, kinematically redundant manipulators for the following reason: a kinematically redundant manipulator requires an arbitrary constraint to solve for the joint rate commands. A space manipulator will not respond to joint rate commands because of these characteristics. A space based manipulator simulation, including free end rigid body dynamics, motor dynamics, motor striction/friction, gearbox backlash, joint striction/friction, and Space Station Remote Manipulator System type configuration parameters, is used to evaluate the performance of a documented resolved rate control law. Alternate schemes which include torque control are also evaluated.

  20. Cyber Security Threats to Safety-Critical, Space-Based Infrastructures

    NASA Astrophysics Data System (ADS)

    Johnson, C. W.; Atencia Yepez, A.

    2012-01-01

    Space-based systems play an important role within national critical infrastructures. They are being integrated into advanced air-traffic management applications, rail signalling systems, energy distribution software etc. Unfortunately, the end users of communications, location sensing and timing applications often fail to understand that these infrastructures are vulnerable to a wide range of security threats. The following pages focus on concerns associated with potential cyber-attacks. These are important because future attacks may invalidate many of the safety assumptions that support the provision of critical space-based services. These safety assumptions are based on standard forms of hazard analysis that ignore cyber-security considerations This is a significant limitation when, for instance, security attacks can simultaneously exploit multiple vulnerabilities in a manner that would never occur without a deliberate enemy seeking to damage space based systems and ground infrastructures. We address this concern through the development of a combined safety and security risk assessment methodology. The aim is to identify attack scenarios that justify the allocation of additional design resources so that safety barriers can be strengthened to increase our resilience against security threats.

  1. Space-Based but not Object-Based Inhibition of Return is Impaired in Parkinson's Disease

    PubMed Central

    Possin, Katherine L.; Filoteo, J. Vincent; Song, David D.; Salmon, David P.

    2009-01-01

    Impairments in certain aspects of attention have frequently been reported in Parkinson's disease (PD), including reduced inhibition of return (IOR). Recent evidence suggests that IOR can occur when attention is directed at objects or locations, but previous investigations of IOR in PD have not systematically compared these two frames of reference. The present study compared the performance of 18 nondemented patients with PD and 18 normal controls on an IOR task with two conditions. In the “object-present” condition, objects surrounded the cues and targets so that attention was cued to both a spatial location and to a specific object. In the “object-absent” condition, surrounding objects were not presented so that attention was cued only to a spatial location. When participants had to rely on space-based cues, PD patients demonstrated reduced IOR compared to controls. In contrast, when objects were present in the display and participants could use object-based cues, PD patients exhibited normal IOR. These results suggest that PD patients are impaired in inhibitory aspects of space-based attention, but are able to overcome this impairment when their attention can be directed at object-based frames of reference. This dissociation supports the view that space-based and object-based components of attention involve distinct neurocognitive processes. PMID:19397864

  2. Performance optimization for space-based sensors: simulation and modelling at Fraunhofer IOSB

    NASA Astrophysics Data System (ADS)

    Schweitzer, Caroline; Stein, Karin

    2014-10-01

    The prediction of the effectiveness of a space-based sensor for its designated application in space (e.g. special earth surface observations or missile detection) can help to reduce the expenses, especially during the phases of mission planning and instrumentation. In order to optimize the performance of such systems we simulate and analyse the entire operational scenario, including: - optional waveband - various orbit heights and viewing angles - system design characteristics, e. g. pixel size and filter transmission - atmospheric effects, e. g. different cloud types, climate zones and seasons In the following, an evaluation of the appropriate infrared (IR) waveband for the designated sensor application is given. The simulation environment is also capable of simulating moving objects like aircraft or missiles. Therefore, the spectral signature of the object/missile as well as its track along a flight path is implemented. The resulting video sequence is then analysed by a tracking algorithm and an estimation of the effectiveness of the sensor system can be simulated. This paper summarizes the work carried out at Fraunhofer IOSB in the field of simulation and modelling for the performance optimization of space based sensors. The paper is structured as follows: First, an overview of the applied simulation and modelling software is given. Then, the capability of those tools is illustrated by means of a hypothetical threat scenario for space-based early warning (launch of a long-range ballistic missile (BM)).

  3. Microlensing discovery of a tight, low-mass-ratio planetary-mass object around an old field brown dwarf

    SciTech Connect

    Han, C.; Jung, Y. K.; Udalski, A.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Skowron, J.; Kozłowski, S.; Poleski, R.; Ulaczyk, K.; Wyrzykowski, Ł.; Pietrukowicz, P.; Sumi, T.; Gaudi, B. S.; Gould, A.; Bennett, D. P.; Tsapras, Y.; Abe, F.; Bond, I. A.; Collaboration: OGLE Collaboration; MOA Collaboration; μFUN Collaboration; RoboNet Collaboration; and others

    2013-11-20

    Observations of accretion disks around young brown dwarfs (BDs) have led to the speculation that they may form planetary systems similar to normal stars. While there have been several detections of planetary-mass objects around BDs (2MASS 1207-3932 and 2MASS 0441-2301), these companions have relatively large mass ratios and projected separations, suggesting that they formed in a manner analogous to stellar binaries. We present the discovery of a planetary-mass object orbiting a field BD via gravitational microlensing, OGLE-2012-BLG-0358Lb. The system is a low secondary/primary mass ratio (0.080 ± 0.001), relatively tightly separated (∼0.87 AU) binary composed of a planetary-mass object with 1.9 ± 0.2 Jupiter masses orbiting a BD with a mass 0.022 M {sub ☉}. The relatively small mass ratio and separation suggest that the companion may have formed in a protoplanetary disk around the BD host in a manner analogous to planets.

  4. Opto-mechanical analysis of nonlinear elastomer membrane deformation under hydraulic pressure for variable-focus liquid-filled microlenses.

    PubMed

    Choi, Seung Tae; Son, Byeong Soo; Seo, Gye Won; Park, Si-Young; Lee, Kyung-Sick

    2014-03-10

    Nonlinear large deformation of a transparent elastomer membrane under hydraulic pressure was analyzed to investigate its optical performance for a variable-focus liquid-filled membrane microlens. In most membrane microlenses, actuators control the hydraulic pressure of optical fluid so that the elastomer membrane together with the internal optical fluid changes its shape, which alters the light path of the microlens to adapt its optical power. A fluid-structure interaction simulation was performed to estimate the transient behavior of the microlens under the operation of electroactive polymer actuators, demonstrating that the viscosity of the optical fluid successfully stabilizes the fluctuations within a fairly short period of time during dynamic operations. Axisymmetric nonlinear plate theory was used to calculate the deformation profile of the membrane under hydrostatic pressure, with which optical characteristics of the membrane microlens were estimated. The effects of gravitation and viscoelastic behavior of the elastomer membrane on the optical performance of the membrane microlens were also evaluated with finite element analysis.

  5. Shock and vibration testing of digital micromirror devices (DMDs) for space-based applications

    NASA Astrophysics Data System (ADS)

    Vorobiev, Dmitry; Travinsky, Anton; Raisanen, Alan D.; Ninkov, Zoran; Schwartz, Timothy A.; Robberto, Massimo; Heap, Sara

    2016-07-01

    Digital micromirror devices (DMDs) are a mature commercial technology, with several potential applications in space-based instruments. In particular, DMDs are currently the only practical alternative to microshutter arrays as slit mask generators for space-based multi-object spectrometers (MOS). A DMD is an array of micromirrors which can be addressed individually and tilted into one of two states (+/- 12 w.r.t. the device plane), which makes it a very versatile binary light modulator. These devices are widely utilized in a variety of optical systems, especially projectors. Recently, the use of DMDs for ground-based multi-object spectrometers has been demonstrated. The compact size and small weight of DMDs makes them especially attractive for a space- based MOS, where the only current alternative is an array of microshutters. DMDs were originally designed for visible range applications; therefore the protective glass window they are supplied with does not have sufficient throughput in the UV or IR and has to be replaced. In this work, we describe the procedure by which we replaced the standard window with UV-grade fused silica, sapphire and magnesium fluoride. We performed initial shock and vibrational tests to evaluate the mechanical robustness of the re-windowed devices, to investigate the ability of these devices to survive launch conditions. We performed residual gas analysis to study the outgassing properties of the new DMDs and evaluate the ability of the new seals to protect the device. The tested devices show near-hermetic seals before and after the mechanical testing.

  6. Interdependent Multi-Layer Networks: Modeling and Survivability Analysis with Applications to Space-Based Networks

    PubMed Central

    Castet, Jean-Francois; Saleh, Joseph H.

    2013-01-01

    This article develops a novel approach and algorithmic tools for the modeling and survivability analysis of networks with heterogeneous nodes, and examines their application to space-based networks. Space-based networks (SBNs) allow the sharing of spacecraft on-orbit resources, such as data storage, processing, and downlink. Each spacecraft in the network can have different subsystem composition and functionality, thus resulting in node heterogeneity. Most traditional survivability analyses of networks assume node homogeneity and as a result, are not suited for the analysis of SBNs. This work proposes that heterogeneous networks can be modeled as interdependent multi-layer networks, which enables their survivability analysis. The multi-layer aspect captures the breakdown of the network according to common functionalities across the different nodes, and it allows the emergence of homogeneous sub-networks, while the interdependency aspect constrains the network to capture the physical characteristics of each node. Definitions of primitives of failure propagation are devised. Formal characterization of interdependent multi-layer networks, as well as algorithmic tools for the analysis of failure propagation across the network are developed and illustrated with space applications. The SBN applications considered consist of several networked spacecraft that can tap into each other's Command and Data Handling subsystem, in case of failure of its own, including the Telemetry, Tracking and Command, the Control Processor, and the Data Handling sub-subsystems. Various design insights are derived and discussed, and the capability to perform trade-space analysis with the proposed approach for various network characteristics is indicated. The select results here shown quantify the incremental survivability gains (with respect to a particular class of threats) of the SBN over the traditional monolith spacecraft. Failure of the connectivity between nodes is also examined, and the

  7. The Role Played by Space-based Probes in our Understanding of the Cosmos

    NASA Astrophysics Data System (ADS)

    Macchetto, Ferdinando Duccio

    Over the last fifteen years a growing fleet of modern space-based astronomical telescopes has changed drastically our view of the universe. Most of these accomplishments build upon the work of ground-based astronomers over many decades, or even centuries. The combination of telescopes observing the universe at many different wavelengths has converted many prior hypotheses, for which supporting empirical data were scant, ambiguous and painfully difficult to obtain, into clearly and decisively demonstrated truth. But space observatories have gone well beyond that. In particular the Hubble Space Telescope with its combination of sharp images and deep dynamic range, has provided a detailed view of the unimagined complexity and diversity of the universe, as well as its startling beauty. It has yielded numerous surprises and raised new fundamental questions on the basic structure and laws that govern the universe. To answer these questions will require the efforts of ground-based and new space-based observatories working in combined programs over many years. In my talk I will illustrate some of the key discoveries that these space-based observatories have made such as: the deep imaging the distant universe; the calibration of the distance scale and the determination of the age of the universe; the discovery of the acceleration of the expansion rate of the universe, which requires a "dark energy" or new physics to explain it; the detection and measurement of supermassive black holes and the solution to the long standing problem of the nature of Quasars; the solution to the problem of whether Gamma Ray sources originated in our galaxy or at cosmological distances; the renewed interest in the problem of the birth of Stars and the formation of Planetary Systems; the death of Stars and the formation of supernovae, black holes and neutron stars and last but not least the exciting studies of the planets and satellites in our own dynamic solar system

  8. Manned space flight nuclear system safety. Volume 6: Space base nuclear system safety plan

    NASA Technical Reports Server (NTRS)

    1972-01-01

    A qualitative identification of the steps required to assure the incorporation of radiological system safety principles and objectives into all phases of a manned space base program are presented. Specific areas of emphasis include: (1) radiological program management, (2) nuclear system safety plan implementation, (3) impact on program, and (4) summary of the key operation and design guidelines and requirements. The plan clearly indicates the necessity of considering and implementing radiological system safety recommendations as early as possible in the development cycle to assure maximum safety and minimize the impact on design and mission plans.

  9. The SAMEX Vector Magnetograph: A Design Study for a Space-Based Solar Vector Magnetograph

    NASA Technical Reports Server (NTRS)

    Hagyard, M. J.; Gary, G. A.; West, E. A.

    1988-01-01

    This report presents the results of a pre-phase A study performed by the Marshall Space Flight Center (MSFC) for the Air Force Geophysics Laboratory (AFGL) to develop a design concept for a space-based solar vector magnetograph and hydrogen-alpha telescope. These are two of the core instruments for a proposed Air Force mission, the Solar Activities Measurement Experiments (SAMEX). This mission is designed to study the processes which give rise to activity in the solar atmosphere and to develop techniques for predicting solar activity and its effects on the terrestrial environment.

  10. Nuclear reactor power as applied to a space-based radar mission

    NASA Technical Reports Server (NTRS)

    Jaffe, L.; Fujita, T.; Beatty, R.; Bhandari, P.; Chow, E.; Deininger, W.; Ewell, R.; Grossman, M.; Kia, T.; Nesmith, B.

    1988-01-01

    The SP-100 Project was established to develop and demonstrate feasibility of a space reactor power system (SRPS) at power levels of 10's of kilowatts to a megawatt. To help determine systems requirements for the SRPS, a mission and spacecraft were examined which utilize this power system for a space-based radar to observe moving objects. Aspects of the mission and spacecraft bearing on the power system were the primary objectives of this study; performance of the radar itself was not within the scope. The study was carried out by the Systems Design Audit Team of the SP-100 Project.

  11. High Stability Low Scatter Telescope for a Space-based Gravitational Wave Observatory

    NASA Astrophysics Data System (ADS)

    Livas, Jeffrey; Sankar, Shannon

    2017-01-01

    A laser interferometer space-based gravitational wave observatory requires an optical telescope to efficiently transfer laser light between pairs of widely-separated sciencecraft. The application is precision interferometric metrology, and therefore requires the telescope to have high optical pathlength stability, and low scattered light performance. We discuss the expected on-orbit environment and present the latest design, including materials choice trades, surface roughness and cleanliness requirements, and an optical prescription optimized to reduce scattered light. We will also discuss some of the remaining system-level trades. This work is supported by NASA Strategic Astrophysics Technology grant 14-SAT14-0014.

  12. Space-Based Gravitational-Wave Observatory (SGO) Mission Concept Study

    NASA Technical Reports Server (NTRS)

    Livas, Jeffrey; McNamara, Paul; Jennrich, Oliver

    2012-01-01

    The LISA Mission Concept has been under study for over two decades as a space-based gravitational-wave detector capable of observing astrophysical sources in the 0.0001 to 1 Hz band. The concept has consistently received strong recommendations from various review panels based on the expected science, most recently from the US Astr02010 Decadal Review. Budget constraints have led both the US and European Space agencies to search for lower cost options. We report results from the US effort to explore the tradeoffs between mission cost and science return.

  13. Progress and Prospects toward a Space-based Gravitational-Wave Observatory

    NASA Technical Reports Server (NTRS)

    Baker, John

    2012-01-01

    Over the last few years there has been much activity in the effort to produce a space-based gravitational-wave observatory. These efforts have enriched the understanding of the scientific capabilities of such an observatory leading to broad recognition of its value as an astronomical instrument. At the same time, rapidly developing events in the US and Europe have lead to a more complicated outlook than the baseline Laser Interferometer Space Antenna (LISA) project plan of a few years ago. I will discuss recent progress and developments resulting from the European eLISA study and the SGO study in the US and prospects looking forward.

  14. Solid-State, High Energy 2-Micron Laser Development for Space-Based Remote Sensing

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.

    2010-01-01

    Lidar (light detection and ranging) remote sensing enjoys the advantages of excellent vertical and horizontal resolution; pointing capability; a signal source independent from natural light; and control and knowledge of transmitted wavelength, pulse shape, and polarization and received polarization. Lidar in space is an emerging technology now being developing to fit applications where passive sensors cannot meet current measurement requirements. Technical requirements for space lidar are more demanding than for ground-based or airborne systems. Perhaps the most distinguishing characteristics of space lidars are the environmental requirements. Space lidar systems must be specially designed to survive the mechanical vibration loads of launch and operate in the vacuum of space where exposure to ionizing radiation limits the electronic components available. Finally, space lidars must be designed to be highly reliable because they must operate without the need for repair or adjustment. Lifetime requirements tend to be important drivers of the overall system design. The maturity of the required technologies is a key to the development of any space lidar system. NASA entered a new era in the 1990 s with the approval of several space-based remote sensing missions employing laser radar (lidar) techniques. Following the steps of passive remote sensing and then active radar remote sensing, lidar sensors were a logical next step, providing independence from natural light sources, and better spatial resolution and smaller sensor size than radar sensors. The shorter electromagnetic wavelengths of laser light also allowed signal reflectance from air molecules and aerosol particles. The smaller receiver apertures allowed the concept of scanning the sensor field of view. However, technical problems with several space-based lidar missions during that decade led to concern at NASA about the risk of lidar missions. An external panel was convened to make recommendations to NASA. Their

  15. Orbits and Pointing Strategies for Space-Based Telescopes into a European Space Surveillance System

    NASA Astrophysics Data System (ADS)

    Olmedo, Estrella; Sanchez-Ortiz, Noelia; Ramos-Lerate, Mercedes

    2009-03-01

    This paper describes the inclusion of optical images acquired from orbiting telescopes into an autonomous European space surveillance system via the Advance Space Surveillance System Simulator (AS4). Special interest on space-based observation of GEO objects exists since it avoids the weather dependence and longitudinal restrictions of ground-based observations of those objects. Furthermore, space-based observations allow the detection of small objects that are not detected from ground-based sensors.In order to analyze the impact of space-based telescopes images, several aspects have to be studied. The first consideration is the selection of the appropriate orbits to locate the telescopes. A description of the most suitable orbits and strategies for the observation of space debris population will be provided.Once an appropriated orbit has been selected, the next important consideration is the analysis of an optimized pointing strategy and its associated requirements for feasibility. Several pointing strategies will be exposed by analyzing, among other factors, the impact of luminosity conditions in the most populated regions to be observed. Numerical results are presented in the form of statistics, which reflect the compromise between the density of detected objects, and other important parameters for orbit determination and cataloguing purposes as re-acquisition times or measurement track duration.Finally, overall analyses of possible space-based constellations are presented. Such constellations are aimed to solve the main drawbacks in considering only one satellite at the selected orbit. This is for example the case of revisit times when considering a sub GEO orbiting telescope which can be solve by re-distributing several sensors in the orbit. It will also allow carrying on more complex pointing strategies by the definition of several sensors located at same orbit pointed at two different regions.The AS4 was developed by DEIMOS Space ([1], [2] and also [5]). The

  16. Testing Gravitational Physics with Space-based Gravitational-wave Observations

    NASA Technical Reports Server (NTRS)

    Baker, John G.

    2011-01-01

    Gravitational wave observations provide exceptional and unique opportunities for precision tests of gravitational physics, as predicted by general relativity (GR). Space-based gravitational wave measurements, with high signal-to-noise ratios and large numbers of observed events may provide the best-suited gravitational-wave observations for testing GR with unprecedented precision. These observations will be especially useful in testing the properties of gravitational waves and strong-field aspects of the theory which are less relevant in other observations. We review the proposed GR test based on observations of massive black hole mergers, extreme mass ratio inspirals, and galactic binary systems.

  17. Primary propulsion of electrothermal, ion and chemical systems for space-based radar orbit transfer

    NASA Technical Reports Server (NTRS)

    Wang, S. Y.; Staiger, P. J.

    1985-01-01

    An orbit transfer mission concept has been studied for a Space-Based Radar (SBR) where 40 kW required for radar operation is assumed available for orbit transfer propulsion. Arcjet, pulsed electrothermal (PET), ion, and storable chemical systems are considered for the primary propulsion. Transferring two SBR per shuttle flight to 1112 km/60 deg using electrical propulsion systems offers an increased payload at the expense of increased trip time, up to 2000 kg each, which may be critical for survivability. Trade offs between payload mass, transfer time, launch site, inclination, and height of parking orbits are presented.

  18. Primary propulsion of electrothermal, ion, and chemical systems for space-based radar orbit transfer

    NASA Technical Reports Server (NTRS)

    Wang, S.-Y.; Staiger, P. J.

    1985-01-01

    An orbit transfer mission concept has been studied for a Space-Based Radar (SBR) where 40 kW required for radar operation is assumed available for orbit transfer propulsion. Arcjet, pulsed electrothermal (PET), ion, and storable chemical systems are considered for the primary propulsion. Transferring two SBR per shuttle flight to 1112 km/60 deg using eiectrical propulsion systems offers an increased payload at the expense of increased trip time, up to 2000 kg each, which may be critical for survivability. Trade offs between payload mass, transfer time, launch site, inclination, and height of parking orbits are presented.

  19. Ground and space based optical analysis of materials degradation in low-Earth-orbit

    NASA Technical Reports Server (NTRS)

    Woollam, John A.; Synowicki, Ron; Hale, Jeffrey S.; Peterkin, Jane; Machlab, Hassanayn; De, Bhola N.; Johs, Blaine

    1991-01-01

    There is strong interest in being able to accurately and sensitively monitor materials degradation in both ground-based and space-based environments. Two optical techniques for sensitive degradation monitoring are reviewed: spectroscopic ellipsometry and photothermal spectroscopy. These techniques complement each other in that ellipsometry is sensitive to atomically thin surface and subsurface changes, and photothermal spectroscopy is sensitive to local defects, pin-holes, subsurface defects, and delamination. Progress in applying these spectroscopies (both ex situ and in situ) to atomic oxygen degradation of space materials is reviewed.

  20. Innovative Approaches to Space-Based Manufacturing and Rapid Prototyping of Composite Materials

    NASA Technical Reports Server (NTRS)

    Hill, Charles S.

    2012-01-01

    The ability to deploy large habitable structures, construct, and service exploration vehicles in low earth orbit will be an enabling capability for continued human exploration of the solar system. It is evident that advanced manufacturing methods to fabricate replacement parts and re-utilize launch vehicle structural mass by converting it to different uses will be necessary to minimize costs and allow flexibility to remote crews engaged in space travel. Recent conceptual developments and the combination of inter-related approaches to low-cost manufacturing of composite materials and structures are described in context leading to the possibility of on-orbit and space-based manufacturing.

  1. International Cooperation for Space-Based Global Maritime Awareness- The Next Step

    NASA Astrophysics Data System (ADS)

    Greidanus, H.; Thomas, G. G.; Campbell, G.; Bryan, K.

    2013-03-01

    This paper aims to put forward for discussion a number of possible ways to promote international cooperation for global maritime awareness, in particular using space-based assets. Maritime awareness concerns the knowledge of human activities going on at sea, so for a large part equates to ship traffic detection and monitoring for safety, security and protection of resources and the environment. The essential benefits and challenges for cooperation, and related sharing of information, are recounted. Several concrete options for global cooperation that should be viable also in view of the challenges are proposed. A public discussion with global stakeholders should follow, leading to convergence on a mechanism that should be subsequently implemented.

  2. Frequency stabilization for space-based missions using optical fiber interferometry.

    PubMed

    McRae, Terry G; Ngo, Silvie; Shaddock, Daniel A; Hsu, Magnus T L; Gray, Malcolm B

    2013-02-01

    We present measurement results for a laser frequency reference, implemented with an all-optical fiber Michelson interferometer, down to frequencies as low as 1 mHz. Optical fiber is attractive for space-based operations as it is physically robust, small and lightweight. The small free spectral range of fiber interferometers also provides the possibility to prestabilize two lasers on two distant spacecraft and ensures that the beatnote remains within the detector bandwidth. We demonstrate that these fiber interferometers are viable candidates for future laser-based gravity recovery and climate experiment missions requiring a stability of 30 Hz/√Hz over a 10 mHz-1 Hz bandwidth.

  3. On the Use of Low-Z Targets in Space-Based Hadron Calorimetry

    NASA Astrophysics Data System (ADS)

    Ganel, Opher

    In space-based experiments, detector mass is a critical concern. To allow an acceptable geometric acceptance, calorimeters used in such situations must be thin, and will thus not fully contain hadron showers. We discuss the benefits of using a low-Z target in front of thin calorimeters to force nuclear interactions and improve resolution. We report simulation results comparing several target options and a 'monolithic' configuration. The results demonstrate how calorimeter configuration, available mass, required energy resolution and 'good event' definitions can affect the optimal division of mass between the target and the calorimeter. Finally we suggest a method to optimize design choices based on the parameters of the experiment.

  4. Carbon Fiber Reinforced Glass Matrix Composites for Structural Space Based Applications

    DTIC Science & Technology

    1989-07-31

    1988) 2745-2752. 2 R89-917704-1 10. V. C. Nardone and K. M. Prewo, "Tensile Performance of Carbon-Fibre-Reinforced Glass," J. Mater. Sci., 23 (1988...168-180. 11. K. M. Prewo and V. C. Nardone , "Carbon Fiber Reinforced Glass Matrix Composites for Space Based Applications," UTRC Report R86-917161-1...Mater. Sci., 23 (1988) 2745-2752. 11. V. C. Nardone and K. M. Prewo, "Tensile Performance of Carbon-Fibre-Reinforced Glass," J. Mater. Sci., 23 (1988

  5. The role of space-based observation in understanding and responding to active tectonics and earthquakes

    NASA Astrophysics Data System (ADS)

    Elliott, J. R.; Walters, R. J.; Wright, T. J.

    2016-12-01

    The quantity and quality of satellite-geodetic measurements of tectonic deformation have increased dramatically over the past two decades improving our ability to observe active tectonic processes. We now routinely respond to earthquakes using satellites, mapping surface ruptures and estimating the distribution of slip on faults at depth for most continental earthquakes. Studies directly link earthquakes to their causative faults allowing us to calculate how resulting changes in crustal stress can influence future seismic hazard. This revolution in space-based observation is driving advances in models that can explain the time-dependent surface deformation and the long-term evolution of fault zones and tectonic landscapes.

  6. Space-Based Remote Sensing of the Earth: A Report to the Congress

    NASA Technical Reports Server (NTRS)

    1987-01-01

    The commercialization of the LANDSAT Satellites, remote sensing research and development as applied to the Earth and its atmosphere as studied by NASA and NOAA is presented. Major gaps in the knowledge of the Earth and its atmosphere are identified and a series of space based measurement objectives are derived. The near-term space observations programs of the United States and other countries are detailed. The start is presented of the planning process to develop an integrated national program for research and development in Earth remote sensing for the remainder of this century and the many existing and proposed satellite and sensor systems that the program may include are described.

  7. Multi-Disciplinary Techniques for Understanding Time-Varying Space-Based Imagery.

    DTIC Science & Technology

    1987-04-29

    space-based image processing . A special feature of this effort is the attempt to use both optical and digital processing methods. Subpixel target...Framework for Hybrid Optical/Digital Image Processing 3 1.3. Problem Definition 3 1.4. Benefit to Air Force Technology 9 0 1.5. Summary of Research...Generation of Synthetic Imagery 21 2.2.1. Ground-Level Imagery 21 2.2.2. Detector Imagery 23 2.3. Processing Algorithms 25 2.3.1. Single Differencing 26 0

  8. Working fluid selection for space-based two-phase heat transport systems

    NASA Technical Reports Server (NTRS)

    Mclinden, Mark O.

    1988-01-01

    The working fluid for externally-mounted, space-based two-phase heat transport systems is considered. A sequence of screening criteria involving freezing and critical point temperatures and latent heat of vaporization and vapor density are applied to a data base of 860 fluids. The thermal performance of the 52 fluids which pass this preliminary screening are then ranked according to their impact on the weight of a reference system. Upon considering other nonthermal criteria (flammability, toxicity, and chemical stability) a final set of 10 preferred fluids is obtained. The effects of variations in system parameters is investigated for these 10 fluids by means of a factorial design.

  9. Cancellation of Laser Noise in Space-Based Interferometer Detectors of Gravitational Radiation

    NASA Technical Reports Server (NTRS)

    Tinto, Massimo

    1999-01-01

    We presented a time-domain procedure for accurately cancelling laser noise fluctuations in an unequal-arm Michelson interferometer. The method involves separately measuring the phase of the returning light relative to the phase of the transmitted light in each arm. By suitable offsetting and differencing of these two time series, the common laser noise is cancelled exactly. The technique presented in this paper is general, in such that it can be implemented with any (Earth as well as space-based) unequal-arms Michelson interferometers,

  10. Science with the space-based interferometer LISA. IV: probing inflation with gravitational waves

    NASA Astrophysics Data System (ADS)

    Bartolo, Nicola; Caprini, Chiara; Domcke, Valerie; Figueroa, Daniel G.; Garcia-Bellido, Juan; Chiara Guzzetti, Maria; Liguori, Michele; Matarrese, Sabino; Peloso, Marco; Petiteau, Antoine; Ricciardone, Angelo; Sakellariadou, Mairi; Sorbo, Lorenzo; Tasinato, Gianmassimo

    2016-12-01

    We investigate the potential for the LISA space-based interferometer to detect the stochastic gravitational wave background produced from different mechanisms during inflation. Focusing on well-motivated scenarios, we study the resulting contributions from particle production during inflation, inflationary spectator fields with varying speed of sound, effective field theories of inflation with specific patterns of symmetry breaking and models leading to the formation of primordial black holes. The projected sensitivities of LISA are used in a model-independent way for various detector designs and configurations. We demonstrate that LISA is able to probe these well-motivated inflationary scenarios beyond the irreducible vacuum tensor modes expected from any inflationary background.

  11. Taking the Politics Out of Satellite and Space-Based Communications Protocols

    NASA Technical Reports Server (NTRS)

    Ivancic, William D.

    2006-01-01

    After many years of studies, experimentation, and deployment, large amounts of misinformation and misconceptions remain regarding applicability of various communications protocols for use in satellite and space-based networks. This paper attempts to remove much of the politics, misconceptions, and misinformation that have plagued spacebased communications protocol development and deployment. This paper provides a common vocabulary for communications; a general discussion of the requirements for various communication environments; an evaluation of tradeoffs between circuit and packet-switching technologies, and the pros and cons of various link, network, transport, application, and security protocols. Included is the applicability of protocol enhancing proxies to NASA, Department of Defense (DOD), and commercial space communication systems.

  12. Probing the Dark Matter Radial Profile in Lens Galaxies and the Size of X-Ray Emitting Region in Quasars with Microlensing

    NASA Astrophysics Data System (ADS)

    Jiménez-Vicente, J.; Mediavilla, E.; Kochanek, C. S.; Muñoz, J. A.

    2015-06-01

    We use X-ray and optical microlensing measurements to study the shape of the dark matter density profile in the lens galaxies and the size of the (soft) X-ray emission region. We show that single epoch X-ray microlensing is sensitive to the source size. Our results, in good agreement with previous estimates, show that the size of the X-ray emission region scales roughly linearly with the black hole mass, with a half-light radius of {{R}}1/2≃ (24+/- 14){{r}}{\\boldsymbol{g}} where {r}g={{GM}}{BH}/{c}2. This corresponds to a size of {log}({{R}}1/2/{cm})={15.6}-0.3+0.3 or ˜1 lt-day for a black hole mass of {M}{BH}={10}9 {M}⊙ . We simultaneously estimated the fraction of the local surface mass density in stars, finding that the stellar mass fraction is α = 0.20 ± 0.05 at an average radius of ˜ 1.9{R}e, where Re is the effective radius of the lens. This stellar mass fraction is insensitive to the X-ray source size and in excellent agreement with our earlier results based on optical data. By combining X-ray and optical microlensing data, we can divide this larger sample into two radial bins. We find that the surface mass density in the form of stars is α = 0.31 ± 0.15 and α = 0.13 ± 0.05 at (1.3+/- 0.3){R}e and (2.3+/- 0.3){R}e, respectively, in good agreement with expectations and some previous results.

  13. A survey of surveys

    SciTech Connect

    Kent, S.M.

    1994-11-01

    A new era for the field of Galactic structure is about to be opened with the advent of wide-area digital sky surveys. In this article, the author reviews the status and prospects for research for 3 new ground-based surveys: the Sloan Digital Sky Survey (SDSS), the Deep Near-Infrared Survey of the Southern Sky (DENIS) and the Two Micron AU Sky Survey (2MASS). These surveys will permit detailed studies of Galactic structure and stellar populations in the Galaxy with unprecedented detail. Extracting the information, however, will be challenging.

  14. A simple method to determine time delays in the presence of microlensing: application to HE 0435-1112 and PG 1115+080

    NASA Astrophysics Data System (ADS)

    Tsvetkova, V. S.; Shulga, V. M.; Berdina, L. A.

    2016-10-01

    A method for determining the time delays in gravitationally lensed quasars is proposed. This method offers a simple and transparent procedure to mitigate the effects of microlensing. It is based on the fundamental properties of representation of quadratically integrable functions by their expansions in orthogonal polynomials series. The method was tested on the artificial light curves simulated for the Time Delay Challenge campaign (TDC0). The new estimates of the time delays in the gravitationally lensed quasars HE 0435-1223 and PG 1115+080 are obtained and compared with the results reported earlier by other authors.

  15. Constraint-based integration of planning and scheduling for space-based observatory management

    NASA Technical Reports Server (NTRS)

    Muscettola, Nicola; Smith, Steven F.

    1994-01-01

    Progress toward the development of effective, practical solutions to space-based observatory scheduling problems within the HSTS scheduling framework is reported. HSTS was developed and originally applied in the context of the Hubble Space Telescope (HST) short-term observation scheduling problem. The work was motivated by the limitations of the current solution and, more generally, by the insufficiency of classical planning and scheduling approaches in this problem context. HSTS has subsequently been used to develop improved heuristic solution techniques in related scheduling domains and is currently being applied to develop a scheduling tool for the upcoming Submillimeter Wave Astronomy Satellite (SWAS) mission. The salient architectural characteristics of HSTS and their relationship to previous scheduling and AI planning research are summarized. Then, some key problem decomposition techniques underlying the integrated planning and scheduling approach to the HST problem are described; research results indicate that these techniques provide leverage in solving space-based observatory scheduling problems. Finally, more recently developed constraint-posting scheduling procedures and the current SWAS application focus are summarized.

  16. CEOS Contributions to Informing Energy Management and Policy Decision Making Using Space-Based Earth Observations

    NASA Technical Reports Server (NTRS)

    Eckman, Richard S.

    2009-01-01

    Earth observations are playing an increasingly significant role in informing decision making in the energy sector. In renewable energy applications, space-based observations now routinely augment sparse ground-based observations used as input for renewable energy resource assessment applications. As one of the nine Group on Earth Observations (GEO) societal benefit areas, the enhancement of management and policy decision making in the energy sector is receiving attention in activities conducted by the Committee on Earth Observation Satellites (CEOS). CEOS has become the "space arm" for the implementation of the Global Earth Observation System of Systems (GEOSS) vision. It is directly supporting the space-based, near-term tasks articulated in the GEO three-year work plan. This paper describes a coordinated program of demonstration projects conducted by CEOS member agencies and partners to utilize Earth observations to enhance energy management end-user decision support systems. I discuss the importance of engagement with stakeholders and understanding their decision support needs in successfully increasing the uptake of Earth observation products for societal benefit. Several case studies are presented, demonstrating the importance of providing data sets in formats and units familiar and immediately usable by decision makers. These projects show the utility of Earth observations to enhance renewable energy resource assessment in the developing world, forecast space-weather impacts on the power grid, and improve energy efficiency in the built environment.

  17. The PLATO Simulator: modelling of high-precision high-cadence space-based imaging

    NASA Astrophysics Data System (ADS)

    Marcos-Arenal, P.; Zima, W.; De Ridder, J.; Aerts, C.; Huygen, R.; Samadi, R.; Green, J.; Piotto, G.; Salmon, S.; Catala, C.; Rauer, H.

    2014-06-01

    Context. Many aspects of the design trade-off of a space-based instrument and its performance can best be tackled through simulations of the expected observations. The complex interplay of various noise sources in the course of the observations make such simulations an indispensable part of the assessment and design study of any space-based mission. Aims: We present a formalism to model and simulate photometric time series of CCD images by including models of the CCD and its electronics, the telescope optics, the stellar field, the jitter movements of the spacecraft, and all of the important natural noise sources. Methods: This formalism has been implemented in a versatile end-to-end simulation software tool, specifically designed for the PLATO (Planetary Transists and Oscillations of Stars) space mission to be operated from L2, but easily adaptable to similar types of missions. We call this tool Plato Simulator. Results: We provide a detailed description of several noise sources and discuss their properties in connection with the optical design, the allowable level of jitter, the quantum efficiency of the detectors, etc. The expected overall noise budget of generated light curves is computed, as a function of the stellar magnitude, for different sets of input parameters describing the instrument properties. The simulator is offered to the scientific community for future use. Software package available at the Plato Simulator web site (http://https://fys.kuleuven.be/ster/Software/PlatoSimulator/).

  18. Extra-solar planetary imager (ESPI) for space-based Jovian planetary detection

    NASA Astrophysics Data System (ADS)

    Lyon, Richard G.; Gezari, Daniel Y.; Melnick, Gary J.; Nisenson, Peter; Papaliolios, Costas D.; Ridgway, Stephen T.; Friedman, Edward J.; Harwit, Martin; Graf, Paul

    2003-02-01

    The Extra-Solar Planetary Imager (ESPI) is envisioned as a space based, high dynamic range, visible imager capable of detecting Jovian like planets. Initially proposed as a NASA Midex (NASA/Medium Class Explorer) mission (PI:Gary Melnick), as a space-based 1.5 x 1.5 m2 Jacquinot apodized square aperture telescope. The combination of apodization and a square aperture telescope reduces the diffracted light from a bright central source increasing the planetary to stellar contrast over much of the telescope focal plane. As a result, observations of very faint astronomical objects next to bright sources with angular separations as small as 0.32 arcseconds become possible. This permits a sensitive search for exo-planets in reflected light. ESPI is capable of detecting a Jupiter-like planet in a relatively long-period orbit around as many as 160 to 175 stars with a signal-to-noise ratio > 5 in observations lasting maximally 100 hours per star out to ~16 parsecs. We discuss the scientific ramifications, an overview of the system design including apodizing a square aperture, signal to noise issues and the effect of wavefront errors and the scalability of ESPI with respect to NASA's Terrestrial Planet Finder mission.

  19. Effect of Clouds on Apertures of Space-based Air Fluorescence Detectors

    NASA Technical Reports Server (NTRS)

    Sokolsky, P.; Krizmanic, J.

    2003-01-01

    Space-based ultra-high-energy cosmic ray detectors observe fluorescence light from extensive air showers produced by these particles in the troposphere. Clouds can scatter and absorb this light and produce systematic errors in energy determination and spectrum normalization. We study the possibility of using IR remote sensing data from MODIS and GOES satellites to delimit clear areas of the atmosphere. The efficiency for detecting ultra-high-energy cosmic rays whose showers do not intersect clouds is determined for real, night-time cloud scenes. We use the MODIS SST cloud mask product to define clear pixels for cloud scenes along the equator and use the OWL Monte Carlo to generate showers in the cloud scenes. We find the efficiency for cloud-free showers with closest approach of three pixels to a cloudy pixel is 6.5% exclusive of other factors. We conclude that defining a totally cloud-free aperture reduces the sensitivity of space-based fluorescence detectors to unacceptably small levels.

  20. Modeling and validation of photometric characteristics of space targets oriented to space-based observation.

    PubMed

    Wang, Hongyuan; Zhang, Wei; Dong, Aotuo

    2012-11-10

    A modeling and validation method of photometric characteristics of the space target was presented in order to track and identify different satellites effectively. The background radiation characteristics models of the target were built based on blackbody radiation theory. The geometry characteristics of the target were illustrated by the surface equations based on its body coordinate system. The material characteristics of the target surface were described by a bidirectional reflectance distribution function model, which considers the character of surface Gauss statistics and microscale self-shadow and is obtained by measurement and modeling in advance. The contributing surfaces of the target to observation system were determined by coordinate transformation according to the relative position of the space-based target, the background radiation sources, and the observation platform. Then a mathematical model on photometric characteristics of the space target was built by summing reflection components of all the surfaces. Photometric characteristics simulation of the space-based target was achieved according to its given geometrical dimensions, physical parameters, and orbital parameters. Experimental validation was made based on the scale model of the satellite. The calculated results fit well with the measured results, which indicates the modeling method of photometric characteristics of the space target is correct.

  1. Mission planning for space based satellite surveillance experiments with the MSX

    NASA Technical Reports Server (NTRS)

    Sridharan, R.; Fishman, T.; Robinson, E.; Viggh, H.; Wiseman, A.

    1994-01-01

    The Midcourse Space Experiment is a BMDO-sponsored scientific satellite set for launch within the year. The satellite will collect phenomenology data on missile targets, plumes, earth limb backgrounds and deep space backgrounds in the LWIR, visible and ultra-violet spectral bands. It will also conduct functional demonstrations for space-based space surveillance. The Space-Based Visible sensor, built by Lincoln Laboratory, Massachusetts Institute of Technology, is the primary sensor on board the MSX for demonstration of space surveillance. The SBV Processing, Operations and Control Center (SPOCC) is the mission planning and commanding center for all space surveillance experiments using the SBV and other MSX instruments. The guiding principle in the SPOCC Mission Planning System was that all routine functions be automated. Manual analyst input should be minimal. Major concepts are: (I) A high level language, called SLED, for user interface to the system; (2) A group of independent software processes which would generally be run in a pipe-line mode for experiment commanding but can be run independently for analyst assessment; (3) An integrated experiment cost computation function that permits assessment of the feasibility of the experiment. This paper will report on the design, implementation and testing of the Mission Planning System.

  2. Space based optical staring sensor LOS determination and calibration using GCPs observation

    NASA Astrophysics Data System (ADS)

    Chen, Jun; An, Wei; Deng, Xinpu; Yang, Jungang; Sha, Zhichao

    2016-10-01

    Line of sight (LOS) attitude determination and calibration is the key prerequisite of tracking and location of targets in space based infrared (IR) surveillance systems (SBIRS) and the LOS determination and calibration of staring sensor is one of the difficulties. This paper provides a novel methodology for removing staring sensor bias through the use of Ground Control Points (GCPs) detected in the background field of the sensor. Based on researching the imaging model and characteristics of the staring sensor of SBIRS geostationary earth orbit part (GEO), the real time LOS attitude determination and calibration algorithm using landmark control point is proposed. The influential factors (including the thermal distortions error, assemble error, and so on) of staring sensor LOS attitude error are equivalent to bias angle of LOS attitude. By establishing the observation equation of GCPs and the state transition equation of bias angle, and using an extend Kalman filter (EKF), the real time estimation of bias angle and the high precision sensor LOS attitude determination and calibration are achieved. The simulation results show that the precision and timeliness of the proposed algorithm meet the request of target tracking and location process in space based infrared surveillance system.

  3. Sub-Femto-g Free Fall for Space-Based Gravitational Wave Observatories: LISA Pathfinder Results

    NASA Astrophysics Data System (ADS)

    Armano, M.; Audley, H.; Auger, G.; Baird, J. T.; Bassan, M.; Binetruy, P.; Born, M.; Bortoluzzi, D.; Brandt, N.; Caleno, M.; Carbone, L.; Cavalleri, A.; Cesarini, A.; Ciani, G.; Congedo, G.; Cruise, A. M.; Danzmann, K.; de Deus Silva, M.; De Rosa, R.; Diaz-Aguiló, M.; Di Fiore, L.; Diepholz, I.; Dixon, G.; Dolesi, R.; Dunbar, N.; Ferraioli, L.; Ferroni, V.; Fichter, W.; Fitzsimons, E. D.; Flatscher, R.; Freschi, M.; García Marín, A. F.; García Marirrodriga, C.; Gerndt, R.; Gesa, L.; Gibert, F.; Giardini, D.; Giusteri, R.; Guzmán, F.; Grado, A.; Grimani, C.; Grynagier, A.; Grzymisch, J.; Harrison, I.; Heinzel, G.; Hewitson, M.; Hollington, D.; Hoyland, D.; Hueller, M.; Inchauspé, H.; Jennrich, O.; Jetzer, P.; Johann, U.; Johlander, B.; Karnesis, N.; Kaune, B.; Korsakova, N.; Killow, C. J.; Lobo, J. A.; Lloro, I.; Liu, L.; López-Zaragoza, J. P.; Maarschalkerweerd, R.; Mance, D.; Martín, V.; Martin-Polo, L.; Martino, J.; Martin-Porqueras, F.; Madden, S.; Mateos, I.; McNamara, P. W.; Mendes, J.; Mendes, L.; Monsky, A.; Nicolodi, D.; Nofrarias, M.; Paczkowski, S.; Perreur-Lloyd, M.; Petiteau, A.; Pivato, P.; Plagnol, E.; Prat, P.; Ragnit, U.; Raïs, B.; Ramos-Castro, J.; Reiche, J.; Robertson, D. I.; Rozemeijer, H.; Rivas, F.; Russano, G.; Sanjuán, J.; Sarra, P.; Schleicher, A.; Shaul, D.; Slutsky, J.; Sopuerta, C. F.; Stanga, R.; Steier, F.; Sumner, T.; Texier, D.; Thorpe, J. I.; Trenkel, C.; Tröbs, M.; Tu, H. B.; Vetrugno, D.; Vitale, S.; Wand, V.; Wanner, G.; Ward, H.; Warren, C.; Wass, P. J.; Wealthy, D.; Weber, W. J.; Wissel, L.; Wittchen, A.; Zambotti, A.; Zanoni, C.; Ziegler, T.; Zweifel, P.

    2016-06-01

    We report the first results of the LISA Pathfinder in-flight experiment. The results demonstrate that two free-falling reference test masses, such as those needed for a space-based gravitational wave observatory like LISA, can be put in free fall with a relative acceleration noise with a square root of the power spectral density of 5.2 ±0.1 fm s-2/√{Hz } , or (0.54 ±0.01 ) ×10-15 g/√{Hz } , with g the standard gravity, for frequencies between 0.7 and 20 mHz. This value is lower than the LISA Pathfinder requirement by more than a factor 5 and within a factor 1.25 of the requirement for the LISA mission, and is compatible with Brownian noise from viscous damping due to the residual gas surrounding the test masses. Above 60 mHz the acceleration noise is dominated by interferometer displacement readout noise at a level of (34.8 ±0.3 ) fm /√{Hz } , about 2 orders of magnitude better than requirements. At f ≤0.5 mHz we observe a low-frequency tail that stays below 12 fm s-2/√{Hz } down to 0.1 mHz. This performance would allow for a space-based gravitational wave observatory with a sensitivity close to what was originally foreseen for LISA.

  4. Vulnerability assessment of a space based weapon platform electronic system exposed to a thermonuclear weapon detonation

    NASA Astrophysics Data System (ADS)

    Perez, C. L.; Johnson, J. O.

    Rapidly changing world events, the increased number of nations with inter-continental ballistic missile capability, and the proliferation of nuclear weapon technology will increase the number of nuclear threats facing the world today. Monitoring these nation's activities and providing an early warning and/or intercept system via reconnaissance and surveillance satellites and space based weapon platforms is a viable deterrent against a surprise nuclear attack. However, the deployment of satellite and weapon platform assets in space will subject the sensitive electronic equipment to a variety of natural and man-made radiation environments. These include Van Allen Belt protons and electrons; galactic and solar flare protons; and neutrons, gamma rays, and x-rays from intentionally detonated fission and fusion weapons. In this paper, the MASH vl.0 code system is used to estimate the dose to the critical electronics components of an idealized space based weapon platform from neutron and gamma-ray radiation emitted from a thermonuclear weapon detonation in space. Fluence and dose assessments were performed for the platform fully loaded, and in several stages representing limited engagement scenarios. The results indicate vulnerabilities to the Command, Control, and Communication bay instruments from radiation damage for a nuclear weapon detonation for certain source/platform orientations. The distance at which damage occurs will depend on the weapon yield (n,(gamma)/kiloton) and size (kilotons).

  5. Performance of a space-based wavelet compressor for plasma count data on the MMS Fast Plasma Investigation

    NASA Astrophysics Data System (ADS)

    Barrie, A. C.; Smith, S. E.; Dorelli, J. C.; Gershman, D. J.; Yeh, P.; Schiff, C.; Avanov, L. A.

    2017-01-01

    Data compression has been a staple of imaging instruments for years. Recently, plasma measurements have utilized compression with relatively low compression ratios. The Fast Plasma Investigation (FPI) on board the Magnetospheric Multiscale (MMS) mission generates data roughly 100 times faster than previous plasma instruments, requiring a higher compression ratio to fit within the telemetry allocation. This study investigates the performance of a space-based compression standard employing a Discrete Wavelet Transform and a Bit Plane Encoder (DWT/BPE) in compressing FPI plasma count data. Data from the first 6 months of FPI operation are analyzed to explore the error modes evident in the data and how to adapt to them. While approximately half of the Dual Electron Spectrometer (DES) maps had some level of loss, it was found that there is little effect on the plasma moments and that errors present in individual sky maps are typically minor. The majority of Dual Ion Spectrometer burst sky maps compressed in a lossless fashion, with no error introduced during compression. Because of induced compression error, the size limit for DES burst images has been increased for Phase 1B. Additionally, it was found that the floating point compression mode yielded better results when images have significant compression error, leading to floating point mode being used for the fast survey mode of operation for Phase 1B. Despite the suggested tweaks, it was found that wavelet-based compression, and a DWT/BPE algorithm in particular, is highly suitable to data compression for plasma measurement instruments and can be recommended for future missions.

  6. Exploring the Feasibility of Providing Electrical Power to Remote Bases Via Space-Based Solar Power Satellites

    DTIC Science & Technology

    2013-06-01

    Military Bases in Remote Areas ..............................................4 5. Renewable Energy Through Space-Based Solar Power (SSP) Solutions...the countries’ president and its military forces. One concept for delivering large amounts of renewable energy is through a space- based solar power... Solar Power (SSP) satellites for military bases in Afghanistan, where energy is expensive and/or very difficult to obtain. B. BACKGROUND 1. The

  7. Surveying Future Surveys

    NASA Astrophysics Data System (ADS)

    Carlstrom, John E.

    2016-06-01

    The now standard model of cosmology has been tested and refined by the analysis of increasingly sensitive, large astronomical surveys, especially with statistically significant millimeter-wave surveys of the cosmic microwave background and optical surveys of the distribution of galaxies. This talk will offer a glimpse of the future, which promises an acceleration of this trend with cosmological information coming from new surveys across the electromagnetic spectrum as well as particles and even gravitational waves.

  8. Discovery of the distant cool sub-Neptune mass planet OGLE 2005-BLG-390Lb by microlensing

    SciTech Connect

    Beaulieu, J P; Bennett, D P; Fouque, P; Williams, A; Dominik, M; Jorgensen, U G; Kubas, D; Cassan, A; Coutures, C; Greenhill, J; Hill, K; Menzies, J; Sackett, P D; Albrow, M; Brillant, S; Caldwell, J R; Calitz, J J; Cook, K H; Corrales, E; Desort, M; Dieters, S; Dominis, D; Donatowicz, J; Hoffman, M; Kane, S; Marquette, J B; Martin, R; Meintjes, P; Pollard, K; Sahu, K; Vinter, C; Wambsganss, J; Woller, K; Horne, K; Steele, I; Bramich, D M; Burgdorf, M; Snodgrass, C; Bode, M; Udalski, A; Szymanski, M K; Kubiak, M; Wieckowski, T; Pietrzynski, G; Soszynski, I; Szewczyk, O; Wyrzykowski, L; Paczynski, B; Abe, F; Bond, I A; Britton, T R; Gilmore, A C; Hearnshaw, J B; Itow, Y; Kamiya, K; Kilmartin, P M; Korpela, A V; Masuda, K; Matsubara, Y; Motomura, M; Muraki, Y; Nakamura, S; Okada, C; Ohnishi, K; Rattenbury, N J; Sako, T; Sato, S; Sasaki, M; Sekiguchi, T; Sullivan, D J; Tristram, P J; Yock, P M; Yoskioka, T

    2005-11-07

    The favoured theoretical explanation for planetary systems formation is the core-accretion model in which solid planetesimals accumulate to build up planetary cores, which then accrete nebular gas if they are sufficiently massive. Around M-dwarf stars, the most common stars of our Galaxy, this model favours the formation of Earth- to Neptune-mass planets in a few million years with orbital sizes of 1 to 10 AU, which is consistent with the small number of detections of giant planets with M-dwarf host stars. More than 170 extrasolar planets have been discovered so far with a wide range of masses and orbital periods, but planets of Neptune's mass or less have not previously been detected at separations of more than 0.15 AU from normal stars. Here we report the discovery of a 5.5{sub -2.7}{sup +5.5} Earthmass planetary companion at a separation of 2.6{sub -0.6}{sup +1.5}AU from a 0.22{sub -0.11}{sup +0.21} M{sub e} M-dwarf star, which is the lens star for gravitational microlensing event OGLE 2005-BLG-390. This is the lowest mass ever reported for an extrasolar planet orbiting a main sequence star, although the error bars overlap those for the mass of GJ876d. Our detection suggests that such cool, sub-Neptune mass planets may be common than gas giant planets, as predicted by the core accretion theory.

  9. The Microlensing Planet Finder: A Census Of Planetary Systems Like Our Own and Objects Beyond the Kuiper Belt

    NASA Astrophysics Data System (ADS)

    Bennett, David P.; Cheng, E.; Kimble, R.; Mather, J.; Brown, M.; Gould, A.; Anderson, J.; Beaulieu, J.; Bond, I.; Cook, K.; Friedman, S.; Gaudi, S.; Gilliland, R.; Griest, K.; Jenkins, J.; Minniti, D.; Paczynski, B.; Peale, S.; Rich, M.; Sahu, K.; Shao, M.; Tenerelli, D.; Udalski, A.; Yock, P.

    2006-09-01

    The Microlensing Planet Finder (MPF) will complete the first census of extrasolar planets with sensitivity to planets like those in our own Solar System. MPF uses a proven low-mass planet detection method to detect planets with masses greater than 0.1 Earth masses at all separations greater than 0.5 AU from their host stars. MPF's planetary census provides critical data for understanding planet formation and habitability that cannot be obtained by other means. MPF's results complement those of the Kepler mission, which detects Earth-like planets at separations of 1 AU or less. MPF and Kepler overlap at a 1 AU, in the habitable zone for Solar type stars. MPF's employs a 1.1m telescope with a 0.65 square degree FOV that images in the near IR (600-1700nm). MPF's inclined geosynchronous orbit allows continuous data transmission to a dedicated ground station while maintaining continuous, high angular resolution observations of 2.5 square degrees of the central Galactic bulge. This is necessary to discovery terrestrial extrasolar planets at a wide range of orbital separations. If every planetary system has the same planet-star mass ratios and separations as our own Solar System, then MPF detects 150 terrestrial planets, 6000 gas giants, and 130 ice giants. MPF also detects 60 free-floating Earths if there is one such planet per Galactic star. During the 3 months per year when the Galactic bulge cannot be observed, addresses other science goals, such as the follow-up of Kepler planet candidates observations to exclude "false positive” Kepler planet detections. MPF also searches beyond the Kuiper Belt for objects like Sedna to test theories of the Solar System's formation and runs a General Observer program.

  10. Revisiting the Microlensing Event OGLE 2012-BLG-0026: A Solar Mass Star with Two Cold Giant Planets

    NASA Technical Reports Server (NTRS)

    Beaulieu, J.-P.; Bennett, D. P.; Batista, V.; Fukui, A.; Marquette, J.-B.; Brillant, S.; Cole, A. A.; Rogers, L. A.; Sumi, T.; Abe, F.

    2016-01-01

    Two cold gas giant planets orbiting a G-type main-sequence star in the galactic disk were previously discovered in the high-magnification microlensing event OGLE-2012-BLG-0026. Here, we present revised host star flux measurements and a refined model for the two-planet system using additional light curve data. We performed high angular resolution adaptive optics imaging with the Keck and Subaru telescopes at two epochs while the source star was still amplified. We detected the lens flux, H = 16.39 +/- 0.08. The lens, a disk star, is brighter than predicted from the modeling in the original study. We revisited the light curve modeling using additional photometric data from the B and C telescope in New Zealand and CTIO 1.3 m H-band light curve. We then include the Keck and Subaru adaptive optic observation constraints. The system is composed of an approximately 4-9 Gyr lens star of M(sub lens) = 1.06 +/- 0.05 solar mass at a distance of D(sub lens) = 4.0 +/- 0.3 kpc, orbited by two giant planets of 0.145 +/- 0.008 M(sub Jup) and 0.86 +/- 0.06 M(sub Jup), with projected separations of 4.0 +/- 0.5 au and 4.8 +/- 0.7 au, respectively. Because the lens is brighter than the source star by 16 +/- 8% in H, with no other blend within one arcsec, it will be possible to estimate its metallicity using subsequent IR spectroscopy with 8-10 m class telescopes. By adding a constraint on the metallicity it will be possible to refine the age of the system.

  11. Revisiting the Microlensing Event OGLE 2012-BLG-0026: A Solar Mass Star with Two Cold Giant Planets

    NASA Astrophysics Data System (ADS)

    Beaulieu, J.-P.; Bennett, D. P.; Batista, V.; Fukui, A.; Marquette, J.-B.; Brillant, S.; Cole, A. A.; Rogers, L. A.; Sumi, T.; Abe, F.; Bhattacharya, A.; Koshimoto, N.; Suzuki, D.; Tristram, P. J.; Han, C.; Gould, A.; Pogge, R.; Yee, J.

    2016-06-01

    Two cold gas giant planets orbiting a G-type main-sequence star in the galactic disk were previously discovered in the high-magnification microlensing event OGLE-2012-BLG-0026. Here, we present revised host star flux measurements and a refined model for the two-planet system using additional light curve data. We performed high angular resolution adaptive optics imaging with the Keck and Subaru telescopes at two epochs while the source star was still amplified. We detected the lens flux, H = 16.39 ± 0.08. The lens, a disk star, is brighter than predicted from the modeling in the original study. We revisited the light curve modeling using additional photometric data from the B&C telescope in New Zealand and CTIO 1.3 m H-band light curve. We then include the Keck and Subaru adaptive optic observation constraints. The system is composed of a ˜4-9 Gyr lens star of M lens = 1.06 ± 0.05 M ⊙ at a distance of D lens = 4.0 ± 0.3 kpc, orbited by two giant planets of 0.145 ± 0.008 M Jup and 0.86 ± 0.06 M Jup, with projected separations of 4.0 ± 0.5 au and 4.8 ± 0.7 au, respectively. Because the lens is brighter than the source star by 16 ± 8% in H, with no other blend within one arcsec, it will be possible to estimate its metallicity using subsequent IR spectroscopy with 8-10 m class telescopes. By adding a constraint on the metallicity it will be possible to refine the age of the system.

  12. An Analysis for an Internet Grid to Support Space Based Operations

    NASA Technical Reports Server (NTRS)

    Bradford, Robert; McNair, Ann R. (Technical Monitor)

    2002-01-01

    Currently, and in the past, dedicated communication circuits and "network services" with very stringent performance requirements have been used to support manned and unmanned mission critical ground operations at GSFC, JSC, MSFC, KSC and other NASA facilities. Because of the evolution of network technology, it is time to investigate other approaches to providing mission services for space ground and flight operations. In various scientific disciplines, effort is under way to develop network/komputing grids. These grids consisting of networks and computing equipment are enabling lower cost science. Specifically, earthquake research is headed in this direction. With a standard for network and computing interfaces using a grid, a researcher would not be required to develop and engineer NASA/DoD specific interfaces with the attendant increased cost. Use of the Internet Protocol (IP), CCSDS packet spec, and reed-solomon for satellite error correction etc. can be adopted/standardized to provide these interfaces. Generally most interfaces are developed at least to some degree end to end. This study would investigate the feasibility of using existing standards and protocols necessary to implement a SpaceOps Grid. New interface definitions or adoption/modification of existing ones for the various space operational services is required for voice both space based and ground, video, telemetry, commanding and planning may play a role to some undefined level. Security will be a separate focus in the study since security is such a large issue in using public networks. This SpaceOps Grid would be transparent to users. It would be anagulous to the Ethernet protocol's ease of use in that a researcher would plug in their experiment or instrument at one end and would be connected to the appropriate host or server without further intervention. Free flyers would be in this category as well. They would be launched and would transmit without any further intervention with the researcher or

  13. Development Towards a Space Qualified Laser Stabilization System in Support of Space-Based Optical Interferometers

    NASA Technical Reports Server (NTRS)

    Seidel, David J.; Dubovitsky, Serge

    2000-01-01

    We report on the development, functional performance and space-qualification status of a laser stabilization system supporting a space-based metrology source used to measure changes in optical path lengths in space-based stellar interferometers. The Space Interferometry Mission (SIM) and Deep Space 3 (DS-3) are two missions currently funded by the National Aeronautics and Space Administration (NASA) that are space-based optical interferometers. In order to properly recombine the starlight received at each telescope of the interferometer it is necessary to perform high resolution laser metrology to stabilize the interferometer. A potentially significant error source in performing high resolution metrology length measurements is the potential for fluctuations in the laser gauge itself. If the laser frequency or wavelength is changing over time it will be misinterpreted as a length change in one of the legs of the interferometer. An analysis of the frequency stability requirement for SIM resulted in a fractional frequency stability requirement of square root (S(sub y)(f)) = <2 x 10(exp -12)/square root(Hz) at Fourier frequencies between 10 Hz and 1000 Hz. The DS-3 mission stability requirement is further increased to square root (S(sub y)(f)) = <5 x 10(exp -14)/Square root(Hz) at Fourier frequencies between 0.2 Hz and 10 kHz with a goal of extending the low frequency range to 0.05 Hz. The free running performance of the Lightwave Electronics NPRO lasers, which are the baseline laser for both SIM and DS-3 vary in stability and we have measured them to perform as follows (9 x l0(exp -11)/ f(Hz))(Hz)/square root(Hz)) = <( square root (S(sub y)(f)) = <(1.3 x l0(exp -8)/ f(Hz))/Square root(Hz). In order to improve the frequency stability of the laser we stabilize the laser to a high finesse optical cavity by locking the optical frequency of the laser to one of the transmission modes of the cavity. At JPL we have built a prototype space-qualifiable system meeting the

  14. Advanced Technologies for Future Spacecraft Cockpits and Space-based Control Centers

    NASA Technical Reports Server (NTRS)

    Garcia-Galan, Carlos; Uckun, Serdar; Gregory, William; Williams, Kerry

    2006-01-01

    The National Aeronautics and Space Administration (NASA) is embarking on a new era of Space Exploration, aimed at sending crewed spacecraft beyond Low Earth Orbit (LEO), in medium and long duration missions to the Lunar surface, Mars and beyond. The challenges of such missions are significant and will require new technologies and paradigms in vehicle design and mission operations. Current roles and responsibilities of spacecraft systems, crew and the flight control team, for example, may not be sustainable when real-time support is not assured due to distance-induced communication lags, radio blackouts, equipment failures, or other unexpected factors. Therefore, technologies and applications that enable greater Systems and Mission Management capabilities on-board the space-based system will be necessary to reduce the dependency on real-time critical Earth-based support. The focus of this paper is in such technologies that will be required to bring advance Systems and Mission Management capabilities to space-based environments where the crew will be required to manage both the systems performance and mission execution without dependence on the ground. We refer to this concept as autonomy. Environments that require high levels of autonomy include the cockpits of future spacecraft such as the Mars Exploration Vehicle, and space-based control centers such as a Lunar Base Command and Control Center. Furthermore, this paper will evaluate the requirements, available technology, and roadmap to enable full operational implementation of onboard System Health Management, Mission Planning/re-planning, Autonomous Task/Command Execution, and Human Computer Interface applications. The technology topics covered by the paper include enabling technology to perform Intelligent Caution and Warning, where the systems provides directly actionable data for human understanding and response to failures, task automation applications that automate nominal and Off-nominal task execution based

  15. Size of the Accretion Disk in the Graviationally Lensed Quasar SDSS J1004+4112 from the Statistics of Microlensing Magnifications

    NASA Astrophysics Data System (ADS)

    Fian, C.; Mediavilla, E.; Hanslmeier, A.; Oscoz, A.; Serra-Ricart, M.; Muñoz, J. A.; Jiménez-Vicente, J.

    2016-10-01

    We present eight monitoring seasons of the four brightest images of the gravitational lens SDSS J1004+4112 observed between 2003 December and 2010 October. Using measured time delays for the images A, B, and C and the model predicted time delay for image D we have removed the intrinsic quasar variability, finding microlensing events of about 0.5 and 0.7 mag of amplitude in the images C and D. From the statistics of microlensing amplitudes in images A, C, and D, we have inferred the half-light radius (at {λ }{rest}=2407 \\mathringA ) for the accretion disk using two different methods, {R}1/2={8.7}-5.5+18.5\\sqrt{M/0.3{M}⊙ } (histogram product) and {R}1/2={4.2}-2.2+3.2\\sqrt{M/0.3{M}⊙ } lt-days ({χ }2). The results are in agreement within uncertainties with the size predicted from the black hole mass in SDSS J1004+4112 using thin disk theory.

  16. New method to measure proper motions of microlensed sources: Application to candidate free-floating-planet event MOA-2011-BLG-262

    SciTech Connect

    Skowron, Jan; Udalski, Andrzej; Szymański, Michał K. E-mail: udalski@astrouw.edu.pl; and others

    2014-04-20

    We develop a new method to measure source proper motions in microlensing events, which can partially overcome problems due to blending. It takes advantage of the fact that the source position is known precisely from the microlensing event itself. We apply this method to the event MOA-2011-BLG-262, which has a short timescale t {sub E} = 3.8 day, a companion mass ratio q = 4.7 × 10{sup –3}, and a very high or high lens-source relative proper motion μ{sub rel} = 20 mas yr{sup –1} or 12 mas yr{sup –1} (for two possible models). These three characteristics imply that the lens could be a brown dwarf or a massive planet with a roughly Earth-mass 'moon'. The probability of such an interpretation would be greatly increased if it could be shown that the high lens-source relative proper motion was primarily due to the lens rather than the source. Based on the long-term monitoring data of the Galactic bulge from the Optical Gravitational Lensing Experiment, we measure the source proper motion that is small, μ{sub s}=(−2.3,−0.9)±(2.8,2.6) mas yr{sup −1} in a (north, east) Galactic coordinate frame. These values are then important input into a Bayesian analysis of the event presented in a companion paper by Bennett et al.

  17. Analysis of Light Gathering Abilities of Dynamically Solidified Micro-lenses, and Their Implementation to Improve Sensitivity of Fluorescent PCR Micro-detectors.

    PubMed

    Wu, Jian; Guo, Wei; Wang, Chunyan; Yu, Kuanxin; Chen, Tao; Li, Yinghui

    2015-06-01

    Fluorescent polymerase chain reaction (PCR) is becoming the preferred method of quantitative analysis due to its high specificity and sensitivity. We propose to use a new kind of micro-lens, dynamically solidified with optic glue, to improve the sensitivity of fluorescent PCR micro-detector. We developed light ray track equations for these lenses and used them to calculate relative light intensity distribution curve for stimulation lenses and illumination point probability distribution curve for detection lenses. We manufactured dynamically solidified micro-lenses using optic glue NOA61, and measured their light gathering ability. Lenses with radius/thickness (R/H) ratio of 4 reached light focusing ratio of 3.85 (stimulation lens) and photon collection efficiency of 0.86 (detection lens). We then used dynamically solidified lenses in PCR fluorescence micro-detector and analyzed their effect on the detector sensitivity. We showed that the use of dynamically solidified micro-lenses with R/H = 4 resulted in over 4.4-fold increased sensitivity of the detector.

  18. Comparing Laser Interferometry and Atom Interferometry Approaches to Space-Based Gravitational-Wave Measurement

    NASA Technical Reports Server (NTRS)

    Baker, John; Thorpe, Ira

    2012-01-01

    Thoroughly studied classic space-based gravitational-wave missions concepts such as the Laser Interferometer Space Antenna (LISA) are based on laser-interferometry techniques. Ongoing developments in atom-interferometry techniques have spurred recently proposed alternative mission concepts. These different approaches can be understood on a common footing. We present an comparative analysis of how each type of instrument responds to some of the noise sources which may limiting gravitational-wave mission concepts. Sensitivity to laser frequency instability is essentially the same for either approach. Spacecraft acceleration reference stability sensitivities are different, allowing smaller spacecraft separations in the atom interferometry approach, but acceleration noise requirements are nonetheless similar. Each approach has distinct additional measurement noise issues.

  19. Plans for a Next Generation Space-Based Gravitational-Wave Observatory (NGO)

    NASA Technical Reports Server (NTRS)

    Livas, Jeffrey C.; Stebbins, Robin T.; Jennrich, Oliver

    2012-01-01

    The European Space Agency (ESA) is currently in the process of selecting a mission for the Cosmic Visions Program. A space-based gravitational wave observatory in the low-frequency band (0.0001 - 1 Hz) of the gravitational wave spectrum is one of the leading contenders. This low frequency band has a rich spectrum of astrophysical sources, and the LISA concept has been the key mission to cover this science for over twenty years. Tight budgets have recently forced ESA to consider a reformulation of the LISA mission concept that wi" allow the Cosmic Visions Program to proceed on schedule either with the US as a minority participant, or independently of the US altogether. We report on the status of these reformulation efforts.

  20. Advancement of High Power Quasi-CW Laser Diode Arrays For Space-based Laser Instruments

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin; Meadows, Byron L.; Baker, nathaniel R.; Baggott, Renee S.; Singh, Upendra N.; Kavaya, Michael J.

    2004-01-01

    Space-based laser and lidar instruments play an important role in NASA s plans for meeting its objectives in both Earth Science and Space Exploration areas. Almost all the lidar instrument concepts being considered by NASA scientist utilize moderate to high power diode-pumped solid state lasers as their transmitter source. Perhaps the most critical component of any solid state laser system is its pump laser diode array which essentially dictates instrument efficiency, reliability and lifetime. For this reason, premature failures and rapid degradation of high power laser diode arrays that have been experienced by laser system designers are of major concern to NASA. This work addresses these reliability and lifetime issues by attempting to eliminate the causes of failures and developing methods for screening laser diode arrays and qualifying them for operation in space.