Science.gov

Sample records for finder coronagraph simulations

  1. Terrestrial Planet Finder Coronagraph Observatory summary

    NASA Technical Reports Server (NTRS)

    Ford, Virginia; Levine-Westa, Marie; Kissila, Andy; Kwacka, Eug; Hoa, Tim; Dumonta, Phil; Lismana, Doug; Fehera, Peter; Cafferty, Terry

    2005-01-01

    Creating an optical space telescope observatory capable of detecting and characterizing light from extra-solar terrestrial planets poses technical challenges related to extreme wavefront stability. The Terrestrial Planet Finder Coronagraph design team has been developing an observatory based on trade studies, modeling and analysis that has guided us towards design choices to enable this challenging mission. This paper will describe the current flight baseline design of the observatory and the trade studies that have been performed. The modeling and analysis of this design will be described including predicted performance and the tasks yet to be done.

  2. Terrestrial Planet Finder coronagraph status and enabling technologies

    NASA Technical Reports Server (NTRS)

    Ford, Virginia G.; Lisman, Douglas; Shaklan, Stuart B.; Ho, Timothy Y.; Kissil, Andrew; Kwack, Eug-Yun; Lowman, Andrew

    2004-01-01

    The goal of the Terrestrial Planet Finder Project Mission is to find life-bearing planets around nearby stars. Two types of instruments are competing for flight in 2015: a visible coronagraph and an infrared interferometer.

  3. Terrestrial Planet Finder coronagraph status and enabling technologies

    NASA Technical Reports Server (NTRS)

    Ford, Virginia G.; Lisman, Douglas; Shaklan, Stuart B.; Ho, Timothy Y.; Kissil, Andrew; Kwack, Eug-Yun; Lowman, Andrew

    2004-01-01

    The goal of the Terrestrial Planet Finder Project Mission is to find life-bearing planets around nearby stars. Two types of instruments are competing for flight in 2015: a visible coronagraph and an infrared interferometer.

  4. The Terrestrial Planet Finder coronagraph dynamics error budget

    NASA Technical Reports Server (NTRS)

    Shaklan, Stuart B.; Marchen, Luis; Green, Joseph J.; Lay, Oliver P.

    2005-01-01

    The Terrestrial Planet Finder Coronagraph (TPF-C) demands extreme wave front control and stability to achieve its goal of detecting earth-like planets around nearby stars. We describe the performance models and error budget used to evaluate image plane contrast and derive engineering requirements for this challenging optical system.

  5. The Terrestrial Planet Finder coronagraph dynamics error budget

    NASA Technical Reports Server (NTRS)

    Shaklan, Stuart B.; Marchen, Luis; Green, Joseph J.; Lay, Oliver P.

    2005-01-01

    The Terrestrial Planet Finder Coronagraph (TPF-C) demands extreme wave front control and stability to achieve its goal of detecting earth-like planets around nearby stars. We describe the performance models and error budget used to evaluate image plane contrast and derive engineering requirements for this challenging optical system.

  6. Comparison of several coronagraphic approaches to the Terrestrial Planet Finder

    NASA Astrophysics Data System (ADS)

    Ridgway, Stephen T.; Burrows, Christopher J.; Friedman, Edward J.; Gezari, Daniel Y.; Harwit, Martin O.; Kaplan, Michael H.; Kaylor, Larry; Lyon, Richard G.; Melnick, Gary J.; Nisenson, Peter; Peterson, Lee D.; Spergel, David N.; Woodruff, Robert A.

    2003-10-01

    Planetological and technical issues have led to a renewed interest in visible coronographic concepts for a Terrestrial Planet Finder mission. This has stimulated rapid development of new, generalized coronagraphic techniques, including exotic apodizations and nulling schemes. Hitherto, it has been difficult to compare different concepts, owing to the complex interaction between details of the concepts and instrument and mission parameters and optimization.

  7. High Contrast Imaging Testbed for the Terrestrial Planet Finder Coronagraph

    NASA Technical Reports Server (NTRS)

    Lowmman, Andrew E.; Trauger, John T.; Gordon, Brian; Green, Joseph J.; Moody, Dwight; Niessner, Albert F.; Shi, Fang

    2004-01-01

    The Terrestrial Planet Finder (TPF) mission is planning to launch a visible coronagraphic space telescope in 2014. To achieve TPF science goals, the coronagraph must have extreme levels of wavefront correction (less than 1 Angstrom rms over controllable spatial frequencies) and stability to get the necessary suppression of diffracted starlight (approximately l0(exp -10)) contrast at an angular separation approximately 4 (lamda)/D). TPF Coronagraph's primary platform for experimentation is the High Contrast Imaging Testbed, which will provide laboratory validation of key technologies as well as demonstration of a flight-traceable approach to implementation. Precision wavefront control in the testbed is provided by a high actuator density deformable mirror. Diffracted light control is achieved through use of occulting or apodizing masks and stops. Contrast measurements will establish the technical feasibility of TPF requirements, while model and error budget validation will demonstrate implementation viability. This paper describes the current testbed design, development approach, and recent experimental results.

  8. Metrology system for the Terrestrial Planet Finder Coronagraph

    NASA Technical Reports Server (NTRS)

    Shaklin, Stuart; Marchen, Luis; Zhao, Feng; Peters, Robert D.; Ho, Tim; Holmes, Buck

    2004-01-01

    The Terrestrial Planet Finder (TPF) employs an aggressive coronagraph designed to obtain better than 1e-10 contrast inside the third Airy ring. Minute changes in low-order aberration content scatter significant light at this position. One implication is the requirement to control low-order aberrations induced by motion of the secondary mirror relative to the primary mirror; sub-nanometer relative positional stability is required. We propose a 6-beam laser truss to monitor the relative positions of the two mirrors. The truss is based on laser metrology developed for the Space Interferometry Mission.

  9. Terrestrial Planet Finder Coronagraph overview of technology development & system design

    NASA Technical Reports Server (NTRS)

    Balasubramanian, Kunjuthapatham; Ford, Virginia; Mouroulis, Pantazis; Hoppe, Daniel; Shaklan, Stuart

    2004-01-01

    Astronomers have discovered over 150 planets orbiting other stars. NASA mission; Find and characterize terrestrial (or rocky) exo-planets that might harbor life (like Earth)liquid water on the planet (habitable zone). An atmosphere that indicates the presence of life water, oxygen, ozone, carbon dioxide, chlorophyll, and methane. Two missions under development: A coronagraph and an interferometer.

  10. The Terrestrial Planet Finder Coronagraph Optical Surface Requirements

    NASA Technical Reports Server (NTRS)

    Shaklan, Stuart B.; Green, Joseph J.; Palacios, David M.

    2006-01-01

    Coronagraph telescope and instrument optics for spatial frequencies within and beyond the spatial control bandwidth of the wave front control system. Three different wave front control systems are considered: a zero-path difference Michelson interferometer with two deformable mirrors at a pupil image; a sequential pair of deformable mirrors with one placed at a pupil image; and the Visible Nuller spatially-filtered controller. We show that the optical bandwidth limits the useful outer working angle.

  11. A vector diffraction model of wave propagation in a coronagraphic terrestrial planet finder

    NASA Astrophysics Data System (ADS)

    Shiri, Shahram; Lyon, Richard G.; Woodruff, Robert A.; Antosik, Roman

    2004-10-01

    In this work we study vector electromagnetic wave propagation in a visible-light coronagraph for applications to the design and analysis of Terrestrial Planet Finder (TPF). A visible light coronagraph in TPF requires detection of a terrestrial planet which is ~1010 dimmer than the central stellar source. Consequently, any theory used to design and analyze TPF requires accuracy better than 10-10 in intensity or 10-5 in electric field. Current coronagraphic approaches to TPF have relied on scalar diffraction theory. However, the vector nature of light requires a vector approach to the problem. In this study we employ a time-harmonic vector theory to study the electromagnetic field propagation through metallic focal plane occulting mask on dielectric substrate. We use parallelized edge-based vector finite element model to compute the wave propagation in a three-dimensional tetrahedral grid representing the geometry of the coronagraph. The edge-based finite element method overcomes the problem of modal propagation and rigorously enforces the field divergence to be zero. The reflectivity and transmittivity in the geometry are computed through the gold metal in various shapes using a planar incident beam. Subsequently, the near-field beam diffraction around the mask is investigated.

  12. Terrestrial Planet Finder Coronagraph 2005: Overview of Technology Development and System Design Studies

    NASA Technical Reports Server (NTRS)

    Ford, Virginia G.

    2005-01-01

    Technology research, design trades, and modeling and analysis guide the definition of a Terrestrial Planet Finder Coronagraph Mission that will search for and characterize earth-like planets around near-by stars. Operating in visible wavebands, this mission will use coronagraphy techniques to suppress starlight to enable capturing and imaging the reflected light from a planet orbiting in the habitable zone of its parent star. The light will be spectrally characterized to determine the presence of life-indicating chemistry in the planet atmosphere.

  13. Terrestrial Planet Finder Coronagraph 2005: Overview of Technology Development and System Design Studies

    NASA Technical Reports Server (NTRS)

    Ford, Virginia G.

    2005-01-01

    Technology research, design trades, and modeling and analysis guide the definition of a Terrestrial Planet Finder Coronagraph Mission that will search for and characterize earth-like planets around near-by stars. Operating in visible wavebands, this mission will use coronagraphy techniques to suppress starlight to enable capturing and imaging the reflected light from a planet orbiting in the habitable zone of its parent star. The light will be spectrally characterized to determine the presence of life-indicating chemistry in the planet atmosphere.

  14. Passive isolator design for jitter reduction in the Terrestrial Planet Finder Coronagraph

    NASA Technical Reports Server (NTRS)

    Blaurock, Carl; Liu, Kuo-Chia; Dewell, Larry; Alexander, James

    2005-01-01

    Terrestrial Planet Finder (TPF) is a mission to locate and study extrasolar Earth-like planets. The TPF Coronagraph (TPF-C), planned for launch in the latter half of the next decade, will use a coronagraphic mask and other optics to suppress the light of the nearby star in order to collect visible light from such planets. The required contrast ratio of 5e-11 can only be achieved by maintaining pointing accuracy to 4 milli-arcseconds, and limiting optics jitter to below 5 nm. Numerous mechanical disturbances act to induce jitter. This paper concentrates on passive isolation techniques to minimize the optical degradation introduced by disturbance sources. A passive isolation system, using compliant mounts placed at an energy bottleneck to reduce energy transmission above a certain frequency, is a low risk, flight proven design approach. However, the attenuation is limited, compared to an active system, so the feasibility of the design must be demonstrated by analysis. The paper presents the jitter analysis for the baseline TPF design, using a passive isolation system. The analysis model representing the dynamics of the spacecraft and telescope is described, with emphasis on passive isolator modeling. Pointing and deformation metrics, consistent with the TPF-C error budget, are derived. Jitter prediction methodology and results are presented. Then an analysis of the critical design parameters that drive the TPF-C jitter response is performed.

  15. An extensive coronagraphic simulation applied to LBT

    NASA Astrophysics Data System (ADS)

    Vassallo, D.; Carolo, E.; Farinato, J.; Bergomi, M.; Bonavita, M.; Carlotti, A.; D'Orazi, V.; Greggio, D.; Magrin, D.; Mesa, D.; Pinna, E.; Puglisi, A.; Stangalini, M.; Verinaud, C.; Viotto, V.

    2016-08-01

    In this article we report the results of a comprehensive simulation program aimed at investigating coronagraphic capabilities of SHARK-NIR, a camera selected to proceed to the final design phase at Large Binocular Telescope. For the purpose, we developed a dedicated simulation tool based on physical optics propagation. The code propagates wavefronts through SHARK optical train in an end-to-end fashion and can implement any kind of coronagraph. Detection limits can be finally computed, exploring a wide range of Strehl values and observing conditions.

  16. Linear Thermal Expansion Measurements of Lead Magnesium Niobate (PMN) Electroceramic Material for the Terrestrial Planet Finder Coronagraph

    NASA Technical Reports Server (NTRS)

    Karlmann, Paul B.; Halverson, Peter G.; Peters, Robert D.; Levine, Marie B.; VanBuren, David; Dudik, Matthew J.

    2005-01-01

    Linear thermal expansion measurements of nine samples of Lead Magnesium Niobate (PMN) electroceramic material were recently performed in support of NASA's Terrestrial Planet Finder Coronagraph (TPF-C) mission. The TPF-C mission is a visible light coronagraph designed to look at roughly 50 stars pre- selected as good candidates for possessing earth-like planets. Upon detection of an earth-like planet, TPF-C will analyze the visible-light signature of the planet's atmosphere for specific spectroscopic indicators that life may exist there. With this focus, the project's primary interest in PMN material is for use as a solid-state actuator for deformable mirrors or compensating optics. The nine test samples were machined from three distinct boules of PMN ceramic manufactured by Xinetics Inc. Thermal expansion measurements were performed in 2005 at NASA Jet Propulsion Laboratory (JPL) in their Cryogenic Dilatometer Facility. All measurements were performed in vacuum with sample temperature actively controlled over the range of 270K to 3 10K. Expansion and contraction of the test samples with temperature was measured using a JPL developed interferometric system capable of sub-nanometer accuracy. Presented in this paper is a discussion of the sample configuration, test facilities, test method, data analysis, test results, and future plans.

  17. Linear Thermal Expansion Measurements of Lead Magnesium Niobate (PMN) Electroceramic Material for the Terrestrial Planet Finder Coronagraph

    NASA Technical Reports Server (NTRS)

    Karlmann, Paul B.; Halverson, Peter G.; Peters, Robert D.; Levine, Marie B.; VanBuren, David; Dudik, Matthew J.

    2005-01-01

    Linear thermal expansion measurements of nine samples of Lead Magnesium Niobate (PMN) electroceramic material were recently performed in support of NASA's Terrestrial Planet Finder Coronagraph (TPF-C) mission. The TPF-C mission is a visible light coronagraph designed to look at roughly 50 stars pre- selected as good candidates for possessing earth-like planets. Upon detection of an earth-like planet, TPF-C will analyze the visible-light signature of the planet's atmosphere for specific spectroscopic indicators that life may exist there. With this focus, the project's primary interest in PMN material is for use as a solid-state actuator for deformable mirrors or compensating optics. The nine test samples were machined from three distinct boules of PMN ceramic manufactured by Xinetics Inc. Thermal expansion measurements were performed in 2005 at NASA Jet Propulsion Laboratory (JPL) in their Cryogenic Dilatometer Facility. All measurements were performed in vacuum with sample temperature actively controlled over the range of 270K to 3 10K. Expansion and contraction of the test samples with temperature was measured using a JPL developed interferometric system capable of sub-nanometer accuracy. Presented in this paper is a discussion of the sample configuration, test facilities, test method, data analysis, test results, and future plans.

  18. Linear thermal expansion measurements of lead magnesium niobate (PMN) electroceramic material for the Terrestrial Planet Finder Coronagraph

    NASA Astrophysics Data System (ADS)

    Karlmann, Paul B.; Klein, Kerry J.; Halverson, Peter G.; Peters, Robert D.; Levine, Marie B.; Van Buren, David; Dudik, Matthew J.

    2005-08-01

    Linear thermal expansion measurements of nine samples of Lead Magnesium Niobate (PMN) electroceramic material were recently performed in support of NASA's Terrestrial Planet Finder Coronagraph (TPF-C) mission. The TPF-C mission is a visible light coronagraph designed to look at roughly 50 stars pre-selected as good candidates for possessing earth-like planets. Upon detection of an earth-like planet, TPF-C will analyze the visible-light signature of the planet's atmosphere for specific spectroscopic indicators that life may exist there. With this focus, the project's primary interest in PMN material is for use as a solid-state actuator for deformable mirrors or compensating optics. The nine test samples were machined from three distinct boules of PMN ceramic manufactured by Xinetics Inc. Thermal expansion measurements were performed in 2005 at NASA Jet Propulsion Laboratory (JPL) in their Cryogenic Dilatometer Facility. All measurements were performed in vacuum with sample temperature actively controlled over the range of 270K to 310K. Expansion and contraction of the test samples with temperature was measured using a JPL-developed interferometric system capable of sub-nanometer accuracy. Presented in this paper is a discussion of the sample configuration, test facilities, test method, data analysis, test results, and future plans.

  19. Development of the Terrestrial Planet Finder Coronagraph membrane V-grooves

    NASA Technical Reports Server (NTRS)

    Fang, Houfei; Ho, Timothy; Chen, Gun-Shing; Quijano, Ubaldo

    2004-01-01

    The Terrestrial Planet Finder mission will study all aaspecs of planets outside our solar system: from their formation and development in disks of dust and gas around newly forming stars to the presence of those planets orbiting the nearest stars; from the numbers at various sizes and places to their suitability as an abode for life.

  20. Simulations of JWST MIRI 4QPM coronagraphs operations and performances

    NASA Astrophysics Data System (ADS)

    Lajoie, Charles-Philippe; Soummer, Rémi; Hines, Dean C.; Rieke, George H.

    2014-08-01

    We present the results of ongoing coronagraphic simulations aimed at designing strategies for optimizing oper- ations of the coronagraphs in the mid-infrared instrument (MIRI) on-board the James Webb Space Telescope (JWST). In particular, the adverse effects on the point spread function caused by the phase mask coronagraphs and the observatory slew accuracy are known to limit our ability to position stars at the center of the coron- agraph. Here, we investigate these two effects on our ability to perform target acquisition (TA) and consider different scenarios involving single and multiple acquisitions to mitigate them. We assess the performance of the coronagraphs under various slew accuracy models as well as noise sources. In general, we find that scenarios that require fewer acquisitions yield final positions with smaller dispersions but larger offsets. Our Single TA scenario yields the best repeatability for all three slew accuracy models that we considered although a dual Twin TA strategy generally yields more accurate centering. We also investigate the use of the contamination control cover (CCC) inside MIRI during TA of bright objects, and ways to mitigate the resulting latent images when the CCC is not used. Our results are expressed in terms of achieved contrast with simple, single reference star subtraction. Given our preliminary prescription for latency, our simulations suggest that the CCC need not be used except for very bright sources; detailed guidelines will require additional information on the latent image decay time scale. Furthermore, we find that contrast is dependent on the observatory slew accuracy at any wavelength. The highest contrast is achieved with the highest slew accuracy model, although the background photon noise limits the contrast at longer wavelengths.

  1. Advanced computer graphic techniques for laser range finder (LRF) simulation

    NASA Astrophysics Data System (ADS)

    Bedkowski, Janusz; Jankowski, Stanislaw

    2008-11-01

    This paper show an advanced computer graphic techniques for laser range finder (LRF) simulation. The LRF is the common sensor for unmanned ground vehicle, autonomous mobile robot and security applications. The cost of the measurement system is extremely high, therefore the simulation tool is designed. The simulation gives an opportunity to execute algorithm such as the obstacle avoidance[1], slam for robot localization[2], detection of vegetation and water obstacles in surroundings of the robot chassis[3], LRF measurement in crowd of people[1]. The Axis Aligned Bounding Box (AABB) and alternative technique based on CUDA (NVIDIA Compute Unified Device Architecture) is presented.

  2. Band-limited image plane masks for the Terrestrial Planet Finder coronagraph: materials and designs for broadband performance.

    PubMed

    Balasubramanian, Kunjithapatham

    2008-01-10

    Coronagraphs for detection and characterization of exosolar earthlike planets require accurate masks with broadband performance in the visible and near infrared spectrum. Design and fabrication of image plane masks capable of suppressing broadband starlight to 10(-10) level contrast presents technical challenges. We discuss basic approaches, material choices, designs, and fabrication options for image plane masks with particular focus on material properties to obtain adequate spectral performance. Based on theoretical analysis, we show that metals such as Pt and Ni, and alloys such as Inconel, may be employed as promising mask materials that can meet broadband performance requirements.

  3. End-to-end simulations of the E-ELT/METIS coronagraphs

    NASA Astrophysics Data System (ADS)

    Carlomagno, Brunella; Absil, Olivier; Kenworthy, Matthew; Ruane, Garreth; Keller, Christoph U.; Otten, Gilles; Feldt, Markus; Hippler, Stefan; Huby, Elsa; Mawet, Dimitri; Delacroix, Christian; Surdej, Jean; Habraken, Serge; Forsberg, Pontus; Karlsson, Mikael; Vargas Catalan, Ernesto; Brandl, Bernhard R.

    2016-07-01

    The direct detection of low-mass planets in the habitable zone of nearby stars is an important science case for future E-ELT instruments such as the mid-infrared imager and spectrograph METIS, which features vortex phase masks and apodizing phase plates (APP) in its baseline design. In this work, we present end-to-end performance simulations, using Fourier propagation, of several METIS coronagraphic modes, including focal-plane vortex phase masks and pupil-plane apodizing phase plates, for the centrally obscured, segmented E-ELT pupil. The atmosphere and the AO contributions are taken into account. Hybrid coronagraphs combining the advantages of vortex phase masks and APPs are considered to improve the METIS coronagraphic performance.

  4. Comparison of Simulated Contrast Performance of Different Phase Induced Amplitude Apodization (PIAA) Coronagraph Configurations

    NASA Technical Reports Server (NTRS)

    Sidick, Erkin; Kern, Brian; Kuhnert, Andreas; Shaklan, Stuart

    2013-01-01

    We compare the broadband contrast performances of several Phase Induced Amplitude Apodization (PIAA) coronagraph configurations through modeling and simulations. The basic optical design of the PIAA coronagraph is the same as NASA's High Contrast Imaging Testbed (HCIT) setup at the Jet Propulsion Laboratory (JPL). Using a deformable mirror and a broadband wavefront sensing and control algorithm, we create a "dark hole" in the broadband point-spread function (PSF) with an inner working angle (IWA) of 2(f lambda/D)(sub sky). We evaluate two systems in parallel. One is a perfect system having a design PIAA output amplitude and not having any wavefront error at its exit-pupil. The other is a realistic system having a design PIAA output amplitude and the measured residual wavefront error. We also investigate the effect of Lyot stops of various sizes when a postapodizer is and is not present. Our simulations show that the best 7.5%-broadband contrast value achievable with the current PIAA coronagraph is approximately 1.5x10(exp -8).

  5. TPF coronagraph instrument design

    NASA Technical Reports Server (NTRS)

    Shaklan, S B.; Balasubramanian, K.; Ceperly, D.; Green, J.; Hoppe, D.; Lay, O. P.; Lisman, P. D.; Mouroulis, P. Z.

    2005-01-01

    For the past 2 years, NASA has invested substantial resources to study the design and performance of the Terrestrial Planet Finder Coronagraph (TPF-C). The work, led by the Jet Propulsion Laboratory with collaboration from Goddard Space Flight Center and several university and commercial entities, encompasses observatory design, performance modeling, materials characterization, primary mirror studies, and a significant technology development effort including a high-contrast imaging testbed that has achieved 1e-9 contrast in a laboratory experiment.

  6. Accurate time delay technology in simulated test for high precision laser range finder

    NASA Astrophysics Data System (ADS)

    Chen, Zhibin; Xiao, Wenjian; Wang, Weiming; Xue, Mingxi

    2015-10-01

    With the continuous development of technology, the ranging accuracy of pulsed laser range finder (LRF) is higher and higher, so the maintenance demand of LRF is also rising. According to the dominant ideology of "time analog spatial distance" in simulated test for pulsed range finder, the key of distance simulation precision lies in the adjustable time delay. By analyzing and comparing the advantages and disadvantages of fiber and circuit delay, a method was proposed to improve the accuracy of the circuit delay without increasing the count frequency of the circuit. A high precision controllable delay circuit was designed by combining the internal delay circuit and external delay circuit which could compensate the delay error in real time. And then the circuit delay accuracy could be increased. The accuracy of the novel circuit delay methods proposed in this paper was actually measured by a high sampling rate oscilloscope actual measurement. The measurement result shows that the accuracy of the distance simulated by the circuit delay is increased from +/- 0.75m up to +/- 0.15m. The accuracy of the simulated distance is greatly improved in simulated test for high precision pulsed range finder.

  7. Simulating a Direction-Finder Search for an ELT

    NASA Technical Reports Server (NTRS)

    Bream, Bruce

    2005-01-01

    A computer program simulates the operation of direction-finding equipment engaged in a search for an emergency locator transmitter (ELT) aboard an aircraft that has crashed. The simulated equipment is patterned after the equipment used by the Civil Air Patrol to search for missing aircraft. The program is designed to be used for training in radio direction-finding and/or searching for missing aircraft without incurring the expense and risk of using real aircraft and ground search resources. The program places a hidden ELT on a map and enables the user to search for the location of the ELT by moving a 14 NASA Tech Briefs, March 2005 small aircraft image around the map while observing signal-strength and direction readings on a simulated direction- finding locator instrument. As the simulated aircraft is turned and moved on the map, the program updates the readings on the direction-finding instrument to reflect the current position and heading of the aircraft relative to the location of the ELT. The software is distributed in a zip file that contains an installation program. The software runs on the Microsoft Windows 9x, NT, and XP operating systems.

  8. Simulations of Detectability of Extrasolar Planets by a Joint Doppler and WFIRST-AFTA Coronagraph Survey

    NASA Astrophysics Data System (ADS)

    Chontos, Ashley; Macintosh, Bruce; Nielsen, Eric L.

    2016-01-01

    A long-term goal for the astronomical community is to image and characterize an Earth-like planet. The WFIRST-AFTA space mission will make advancements towards this goal. WFIRST will include a coronagraphic instrument to discover and characterize new exoplanets and to better characterize already known exoplanets. We present results of simulations using a Doppler survey to find lower mass planets as possible targets for WFIRST. For simulations, simplified completeness estimates (Howard & Fulton 2014) are used to test the sensitivity of a prospective Doppler campaign. We use data from the HARPS spectrograph to determine exposure times needed to achieve 1 m/s uncertainty. Stellar jitter was randomly sampled from a uniform distribution based on spectral type, treating OBA-type, FGK-type, and M-type stars separately. For survey parameters, we use campaign parameters from the WIYN telescope, assuming 10 hours per night at 100 nights per year over 6 years. In any one simulation, we find roughly 45-50 new planets that are potentially observable by WFIRST. By limiting our targets to FGKM type stars within 10 parsecs, we expect one of those planets to be less than 10 ME.

  9. Path Finder

    SciTech Connect

    Rigdon, J. Brian; Smith, Marcus Daniel; Mulder, Samuel A

    2014-01-07

    PathFinder is a graph search program, traversing a directed cyclic graph to find pathways between labeled nodes. Searches for paths through ordered sequences of labels are termed signatures. Determining the presence of signatures within one or more graphs is the primary function of Path Finder. Path Finder can work in either batch mode or interactively with an analyst. Results are limited to Path Finder whether or not a given signature is present in the graph(s).

  10. Low-order aberration sensitivity of eighth-order coronagraph masks

    NASA Technical Reports Server (NTRS)

    Shaklan, Stuart B.; Green, Joseph J.

    2005-01-01

    In a recent paper, Kuchner, Crepp, and Ge describe new image-plane coronagraph mask designs that reject to eighth order the leakage of starlight caused by image motion at the mask, resulting in a substantial relaxation of image centroiding requirements compared to previous fourth-order and second-order masks. They also suggest that the new masks are effective at rejecting leakage caused by low-order aberrations (e.g., focus, coma, and astigmatism). In this paper, we derive the sensitivity of eighth-order masks to aberrations of any order and provide simulations of coronagraph behavior in the presence of optical aberrations.We find that the masks leak light as the fourth power of focus, astigmatism, coma, and trefoil. This has tremendous performance advantages for the Terrestrial Planet Finder Coronagraph.

  11. Simulation-Based Verification of Autonomous Controllers via Livingstone PathFinder

    NASA Technical Reports Server (NTRS)

    Lindsey, A. E.; Pecheur, Charles

    2004-01-01

    AI software is often used as a means for providing greater autonomy to automated systems, capable of coping with harsh and unpredictable environments. Due in part to the enormous space of possible situations that they aim to addrs, autonomous systems pose a serious challenge to traditional test-based verification approaches. Efficient verification approaches need to be perfected before these systems can reliably control critical applications. This publication describes Livingstone PathFinder (LPF), a verification tool for autonomous control software. LPF applies state space exploration algorithms to an instrumented testbed, consisting of the controller embedded in a simulated operating environment. Although LPF has focused on NASA s Livingstone model-based diagnosis system applications, the architecture is modular and adaptable to other systems. This article presents different facets of LPF and experimental results from applying the software to a Livingstone model of the main propulsion feed subsystem for a prototype space vehicle.

  12. NASA's Terrestrial Planet Finder Missions

    NASA Technical Reports Server (NTRS)

    Coulter, Daniel R.

    2004-01-01

    NASA has decided to move forward with two complementary Terrestrial Planet Finder (TPF) missions, a visible coronagraph and an infrared formation flying interferometer. These missions are major missions in the NASA Office of Space Science Origins Theme. The primary science objectives of the TPF missions are to search for, detect, and characterize planets and planetary systems beyond our own Solar System, including specifically Earth-like planets.

  13. Integrated Modeling Approach for the Terrestrial Planet Finder Mission

    NASA Technical Reports Server (NTRS)

    Levine, Marie; Moore, Gregory; Basinger, Scott A.; Kissil, Andrew; Bloemhof, Eric; Gunter, Steve

    2004-01-01

    Because of the complexity of the Terrestrial Planet Finder (TPF) design concepts, the project will rely heavily on the use of engineering and science simulations to predict on-orbit performance. Furthermore, current understanding of these missions indicates that the 3m to 8m class optical systems need to be as stable as picometers in wavefront and sub-milli arcsec in pointing. These extremely small requirements impose on the models a level of predictive accuracy heretofore never achieved, especially in the area of microgravity effects, material property accuracy, thermal solution convergence, and all other second order modeling effects typically ignored. New modeling tools and analysis paradigms are developed which emphasize computational accuracy and fully integrated analytical simulations. The process is demonstrated on sample problems using the TPF Coronagraph design concept. The TPF project is also planning a suite of testbeds through which various aspects of the models and simulations will be verified.

  14. AHF: AMIGA'S HALO FINDER

    SciTech Connect

    Knollmann, Steffen R.; Knebe, Alexander

    2009-06-15

    Cosmological simulations are the key tool for investigating the different processes involved in the formation of the universe from small initial density perturbations to galaxies and clusters of galaxies observed today. The identification and analysis of bound objects, halos, is one of the most important steps in drawing useful physical information from simulations. In the advent of larger and larger simulations, a reliable and parallel halo finder, able to cope with the ever-increasing data files, is a must. In this work we present the freely available MPI parallel halo finder AHF. We provide a description of the algorithm and the strategy followed to handle large simulation data. We also describe the parameters a user may choose in order to influence the process of halo finding, as well as pointing out which parameters are crucial to ensure untainted results from the parallel approach. Furthermore, we demonstrate the ability of AHF to scale to high-resolution simulations.

  15. Fault finder

    DOEpatents

    Bunch, Richard H.

    1986-01-01

    A fault finder for locating faults along a high voltage electrical transmission line. Real time monitoring of background noise and improved filtering of input signals is used to identify the occurrence of a fault. A fault is detected at both a master and remote unit spaced along the line. A master clock synchronizes operation of a similar clock at the remote unit. Both units include modulator and demodulator circuits for transmission of clock signals and data. All data is received at the master unit for processing to determine an accurate fault distance calculation.

  16. Planet Detection Algorithms for the Terrestrial Planet Finder-C

    NASA Astrophysics Data System (ADS)

    Kasdin, N. J.; Braems, I.

    2005-12-01

    Critical to mission planning for the terrestrial planet finder coronagraph (TPF-C) is the ability to estimate integration times for planet detection. This detection is complicated by the presence of background noise due to local and exo-zodiacal dust, by residual speckle due optical errors, and by the dependence of the PSF shape on the specific coronagraph. In this paper we examine in detail the use of PSF fitting (matched filtering) for planet detection, derive probabilistic bounds for the signal-to-noise ratio by balancing missed detection and false alarm rates, and demonstrate that this is close to the optimal linear detection technique. We then compare to a Bayesian detection approach and show that for very low background the Bayesian method offers integration time improvements, but rapidly approaches the PSF fitting result for reasonable levels of background noise. We confirm via monte-carlo simulations. This work was supported under a grant from the Jet Propulsion Laboratory and by a fellowship from the Institut National de Recherche en Informatique et Automatique (INRIA).

  17. Optimizing WFIRST Coronagraph Science

    NASA Astrophysics Data System (ADS)

    Macintosh, Bruce

    We propose an in-depth scientific investigation that will define how the WFIRST coronagraphic instrument will discover and characterize nearby planetary systems and how it will use observations of planets and disks to probe the diversity of their compositions, dynamics, and formation. Given the enormous diversity of known planetary systems it is not enough to optimize a coronagraph mission plan for the characterization of solar system analogs. Instead, we must design a mission to characterize a wide variety of planets, from gas and ice giant planets at a range of separations to mid-sized planets with no analogs in our solar system. We must consider updated planet distributions based on the results of the Kepler mission, long-term radial velocity (RV) surveys and updated luminosity distributions of exo-zodiacal dust from interferometric thermal infrared surveys of nearby stars. The properties of all these objects must be informed by our best models of planets and disks, and the process of using WFIRST observations to measure fundamental planetary properties such as composition must derive from rigorous methods. Our team brings a great depth of expertise to inform and accomplish these and all of the other tasks enumerated in the SIT proposal call. We will perform end-to-end modeling that starts with model spectra of planets and images of disks, simulates WFIRST data using these models, accounts for geometries of specific star / planet / disk systems, and incorporates detailed instrument performance models. We will develop and implement data analysis techniques to extract well-calibrated astrophysical signals from complex data, and propose observing plans that maximize the mission's scientific yield. We will work with the community to build observing programs and target lists, inform them of WFIRSTs capabilities, and supply simulated scientific observations for data challenges. Our work will be informed by the experience we have gained from building and observing with

  18. Skin Condition Finder

    MedlinePlus

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  19. The AFTA coronagraph instrument

    NASA Astrophysics Data System (ADS)

    Shaklan, Stuart; Levine, Marie; Foote, Marc; Rodgers, Michael; Underhill, Michael; Marchen, Luis; Klein, Dan

    2013-09-01

    The Astrophysics Focused Telescope Assets (AFTA) study in 2012-2013 included a high-contrast stellar coronagraph to complement the wide-field infrared survey (WFIRST) instrument. The idea of flying a coronagraph on this telescope was met with some skepticism because the AFTA pupil has a large central obscuration with six secondary mirror struts that impact the coronagraph sensitivity. However, several promising coronagraph concepts have emerged, and a corresponding initial instrument design has been completed. Requirements on the design include observations centered 0.6 deg off-axis, on-orbit robotic serviceability, operation in a geosynchronous orbit, and room-temperature operation (driven by the coronagraph's deformable mirrors). We describe the instrument performance requirements, the optical design, an observational scenario, and integration times for typical detection and characterization observations.

  20. Skin Condition Finder

    MedlinePlus

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  1. Holographic Vortex Coronagraph

    NASA Technical Reports Server (NTRS)

    Palacios, David

    2010-01-01

    A holographic vortex coronagraph (HVC) has been proposed as an improvement over conventional coronagraphs for use in high-contrast astronomical imaging for detecting planets, dust disks, and other broadband light scatterers in the vicinities of stars other than the Sun. Because such light scatterers are so faint relative to their parent stars, in order to be able to detect them, it is necessary to effect ultra-high-contrast (typically by a factor of the order of 1010) suppression of broadband light from the stars. Unfortunately, the performances of conventional coronagraphs are limited by low throughput, dispersion, and difficulty of satisfying challenging manufacturing requirements. The HVC concept offers the potential to overcome these limitations.

  2. Terrestrial Planet Finder: science overview

    NASA Technical Reports Server (NTRS)

    Unwin, Stephen C.; Beichman, C. A.

    2004-01-01

    The Terrestrial Planet Finder (TPF) seeks to revolutionize our understanding of humanity's place in the universe - by searching for Earth-like planets using reflected light, or thermal emission in the mid-infrared. Direct detection implies that TPF must separate planet light from glare of the nearby star, a technical challenge which has only in recent years been recognized as surmountable. TPF will obtain a low-resolution spectra of each planets it detects, providing some of its basic physical characteristics and its main atmospheric constituents, thereby allowing us to assess the likelihood that habitable conditions exist there. NASA has decided the scientific importance of this research is so high that TPF will be pursued as two complementary space observatories: a visible-light coronagraph and a mid-infrared formation flying interferometer. The combination of spectra from both wavebands is much more valuable than either taken separately, and it will allow a much fuller understanding of the wide diversity of planetary atmospheres that may be expected to exist. Measurements across a broad wavelength range will yield not only physical properties such as size and albedo, but will also serve as the foundations of a reliable and robust assessment of habitability and the presence of life.

  3. Terrestrial Planet Finder: science overview

    NASA Technical Reports Server (NTRS)

    Unwin, Stephen C.; Beichman, C. A.

    2004-01-01

    The Terrestrial Planet Finder (TPF) seeks to revolutionize our understanding of humanity's place in the universe - by searching for Earth-like planets using reflected light, or thermal emission in the mid-infrared. Direct detection implies that TPF must separate planet light from glare of the nearby star, a technical challenge which has only in recent years been recognized as surmountable. TPF will obtain a low-resolution spectra of each planets it detects, providing some of its basic physical characteristics and its main atmospheric constituents, thereby allowing us to assess the likelihood that habitable conditions exist there. NASA has decided the scientific importance of this research is so high that TPF will be pursued as two complementary space observatories: a visible-light coronagraph and a mid-infrared formation flying interferometer. The combination of spectra from both wavebands is much more valuable than either taken separately, and it will allow a much fuller understanding of the wide diversity of planetary atmospheres that may be expected to exist. Measurements across a broad wavelength range will yield not only physical properties such as size and albedo, but will also serve as the foundations of a reliable and robust assessment of habitability and the presence of life.

  4. Scaling An External Occulter Coronagraph Mission

    NASA Astrophysics Data System (ADS)

    Noecker, Martin C.

    2009-01-01

    An excellent candidate for the Terrestrial Planet Finder mission is an external occulter coronagraph like New Worlds Observer, in which the glare of the host star is blocked by an opaque starshade located between the star and the telescope which observes it. It has proven difficult to visualize and manage the interplay between starshade size and distance, telescope size, optical wavelength, and the depth of stellar suppression. The traditional method is to choose some parameters, calculate the stellar suppression, and iterate. This paper presents an alternate approach which exploits scaling relationships, allowing quick calculation of each new case and better visualization of the ramifications of a modest departure from that case. I apply this method to illustrate the pros and cons of a few different cases at different scales.

  5. The Sensitivity of Shaped Pupil Coronagraphs to Optical Aberrations

    NASA Technical Reports Server (NTRS)

    Green, Joseph J.; Shaklan, Stuart B.; Vanderbei, Robert J.; Kasdin, N. Jeremy

    2004-01-01

    Unlike focal-plane coronagraphs that use occulting spots and Lyot stops to eliminate diffraction, pupil-plane coronagraphs operate by shaping the pupil to redirect the diffracted stellar light into a tight core. As in focal-plane coronagraphs, the optical aberrations in the telescope must be sufficiently corrected to enable high contrast imaging. However, in shaped-pupil coronagraphs, the low-order aberrations resulting from misalignment and optical figure drift have a much smaller influence upon the contrast at at the inner working angle. These weaker sensitivities greatly relax the strict low-order wavefront stability required for high-contrast imaging the cost of some throughput. In this paper, we present the simulated performance of the concentric ring shaped pupil concepts comparing them to focal-plane coronagraphs that are optimized for the same inner working angles.

  6. Study of High-Performance Coronagraphic Techniques

    NASA Astrophysics Data System (ADS)

    Tolls, Volker; Aziz, M. J.; Gonsalves, R. A.; Korzennik, S. G.; Labeyrie, A.; Lyon, R. G.; Melnick, G. J.; Somerstein, S.; Vasudevan, G.; Woodruff, R. A.

    2007-05-01

    We will provide a progress report about our study of high-performance coronagraphic techniques. At SAO we have set up a testbed to test coronagraphic masks and to demonstrate Labeyrie's multi-step speckle reduction technique. This technique expands the general concept of a coronagraph by incorporating a speckle corrector (phase or amplitude) and second occulter for speckle light suppression. The testbed consists of a coronagraph with high precision optics (2 inch spherical mirrors with lambda/1000 surface quality), lasers simulating the host star and the planet, and a single Labeyrie correction stage with a MEMS deformable mirror (DM) for the phase correction. The correction function is derived from images taken in- and slightly out-of-focus using phase diversity. The testbed is operational awaiting coronagraphic masks. The testbed control software for operating the CCD camera, the translation stage that moves the camera in- and out-of-focus, the wavefront recovery (phase diversity) module, and DM control is under development. We are also developing coronagraphic masks in collaboration with Harvard University and Lockheed Martin Corp. (LMCO). The development at Harvard utilizes a focused ion beam system to mill masks out of absorber material and the LMCO approach uses patterns of dots to achieve the desired mask performance. We will present results of both investigations including test results from the first generation of LMCO masks obtained with our high-precision mask scanner. This work was supported by NASA through grant NNG04GC57G, through SAO IR&D funding, and by Harvard University through the Research Experience for Undergraduate Program of Harvard's Materials Science and Engineering Center. Central facilities were provided by Harvard's Center for Nanoscale Systems.

  7. Pointing Control System Design and Performance Evaluation for TPF Coronagraph

    NASA Technical Reports Server (NTRS)

    Liu, Kuo-Chia; Blaurock, Carl; Mosier, Gary

    2004-01-01

    The Terrestrial Planet Finder (TPF) program aims to detect and characterize extra-solar Earth-like planets. The coronagraph telescope is one of the four mission concepts being studied. In order to reject the star flux and detect the planet flux in the visible light range, the coronagraph telescope must achieve a rejection ratio on the order of a billion to one. Dynamic jitter, introduced by environmental and on-board mechanical disturbances, degrades the optical performance, as characterized primarily by contrast ratio. The feasibility of using passive vibration isolation combined with active attitude and line-of- sight control systems to stabilize the spacecraft and the optical components to the requisite level is being studied. The telescope is also required to slew between targets. The slew mode control law must be designed to balance the need for efficient large-angle maneuvers while simultaneously avoiding the excitation of flexible modes in order to minimize settling time.

  8. Pointing Control System Design and Performance Evaluation for TPF Coronagraph

    NASA Technical Reports Server (NTRS)

    Liu, Kuo-Chia; Blaurock, Carl; Mosier, Gary

    2004-01-01

    The Terrestrial Planet Finder (TPF) program aims to detect and characterize extra-solar Earth-like planets. The coronagraph telescope is one of the four mission concepts being studied. In order to reject the star flux and detect the planet flux in the visible light range, the coronagraph telescope must achieve a rejection ratio on the order of a billion to one. Dynamic jitter, introduced by environmental and on-board mechanical disturbances, degrades the optical performance, as characterized primarily by contrast ratio. The feasibility of using passive vibration isolation combined with active attitude and line-of- sight control systems to stabilize the spacecraft and the optical components to the requisite level is being studied. The telescope is also required to slew between targets. The slew mode control law must be designed to balance the need for efficient large-angle maneuvers while simultaneously avoiding the excitation of flexible modes in order to minimize settling time.

  9. Terrestrial Planet Finder: Technology Development Plans

    NASA Technical Reports Server (NTRS)

    Lindensmith, Chris

    2004-01-01

    One of humanity's oldest questions is whether life exists elsewhere in the universe. The Terrestrial Planet Finder (TPF) mission will survey stars in our stellar neighborhood to search for planets and perform spectroscopic measurements to identify potential biomarkers in their atmospheres. In response to the recently published President's Plan for Space Exploration, TPF has plans to launch a visible-light coronagraph in 2014, and a separated-spacecraft infrared interferometer in 2016. Substantial funding has been committed to the development of the key technologies that are required to meet these goals for launch in the next decade. Efforts underway through industry and university contracts and at JPL include a number of system and subsystem testbeds, as well as components and numerical modeling capabilities. The science, technology, and design efforts are closely coupled to ensure that requirements and capabilities will be consistent and meet the science goals.

  10. Terrestrial Planet Finder: Technology Development Plans

    NASA Technical Reports Server (NTRS)

    Lindensmith, Chris

    2004-01-01

    One of humanity's oldest questions is whether life exists elsewhere in the universe. The Terrestrial Planet Finder (TPF) mission will survey stars in our stellar neighborhood to search for planets and perform spectroscopic measurements to identify potential biomarkers in their atmospheres. In response to the recently published President's Plan for Space Exploration, TPF has plans to launch a visible-light coronagraph in 2014, and a separated-spacecraft infrared interferometer in 2016. Substantial funding has been committed to the development of the key technologies that are required to meet these goals for launch in the next decade. Efforts underway through industry and university contracts and at JPL include a number of system and subsystem testbeds, as well as components and numerical modeling capabilities. The science, technology, and design efforts are closely coupled to ensure that requirements and capabilities will be consistent and meet the science goals.

  11. Stellar Double Coronagraph: A Multistage Coronagraphic Platform at Palomar Observatory

    NASA Astrophysics Data System (ADS)

    Bottom, Michael; Shelton, J. Chris; Wallace, James K.; Bartos, Randall; Kuhn, Jonas; Mawet, Dimitri; Mennesson, Bertrand; Burruss, Rick; Serabyn, Eugene

    2016-07-01

    We present a new instrument, the “Stellar Double Coronagraph,” a flexible coronagraphic platform. Designed for Palomar Observatory's 200″ Hale telescope, its two focal and pupil planes allow for a number of different observing configurations, including multiple vortex coronagraphs in series for improved contrast at small angles. We describe the motivation, design, observing modes, wavefront control approaches, data reduction pipeline, and early science results. We also discuss future directions for the instrument.

  12. Small-Grid Dithers for the JWST Coronagraphs

    NASA Technical Reports Server (NTRS)

    Lajoie, Charles-Philippe; Soummer, Remi; Pueyo, Laurent; Hines, Dean C.; Nelan, Edmund P.; Perrin, Marshall; Clampin, Mark; Isaacs, John C.

    2016-01-01

    We discuss new results of coronagraphic simulations demonstrating a novel mode for JWST that utilizes sub-pixel dithered reference images, called Small-Grid Dithers, to optimize coronagraphic PSF subtraction. These sub-pixel dithers are executed with the Fine Steering Mirror under fine guidance, are accurate to approx.2-3 milliarcseconds (1-s/axis), and provide ample speckle diversity to reconstruct an optimized synthetic reference PSF using LOCI or KLIP. We also discuss the performance gains of Small-Grid Dithers compared to the standard undithered scenario, and show potential contrast gain factors for the NIRCam and MIRI coronagraphs ranging from 2 to more than 10, respectively.

  13. Study of coronagraphic techniques

    NASA Astrophysics Data System (ADS)

    Tolls, Volker; Aziz, Michael; Gonsalves, Robert A.; Korzennik, Sylvain; Labeyrie, Antoine; Lyon, Richard; Melnick, Gary; Schlitz, Ruth; Somerstein, Steve; Vasudevan, Gopal; Woodruff, Robert

    2006-06-01

    Smithsonian Astrophysical Observatory (SAO) has set up a program to study coronagraphic techniques. The program consists of the development of new fabrication methods of occulter masks, characterization of the manufactured masks, and application of the masks to study speckle reduction technique. Our occulter mask fabrication development utilizes a focused ion beam system to directly shape mask profiles from absorber material. Initial milling trials show that we can shape nearly Gaussian-shaped mask profiles. Part of this development is the characterization of absorber materials, poly(methyl methacrylate) doped with light-stable chromophores. For the characterization of the masks we have built a mask scanner enabling us to scan the transmission function of occulter masks. The real mask transmission profile is retrieved applying the maximum entropy method to deconvolve the mask transmission function from the beam profile of the test laser. Finally, our test bed for studying coronagraphic techniques is nearing completion. The optical setup is currently configured as a classical coronagraph and can easily be re-configured for studying speckle reduction techniques. The development of the test bed control software is under way. This paper we will give an update of the status of the individual program elements.

  14. Apodized Phase Mask Coronagraphs

    NASA Astrophysics Data System (ADS)

    Carlotti, Alexis

    2013-01-01

    Among the optical instruments proposed to detect and characterize exoplanets, phase masks coronagraphs offer very small inner working angles. Designed for off-axis telescopes, their performance is greatly reduced when used with centrally obstructed apertures such as those of the Palomar telescope, the very large telescope, or the James Webb space telescope. However, a clear circular aperture is not the only pupil shape for which a phase mask coronagraph can work properly. In fact, for a given centrally obstructed aperture, we show that it is possible to compute optimal apodizers that help achieve stellar extinction levels similar to those obtained in the ideal case of an off-axis telescope. Trade-offs exist between these levels, the transmission of the apodizer, and the area covered by the Lyot stop. We detail the Fourier optics formalism that makes these optimizations possible, as well as a few examples of shaped pupils. Some are designed for a four-quadrants phase mask, and some others for a vortex phase mask. We also offer a comparison with a coronagraph solely composed of a shaped pupil.

  15. Coronagraphic phase diversity for exoplanet detection

    NASA Astrophysics Data System (ADS)

    Paul, B.; Sauvage, J.-F.; Mugnier, L. M.; N'Diaye, M.; Dohlen, K.; Ferrari, M.; Fusco, T.

    2012-09-01

    The final performance of current and future instruments dedicated to exoplanet detection and characterisation (such as SPHERE on the VLT, GPI on Gemini North or EPICS on E-ELT) is limited by intensity residuals in the scientific image plane, which originate in uncorrected optical aberrations. After correction of the atmospheric turbulence, the main contribution to these residuals are the quasi-static aberrations introduced upstream of the coronagraphic mask. In order to reach the final detectivity, these aberrations have to be estimated and compensated for. Some of these aberrations are not seen by the wave-front sensor of the AO loop but only by the scientific instruments. In order to measure and compensate for these aberrations, we have recently proposed a dedicated focal-plane sensor called COFFEE (for COronagraphic Focal-plane wave-Front Estimation for Exoplanet detection), based on an analytical model for coronagraphic imaging. In this communication, we first present a thorough characterisation of COFFEE's performance, by means of numerical simulations. We additionally present an experimental validation of COFFEE for low orders aberrations using an in-house Adaptive Optics Bench and an apodized Roddier and Roddier phase mask coronagraph.

  16. High-Contrast Coronagraph Performance in the Presence of DM Actuator Defects

    NASA Technical Reports Server (NTRS)

    Sidick, Erkin; Shaklan, Stuart; Cady, Eric

    2015-01-01

    Deformable Mirrors (DMs) are critical elements in high contrast coronagraphs, requiring precision and stability measured in picometers to enable detection of Earth-like exoplanets. Occasionally DM actuators or their associated cables or electronics fail, requiring a wavefront control algorithm to compensate for actuators that may be displaced from their neighbors by hundreds of nanometers. We have carried out experiments on our High-Contrast Imaging Testbed (HCIT) to study the impact of failed actuators in partial fulfillment of the Terrestrial Planet Finder Coronagraph optical model validation milestone. We show that the wavefront control algorithm adapts to several broken actuators and maintains dark-hole contrast in broadband light.

  17. Study of High Performance Coronagraphic Techniques

    NASA Technical Reports Server (NTRS)

    Crane, Phil (Technical Monitor); Tolls, Volker

    2004-01-01

    The goal of the Study of High Performance Coronagraphic Techniques project (called CoronaTech) is: 1) to verify the Labeyrie multi-step speckle reduction method and 2) to develop new techniques to manufacture soft-edge occulter masks preferably with Gaussian absorption profile. In a coronagraph, the light from a bright host star which is centered on the optical axis in the image plane is blocked by an occulter centered on the optical axis while the light from a planet passes the occulter (the planet has a certain minimal distance from the optical axis). Unfortunately, stray light originating in the telescope and subsequent optical elements is not completely blocked causing a so-called speckle pattern in the image plane of the coronagraph limiting the sensitivity of the system. The sensitivity can be increased significantly by reducing the amount of speckle light. The Labeyrie multi-step speckle reduction method implements one (or more) phase correction steps to suppress the unwanted speckle light. In each step, the stray light is rephased and then blocked with an additional occulter which affects the planet light (or other companion) only slightly. Since the suppression is still not complete, a series of steps is required in order to achieve significant suppression. The second part of the project is the development of soft-edge occulters. Simulations have shown that soft-edge occulters show better performance in coronagraphs than hard-edge occulters. In order to utilize the performance gain of soft-edge occulters. fabrication methods have to be developed to manufacture these occulters according to the specification set forth by the sensitivity requirements of the coronagraph.

  18. A New Concept of Coronagraph using Axicon Lenses

    NASA Astrophysics Data System (ADS)

    Choi, Jae Ho

    2017-06-01

    High-contrast direct imaging of faint objects nearby bright stellar is essential to investigate planetary systems. The goal of such effort is to find and characterize planets similar to Earth that is a challenging task due to it requires a high angular resolution and high dynamic range detections concurrently. A coronagraph that can be suppressed the bright stellar light or active galactic nuclei during the direct detection of astrophysical activities became one of the essential instruments to image exoplanets. In this presentation, a novel concept of a coronagraph using axicon-lenses is will be presented that is conjunction with a method of noninterferometric quantitative phase imaging for direct imaging of exoplanets. The essential scheme of the axicon-lenses coronagraph is the apodization carried out by excluding evaginated images of the planetary systems by a pair of axicon lens. The laboratory based coronagraph imaging is carried out with the axicon-lenses coronagraph setup which included the axicon lenses optics and phase contrast imaging unit. A simulated stellar and its companion are provided by illuminating light through small holes drilled on a thin metal plate. Those diffracted light at the edge of the holes bears a similarity to the light from the bright stellar. The images are evaginated about the optical axis by passing the first axicon lens. Then the evaginated beams of its external area have cut off by an iris which means the suppressed its central light of the bright stellar light preferentially. A symbolic calculation also is carried out to verify the scheme of the the axicon-lenses coronagraph using the symbolic computation program. The simulation results are shown that the the axicon-lenses coronagraph has feature of ability to achieve the IWA smaller than l/D. The laboratory based coronagraph imaging and simulation results support its potentials in direct imaging for finding exo-planet and various astrophysical activities.

  19. Fast computation of Lyot-style coronagraph propagation.

    PubMed

    Soummer, R; Pueyo, L; Sivaramakrishnan, A; Vanderbei, R J

    2007-11-26

    We present a new method for numerical propagation through Lyot-style coronagraphs using finite occulting masks. Standard methods for coronagraphic simulations involve Fast Fourier Transforms (FFT) of very large arrays, and computing power is an issue for the design and tolerancing of coronagraphs on segmented Extremely Large Telescopes (ELT) in order to handle both the speed and memory requirements. Our method combines a semi-analytical approach with non-FFT based Fourier transform algorithms. It enables both fast and memory-efficient computations without introducing any additional approximations. Typical speed improvements based on computation costs are of about ten to fifty for propagations from pupil to Lyot plane, with thirty to sixty times less memory needed. Our method makes it possible to perform numerical coronagraphic studies even in the case of ELTs using a contemporary commercial laptop computer, or any standard commercial workstation computer.

  20. Hg-Mask Coronagraph

    NASA Astrophysics Data System (ADS)

    Bourget, P.; Veiga, C. H.; Vieira Martins, R.; Assus, P.; Colas, F.

    In order to optimize the occulting process of a Lyot coronagraph and to provide a high dynamic range imaging, a new kind of occulting disk has been developed at the National Observatory of Rio de Janeiro. A mercury (Hg) drop glued onto an optical window by molecular cohesion and compressed by a pellicle film is used as the occulting disk. The minimum of the superficial tension potential function provides an optical precision (lambda/100) of the toric free surface of the mercury. This process provides a size control for the adaptation to the seeing conditions and to the apparent diameter of a resolved object, and in the case of adaptive optics, to the Airy diameter fraction needed. The occultation is a three dimensional process near the focal plane on the toric free surface that provides an apodization of the occultation. The Hg-Mask coronagraph has been projected for astrometric observations of faint satellites near to Jovian planets and works since 2000 at the 1.6 m telescope of the Pico dos Dias Observatory (OPD - Brazil).

  1. An analytic expression for coronagraphic imaging through turbulence. Application to on-sky coronagraphic phase diversity

    NASA Astrophysics Data System (ADS)

    Herscovici-Schiller, Olivier; Mugnier, Laurent M.; Sauvage, Jean-François

    2017-05-01

    The ultimate performance of coronagraphic high-contrast exoplanet imaging systems such as SPHERE or GPI is limited by quasi-static aberrations. These aberrations produce speckles that can be mistaken for planets in the image. In order to design instruments, correct quasi-static aberrations or analyse data, the expression of the point spread function of a coronagraphic instrument in the presence of residual turbulence is most useful. Here, we derive an analytic expression for this point spread function that is an extension to coronagraphic imaging of Roddier's expression for imaging through turbulence. We give a physical interpretation of its structure, we validate it by numerical simulations and we show that it is computationally efficient. Finally, we incorporate this imaging model into a coronagraphic phase diversity method (COFFEE) and validate by simulations that it allows wave-front reconstruction in the presence of residual turbulence. The preliminary results, which give a sub-nanometric precision in the case of a SPHERE-like system, strongly suggest that quasi-static aberrations could be calibrated during observations by this method.

  2. SPECKLE NOISE SUBTRACTION AND SUPPRESSION WITH ADAPTIVE OPTICS CORONAGRAPHIC IMAGING

    SciTech Connect

    Ren Deqing; Dou Jiangpei; Zhang Xi; Zhu Yongtian

    2012-07-10

    Future ground-based direct imaging of exoplanets depends critically on high-contrast coronagraph and wave-front manipulation. A coronagraph is designed to remove most of the unaberrated starlight. Because of the wave-front error, which is inherit from the atmospheric turbulence from ground observations, a coronagraph cannot deliver its theoretical performance, and speckle noise will limit the high-contrast imaging performance. Recently, extreme adaptive optics, which can deliver an extremely high Strehl ratio, is being developed for such a challenging mission. In this publication, we show that barely taking a long-exposure image does not provide much gain for coronagraphic imaging with adaptive optics. We further discuss a speckle subtraction and suppression technique that fully takes advantage of the high contrast provided by the coronagraph, as well as the wave front corrected by the adaptive optics. This technique works well for coronagraphic imaging with conventional adaptive optics with a moderate Strehl ratio, as well as for extreme adaptive optics with a high Strehl ratio. We show how to substrate and suppress speckle noise efficiently up to the third order, which is critical for future ground-based high-contrast imaging. Numerical simulations are conducted to fully demonstrate this technique.

  3. Post-coronagraphic wave-front sensing dedicated to exoplanet detection

    NASA Astrophysics Data System (ADS)

    Jean-Francois, Sauvage; Laurent, Mugnier; Baptiste, Paul

    2011-09-01

    The final performance of current instruments dedicated to exoplanet search and imaging (such as SPHERE and EPICS) is strongly limited by uncorrected optical aberrations. After correction of the atmospheric turbulence by an extreme AO system, the main contribution comes from the quasi-static aberrations introduced upstream of the coronagraph. In order to measure and precompensate for these, we propose a focal-plane sensor which we call coronagraphic phase diversity (CPD). It is an adaptation of conventional phase diversity to the coronagraphic case and uses an analytical model for coronagraphic imaging. In this communication, we validate two essential aspects of CPD: - we validate by realistic simulations that our analytical imaging model, which assumes a perfect coronagraph, can indeed be used with real-life coronagraphs, and we assess the CPD performance; - we perform the very first validation of CPD on experimental data obtained on an in-house AO bench.

  4. Coronagraph Focal-Plane Phase Masks Based on Photonic Crystal Technology: Recent Progress and Observational Strategy

    NASA Technical Reports Server (NTRS)

    Murakami, Naoshi; Nishikawa, Jun; Sakamoto, Moritsugu; Ise, Akitoshi; Oka, Kazuhiko; Baba, Naoshi; Murakami, Hiroshi; Tamura, Motohide; Traub, Wesley A.; Mawet, Dimitri; hide

    2012-01-01

    Photonic crystal, an artificial periodic nanostructure of refractive indices, is one of the attractive technologies for coronagraph focal-plane masks aiming at direct imaging and characterization of terrestrial extrasolar planets. We manufactured the eight-octant phase mask (8OPM) and the vector vortex mask (VVM) very precisely using the photonic crystal technology. Fully achromatic phase-mask coronagraphs can be realized by applying appropriate polarization filters to the masks. We carried out laboratory experiments of the polarization-filtered 8OPM coronagraph using the High-Contrast Imaging Testbed (HCIT), a state-of-the-art coronagraph simulator at the Jet Propulsion Laboratory (JPL). We report the experimental results of 10-8-level contrast across several wavelengths over 10% bandwidth around 800nm. In addition, we present future prospects and observational strategy for the photonic-crystal mask coronagraphs combined with differential imaging techniques to reach higher contrast. We proposed to apply a polarization-differential imaging (PDI) technique to the VVM coronagraph, in which we built a two-channel coronagraph using polarizing beam splitters to avoid a loss of intensity due to the polarization filters. We also proposed to apply an angular-differential imaging (ADI) technique to the 8OPM coronagraph. The 8OPM/ADI mode avoids an intensity loss due to a phase transition of the mask and provides a full field of view around central stars. We present results of preliminary laboratory demonstrations of the PDI and ADI observational modes with the phase-mask coronagraphs.

  5. Coronagraph Focal-Plane Phase Masks Based on Photonic Crystal Technology: Recent Progress and Observational Strategy

    NASA Technical Reports Server (NTRS)

    Murakami, Naoshi; Nishikawa, Jun; Sakamoto, Moritsugu; Ise, Akitoshi; Oka, Kazuhiko; Baba, Naoshi; Murakami, Hiroshi; Tamura, Motohide; Traub, Wesley A.; Mawet, Dimitri; Moody, Dwight C.; Kern, Brian D.; Trauger, John T.; Serabyn, Eugene; Hamaguchi, Shoki; Oshiyama, Fumika

    2012-01-01

    Photonic crystal, an artificial periodic nanostructure of refractive indices, is one of the attractive technologies for coronagraph focal-plane masks aiming at direct imaging and characterization of terrestrial extrasolar planets. We manufactured the eight-octant phase mask (8OPM) and the vector vortex mask (VVM) very precisely using the photonic crystal technology. Fully achromatic phase-mask coronagraphs can be realized by applying appropriate polarization filters to the masks. We carried out laboratory experiments of the polarization-filtered 8OPM coronagraph using the High-Contrast Imaging Testbed (HCIT), a state-of-the-art coronagraph simulator at the Jet Propulsion Laboratory (JPL). We report the experimental results of 10-8-level contrast across several wavelengths over 10% bandwidth around 800nm. In addition, we present future prospects and observational strategy for the photonic-crystal mask coronagraphs combined with differential imaging techniques to reach higher contrast. We proposed to apply a polarization-differential imaging (PDI) technique to the VVM coronagraph, in which we built a two-channel coronagraph using polarizing beam splitters to avoid a loss of intensity due to the polarization filters. We also proposed to apply an angular-differential imaging (ADI) technique to the 8OPM coronagraph. The 8OPM/ADI mode avoids an intensity loss due to a phase transition of the mask and provides a full field of view around central stars. We present results of preliminary laboratory demonstrations of the PDI and ADI observational modes with the phase-mask coronagraphs.

  6. The Achromatic Interfero Coronagraph

    NASA Astrophysics Data System (ADS)

    Rabbia, Yves; Gay, Jean; Rivet, Jean-Pierre

    2007-04-01

    We report on the Achromatic Interfero Coronagraph, a focal imaging device which aims at rejecting the energy contribution of a point-like source set on-axis, so as to make detectable its angularly-close environment (applicable to stellar environment: circumstellar matter, faint companions, planetary systems, but also conceivably to Active Galactic Nucleii and multiple asteroïds). With AIC, starlight rejection is based on destructive interference, which allows exploration of the star's neighbourhood at an angular resolution better than the diffraction limit of the hosting telescope. Thanks to the focus crossing property of light, rejection is achromatic thus yielding a large spectral bandwidth of work. Descriptions and comments are given regarding the principle, the device itself, the constraints and limitations, and the theoretical performance. Results are presented which demonstrate the close-sensing capability and which show images of a companion obtained in laboratory and ‘on the sky’ as well. A short pictorial description of the alternative AIC concepts, CIAXE and Open-Air CIAXE, currently under study, is given. To cite this article: Y. Rabbia et al., C. R. Physique 8 (2007).

  7. Stability Error Budget for an Aggressive Coronagraph on a 3.8 m Telescope

    NASA Technical Reports Server (NTRS)

    Shaklan, Stuart B.; Marchen, Luis; Krist, John; Rud, Mayer

    2011-01-01

    We evaluate in detail the stability requirements for a band-limited coronagraph with an inner working angle as small as 2 lambda/D coupled to an off-axis, 3.8-m diameter telescope. We have updated our methodologies since presenting a stability error budget for the Terrestrial Planet Finder Coronagraph mission that worked at 4 lambda/D and employed an 8th-order mask to reduce aberration sensitives. In the previous work, we determined the tolerances relative to the total light leaking through the coronagraph. Now, we separate the light into a radial component, which is readily separable from a planet signal, and an azimuthal component, which is easily confused with a planet signal. In the current study, throughput considerations require a 4th-order coronagraph. This, combined with the more aggressive working angle, places extraordinarily tight requirements on wavefront stability and opto-mechanical stability. We find that the requirements are driven mainly by coma that leaks around the coronagraph mask and mimics the localized signal of a planet, and pointing errors that scatter light into the background, decreasing SNR. We also show how the requirements would be relaxed if a low-order aberration detection system could be employed.

  8. Stability Error Budget for an Aggressive Coronagraph on a 3.8 m Telescope

    NASA Technical Reports Server (NTRS)

    Shaklan, Stuart B.; Marchen, Luis; Krist, John; Rud, Mayer

    2011-01-01

    We evaluate in detail the stability requirements for a band-limited coronagraph with an inner working angle as small as 2 lambda/D coupled to an off-axis, 3.8-m diameter telescope. We have updated our methodologies since presenting a stability error budget for the Terrestrial Planet Finder Coronagraph mission that worked at 4 lambda/D and employed an 8th-order mask to reduce aberration sensitives. In the previous work, we determined the tolerances relative to the total light leaking through the coronagraph. Now, we separate the light into a radial component, which is readily separable from a planet signal, and an azimuthal component, which is easily confused with a planet signal. In the current study, throughput considerations require a 4th-order coronagraph. This, combined with the more aggressive working angle, places extraordinarily tight requirements on wavefront stability and opto-mechanical stability. We find that the requirements are driven mainly by coma that leaks around the coronagraph mask and mimics the localized signal of a planet, and pointing errors that scatter light into the background, decreasing SNR. We also show how the requirements would be relaxed if a low-order aberration detection system could be employed.

  9. The VORTEX coronagraphic test bench

    NASA Astrophysics Data System (ADS)

    Jolivet, A.; Piron, P.; Huby, E.; Absil, O.; Delacroix, C.; Mawet, D.; Surdej, J.; Habraken, S.

    2014-07-01

    In this paper, we present the infrared coronagraphic test bench of the University of Liège named VODCA (Vortex Optical Demonstrator for Coronagraphic Applications). The goal of the bench is to assess the performances of the Annular Groove Phase Masks (AGPMs) at near- to mid-infrared wavelengths. The AGPM is a subwavelength grating vortex coronagraph of charge two (SGVC2) made out of diamond. The bench is designed to be completely achromatic and will be composed of a super continuum laser source emitting in the near to mid-infrared, several parabolas, diaphragms and an infrared camera. This way, we will be able to test the different AGPMs in the M, L, K and H bands. Eventually, the bench will also allow the computation of the incident wavefront aberrations on the coronagraph. A reflective Lyot stop will send most of the stellar light to a second camera to perform low-order wavefront sensing. This second system coupled with a deformable mirror will allow the correction of the wavefront aberrations. We also aim to test other pre- and/or post-coronagraphic concepts such as optimal apodization.

  10. The Terrestrial Planet Finder and Darwin Missions

    NASA Technical Reports Server (NTRS)

    Danchi, William C.

    2004-01-01

    Both in the United States and in Europe, teams of scientists and engineers are exploring the feasibility of the Terrestrial Planet Finder (TPF) and Darwin missions, which are designed to search for Earth-like planets in the habitable zone of nearby stars. In the US, the TPF Science Working Group is studying four options - small (4m by 6 m primary mirror) and large (4m by 10 m primary mirror) coronagraphs for planet detection at visible wavelengths, and structurally connected and free-flyer interferometers at thermal infrared wavelengths. The US TPF-SWG is charged with selecting an option for NASA by the end of 2006. In Europe the Darwin Terrestrial Exo-planet Advisory Team (TE- SAT) is exploring the free-flyer interferometer option only at this time. I will discuss the vurtures and difficulties of detecting and characterizing extra-solar planets in both wavelength regions as well as some of the technical challenges and progress in the past year.

  11. Haloes gone MAD: The Halo-Finder Comparison Project

    NASA Astrophysics Data System (ADS)

    Knebe, Alexander; Knollmann, Steffen R.; Muldrew, Stuart I.; Pearce, Frazer R.; Aragon-Calvo, Miguel Angel; Ascasibar, Yago; Behroozi, Peter S.; Ceverino, Daniel; Colombi, Stephane; Diemand, Juerg; Dolag, Klaus; Falck, Bridget L.; Fasel, Patricia; Gardner, Jeff; Gottlöber, Stefan; Hsu, Chung-Hsing; Iannuzzi, Francesca; Klypin, Anatoly; Lukić, Zarija; Maciejewski, Michal; McBride, Cameron; Neyrinck, Mark C.; Planelles, Susana; Potter, Doug; Quilis, Vicent; Rasera, Yann; Read, Justin I.; Ricker, Paul M.; Roy, Fabrice; Springel, Volker; Stadel, Joachim; Stinson, Greg; Sutter, P. M.; Turchaninov, Victor; Tweed, Dylan; Yepes, Gustavo; Zemp, Marcel

    2011-08-01

    We present a detailed comparison of fundamental dark matter halo properties retrieved by a substantial number of different halo finders. These codes span a wide range of techniques including friends-of-friends, spherical-overdensity and phase-space-based algorithms. We further introduce a robust (and publicly available) suite of test scenarios that allow halo finder developers to compare the performance of their codes against those presented here. This set includes mock haloes containing various levels and distributions of substructure at a range of resolutions as well as a cosmological simulation of the large-scale structure of the universe. All the halo-finding codes tested could successfully recover the spatial location of our mock haloes. They further returned lists of particles (potentially) belonging to the object that led to coinciding values for the maximum of the circular velocity profile and the radius where it is reached. All the finders based in configuration space struggled to recover substructure that was located close to the centre of the host halo, and the radial dependence of the mass recovered varies from finder to finder. Those finders based in phase space could resolve central substructure although they found difficulties in accurately recovering its properties. Through a resolution study we found that most of the finders could not reliably recover substructure containing fewer than 30-40 particles. However, also here the phase-space finders excelled by resolving substructure down to 10-20 particles. By comparing the halo finders using a high-resolution cosmological volume, we found that they agree remarkably well on fundamental properties of astrophysical significance (e.g. mass, position, velocity and peak of the rotation curve). We further suggest to utilize the peak of the rotation curve, vmax, as a proxy for mass, given the arbitrariness in defining a proper halo edge. Airport code for Madrid, Spain

  12. Analytical expression of a long exposure coronagraphic point spread function

    NASA Astrophysics Data System (ADS)

    Herscovici-Schiller, Olivier; Mugnier, Laurent M.; Sauvage, Jean-François; Le Duigou, Jean-Michel; Cantalloube, Faustine

    2016-07-01

    The resolution of coronagraphic high contrast exoplanet imaging devices such as SPHERE is limited by quasistatic aberrations. These aberrations produce speckles that can be mistaken for planets in the image. In order to design instruments, correct quasi-static aberrations or analyze data, the expression of the point spread function of a coronagraphic telescope in the presence of residual turbulence is useful. We have derived an analytic formula for this point spread function. We explain physically its structure, we validate it by numerical simulations and we show that it is computationally efficient.

  13. Numerical modeling of the proposed WFIRST-AFTA coronagraphs and their predicted performances

    NASA Astrophysics Data System (ADS)

    Krist, John; Nemati, Bijan; Mennesson, Bertrand

    2016-01-01

    The WFIRST-AFTA 2.37 m telescope will provide the opportunity to host a coronagraph for the imaging and spectroscopy of planets and disks in the next decade. The telescope, however, is not ideal, given its obscured aperture. Only recently have coronagraph designs been thoroughly investigated that can efficiently work with this configuration. Three coronagraph designs, the hybrid Lyot, shaped pupil, and phase-induced amplitude apodization complex mask coronagraph have been selected for further development by the Astrophysics Focused Telescope Asset project. Real-world testbed demonstrations of these have just begun, so for now, the most reliable means of evaluating their potential performance comes from numerical modeling incorporating diffraction propagation, realistic system models, and simulated wavefront sensing and control. Here, we present the methods of performance evaluation and results for the current coronagraph designs.

  14. Designs and Materials for Better Coronagraph Occulting Masks

    NASA Technical Reports Server (NTRS)

    Balasubramanian, Kunjithapatham

    2010-01-01

    New designs, and materials appropriate for such designs, are under investigation in an effort to develop coronagraph occulting masks having broad-band spectral characteristics superior to those currently employed. These designs and materials are applicable to all coronagraphs, both ground-based and spaceborne. This effort also offers potential benefits for the development of other optical masks and filters that are required (1) for precisely tailored spatial transmission profiles, (2) to be characterized by optical-density neutrality and phase neutrality (that is, to be characterized by constant optical density and constant phase over broad wavelength ranges), and/or (3) not to exhibit optical- density-dependent phase shifts. The need for this effort arises for the following reasons: Coronagraph occulting masks are required to impose, on beams of light transmitted through them, extremely precise control of amplitude and phase according to carefully designed transmission profiles. In the original application that gave rise to this effort, the concern has been to develop broad-band occulting masks for NASA s Terrestrial Planet Finder coronagraph. Until now, experimental samples of these masks have been made from high-energy-beam-sensitive (HEBS) glass, which becomes locally dark where irradiated with a high-energy electron beam, the amount of darkening depending on the electron-beam energy and dose. Precise mask profiles have been written on HEBS glass blanks by use of electron beams, and the masks have performed satisfactorily in monochromatic light. However, the optical-density and phase profiles of the HEBS masks vary significantly with wavelength; consequently, the HEBS masks perform unsatisfactorily in broad-band light. The key properties of materials to be used in coronagraph occulting masks are their extinction coefficients, their indices of refraction, and the variations of these parameters with wavelength. The effort thus far has included theoretical

  15. Application of the Premature Chromosome Condensation Assay in Simulated Partial-Body Radiation Exposures: Evaluation of the Use of an Automated Metaphase-Finder

    DTIC Science & Technology

    1995-01-01

    DECLASSIFY ON: SECURITY CLASSIFICATION OF THIS PAGE 4 .ARMED FORCES RADIOSIOLOGY RESEARCH INSTITUTE SCIENTIFIC REPORT SR95-17 Application of the Premature ...Radiation Biophysics Department, Bethesda, Maryland, USA; bLoats Associates, Westminster, Maryland, USA Key Words. Premature chromosome condensation...assay • Lymphocytes • x-ray • Chromosome damage • Biodosimetry • Partial-body exposure • Metaphase-finder Abstract. The premature chromosome condensa

  16. Crazy Engineering Starshade and Coronagraph

    NASA Image and Video Library

    2016-04-26

    Episode 7 of Crazy Engineering series. Host Mike Meacham, Mechanical Engineer at JPL, learns about the two technologies NASA is investing in to image exoplanets: the Starshade and the Coronagraph. Mike interviews Nick Siegler, Program Chief Technologist, NASA Exoplanet Program in the Starshade lab and the High Contrast Imaging Testbed lab.

  17. NICMOS Optimum Coronagraphic Focus Determinaton

    NASA Astrophysics Data System (ADS)

    Schneider, Glenn

    1997-07-01

    This test will ascertain the optimum position of the PAM for maximizing the local contrast ratios in coronagraphic images. Because of the forward motion of the NICMOS optical bench and dewar, the nominal operational position for the PAM is set {for each camera} to achieve diffraction limited focus at the image plane formed at the detector. As a result of the forward motion of the camera 2 detector, hard images are no longer formed coincidentally at the field divider mirror surface {where the coronagraphic hole is located} and at the detector. This will lead to an increase in the diffracted energy in the wings of a PSF from a target placed inside of the coronagraphic hole as the image plane will fall behind the surface of the FDA mirror. The contrast in a coronagraphic image might be enhanced by placing the focus to form an image at either image planes {FDA or detector} or at a place in-between. This is highly dependent on scattering and must be ascertained by direct measurement.

  18. Pointing control system design and performance evaluation of TPF coronagraph

    NASA Astrophysics Data System (ADS)

    Liu, Kuo-Chia; Blaurock, Carl; Mosier, Gary E.

    2004-09-01

    The Terrestrial Planet Finder (TPF) project aims to detect and characterize extra-solar Earth-like planets. The coronagraph telescope is one of the two mission concepts being studied. To reject the star flux and detect the planet flux in the visible light range, the coronagraph telescope must achieve a rejection ratio on the order of a billion to one. Dynamic jitter, introduced by environmental and on-board mechanical disturbances, degrades the optical performance, as characterized primarily by contrast ratio. The feasibility of using passive vibration isolation combined with active attitude and line-of-sight (LOS) control systems to stabilize the spacecraft and the optical components to the requisite level is being studied. The telescope is also required to slew between targets or rotate around the LOS. The slew mode control law must be designed to balance the need for efficient large-angle maneuvers while simultaneously avoiding the excitation of flexible modes in order to minimize settling time. This paper provides an overview of the current control design concept and sensor/actuator topology for TPF Coronagraph and illustrates the fine pointing performance of the telescope. This performance is primarily a function of the rejection of high-frequency dynamic disturbances, in this case due to reaction wheel disturbance forces/torques transmitted through the passive isolation stage. Trade studies between isolator force rejection and disturbance level reduction via wheel redesign are also presented to illustrate the requirements imposed on current technologies. Finally, the paper summarizes preliminary results on the slew/settle performance of the telescope.

  19. Stray-light sources from pupil mask edges and mitigation techniques for the TPF Coronagraph

    NASA Astrophysics Data System (ADS)

    Ceperley, Daniel; Neureuther, Andrew; Miller, Marshall; Lieber, Michael; Kasdin, Jeremy

    2006-06-01

    Stray-light sources from pupil plane masks that may limit Terrestrial Planet Finder Coronagraph (TPF-C) performance are characterized 1,2 and mitigation strategies are discussed to provide a guide for future development. Rigorous vector simulation with the Finite-Difference Time-Domain (FDTD) method is used to characterize waveguiding effects in narrow openings, sidewall interactions, manufacturing tool-marks, manufacturing roughness, mask tilt, and cross-wavelength performance of thick Silicon mask structures. These effects cause stray-light that is not accounted for in scalar thin-mask diffraction theory, the most important of which are sidewall interactions, waveguiding effects in narrow openings, and tilt. These results have been used to improve the scalar thin-mask theory used to simulate the TPF-C with the Integrated Telescope Model. 3 Of particular interest are simulations of 100m thick vertical sidewall openings that model features typically found on Ripple masks 4 fabricated by Reactive Ion Etching (RIE) processes. 5 This paper contributes fundamental data for systematically modeling these effects in end-to-end system simulation. Leakage straight through the mask material varies greatly with wavelength, especially in Silicon (an attractive mask material due to the precision manufacturing techniques developed by the IC industry). Coating Silicon with 200nm of Chrome effectively mitigates the leakage without causing additional scattering. Thick-mask diffraction differs from the predictions of scalar thin-mask theory because diffraction spreading is confined by the mask's sidewalls. This confinement can make a mask opening look electro-magnetically larger or smaller than designed, by up to 3λ per vertical sidewall on a 50μm thick mask yet this can be reduced an order of magnitude by undercutting the sidewalls 20°. These confinement effects are sensitive to mask tilt (if light reaches the sidewalls) which can lead to an imbalance in stray-light sources and

  20. Proposed Missions - Terrestrial Planet Finder

    NASA Image and Video Library

    2003-06-20

    NASA Terrestrial Planet Finder will use multiple telescopes working together to take family portraits of stars and their orbiting planets and determine which planets may have the right chemistry to sustain life.

  1. Aspects of error budgeting for coronagraphic differential imaging: effects of dust and cosmetic errors

    NASA Astrophysics Data System (ADS)

    Dohlen, Kjetil

    2008-07-01

    The SPHERE (Spectro-Polarimetric High-contrast Exoplanet Research) planet finder instrument for ESO's VLT telescope, scheduled for first light in 2011, aims to detect giant extra-solar planets in the vicinity of bright stars by the aid of an extreme-AO turbulence compensation system and coronagraphic diffraction suppression. Objects found will be characterized through spectroscopic and polarimetric observations. I consider here the effects of micro-obstructions of the beam due to dust and cosmetic defects on the SPHERE image quality.

  2. Requirements for an Operational Coronagraph

    NASA Astrophysics Data System (ADS)

    Howard, R.; Vourlidas, A.; Harrison, R. A.; Bisi, M. M.; Plunkett, S. P.; Socker, D. G.; Eyles, C. J.; Webb, D. F.; DeForest, C. E.; Davies, J. A.; Howard, T. A.; de Koning, C. A.; Gopalswamy, N.; Davila, J. M.; Tappin, J.; Jackson, B. V.

    2015-12-01

    Coronal mass ejections (CMEs) have been shown to be the major driver of the non-recurrent space weather events and geomagnetic storms. The utility of continuously monitoring such events has been very effectively demonstrated by the LASCO experiment on the SOHO mission. However SOHO is aging, having been launched 20 years ago on Dec 2, 1995. The STEREO mission, in which two spacecraft in orbits about the sun are drifting away from earth, has shown the utility of multiple viewpoints off the sun-earth line. Up to now the monitoring of CMES has been performed by scientific instruments such as LASCO and SECCHI with capabilities beyond those required to record the parameters that are needed to forecast the impact at earth. However, there is great interest within the US NOAA and the UK Met Office to launch operational coronagraphs to L1 and L5. An ad-hoc group was formed to define the requirements of the L5 coronagraph. In this paper we present some requirements that must be met by operational coronagraphs. The Office of Naval Research is gratefully acknowledged.

  3. Precursor Science for the Terrestrial Planet Finder

    NASA Technical Reports Server (NTRS)

    Lawson, P. R. (Editor); Unwin, S. C. (Editor); Beichman, C. A. (Editor)

    2004-01-01

    This document outlines a path for the development of the field of extrasolar planet research, with a particular emphasis on the goals of the Terrestrial Planet Finder (TPF). Over the past decade, a new field of research has developed, the study of extrasolar planetary systems, driven by the discovery of massive planets around nearby stars. The planet count now stands at over 130. Are there Earth-like planets around nearby stars? Might any of those planets be conducive to the formation and maintenance of life? These arc the questions that TPF seeks to answer. TPF will be implemented as a suite of two space observatories, a 6-m class optical coronagraph, to be launched around 20 14, and a formation flying mid-infrared interferometer, to be launched sometime prior to 2020. These facilities will survey up to 165 or more nearby stars and detect planets like Earth should they be present in the 'habitable zone' around each star. With observations over a broad wavelength range, TPF will provide a robust determination of the atmospheric composition of planets to assess habitability and the presence of life. At this early stage of TPF's development, precursor observational and theoretical programs are essential to help define the mission, to aid our understanding of the planets that TPF could discover, and to characterize the stars that TPF will eventually study. This document is necessarily broad in scope because the significance of individual discoveries is greatly enhanced when viewed in thc context of the field as a whole. This document has the ambitious goal of taking us from our limited knowledge today, in 2004, to the era of TPF observations in the middle of the next decade. We must use the intervening years wisely. This document will be reviewed annually and updated as needed. The most recent edition is available online at http://tpf.jpl.nasa.gov/ or by email request to lawson@hucy.jpl.nasa.gov

  4. Galaxies going MAD: the Galaxy-Finder Comparison Project

    NASA Astrophysics Data System (ADS)

    Knebe, Alexander; Libeskind, Noam I.; Pearce, Frazer; Behroozi, Peter; Casado, Javier; Dolag, Klaus; Dominguez-Tenreiro, Rosa; Elahi, Pascal; Lux, Hanni; Muldrew, Stuart I.; Onions, Julian

    2013-01-01

    With the ever-increasing size and complexity of fully self-consistent simulations of galaxy formation within the framework of the cosmic web, the demands upon object finders for these simulations have simultaneously grown. To this extent we initiated the Halo-Finder Comparison Project that gathered together all the experts in the field and has so far led to two comparison papers, one for dark matter field haloes, and one for dark matter subhaloes. However, as state-of-the-art simulation codes are perfectly capable of not only following the formation and evolution of dark matter but also accounting for baryonic physics, i.e. gas hydrodynamics, star formation, stellar feedback, etc., object finders should also be capable of taking these additional physical processes into consideration. Here we report - for the first time - on a comparison of codes as applied to the Constrained Local UniversE Simulation (CLUES) of the formation of the Local Group which incorporates much of the physics relevant for galaxy formation. We compare both the properties of the three main galaxies in the simulation (representing the Milky Way, Andromeda and M33) and their satellite populations for a variety of halo finders ranging from phase space to velocity space to spherical overdensity based codes, including also a mere baryonic object finder. We obtain agreement amongst codes comparable to (if not better than) our previous comparisons - at least for the total, dark and stellar components of the objects. However, the diffuse gas content of the haloes shows great disparity, especially for low-mass satellite galaxies. This is primarily due to differences in the treatment of the thermal energy during the unbinding procedure. We acknowledge that the handling of gas in halo finders is something that needs to be dealt with carefully, and the precise treatment may depend sensitively upon the scientific problem being studied.

  5. ACHROMATIC EIGHT-OCTANT PHASE-MASK CORONAGRAPH USING PHOTONIC CRYSTAL

    SciTech Connect

    Murakami, Naoshi; Baba, Naoshi; Nishikawa, Jun; Yokochi, Kaito; Tamura, Motohide; Abe, Lyu

    2010-05-01

    We designed and manufactured a photonic-crystal mask which can be used for an achromatic eight-octant phase-mask (EOPM) coronagraph for direct detection of extrasolar planets. Laboratory experiments of the EOPM coronagraph were carried out using two laser light sources as a simulated star (wavelengths of 532 and 633 nm). As a result, we attained high extinction of the simulated starlight in both the wavelengths. Halo intensity levels of about 10{sup -6} and 10{sup -7} were achieved at an angular distance of 3 and 13{lambda}/D, respectively. We also discuss several issues, such as an effect of phase aberration on the coronagraphic performance, a transmittance of the proposed EOPM, and a novel two-channel coronagraphic configuration to improve system throughput.

  6. Target & Propagation Models for the FINDER Radar

    NASA Technical Reports Server (NTRS)

    Cable, Vaughn; Lux, James; Haque, Salmon

    2013-01-01

    Finding persons still alive in piles of rubble following an earthquake, a severe storm, or other disaster is a difficult problem. JPL is currently developing a victim detection radar called FINDER (Finding Individuals in Emergency and Response). The subject of this paper is directed toward development of propagation & target models needed for simulation & testing of such a system. These models are both physical (real rubble piles) and numerical. Early results from the numerical modeling phase show spatial and temporal spreading characteristics when signals are passed through a randomly mixed rubble pile.

  7. Rockstar: Phase-space halo finder

    NASA Astrophysics Data System (ADS)

    Behroozi, Peter; Wechsler, Risa; Wu, Hao-Yi

    2012-10-01

    Rockstar (Robust Overdensity Calculation using K-Space Topologically Adaptive Refinement) identifies dark matter halos, substructure, and tidal features. The approach is based on adaptive hierarchical refinement of friends-of-friends groups in six phase-space dimensions and one time dimension, which allows for robust (grid-independent, shape-independent, and noise-resilient) tracking of substructure. Our method is massively parallel (up to 10^5 CPUs) and runs on the largest current simulations (>10^10 particles) with high efficiency (10 CPU hours and 60 gigabytes of memory required per billion particles analyzed). Rockstar offers significant improvement in substructure recovery as compared to several other halo finders.

  8. Target & Propagation Models for the FINDER Radar

    NASA Technical Reports Server (NTRS)

    Cable, Vaughn; Lux, James; Haque, Salmon

    2013-01-01

    Finding persons still alive in piles of rubble following an earthquake, a severe storm, or other disaster is a difficult problem. JPL is currently developing a victim detection radar called FINDER (Finding Individuals in Emergency and Response). The subject of this paper is directed toward development of propagation & target models needed for simulation & testing of such a system. These models are both physical (real rubble piles) and numerical. Early results from the numerical modeling phase show spatial and temporal spreading characteristics when signals are passed through a randomly mixed rubble pile.

  9. Gemini Planet Imager Coronagraph Testbed Results

    SciTech Connect

    Sivaranmakrishnan, A.; Carr, G.; Soummer, R.; Oppenheimer, B.R.; Mey, J.L.; Brenner, D.; Mandeville, C.W.; Zimmerman, N. Macintosh, B.A.; Graham, J.R.; Saddlemyer, L.; Bauman, B.; Carlotti, A.; Pueyo, L.; Tuthill, P.G.; Dorrer, C.; Roberts, R.; Greenbaum, A.

    2010-12-08

    The Gemini Planet Imager (GPI) is an extreme AO coronagraphic integral field unit YJHK spectrograph destined for first light on the 8m Gemini South telescope in 2011. GPI fields a 1500 channel AO system feeding an apodized pupil Lyot coronagraph, and a nIR non-common-path slow wavefront sensor. It targets detection and characterizion of relatively young (<2GYr), self luminous planets up to 10 million times as faint as their primary star. We present the coronagraph subsystem's in-lab performance, and describe the studies required to specify and fabricate the coronagraph. Coronagraphic pupil apodization is implemented with metallic half-tone screens on glass, and the focal plane occulters are deep reactive ion etched holes in optically polished silicon mirrors. Our JH testbed achieves H-band contrast below a million at separations above 5 resolution elements, without using an AO system. We present an overview of the coronagraphic masks and our testbed coronagraphic data. We also demonstrate the performance of an astrometric and photometric grid that enables coronagraphic astrometry relative to the primary star in every exposure, a proven technique that has yielded on-sky precision of the order of a milliarsecond.

  10. Gemini Planet Imager coronagraph testbed results

    NASA Astrophysics Data System (ADS)

    Sivaramakrishnan, Anand; Soummer, Rémi; Oppenheimer, Ben R.; Carr, G. Lawrence; Mey, Jacob L.; Brenner, Doug; Mandeville, Charles W.; Zimmerman, Neil; Macintosh, Bruce A.; Graham, James R.; Saddlemyer, Les; Bauman, Brian; Carlotti, Alexis; Pueyo, Laurent; Tuthill, Peter G.; Dorrer, Christophe; Roberts, Robin; Greenbaum, Alexandra

    2010-07-01

    The Gemini Planet Imager (GPI) is an extreme AO coronagraphic integral field unit YJHK spectrograph destined for first light on the 8m Gemini South telescope in 2011. GPI fields a 1500 channel AO system feeding an apodized pupil Lyot coronagraph, and a nIR non-common-path slow wavefront sensor. It targets detection and characterizion of relatively young (<2GYr), self luminous planets up to 10 million times as faint as their primary star. We present the coronagraph subsystem's in-lab performance, and describe the studies required to specify and fabricate the coronagraph. Coronagraphic pupil apodization is implemented with metallic half-tone screens on glass, and the focal plane occulters are deep reactive ion etched holes in optically polished silicon mirrors. Our JH testbed achieves H-band contrast below a million at separations above 5 resolution elements, without using an AO system. We present an overview of the coronagraphic masks and our testbed coronagraphic data. We also demonstrate the performance of an astrometric and photometric grid that enables coronagraphic astrometry relative to the primary star in every exposure, a proven technique that has yielded on-sky precision of the order of a milliarsecond.

  11. Extrasolar Planetary Imaging Coronagraph: Visible Nulling Coronagraph Testbed Results

    NASA Technical Reports Server (NTRS)

    Lyon, Richard G.

    2008-01-01

    The Extrasolar Planetary Imaging Coronagraph (EPIC) is a proposed NASA Discovery mission to image and characterize extrasolar giant planets in orbits with semi-major axes between 2 and 10 AU. EPIC will provide insights into the physical nature of a variety of planets in other solar systems complimenting radial velocity (RV) and astrometric planet searches. It will detect and characterize the atmospheres of planets identified by radial velocity surveys, determine orbital inclinations and masses, characterize the atmospheres around A and F stars, observed the inner spatial structure and colors of inner Spitzer selected debris disks. EPIC would be launched to heliocentric Earth trailing drift-away orbit, with a 3-year mission lifetime ( 5 year goal) and will revisit planets at least three times at intervals of 9 months. The starlight suppression approach consists of a visible nulling coronagraph (VNC) that enables high order starlight suppression in broadband light. To demonstrate the VNC approach and advance it's technology readiness the NASA Goddard Space Flight Center and Lockheed-Martin have developed a laboratory VNC and have demonstrated white light nulling. We will discuss our ongoing VNC work and show the latest results from the VNC testbed,

  12. Optimal Jet Finder

    NASA Astrophysics Data System (ADS)

    Grigoriev, D. Yu.; Jankowski, E.; Tkachov, F. V.

    2003-09-01

    We describe a FORTRAN 77 implementation of the optimal jet definition for identification of jets in hadronic final states of particle collisions. We discuss details of the implementation, explain interface subroutines and provide a usage example. The source code is available from http://www.inr.ac.ru/~ftkachov/projects/jets/. Program summaryTitle of program: Optimal Jet Finder (OJF_014) Catalogue identifier: ADSB Program Summary URL:http://cpc.cs.qub.ac.uk/summaries/ADSB Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Computer: Any computer with the FORTRAN 77 compiler Tested with: g77/Linux on Intel, Alpha and Sparc; Sun f77/Solaris (thwgs.cern.ch); xlf/AIX (rsplus.cern.ch); MS Fortran PowerStation 4.0/Win98 Programming language used: FORTRAN 77 Memory required: ˜1 MB (or more, depending on the settings) Number of bytes in distributed program, including examples and test data: 251 463 Distribution format: tar gzip file Keywords: Hadronic jets, jet finding algorithms Nature of physical problem: Analysis of hadronic final states in high energy particle collision experiments often involves identification of hadronic jets. A large number of hadrons detected in the calorimeter is reduced to a few jets by means of a jet finding algorithm. The jets are used in further analysis which would be difficult or impossible when applied directly to the hadrons. Grigoriev et al. [ hep-ph/0301185] provide a brief introduction to the subject of jet finding algorithms and a general review of the physics of jets can be found in [Rep. Prog. Phys. 36 (1993) 1067]. Method of solution: The software we provide is an implementation of the so-called optimal jet definition ( OJD). The theory of OJD was developed by Tkachov [Phys. Rev. Lett. 73 (1994) 2405; 74 (1995) 2618; Int. J. Mod. Phys. A 12 (1997) 5411; 17 (2002) 2783]. The desired jet configuration is obtained as the one that minimizes Ω R, a certain function of the input particles and jet

  13. Extrasolar Planetary Imaging Coronagraph (EPIC)

    NASA Technical Reports Server (NTRS)

    Clampin, Mark

    2009-01-01

    EPIC is a NASA mission being studied to detect and characterize Jovian and superEarth planets, and, the dust/debris disks surrounding the parent star. It will be launched into a heliocentric Earth trailing orbit and operate for 5 years. EPIC would operate over the wavelength range of 480 - 960 nm with spectral resolutions of R < 50 and employs a visible nulling coronagraph (VNC) to suppress the starlight, yielding contrast ratios of greater than 9 orders of magnitude. We will discuss the science mission, and its role in the search for habitable planets.

  14. Computer assisted performance tests of the Lyman Alpha Coronagraph

    NASA Technical Reports Server (NTRS)

    Parkinson, W. H.; Kohl, J. L.

    1979-01-01

    Preflight calibration and performance tests of the Lyman Alpha Coronagraph rocket instrument in the laboratory, with the experiment in its flight configuration and illumination levels near those expected during flight were successfully carried out using a pulse code modulation telemetry system simulator interfaced in real time to a PDP 11/10 computer system. Post acquisition data reduction programs developed and implemented on the same computer system aided in the interpretation of test and calibration data.

  15. Data-Parallel Halo Finder Operator in PISTON

    SciTech Connect

    Widanagamaachchi, W. N.

    2012-08-01

    PISTON is a portable framework which supports the development of visualization and analysis operators using a platform-independent, data-parallel programming model. Operators such as isosurface, cut-surface and threshold have been implemented in this framework, with the exact same operator code achieving good parallel performance on different architectures. An important analysis operator in cosmology is the halo finder. A halo is a cluster of particles and is considered a common feature of interest found in cosmology data. As the number of cosmological simulations carried out in the recent past has increased, the resultant data of these simulations and the required analysis tasks have increased as well. As a consequence, there is a need to develop scalable and efficient tools to carry out the needed analysis. Therefore, we are currently implementing a halo finder operator using PISTON. Researchers have developed a wide variety of techniques to identify halos in raw particle data. The most basic algorithm is the friend-of-friends (FOF) halo finder, where the particles are clustered based on two parameters: linking length and halo size. In a FOF halo finder, all particles which lie within the linking length are considered as one halo and the halos are filtered based on the halo size parameter. A naive implementation of a FOF halo finder compares each and every particle pair, requiring O(n{sup 2}) operations. Our data-parallel halo finder operator uses a balanced k-d tree to reduce this number of operations in the average case, and implements the algorithm using only the data-parallel primitives in order to achieve portability and performance.

  16. Coronagraphic Observations of Lunar Sodium

    NASA Technical Reports Server (NTRS)

    Hunten, D. M.; Sprague, A. L.

    1997-01-01

    This grant supported an investigation of lunar sodium by our coronagraph and spectrograph on nearby Mount Lemmon. We report successful operation and data analysis during International Lunar Atmosphere Week, September 15 - 22, 1995, and submittal of a paper to Icarus. The core of the proposed work was to observe the lunar sodium atmosphere with our classical Lyot coronagraph and specially-built grating spectrograph on Mount Lemmon, a 9400-foot peak about an hour's drive from Tucson. It is optimized for low scattered light and for observing from the Moon's limb to an altitude of approx.1 lunar radius. The grating has 600 lines/mm and a blaze angle of 49 deg., and is used with a somewhat wide slit at a resolving power of about 5000. It is called DARRK for the initials of the people who designed it. The rejection of stray light from the Moon's disk is spectacularly good: when the sky is clear this light is absent right up to a few arcsec from the limb. We use an excellent 1024 by 1024 pixel CCD camera, operated at -100 C; the exposures are 10 to 30 min. Data reduction is done with IRAF running on a Sun Sparcstation.

  17. Visible Nulling Coronagraph Testbed Results

    NASA Technical Reports Server (NTRS)

    Lyon, Richard G.; Clampin, Mark; Melnick, Gary; Tolls, Volker; Woodruff, Robert; Vasudevan, Gopal; Rizzo, Maxime; Thompson, Patrick

    2009-01-01

    The Extrasolar Planetary Imaging Coronagraph (EPIC) is a NASA Astrophysics Strategic Mission Concept study and a proposed NASA Discovery mission to image and characterize extrasolar giant planets in orbits with semi-major axes between 2 and 10 AU. EPIC would provide insights into the physical nature of a variety of planets in other solar systems complimenting radial velocity (RV) and astrometric planet searches. It will detect and characterize the atmospheres of planets identified by radial velocity surveys, determine orbital inclinations and masses, characterize the atmospheres around A and F stars, observed the inner spatial structure and colors of inner Spitzer selected debris disks. EPIC would be launched to heliocentric Earth trailing drift-away orbit, with a 5-year mission lifetime. The starlight suppression approach consists of a visible nulling coronagraph (VNC) that enables starlight suppression in broadband light from 480-960 nm. To demonstrate the VNC approach and advance it's technology readiness we have developed a laboratory VNC and have demonstrated white light nulling. We will discuss our ongoing VNC work and show the latest results from the VNC testbed.

  18. Sensing Phase Aberrations behind Lyot Coronagraphs

    NASA Astrophysics Data System (ADS)

    Sivaramakrishnan, Anand; Soummer, Rémi; Pueyo, Laurent; Wallace, J. Kent; Shao, Michael

    2008-11-01

    Direct detection of young extrasolar planets orbiting nearby stars can be accomplished from the ground with extreme adaptive optics and coronagraphy in the near-infrared, as long as this combination can provide an image with a dynamic range of 107 after the data are processed. Slowly varying speckles due to residual phase aberrations that are not measured by the primary wave-front sensor are the primary obstacle to achieving such a dynamic range. In particular, non-common optical path aberrations occurring between the wave-front sensor and the coronagraphic occulting spot degrade performance the most. We analyze the passage of both low and high spatial frequency phase ripples, as well as low-order Zernike aberrations, through an apodized pupil Lyot coronagraph in order to demonstrate the way coronagraphic filtering affects various aberrations. We derive the coronagraphically induced cutoff frequency of the filtering and estimate coronagraphic contrast losses due to low-order Zernike aberrations: tilt, astigmatism, defocus, coma, and spherical aberration. Such slowly varying path errors can be measured behind a coronagraph and corrected by a slowly updated optical path delay precompensation or offset asserted on the wave front by the adaptive optics (AO) system. We suggest ways of measuring and correcting all but the lowest spatial frequency aberrations using Lyot plane wave-front data, in spite of the complex interaction between the coronagraph and those mid-spatial frequency aberrations that cause image plane speckles near the coronagraphic focal plane mask occulter's edge. This investigation provides guidance for next-generation coronagraphic instruments currently under construction.

  19. A new deformable mirror architecture for coronagraphic instrumentation

    NASA Astrophysics Data System (ADS)

    Groff, Tyler D.; Lemmer, Aaron; Eldorado Riggs, A. J.

    2016-07-01

    Coronagraphs are a promising solution for the next generation of exoplanet imaging instrumentation. While a coronagraph can have very good contrast and inner working angle performance, it is highly sensitive to optical aberrations. This necessitates a wavefront control system to correct aberrations within the telescope. The wavefront requirements and desired search area in a deformable mirror (DM) demand control of the electric field out to relatively high spatial frequencies. Conventional wisdom leads us to high stroke, high actuator density DMs that are capable of reaching these spatial frequencies on a single surface. Here we model a different architecture, where nearly every optical surface, powered or unpowered, is a controllable element. Rather than relying on one or two controllable surfaces for the success of the entire instrument the modeled instrument consists of a series of lower actuator count deformable mirrors to achieve the same result by leveraging the conjugate planes that exist in a coronagraphic instrument. To make such an instrument concept effective the imaging optics themselves must become precision deformable elements, akin to the deformable secondary mirrors at major telescope facilities. Such a DM does not exist commercially; all current DMs, while not necessarily incapable of carrying optical power, are manufactured with flat nominal surfaces. This simplifies control and manufacturing, but complicates their integration into an optical system because there is oftentimes a need to pack several into collimated space. Furthermore, high actuator count DMs cannot approximate low order shapes such as focus or tip-tilt without significant mid-spatial frequency residuals, which is not acceptable for a coronagraphic high-contrast imager. The ability to integrate the wavefront control system into the nominal coronagraphic optical train simplifies packaging, reduces cost and complexity, and increases optical throughput of any coronagraphic instrument

  20. Coronagraph for astronomical imaging and spectrophotometry

    NASA Technical Reports Server (NTRS)

    Vilas, Faith; Smith, Bradford A.

    1987-01-01

    A coronagraph designed to minimize scattered light in astronomical observations caused by the structure of the primary mirror, secondary mirror, and secondary support structure of a Cassegrainian telescope is described. Direct (1:1) and reducing (2.7:1) imaging of astronomical fields are possible. High-quality images are produced. The coronagraph can be used with either a two-dimensional charge-coupled device or photographic film camera. The addition of transmission dispersing optics converts the coronagraph into a low-resolution spectrograph. The instrument is modular and portable for transport to different observatories.

  1. Lyman alpha coronagraph research sounding rocket program

    NASA Technical Reports Server (NTRS)

    Parkinson, W. H.; Kohl, J. L.

    1985-01-01

    The ultraviolet light coronagraph was developed and successfully flown on three rocket flights on 13 April 1979, 16 February 1980 and 20 July 1982. During each of these flights, the Ultraviolet Light Coronagraph was flown jointly with the White Light Coronagraph provided by the High Altitude Observatory. Ultraviolet diagnostic techniques and instrumentation for determining the basic plasma parameters of solar wind acceleration regions in the extended corona were developed and verified and the understanding of the physics of the corona through the performance, analysis and interpretation of solar observations advanced. Valuable UV diagnostics can be performed in the absence of a natural solar eclipse.

  2. Coronagraphic Observations of Lunar Sodium

    NASA Technical Reports Server (NTRS)

    Hunten, D. M.; Sprague, A. L.

    1997-01-01

    The core of the proposed work was to observe the lunar sodium atmosphere with our classical Lyot coronagraph and specially-built grating spectrograph on Mount Lemmon, a 9400-foot peak about an hour's drive from Tucson. It is optimized for low scattered light and for observing from the Moon's limb to an altitude of approx. 1 lunar radius. The grating has 600 lines/mm and a blaze angle of 49 deg, and is used with a somewhat wide slit at a resolving power of about 5000. It is called DARRK for the initials of the people who designed it. The rejection of stray light from the Moon's disk is spectacularly good: when the sky is clear this light is absent right up to a few arcsec from the limb. We use an excellent 1024 by 1024 pixel CCD camera, operated at -100 C; the exposures are 10 to 30 min. Data reduction is done with ERAF running on a Sun Sparcstation.

  3. X-ray beam finder

    DOEpatents

    Gilbert, H.W.

    1983-06-16

    An X-ray beam finder for locating a focal spot of an X-ray tube includes a mass of X-ray opaque material having first and second axially-aligned, parallel-opposed faces connected by a plurality of substantially identical parallel holes perpendicular to the faces and a film holder for holding X-ray sensitive film tightly against one face while the other face is placed in contact with the window of an X-ray head.

  4. Propulsion PathFinder (PPF)

    NASA Technical Reports Server (NTRS)

    Marmie, John A.

    2015-01-01

    NASA's Propulsion PathFinder (PPF) project will flight test a variety of CubeSat propulsion systems in a relevant space environment, thereby elevating the Technology Readiness Level (TRL), or technology maturity level, of these subsystems to TRL 7. A series of flights are planned in low Earth orbit to characterize the performance of each propulsion system and demonstrate the capability to perform orbital maneuvers.

  5. Final A&T stages of the Gemini Planet Finder

    NASA Astrophysics Data System (ADS)

    Hartung, Markus; Macintosh, Bruce; Poyneer, Lisa; Savransky, Dimitri; Gavel, Donald; Palmer, Dave; Thomas, Sandrine; Dillon, Daren; Chilcote, Jeffrey; Ingraham, Patrick; Sadakuni, Naru; Wallace, Kent; Perrin, Marshall; Marois, Christian; Maire, Jerome; Rantakyro, Fredrik; Hibon, Pascale; Saddlemyer, Les; Goodsell, Stephen

    2013-12-01

    The Gemini Planet Finder (GPI) is currently in its final Acceptance & Testing stages at the University of Santa Cruz, California. GPI is an XAO system based on a tweeter & woofer architecture (43 & 9 actuators across the pupil), with the tweeter being a Boston Michromachines 64^2 MEMS device. The XAO AO system is tightly integrated with a Lyot apodizing coronagraph. Acceptance has started in February 2013. After the conclusive acceptance review shipment is scheduled mid 2013 to ensure readiness for commissioning at the Gemini South telescope on Cerro Pachon, Chile, end of 2013, matching the summer window of the southern hemisphere. According to current estimates the 3 year (~800 allocated hours) planet finding campaign might discover, image, and spectroscopically analyze 20 to 40 new exo-planets.Final acceptance testing of the integrated instrument can always emerge a number of unforeseen challenges as we are eventually using cold chamber and flexure rig installations. The latest developments will be reported. Also, we will give an overview of GPI's lab performance, the interplay between subsystems such as the calibration unit (CAL) with the AO bench. (The CAL principal purpose is to maintain a clean and centered XAO PSF on the coronagraph.) We report on-going optimizations on the AO controler loop to filter vibrations and last but not least achieved contrast performance applying speckle nulling. Furthermore, we will give an outlook of possible but challenging future upgrades as the implementation of a predictive controler or exchanging the conventional 48x48 SH WFS with a pyramid. With the ELT area arising, GPI will proof as a versatile and path-finding testbed for AO technologies on the next generation of ground-based telescopes.

  6. Coronagraphic phase diversity: performance study and laboratory demonstration

    NASA Astrophysics Data System (ADS)

    Paul, B.; Sauvage, J.-F.; Mugnier, L. M.

    2013-04-01

    Context. The final performance of current and future instruments dedicated to exoplanet detection and characterization (such as SPHERE on the European Very Large Telescope, GPI on Gemini North, or future instruments on Extremely Large Telescopes) is limited by uncorrected quasi-static aberrations. These aberrations create long-lived speckles in the scientific image plane, which can easily be mistaken for planets. Aims: Common adaptive optics systems require dedicated components to perform wave-front analysis. The ultimate wave-front measurement performance is thus limited by the unavoidable differential aberrations between the wave-front sensor and the scientific camera. To reach the level of detectivity required by high-contrast imaging, these differential aberrations must be estimated and compensated for. In this paper, we characterize and experimentally validate a wave-front sensing method that relies on focal-plane data. Methods: Our method, called COFFEE (for COronagraphic Focal-plane wave-Front Estimation for Exoplanet detection), is based on a Bayesian approach, and it consists in an extension of phase diversity to high-contrast imaging. It estimates the differential aberrations using only two focal-plane coronagraphic images recorded from the scientific camera itself. Results: We first present a thorough characterization of COFFEE's performance by means of numerical simulations. This characterization is then compared with an experimental validation of COFFEE using an in-house adaptive optics bench and an apodized Roddier & Roddier phase mask coronagraph. An excellent match between experimental results and the theoretical study is found. Lastly, we present a preliminary validation of COFFEE's ability to compensate for the aberrations upstream of a coronagraph.

  7. Technology Plan for the Terrestrial Planet Finder Interferometer

    NASA Technical Reports Server (NTRS)

    Lawson, Peter R. (Editor); Dooley, Jennifer A. (Editor)

    2005-01-01

    The technology plan for the Terrestrial Planet Finder Interferometer (TPF-I) describes the breadth of technology development currently envisaged to enable TPF-I to search for habitable worlds around nearby stars. TPF-I is currently in Pre-Phase A (the Advanced Study Phase) of its development. For planning purposes, it is expected to enter into Phase A in 2010 and be launched sometime before 2020. TPF-I is being developed concurrently with the Terrestrial Planet Finder Coronagraph (TPF-C), whose launch is anticipated in 201 6. The missions are being designed with the capability to detect Earth-like planets should they exist in the habitable zones of Sun-like (F,G, and K) stars out to a distance of about 60 light-years. Each mission will have the starlight-suppression and spectroscopic capability to enable the characterization of extrasolar planetary atmospheres, identifying biomarkers and signs of life. TPF-C is designed as a visible-light coronagraph; TPF-I is designed as a mid-infrared formation-flying interferometer. The two missions, working together, promise to yield unambiguous detections and characterizations of Earth-like planets. The challenges of planet detections with mid-infrared formation-flying interferometry are described within this technology plan. The approach to developing the technology is described through roadmaps that lead from our current state of the art through the different phases of mission development to launch. Technology metrics and milestones are given to measure progress. The emphasis of the plan is development and acquisition of technology during pre-Phase A to establish feasibility of the mission to enter Phase A sometime around 2010. Plans beyond 2010 are outlined. The plan contains descriptions of the development of new component technology as well as testbeds that demonstrate the viability of new techniques and technology required for the mission. Starlight-suppression (nulling) and formation-flying technology are highlighted

  8. Fine Guidance Sensing for Coronagraphic Observatories

    NASA Technical Reports Server (NTRS)

    Brugarolas, Paul; Alexander, James W.; Trauger, John T.; Moody, Dwight C.

    2011-01-01

    Three options have been developed for Fine Guidance Sensing (FGS) for coronagraphic observatories using a Fine Guidance Camera within a coronagraphic instrument. Coronagraphic observatories require very fine precision pointing in order to image faint objects at very small distances from a target star. The Fine Guidance Camera measures the direction to the target star. The first option, referred to as Spot, was to collect all of the light reflected from a coronagraph occulter onto a focal plane, producing an Airy-type point spread function (PSF). This would allow almost all of the starlight from the central star to be used for centroiding. The second approach, referred to as Punctured Disk, collects the light that bypasses a central obscuration, producing a PSF with a punctured central disk. The final approach, referred to as Lyot, collects light after passing through the occulter at the Lyot stop. The study includes generation of representative images for each option by the science team, followed by an engineering evaluation of a centroiding or a photometric algorithm for each option. After the alignment of the coronagraph to the fine guidance system, a "nulling" point on the FGS focal point is determined by calibration. This alignment is implemented by a fine alignment mechanism that is part of the fine guidance camera selection mirror. If the star images meet the modeling assumptions, and the star "centroid" can be driven to that nulling point, the contrast for the coronagraph will be maximized.

  9. Extra Solar Planetary Imaging Coronagraph and Science Requirements for the James Webb Telescope Observatory

    NASA Technical Reports Server (NTRS)

    Clampin, Mark

    2004-01-01

    1) Extra solar planetary imaging coronagraph. Direct detection and characterization of Jovian planets, and other gas giants, in orbit around nearby stars is a necessary precursor to Terrestrial Planet Finder 0 in order to estimate the probability of Terrestrial planets in our stellar neighborhood. Ground based indirect methods are biased towards large close in Jovian planets in solar systems unlikely io harbor Earthlike planets. Thus to estimate the relative abundances of terrestrial planets and to determine optimal observing strategies for TPF a pathfinder mission would be desired. The Extra-Solar Planetary Imaging Coronagraph (EPIC) is such a pathfinder mission. Upto 83 stellar systems are accessible with a 1.5 meter unobscured telescope and coronagraph combination located at the Earth-Sun L2 point. Incorporating radiometric and angular resolution considerations show that Jovians could be directly detected (5 sigma) in the 0.5 - 1.0 micron band outside of an inner working distance of 5/D with integration times of -10 - 100 hours per observation. The primary considerations for a planet imager are optical wavefront quality due to manufacturing, alignment, structural and thermal considerations. pointing stability and control, and manufacturability of coronagraphic masks and stops to increase the planetary-to- stellar contrast and mitigate against straylight. Previously proposed coronagraphic concepts are driven to extreme tolerances. however. we have developed and studied a mission, telescope and coronagraphic detection concept, which is achievable in the time frame of a Discovery class NASA mission. 2) Science requirements for the James Webb Space Telescope observatory. The James Webb Space Observatory (JWST) is an infrared observatory, which will be launched in 201 1 to an orbit at L2. JWST is a segmented, 18 mirror segment telescope with a diameter of 6.5 meters, and a clear aperture of 25 mA2. The telescope is designed to conduct imaging and spectroscopic

  10. STAR cluster-finder ASIC

    SciTech Connect

    Botlo, M.; LeVine, M.J.; Scheetz, R.A.

    1997-12-31

    The STAR experiment reads out a TPC and an SVT (silicon vertex tracker), both of which require in-line pedestal subtraction, compression of ADC values from 10-bit to 8-bit, and location of time sequences representing responses to charged-particle tracks. The STAR cluster finder ASIC responds to all of these needs. Pedestal subtraction and compression are performed using lookup tables in attached RAM. We describe its design and implementation, as well as testing methodology and results of tests performed on foundry prototypes.

  11. New Mauna Loa coronagraph systems.

    PubMed

    Fisher, R R; Lee, R H; Macqueen, R M; Poland, A I

    1981-03-15

    A new set of instruments, consisting of two coronagraph systems, has been installed and is operating at the Mauna Loa Observing Station, Hawaii, operated by the High Altitude Observatory of Boulder, Colorado. The instruments are the 23-cm objective Mark III K-coronameter (K-III) system, a photoelectric instrument used to observe the inner solar corona from 1.2 R(0) to 2.2 R(0) and the 12.5-cm objective Prominence Monitor system used for the detection of H(alpha) limb activity. New features of the K-coronameter system include the use of achromatic wave plates for wide bandpass operation and linear diode array detectors. Raster scans of the coronal image are obtained in 1.5 min for a critical sampling scheme of 20-sec of arc resolution (10 x 10-sec of arc pixels) in the coronal p(B) image. This represents a 350 information gain factor for each detection channel when compared with the previous Mauna Loa K-coronameters.

  12. A laboratory experiment for a new free-standing pupil mask coronagraph

    NASA Astrophysics Data System (ADS)

    Haze, K.; Enya, K.; Kotani, T.; Abe, L.; Nakagawa, T.; Matsuhara, H.; Sato, T.; Yamamuro, T.

    2012-09-01

    This paper presents the results of a laboratory experiment on a new free-standing pupil mask coronagraph for the direct observation of exoplanets. We focused on a binary-shaped pupil coronagraph, which is planned for installation in the next-generation infrared space telescope SPICA. Our laboratory experiments on the coronagraph were implemented inside a vacuum chamber (HOCT) to achieve greater thermal stability and to avoid air turbulence, and a contrast of 1.3×10-9 was achieved with PSF subtraction. We also carried out multi-color/broadband experiments to demonstrate that the pupil mask coronagraph works, in principle, at all wavelengths. We had previously manufactured a checker-board mask, a type of binary-shaped pupil mask, on a glass substrate, which had the disadvantages of light loss by transmission, ghosting from residual reflectance and a slightly different refractive index for each wavelength. Therefore, we developed a new free-standing mask in sheet metal, for which no substrate was needed. As a result of a He-Ne laser experiment with the free-standing mask, a contrast of 1.0×10-7 was achieved for the raw coronagraphic image. We also conducted rotated mask subtractions and numerical simulations of some errors in the mask shape and WFEs. Speckles are the major limiting factor. The free-standing mask exhibited about the same ability to improve contrast as the substrate mask. Consequently, the results of this study suggest that the binary-shaped pupil mask coronagraph can be applied to coronagraphic observations by SPICA and other telescopes.

  13. Artemis: A Stratospheric Planet Finder

    NASA Technical Reports Server (NTRS)

    Ford, H. C.; Petro, L. D.; Burrows, C.; Ftaclas, C.; Roggemann, M. C.; Trauger, J. T.

    2003-01-01

    The near-space environment of the stratosphere is far superior to terrestrial sites for optical and infrared observations. New balloon technologies will enable flights and safe recovery of 2-ton payloads at altitudes of 35 km for 100 days and longer. The combination of long flights and superb observing conditions make it possible to undertake science programs that otherwise could only be done from orbit. We propose to fly an "Ultra-Hubble" Stratospheric Telescope (UHST) equipped with a coronagraphic camera and active optics at 35 km to search for planets around 200 of the nearest stars. This ULDB mission will establish the frequency of solar-type planetary systems, and provide targets to search for earth-like planets.

  14. Solar Energetic Particle Warnings from a Coronagraph

    NASA Technical Reports Server (NTRS)

    St Cyr, O. C.; Posner, A.; Burkepile, J. T.

    2017-01-01

    We report here the concept of using near-real time observations from a coronagraph to provide early warning of a fast coronal mass ejection (CME) and the possible onset of a solar energetic particle (SEP) event. The 1 January 2016, fast CME, and its associated SEP event are cited as an example. The CME was detected by the ground-based K-Cor coronagraph at Mauna Loa Solar Observatory and by the SOHO Large Angle and Spectrometric Coronagraph. The near-real-time availability of the high-cadence K-Cor observations in the low corona leads to an obvious question: Why has no one attempted to use a coronagraph as an early warning device for SEP events? The answer is that the low image cadence and the long latency of existing spaceborne coronagraphs make them valid for archival studies but typically unsuitable for near-real-time forecasting. The January 2016 event provided favorable CME viewing geometry and demonstrated that the primary component of a prototype ground-based system for SEP warnings is available several hours on most days. We discuss how a conceptual CME-based warning system relates to other techniques, including an estimate of the relative SEP warning times, and how such a system might be realized.

  15. Wide-band six-region phase mask coronagraph.

    PubMed

    Hou, Fanzhen; Cao, Qing; Zhu, Minning; Ma, Ourui

    2014-01-27

    An achromatic six-region phase mask coronagraph, used for the detection of exoplanets, is proposed. The mask has six regions in angular direction and could work in wideband. Furthermore, a six-level phase mask, as an example of the six-region phase mask, is theoretically investigated. According to numerical simulations, this specific mask has a deep elimination of starlight, good performance of achromatism and small inner working angle. As a single phase mask, the ratio of the remaining starlight of the six-level phase mask to the total incident starlight is less than 0.001 when the wavelength is between 500 nm and 600 nm.

  16. Effect of DM Actuator Errors on the WFIRST/AFTA Coronagraph Contrast Performance

    NASA Technical Reports Server (NTRS)

    Sidick, Erkin; Shi, Fang

    2015-01-01

    The WFIRST/AFTA 2.4 m space telescope currently under study includes a stellar coronagraph for the imaging and the spectral characterization of extrasolar planets. The coronagraph employs two sequential deformable mirrors (DMs) to compensate for phase and amplitude errors in creating dark holes. DMs are critical elements in high contrast coronagraphs, requiring precision and stability measured in picometers to enable detection of Earth-like exoplanets. Working with a low-order wavefront-sensor the DM that is conjugate to a pupil can also be used to correct low-order wavefront drift during a scientific observation. However, not all actuators in a DM have the same gain. When using such a DM in low-order wavefront sensing and control subsystem, the actuator gain errors introduce high-spatial frequency errors to the DM surface and thus worsen the contrast performance of the coronagraph. We have investigated the effects of actuator gain errors and the actuator command digitization errors on the contrast performance of the coronagraph through modeling and simulations, and will present our results in this paper.

  17. Technology Development Towards a Flight Coronagraph

    NASA Astrophysics Data System (ADS)

    Siegler, N.

    2014-03-01

    The first biosignatures in the spectrum of an Earth-like planet will be measured by a spectrometer aboard a future space telescope. But before the planet's light can be captured and characterized, the host star's light may have to be suppressed by a factor of about 10 billion. One of these instruments may likely be an internal coronagraph working at visible wavelengths. Thanks to both a potential funding wedge in FY17 created by a JWST ramp-down to launch and a "gift" 2.4m telescope from the NRO being converted into a possible "AFTA-WFIRST" mission, NASA has already begun funding technology development towards flight coronagraphs that will take astronomers one step closer towards their goal. This talk will focus on the technology development underway and planned over the next few years for a flight coronagraph on an AFTA-WFIRST mission.

  18. A broadband scalar optical vortex coronagraph

    NASA Astrophysics Data System (ADS)

    Errmann, Ronnie; Minardi, Stefano; Pertsch, Thomas

    2014-07-01

    In recent years, new coronagraphic schemes have been proposed, the most promising being the optical vortex phase mask coronagraphs. In our work, a new scheme of broadband optical scalar vortex coronagraph is proposed and characterized experimentally in the laboratory. Our setup employs a pair of computer generated phase gratings (one of them containing a singularity) to control the chromatic dispersion of phase plates and achieves a constant peak-to-peak attenuation below 1:1000 over a bandwidth of 120 nm centered at 700 nm. An inner working angle of λ/D is demonstrated along with a raw contrast of 11.5magnitudes at 2λ/D. A more compact setup achieves a peak-to-peak attenuation below 1:1000 over a bandwidth of 60 nm with the other results remaining the same.

  19. Hybrid Lyot Coronagraph for the ACCESS Mission

    NASA Astrophysics Data System (ADS)

    Trauger, J.; ACCESS Science and Engineering Team

    2010-10-01

    We report the design and fabrication of hybrid focal-plane masks for Lyot coronagraphy, supported this year by NASA's Technology Demonstration for Exoplanet Missions (TDEM) program. These masks are composed of thickness-profiled metallic and dielectric thin films, and manufactured by vacuum deposition on a glass substrate. Hybrid masks are in principle band-limited in both the real and imaginary parts of the complex amplitude characteristics, providing the theoretical basis for mathematically perfect starlight suppression. Together with a deformable mirror for control of wavefront phase, these masks achieve contrast levels of 2e-10 at inner working angles of 3 lambda/D, over spectral bandwidths of 20% or more, and with throughput efficiencies of 60%. We evaluate the science potential of these coronagaph masks in the context of ACCESS, a representative exoplanet mission concept. ACCESS is one of four medium-class concepts studied in 2008-2009 under NASA's Astrophysics Strategic Mission Concepts Study program. In a nutshell, the ACCESS study seeks the most capable medium-class coronagraphic mission that is possible with high-readiness telescope, instrument, and spacecraft technologies available today. The ACCESS study compared the performance of four major coronagraph architectures. It defined a conceptual space observatory platform as the "level playing field" for comparisons among coronagraph types. And it used laboratory validation of the representative coronagraph types as a second "level playing field" for assessing coronagraph hardware readiness. ACCESS identifies a class of scientifically compelling mission concepts built upon mature (TRL6+) subsystem technologies, and evaluates science reach of a medium-class coronagraph mission. Using current high-TRL technologies, the ACCESS minimum science program surveys the nearest 120+ AFGK stars for exoplanet systems, and surveys the majority of those for exozodiacal dust to the level of 1 zodi at 3 AU. Discoveries are

  20. Results from the adaptive optics coronagraph at the William Herschel Telescope

    NASA Astrophysics Data System (ADS)

    Thompson, S. J.; Doel, A. P.; Bingham, R. G.; Charalambous, A.; Myers, R. M.; Bissonauth, N.; Clark, P.; Talbot, G.

    2005-12-01

    Described here is the design and commissioning of a coronagraph facility for the 4.2-m William Herschel Telescope (WHT) and its Nasmyth Adaptive Optics for Multi-purpose Instrumentation (NAOMI). The use of the NAOMI system gives an improved image resolution of ~0.15 arcsec at a wavelength of 2.2μm. This enables the Optimised Stellar Coronagraph for Adaptive optics (OSCA) to suppress stellar light using smaller occulting masks and thus allows regions closer to bright astronomical objects to be imaged. OSCA provides a selection of 10 different occulting masks with sizes of 0.25-2.0arcsec in diameter, including two with full grey-scale Gaussian profiles. There is also a choice of different sized and shaped Lyot stops (pupil plane masks). Computer simulations of the different coronagraphic options with the NAOMI segmented mirror have relevance for the next generation of highly segmented extremely large telescopes.

  1. Digital laser range finder emulator

    NASA Astrophysics Data System (ADS)

    McDowell, Vaughn P.; Holland, Orgal T.; Wilkerson, Christina G.

    1993-05-01

    A digital laser range finder emulator receives N-bits of range-to-target data in a parallel format and generates N-bits of serial data representative of the range-to-target data and an external synchronization pulse whose presence is indicative of valid serial data. First and second clock pulses are generated such that the second clock pulse is delayed with respect to the first clock pulse. Control logic, responsive to the first clock pulse, generates validity logic while control logic, responsive to the second clock pulse, generates transmit logic. The parallel format range-to-target data is converted into the serial data in response to the first clock pulse. The serial data is then output in response to the transmit logic. A gate, responsive to the second clock pulse and the validity logic, generates the synchronization pulse when the second clock pulse and validity logic occupy a common logic state.

  2. The CMS Level-1 Trigger Barrel Track Finder

    NASA Astrophysics Data System (ADS)

    Ero, J.; Evangelou, I.; Flouris, G.; Foudas, C.; Guiducci, L.; Loukas, N.; Manthos, N.; Papadopoulos, I.; Paradas, E.; Sotiropoulos, S.; Sphicas, P.; Triossi, A.; Wulz, C.

    2016-03-01

    The design and performance of the upgraded CMS Level-1 Trigger Barrel Muon Track Finder (BMTF) is presented. Monte Carlo simulation data as well as cosmic ray data from a CMS muon detector slice test have been used to study in detail the performance of the new track finder. The design architecture is based on twelve MP7 cards each of which uses a Xilinx Virtex-7 FPGA and can receive and transmit data at 10 Gbps from 72 input and 72 output fibers. According to the CMS Trigger Upgrade TDR the BMTF receives trigger primitive data which are computed using both RPC and DT data and transmits data from a number of muon candidates to the upgraded Global Muon Trigger. Results from detailed studies of comparisons between the BMTF algorithm results and the results of a C++ emulator are also presented. The new BMTF will be commissioned for data taking in 2016.

  3. Internal polarization limits coronagraph contrast

    NASA Astrophysics Data System (ADS)

    Breckinridge, James Bernard; Lam, Wai Sze T.; Chipman, Russell A.

    2015-08-01

    The performance of exoplanet imaging coronagraphs is limited by internal polarization. The point spread function (PSF) of these systems is determined by the details of the opto-mechanical layout selected to package the system and by the highly reflective metal thin films needed to maintain high optical system transmittance. To obtain the high contrast levels needed for terrestrial exoplanet science requires a comprehensive understanding of the vector electromagnetic wave from the source through the system. The literature contains many studies of polarization transmissivity of telescopes and instruments for the purpose of photo-polarimetry. Here we report for the first time the effects of polarization on high-performance image quality.We modeled a typical 2.4-meter Cassegrain telescope system with one 90-degree fold mirror and analyzed the system for polarization aberrations.We find: 1. The image plane irradiance distribution is the linear superposition of four PSF images: One for each of the two orthogonal polarizations and one for each of two cross-product polarization terms. 2. The PSF image is brighter by 9% for one polarization component compared to its orthogonal state. 3. The image of the PSF for orthogonal components are shifted across the focal plane with respect to each other, causing the PSF image for astronomical sources (polarized or unpolarized) to become slightly elongated (elliptical) with a centroid separation of about 0.6 masec. 4. The orthogonally polarized components of unpolarized sources contain different wavefront aberrations, which are separated by approximately 32 milliwaves. This implies that a wavefront correction system cannot optimally correct the aberrations for all polarizations simultaneously. 5. The polarization aberrations couple small parts (~1E-5) of each polarization component of the light into the orthogonal polarization to create highly distorted secondary, or “ghost” PSF image.. The radius of the spatial extent of the 90

  4. 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.

  5. Linear-constraint wavefront control for exoplanet coronagraphic imaging systems

    NASA Astrophysics Data System (ADS)

    Sun, He; Eldorado Riggs, A. J.; Kasdin, N. Jeremy; Vanderbei, Robert J.; Groff, Tyler Dean

    2017-01-01

    A coronagraph is a leading technology for achieving high-contrast imaging of exoplanets in a space telescope. It uses a system of several masks to modify the diffraction and achieve extremely high contrast in the image plane around target stars. However, coronagraphic imaging systems are very sensitive to optical aberrations, so wavefront correction using deformable mirrors (DMs) is necessary to avoid contrast degradation in the image plane. Electric field conjugation (EFC) and Stroke minimization (SM) are two primary high-contrast wavefront controllers explored in the past decade. EFC minimizes the average contrast in the search areas while regularizing the strength of the control inputs. Stroke minimization calculates the minimum DM commands under the constraint that a target average contrast is achieved. Recently in the High Contrast Imaging Lab at Princeton University (HCIL), a new linear-constraint wavefront controller based on stroke minimization was developed and demonstrated using numerical simulation. Instead of only constraining the average contrast over the entire search area, the new controller constrains the electric field of each single pixel using linear programming, which could led to significant increases in speed of the wavefront correction and also create more uniform dark holes. As a follow-up of this work, another linear-constraint controller modified from EFC is demonstrated theoretically and numerically and the lab verification of the linear-constraint controllers is reported. Based on the simulation and lab results, the pros and cons of linear-constraint controllers are carefully compared with EFC and stroke minimization.

  6. A Nulling Coronagraph for TPF-C

    NASA Technical Reports Server (NTRS)

    Shao, Michael; Levine, Bruce Martin; Wallace, James Kent; Orton, Glenn S.; Schmidtlin, Edouard; Lane, Benjamin F.; Seager, Sara; Tolls, Volker; Lyon, Richard G.; Samuele, Rocco; hide

    2006-01-01

    The nulling coronagraph is one of 5 instrument concepts selected by NASA for study for potential use in the TPF-C mission. This concept for extreme starlight suppression has two major components, a nulling interferometer to suppress the starlight to 10(sup -10) per airy spot within 2 (lamda)/D of the star, and a calibration interferometer to measure the residual scattered starlight. The ability to work at 2 (lamda)/D dramatically improves the science throughput of a space based coronagraph like TPF-C. The calibration interferometer is an equally important part of the starlight suppression system. It measures the measures the wavefront of the scattered starlight with very high SNR, to 0.05nm in less than 5 minutes on a 5mag star. In addition, the post coronagraph wavefront sensor will be used to measure the residual scattered light after the coronagraph and subtract it in post processing to 12x10(sup -11) to enable detection of an Earthlike planet with a SNR of 510.

  7. Coronagraphic Imaging with HST and STIS

    NASA Technical Reports Server (NTRS)

    Grady, C. A.; Proffitt, C.; Malumuth, E.; Woodgate, B. E.; Gull, T. R.; Bowers, C. W.; Heap, S. R.; Kimble, R. A.; Lindler, D.; Plait, P.

    2002-01-01

    Revealing faint circumstellar nebulosity and faint stellar or substellar companions to bright stars typically requires use of techniques for rejecting the direct, scattered, and diffracted light of the star. One such technique is Lyot coronagraphy. We summarize the performance of the white-light coronagraphic capability of the Space Telescope Imaging spectrograph, on board the Hubble Space Telescope.

  8. The four-quadrant phase-mask coronagraph: white light laboratory results with an achromatic device

    NASA Astrophysics Data System (ADS)

    Mawet, D.; Riaud, P.; Baudrand, J.; Baudoz, P.; Boccaletti, A.; Dupuis, O.; Rouan, D.

    2006-03-01

    Achromatic coronagraphs are the subject of intensive research since they will be mandatory for many programs which aim at detecting and characterizing exoplanets. We report a laboratory experiment assessing the performance of the Four-Quadrant Phase-Mask coronagraph (FQPM) over a broadband wavelength range (R≈ 2). The achromatization of the FQPM is provided by achromatic halfwave plates (HWP). These phase shifters combine birefringent plates made of different materials with properly chosen thicknesses. The HWP thickness control is relaxed by two orders of magnitudes with respect to the classical (non-birefringent) dispersive plate approach. In our experiment we used a two stage stack of Quartz and MgF2. This combination allows to cover a large spectral range in the visible (500-900 nm) with a small phase error residual around π (≈ 0.12 rad rms). With this achromatization, we obtained an attenuation of 755 on the white light PSF peak. This solution is directly applicable to ground-based telescopes using high order adaptive optics such as the ESO's VLT-Planet Finder project and could easily be transposed in the mid-infrared domain for future space-based missions like DARWIN/TPF.

  9. AMA Physician Select: Online Doctor Finder

    MedlinePlus

    ... members must adhere to the AMA's Principles of Medical Ethics. DoctorFinder Usage Verification Type the two words you see in the picture below: Copyright 1995- American Medical Association All rights reserved. Contact Us | Terms of ...

  10. Post-coronagraphic tip-tilt sensing for vortex phase masks: The QACITS technique

    NASA Astrophysics Data System (ADS)

    Huby, E.; Baudoz, P.; Mawet, D.; Absil, O.

    2015-12-01

    Context. Small inner working angle coronagraphs, such as the vortex phase mask, are essential to exploit the full potential of ground-based telescopes in the context of exoplanet detection and characterization. However, the drawback of this attractive feature is a high sensitivity to pointing errors, which degrades the performance of the coronagraph. Aims: We propose a tip-tilt retrieval technique based on the analysis of the final coronagraphic image, hereafter called Quadrant Analysis of Coronagraphic Images for Tip-tilt Sensing (QACITS). Methods: Under the assumption of small phase aberrations, we show that the behavior of the vortex phase mask can be simply described from the entrance pupil to the Lyot stop plane with Zernike polynomials. This convenient formalism is used to establish the theoretical basis of the QACITS technique. We performed simulations to demonstrate the validity and limits of the technique, including the case of a centrally obstructed pupil. Results: The QACITS technique principle is validated with experimental results in the case of an unobstructed circular aperture, as well as simulations in presence of a central obstruction. The typical configuration of the Keck telescope (24% central obstruction) has been simulated with additional high order aberrations. In these conditions, our simulations show that the QACITS technique is still adapted to centrally obstructed pupils and performs tip-tilt retrieval with a precision of 5 × 10-2λ/D when wavefront errors amount to λ/ 14 rms and 10-2λ/D for λ/ 70 rms errors (with λ the wavelength and D the pupil diameter). Conclusions: We have developed and demonstrated a tip-tilt sensing technique for vortex coronagraphs. The implementation of the QACITS technique is based on the analysis of the scientific image and does not require any modification of the original setup. Current facilities equipped with a vortex phase mask can thus directly benefit from this technique to improve the contrast

  11. Sensitivity of the terrestrial planet finder

    NASA Technical Reports Server (NTRS)

    Beichman, Charles

    1998-01-01

    A key long-term goal of NASA's Origins program is the detection and characterization of habitable planets orbiting stars within the solar neighborhood. A cold, space-borne interferometer operating in the mid-infrared with a approx. 75 m baseline can null the light of a parent star and detect the million-times fainter radiation from an Earth-like planet located in the "habitable zone" around stars as far as 15 pc away. Such an interferometer, designated the Terrestrial Planet Finder (TPF) by NASA, could even detect atmospheric signatures of species such as CO2, O3, and H2O indicative of either the possibility or presence of primitive life. This talk highlights some of the sensitivity issues affecting the detectability of terrestrial planets. Sensitivity calculations show that a system consisting of 2 m apertures operating at 5 AU or 4 m apertures operating at 1 AU can detect terrestrial planets in reasonable integration times for levels of exo-zodiacal emission up to 10 times that seen in our solar system (hereafter denoted as 10xSS). Additionally, simulations show that confusion noise from structures in the exo-zodiacal cloud should not impede planet detection until the exo-zodiacal emission reaches the 10xSS level.

  12. Mid-infrared coronagraph for SPICA

    NASA Astrophysics Data System (ADS)

    Enya, K.; Abe, L.; Haze, K.; Tanaka, S.; Nakagawa, T.; Kataza, H.; Higuchi, S.; Miyata, T.; Sako, S.; Nakamura, T.; Tamura, M.; Nishikawa, J.; Murakami, N.; Itoh, Y.; Wakayama, T.; Sato, T.; Nakagiri, N.; Guyon, O.; Venet, M.; Bierden, P.

    2008-07-01

    The SPace Infrared telescope for Cosmology and Astrophysics (SPICA) is a infrared space-borne telescope mission of the next generation following AKARI. SPICA will carry a telescope with a 3.5 m diameter monolithic primary mirror and the whole telescope will be cooled to 5 K. SPICA is planned to be launched in 2017, into the sun-earth L2 libration halo orbit by an H II-A rocket and execute infrared observations at wavelengths mainly between 5 and 200 micron. The large telescope aperture, the simple pupil shape, the capability of infrared observations from space, and the early launch gives us with the SPICA mission a unique opportunity for coronagraphic observation. We have started development of a coronagraphic instrument for SPICA. The primary target of the SPICA coronagraph is direct observation of extra-solar Jovian planets. The main wavelengths of observation, the required contrast and the inner working angle (IWA) of the SPICA coronagraph are set to be 5-27 micron (3.5-5 micron is optional), 10-6, and a few λ/D (and as small as possible), respectively, in which λ is the observation wavelength and D is the diameter of the telescope aperture (3.5m). For our laboratory demonstration, we focused first on a coronagraph with a binary shaped pupil mask as the primary candidate for SPICA because of its feasibility. In an experiment with a binary shaped pupil coronagraph with a He-Ne laser (λ=632.8nm), the achieved raw contrast was 6.7×10-8, derived from the average measured in the dark region without active wavefront control. On the other hand, a study of Phase Induced Amplitude Apodization (PIAA) was initiated in an attempt to achieve better performance, i.e., smaller IWA and higher throughput. A laboratory experiment was performed using a He-Ne laser with active wavefront control, and a raw contrast of 6.5×10-7 was achieved. We also present recent progress made in the cryogenic active optics for SPICA. Prototypes of cryogenic deformable by Micro Electro

  13. Demonstration of vortex coronagraph concepts for on-axis telescopes on the Palomar Stellar Double Coronagraph

    NASA Astrophysics Data System (ADS)

    Mawet, Dimitri; Shelton, Chris; Wallace, James; Bottom, Michael; Kuhn, Jonas; Mennesson, Bertrand; Burruss, Rick; Bartos, Randy; Pueyo, Laurent; Carlotti, Alexis; Serabyn, Eugene

    2014-08-01

    Here we present preliminary results of the integration of two recently proposed vortex coronagraph (VC) concepts for on-axis telescopes on the Stellar Double Coronagraph (SDC) bench behind PALM-3000, the extreme adaptive optics system of the 200-inch Hale telescope of Palomar observatory. The multi-stage vortex coronagraph (MSVC) uses the ability of the vortex to move light in and out of apertures through multiple VC in series to restore the nominal attenuation capability of the charge 2 vortex regardless of the aperture obscurations. The ring-apodized vortex coronagraph (RAVC) is a one-stage apodizer exploiting the VC Lyot-plane amplitude distribution in order to perfectly null the diffraction from any central obscuration size, and for any vortex topological charge. The RAVC is thus a simple concept that makes the VC immune to diffraction effects of the secondary mirror. It combines a vortex phase mask in the image plane with a single pupil-based amplitude ring apodizer, tailor-made to exploit the unique convolution properties of the VC at the Lyot-stop plane. The prototype apodizer uses the same microdot technology that was used to manufacture the apodized pupil Lyot coronagraph (APLC) equipping SPHERE, GPI and P1640.

  14. Modern Concepts for a Terrestrial Planet Finder Space Telescope

    NASA Astrophysics Data System (ADS)

    Kasting, James

    2012-01-01

    Astronomers have now found over 500 exoplanets from radial velocity measurements and another 1200 or more "planet candidates” using the transit method from Kepler. Some of these planets are small enough to be rocky, like Earth, and orbit within the liquid water habitable zone of their parent star. We know next to nothing about conditions on these planets, though, because we have not yet developed the tools needed to study them. Even JWST, if it flies, will likely be unable to characterize the atmosphere of an Earth-analogue exoplanet. What we need for this task is a direct imaging mission that combines a large optical/near-IR telescope with a device that can block out the light from the star and retain the light from a nearby exoplanet. Both internal coronagraphs and external occulters (starshades) are being studied for this purpose. In principle, a thermal-IR telescope operating as an interferometer could accomplish the same task, but this would require formation flying of multiple cooled telescopes and is thought to be a more expensive option. The size of the optical telescope that would be needed to find and characterize an Earth depends on the frequency of Earth-like planet, Earth, and the brightness of the average exozodiacal background. The first parameter will hopefully be determined by Kepler, and the second may be measured by the Large Binary Telescope Interferometer, LBTI. Once this information is in hand, and if sufficient money can be found--currently, a big `if'--there should be little reason to hold back on designing and launching such a Terrestrial Planet Finder telescope.

  15. Compensation of high-order quasi-static aberrations on SPHERE with the coronagraphic phase diversity (COFFEE)

    NASA Astrophysics Data System (ADS)

    Paul, B.; Sauvage, J.-F.; Mugnier, L. M.; Dohlen, K.; Petit, C.; Fusco, T.; Mouillet, D.; Beuzit, J.-L.; Ferrari, M.

    2014-12-01

    Context. The second-generation instrument SPHERE, dedicated to high-contrast imaging, will soon be in operation on the European Very Large Telescope. Such an instrument relies on an extreme adaptive optics system coupled with a coronagraph that suppresses most of the diffracted stellar light. However, the coronagraph performance is strongly limited by quasi-static aberrations that create long-lived speckles in the scientific image plane, which can easily be mistaken for planets. Aims: The wavefront analysis performed by SPHERE's adaptive optics system uses a dedicated wavefront sensor. The ultimate performance is thus limited by the unavoidable differential aberrations between the wavefront sensor and the scientific camera, which have to be estimated and compensated for. In this paper, we use the COFFEE approach to measure and compensate for SPHERE's quasi-static aberrations. Methods: COronagraphic Focal-plane waveFront Estimation for Exoplanet detection (COFFEE), which consists in an extension of phase diversity to coronagraphic imaging, estimates the quasi-static aberrations, including the differential ones, using only two focal plane images recorded by the scientific camera. In this paper, we use coronagraphic images recorded from SPHERE's infrared detector IRDIS to estimate the aberrations upstream of the coronagraph, which are then compensated for using SPHERE's extreme adaptive optics loop SAXO. Results: We first validate the ability of COFFEE to estimate high-order aberrations by estimating a calibrated influence function pattern introduced upstream of the coronagraph. We then use COFFEE in an original iterative compensation process to compensate for the estimated aberrations, leading to a contrast improvement by a factor that varies from 1.4 to 4.7 between 2λ/D and 15λ/D on IRDIS. The performance of the compensation process is also evaluated through simulations. An excellent match between experimental results and these simulations is found.

  16. SMM coronagraph observations of particulate contamination

    NASA Technical Reports Server (NTRS)

    St. Cyr, O. C.; Warner, T.

    1991-01-01

    Some recent images taken by the white light coronagraph telescope aboard the Solar Maximum Mission (SMM) observatory show bright streaks that are apparently caused by particles associated with the spacecraft. In this report we describe these observations, and we analyze the times of their occurrence. We demonstrate that the sightings occur most often near SMM's orbital dawn, and we speculate that thermal shock is the mechanism that produces the particles. Although these sightings have not seriously affected the coronagraph's scientific operations, the unexpected passage of bright material through the field of view of sensitive spaceborne telescopes can lead to data loss or, in some cases, serious detector damage. The topic of space debris has become a significant concern for designers of both manned and unmanned orbiting platforms. The returned samples from the SMM spacecraft and the observations reported here provide a baseline of experience for future orbital platforms that plan long duration missions.

  17. An Extended Coronagraphic Survey of Nearby Stars

    NASA Astrophysics Data System (ADS)

    Sullivan, Sean A.; Creech-Eakman, M. J.

    2007-12-01

    We present astrometry and photometry on a sample of stars at distances between 8 and 16 parsecs imaged with the Johns Hopkins’ Adaptive Optics Coronagraph mounted on the Palomar 60-inch telescope from September, 1998 to November, 2000. These data (taken in the Gunn r, i, and z filters) extend the 8 parsec sample from Oppenheimer et al. (2001) originally used to identify the brown dwarf GL 229B. Coronagraphic imaging allows the occlusion of a bright central star, thus permitting the direct imaging of spatially nearby objects otherwise not visible. This technique is particularly useful in the search for low mass/luminosity companions close to bright stars. This work was supported by a grant from NASA's Jet Propulsion Lab number 1303801.

  18. Low-angle optical vortex coronagraphic scatterometer.

    PubMed

    Wan, Lingyu; Ruane, Garreth J; Swartzlander, Grover A

    2016-11-01

    The important, but difficult-to-measure zero and low-angle scattering spectrum, as well as the broader angular spectrum, was obtained by use of an optical vortex coronagraphic scatterometer (patent pending). The experimental measurements agreed well with the predictions from the Mie scattering theory. High contrast discrimination allowed us to remove the unscattered coherent illumination, revealing a low-angle superimposed scattered signal.

  19. The JWST/NIRCam Coronagraph Flight Occulters

    NASA Technical Reports Server (NTRS)

    Krist, John E.; Balasubramanian, Kunjithapatham; Muller, Richard E.; Shaklan, Stuart B.; Kelly, Douglas M.; Wilson, Daniel W.; Beichman, Charles A.; Serabyn, Eugene; Mao, Yalan; Echternach, Pierre M.; hide

    2010-01-01

    The NIRCam instrument on the James Webb Space Telescope will have a Lyot coronagraph for high contrast imaging of extrasolar planets and circumstellar disks at lambda = 2 - 5 micrometers. Half-tone patterns are used to create graded-transmission image plane masks. These are generated using electron beam lithography and reactive ion etching of a metal layer on an antireflection coated sapphire substrate. We report here on the manufacture and evaluation of the flight occulters.

  20. The JWST/NIRCam Coronagraph Flight Occulters

    NASA Technical Reports Server (NTRS)

    Krist, John E.; Balasubramanian, Kunjithapatham; Muller, Richard E.; Shaklan, Stuart B.; Kelly, Douglas M.; Wilson, Daniel W.; Beichman, Charles A.; Serabyn, Eugene; Mao, Yalan; Echternach, Pierre M.; Trauger, John T.; Liewer, Kurt M.

    2010-01-01

    The NIRCam instrument on the James Webb Space Telescope will have a Lyot coronagraph for high contrast imaging of extrasolar planets and circumstellar disks at lambda = 2 - 5 micrometers. Half-tone patterns are used to create graded-transmission image plane masks. These are generated using electron beam lithography and reactive ion etching of a metal layer on an antireflection coated sapphire substrate. We report here on the manufacture and evaluation of the flight occulters.

  1. SCORE - Sounding-rocket Coronagraphic Experiment

    NASA Astrophysics Data System (ADS)

    Fineschi, Silvano; Moses, Dan; Romoli, Marco

    The Sounding-rocket Coronagraphic Experiment - SCORE - is a The Sounding-rocket Coronagraphic Experiment - SCORE - is a coronagraph for multi-wavelength imaging of the coronal Lyman-alpha lines, HeII 30.4 nm and HI 121.6 nm, and for the broad.band visible-light emission of the polarized K-corona. SCORE has flown successfully in 2009 acquiring the first images of the HeII line-emission from the extended corona. The simultaneous observation of the coronal Lyman-alpha HI 121.6 nm, has allowed the first determination of the absolute helium abundance in the extended corona. This presentation will describe the lesson learned from the first flight and will illustrate the preparations and the science perspectives for the second re-flight approved by NASA and scheduled for 2016. The SCORE optical design is flexible enough to be able to accommodate different experimental configurations with minor modifications. This presentation will describe one of such configurations that could include a polarimeter for the observation the expected Hanle effect in the coronal Lyman-alpha HI line. The linear polarization by resonance scattering of coronal permitted line-emission in the ultraviolet (UV) can be modified by magnetic fields through the Hanle effect. Thus, space-based UV spectro-polarimetry would provide an additional new tool for the diagnostics of coronal magnetism.

  2. Speckle temporal stability in XAO coronagraphic images

    NASA Astrophysics Data System (ADS)

    Martinez, P.; Loose, C.; Aller Carpentier, E.; Kasper, M.

    2012-05-01

    Context. The major source of noise limiting high-contrast imaging is caused by quasi-static speckles. Speckle noise originates from wavefront errors caused by various independent sources, and evolves on different timescales depending on their nature. An understanding of how quasi-static speckles originate from instrumental errors is paramount to the search for faint stellar companions. Instrumental speckles average to form a fixed pattern, which can be calibrated to a certain extent, but their temporal evolution ultimately limits this possibility. Aims: This study focuses on the laboratory evidence and characterization of the quasi-static pinned speckle phenomenon. Specifically, we examine the coherent amplification of the static speckle contribution to the noise variance in the scientific image, through its interaction with quasi-static speckles. Methods: The analysis of a time series of adaptively corrected, coronagraphic images recorded in the laboratory enables the characterization of the temporal stability of the residual speckle pattern in both direct and differential coronagraphic images. Results: We estimate that spoiled and rapidly evolving quasi-static speckles present in the system at the angstrom/nanometer level affect the stability of the static speckle noise in the final image after the coronagraph. The temporal evolution of the quasi-static wavefront error exhibits a linear power law, which can be used to first order to model quasi-static speckle evolution in high-contrast imaging instruments.

  3. Life Finder Detectors: An Overview of Detector Technologies for Detecting Life on Other Worlds

    NASA Astrophysics Data System (ADS)

    Rauscher, Bernard J.; Domagal-Goldman, Shawn; Greenhouse, Matthew A.; Hsieh, Wen-Ting; McElwain, Michael W.; Moseley, Samuel H.; Noroozian, Omid; Norton, Tim; Kutyrev, Alexander; Rinehart, Stephen; stock, Joseph

    2015-01-01

    Future large space telescopes will seek evidence for life on other worlds by searching for spectroscopic biosignatures. Atmospheric biosignature gases include oxygen, ozone, water vapor, and methane. Non-biological gases, including carbon monoxide and carbon dioxide, are important for discriminating false positives. All of these gases imprint spectroscopic features in the UV through mid-IR that are potentially detectable using future space based coronagraphs or star shades for starlight suppression.Direct spectroscopic biosignature detection requires sensors capable of robustly measuring photon arrival rates on the order of 10 per resolution element per hour. Photon counting is required for some wavefront sensing and control approaches to achieve the requisite high contrast ratios. We review life finder detector technologies that either exist today, or are under development, that have the potential to meet these challenging requirements. We specifically highlight areas where more work or development is needed.Life finder detectors will be invaluable for a wide variety of other major science programs. Because of its cross cutting nature; UV, optical, and infrared (UVOIR) detector development features prominently in the 2010 National Research Council Decadal Survey, 'New Worlds, New Horizons in Astronomy and Astrophysics', and the NASA Cosmic Origins Program Technology Roadmap.

  4. Coronagraphic Wavefront Control for the ATLAST-9.2m Telescope

    NASA Technical Reports Server (NTRS)

    Lyon, RIchard G.; Oegerle, William R.; Feinberg, Lee D.; Bolcar, Matthew R.; Dean, Bruce H.; Mosier, Gary E.; Postman, Marc

    2010-01-01

    The Advanced Technology for Large Aperture Space Telescope (ATLAST) concept was assessed as one of the NASA Astrophysics Strategic Mission Concepts (ASMC) studies. Herein we discuss the 9.2-meter diameter segmented aperture version and its wavefront sensing and control (WFSC) with regards to coronagraphic detection and spectroscopic characterization of exoplanets. The WFSC would consist of at least two levels of sensing and control: (i) an outer coarser level of sensing and control to phase and control the segments and secondary mirror in a manner similar to the James Webb Space Telescope but operating at higher temporal bandwidth, and (ii) an inner, coronagraphic instrument based, fine level of sensing and control for both amplitude and wavefront errors operating at higher temporal bandwidths. The outer loop would control rigid-body actuators on the primary and secondary mirrors while the inner loop would control one or more segmented deformable mirror to suppress the starlight within the coronagraphic field-of view. Herein we discuss the visible nulling coronagraph (VNC) and the requirements it levies on wavefront sensing and control and show the results of closed-loop simulations to assess performance and evaluate the trade space of system level stability versus control bandwidth.

  5. Extinction controlled adaptive mask coronagraph Lyot and phase mask dual concept for wide extinction area

    NASA Astrophysics Data System (ADS)

    Bourget, P.; Schuhler, N.; Mawet, D.; Haguenauer, P.; Girard, J.; Gonte, Frederic

    2012-09-01

    A dual coronagraph based on the Adaptive Mask concept is presented in this paper. ALyot coronagraph with a variable diameter occulting disk anda nulling stellar coronagraph based on the Adaptive Phase Mask concept using polarization interferometry are presented in this work. Observations on sky and numerical simulations show the usefulness of the proposed method to optimize the nulling efficiency of the coronagraphs. In the case of the phase mask, the active control system will correct for the detrimental effects of image instabilities on the destructive interference (low-order aberrations such as tip-tilt and focus). The phase mask adaptability both in size, phase and amplitude also compensate for manufacturing errors of the mask itself, and potentially for chromatic effects. Liquid-crystal properties are used to provide variable transmission of an annulus around the phase mask, but also to achieve the achromatic π phase shift in the core of the PSF by rotating the polarization by 180°.A compressed mercury (Hg) drop is used as an occulting disk for the Lyot mask, its size control offers an adaptation to the seeing conditions and provides an optimization of the Tip-tilt correction.

  6. General Tool for Evaluating High-Contrast Coronagraphic Telescope Performance Error Budgets

    NASA Technical Reports Server (NTRS)

    Marchen, Luis F.

    2011-01-01

    computations. Other than this, the process is fully automated. The third process was developed based on the Terrestrial Planet Finder coronagraph Error Budget Tool, but was fully automated by using VBA code, form, and ActiveX controls.

  7. Coronagraph project with the SPICA mission

    NASA Astrophysics Data System (ADS)

    Enya, K.; Abe, L.; Tanaka, S.; Haze, K.; Venet, M.; Nakagawa, T.; Kataza, H.; Tamura, M.; Nishikawa, J.; Murakami, N.; Fujita, K.; Itoh, Y.; Guyon, O.; Pluzhnik, E. A.; Wakayama, T.; Sato, T.; Nakagiri, N.

    2007-09-01

    We present the status of the development of a coronagraph for the Space Infrared telescope for Cosmology and Astrophysics (SPICA). SPICA is the next generation of infrared space-borne telescope missions following to AKARI, led by Japan. SPICA will carry a telescope that has a 3.5 m diameter monolithic primary mirror and the whole telescope will be cooled to 4.5 K. It is planned to launch SPICA into the sun-earth L2 libration halo orbit using H II-A rocket in the middle of the 2010s and execute infrared observations at wavelengths mainly between 5 and 200 micron. The SPICA mission gives us a unique opportunity for coronagraph observations, because of the large telescope aperture, the simple pupil shape, the capability of infrared observations from space, and the early launch. We have started development of the SPICA coronagraph in which the primary target is direct observation of extra-solar Jovian planets. The main wavelengths of observation, the required contrast and the inner working angle (IWA) of the SPICA coronagraph instrument are set to be 5-27 micron, 10 -6, and a few λ/D (and as small as possible), respectively, in which λ is the observation wavelength and D is the diameter of the telescope aperture (3.5m). We focused on a coronagraph with a binary shaped pupil mask as the primary candidate for SPICA because of its feasibility. Nano-fabrication technology using electron beam lithography was applied to manufacture a high precision mask and a laboratory experiment with a He-Ne laser (λ=632.8nm) was performed in air without active wavefront control. The raw contrast derived from the average measured in the dark region reached 6.7×10 -8. On the other hand, a study of Phase Induced Amplitude Apodization (PIAA) was started in an attempt to achieve higher performance, i.e., smaller IWA and higher throughput. A hybrid solution using PIAA and a shaped pupil mask was proposed. A laboratory experiment was performed using a He- Ne laser with active wavefront

  8. Laboratory Performance of the Shaped Pupil Coronagraphic Architecture for the WFIRST-AFTA Coronagraph

    NASA Technical Reports Server (NTRS)

    Cady, Eric; Mejia Prada, Camilo; An, Xin; Balasubramanian, Kunjithapatha; Diaz, Rosemary; Kasdin, N. Jeremy; Kern, Brian; Kuhnert, Andreas; Nemati, Bijan; Patterson, Keith; hide

    2015-01-01

    One of the two primary architectures being tested for the WFIRST-AFTA coronagraph instrument is the shaped pupil coronagraph, which uses a binary aperture in a pupil plane to create localized regions of high contrast in a subsequent focal plane. The aperture shapes are determined by optimization, and can be designed to work in the presence of secondary obscurations and spiders-an important consideration for coronagraphy with WFIRSTAFTA. We present the current performance of the shaped pupil testbed, including the results of AFTA Milestone 2, in which approximately 6 × 10(exp -9) contrast was achieved in three independent runs starting from a neutral setting.

  9. High performance military laser range finder

    NASA Astrophysics Data System (ADS)

    Zorgno, M.

    A high-power and high-repetition-frequency military laser range finder based on a Nd:YAG Q-switched laser pumped by a Xenon flash lamp is presented. The laser range finder has an emitted power of 20-30 MW (with a pulselength of 8-10 ns), a beam divergence of 2.2-2.5 mrad, a repetition rate of 15 Hz, and a minimum detectable power of 20 nW. Although the range finder is designed for anti-aircraft fire control systems, its possible applications can include air-ground attack range finding with some modifications and various civilian applications requiring high power infrared laser pulses.

  10. Effect on maximum ranging distance of laser range finder in different visibility with power fluctuation of emitting system

    NASA Astrophysics Data System (ADS)

    Chen, Yu-dan; Zhou, Bing; Xu, Chun-mei; Liu, Jie; Huang, Fu-yu; Zhang, Fang

    2016-01-01

    One of the most important qualifications of laser range finder is the ranging distance. The ranging distance of laser range finder is usually supplied with a atmosphere condition. To reach the qualification of ranging distance, the manufacturers always increase the laser emitting power which the laser range finders can work not only in the ranging distance. It is important to find the real ranging distance in different visibility especially for military application. The maximum ranging distances in different visibility were discussed in the paper. First, the power of different types of laser range finder was got by experiment. The power of two models of laser range finder was got, and the power of same model but two serial numbers was obtained. Then, the fluctuation regularity was discussed. Then, the maximum ranging distances in different visibility were got by numerical simulation. The maximum ranging distances of laser range finder with same model but two serial numbers were calculated. The figures of maximum ranging distances varying with visibility were obtained. It was showed that the maximum ranging distances of laser range finder with same model but two serial numbers were different.

  11. Laboratory Testing of a Phased Induced Amplitude Apodization (PIAA) Coronagraph

    NASA Technical Reports Server (NTRS)

    Kern, Brian; Guyon, Olivier; Give'on, Amir; Kuhnert, Andreas; Niessner, Albert

    2011-01-01

    We present high-contrast images from laboratory testing of a Phase Induced Amplitude Apodization (PIAA) coronagraph at NASA's High Contrast Imaging Testbed (HCIT). Using a deformable mirror and wavefront estimation and control algorithms, we create a 'dark hole' in the monochromatic point-spread function with an inner working angle of (2.05 f lambda/D), with a mean intensity 3.5x10(exp -8). We discuss the contributions to this floor, and the techniques being developed to improve it. We also present simulations that investigate the effect of Lyot stops of various sizes, and conclude that a Lyot stop is necessary for 10(exp -9) performance but that an annular postapodizer is not necessary.

  12. Closing the contrast gap between testbed and model prediction with WFIRST-CGI shaped pupil coronagraph

    NASA Astrophysics Data System (ADS)

    Zhou, Hanying; Nemati, Bijan; Krist, John; Cady, Eric; Prada, Camilo M.; Kern, Brian; Poberezhskiy, Ilya

    2016-07-01

    JPL has recently passed an important milestone in its technology development for a proposed NASA WFIRST mission coronagraph: demonstration of better than 1x10-8 contrast over broad bandwidth (10%) on both shaped pupil coronagraph (SPC) and hybrid Lyot coronagraph (HLC) testbeds with the WFIRST obscuration pattern. Challenges remain, however, in the technology readiness for the proposed mission. One is the discrepancies between the achieved contrasts on the testbeds and their corresponding model predictions. A series of testbed diagnoses and modeling activities were planned and carried out on the SPC testbed in order to close the gap. A very useful tool we developed was a derived "measured" testbed wavefront control Jacobian matrix that could be compared with the model-predicted "control" version that was used to generate the high contrast dark hole region in the image plane. The difference between these two is an estimate of the error in the control Jacobian. When the control matrix, which includes both amplitude and phase, was modified to reproduce the error, the simulated performance closely matched the SPC testbed behavior in both contrast floor and contrast convergence speed. This is a step closer toward model validation for high contrast coronagraphs. Further Jacobian analysis and modeling provided clues to the possible sources for the mismatch: DM misregistration and testbed optical wavefront error (WFE) and the deformable mirror (DM) setting for correcting this WFE. These analyses suggested that a high contrast coronagraph has a tight tolerance in the accuracy of its control Jacobian. Modifications to both testbed control model as well as prediction model are being implemented, and future works are discussed.

  13. CellFinder: a cell data repository.

    PubMed

    Stachelscheid, Harald; Seltmann, Stefanie; Lekschas, Fritz; Fontaine, Jean-Fred; Mah, Nancy; Neves, Mariana; Andrade-Navarro, Miguel A; Leser, Ulf; Kurtz, Andreas

    2014-01-01

    CellFinder (http://www.cellfinder.org) is a comprehensive one-stop resource for molecular data characterizing mammalian cells in different tissues and in different development stages. It is built from carefully selected data sets stemming from other curated databases and the biomedical literature. To date, CellFinder describes 3394 cell types and 50 951 cell lines. The database currently contains 3055 microscopic and anatomical images, 205 whole-genome expression profiles of 194 cell/tissue types from RNA-seq and microarrays and 553 905 protein expressions for 535 cells/tissues. Text mining of a corpus of >2000 publications followed by manual curation confirmed expression information on ∼900 proteins and genes. CellFinder's data model is capable to seamlessly represent entities from single cells to the organ level, to incorporate mappings between homologous entities in different species and to describe processes of cell development and differentiation. Its ontological backbone currently consists of 204 741 ontology terms incorporated from 10 different ontologies unified under the novel CELDA ontology. CellFinder's web portal allows searching, browsing and comparing the stored data, interactive construction of developmental trees and navigating the partonomic hierarchy of cells and tissues through a unique body browser designed for life scientists and clinicians.

  14. Western Michigan University Libraries' "Electronic Journal Finder"

    ERIC Educational Resources Information Center

    Gedeon, Randle; Boston, George

    2005-01-01

    This article describes the development of the "Electronic Journal Finder," a TDNet installation for the University Libraries of Western Michigan University. Topics covered include: rationale for subscription project timeline, content, product customization, set-up, maintenance issues, reporting functions, directing URL links, searching…

  15. Western Michigan University Libraries' "Electronic Journal Finder"

    ERIC Educational Resources Information Center

    Gedeon, Randle; Boston, George

    2005-01-01

    This article describes the development of the "Electronic Journal Finder," a TDNet installation for the University Libraries of Western Michigan University. Topics covered include: rationale for subscription project timeline, content, product customization, set-up, maintenance issues, reporting functions, directing URL links, searching…

  16. First Light for the Lunar Robotic Coronagraph

    NASA Astrophysics Data System (ADS)

    Morgan, T. H.; Tucker, R.; Killen, R. M.

    2013-12-01

    We report first results from a new lunar coronagraphic telescope operated in Sonoita, Arizona. Our coronagraph is an instrument designed for the express purpose of mapping the lunar extended sodium exosphere. Although lunar sodium was identified almost 30 years ago, we still have not identified which of at least three competing processes (sputtering, photon-stimulated-desorption, or impact vaporization) is the dominant source of the observed sodium. The spatial and temporal distributions of at least the prompt sodium produced by each process should be different. Separating out the effects of the respective source processes requires a much higher density of observations across a lunation than has heretofore been available. The spatial distribution of sodium with selenographic latitude and lunar phase will discriminate among the source processes, but only by almost continuous observing can we determine the effects of sporadic events such as meteor showers and coronal mass ejections or solar energetic particle events. Although the lunar exosphere is tenuous, the processes that create and remove sodium and other atoms work on exposed surfaces across the solar system. Thus, developing a detailed understanding of the physical processes at work to produce the sodium exosphere of the Moon (whose surface composition has been directly sampled) has applications across the solar system. This design uses an extremely narrow-band sodium D2 filter to isolate the Na emission. The science dictates a very wide field image that extends to one lunar diameter above the lunar limb. The imager has a 1.5 degree field of view. To image the extremely faint extended exospheric Na, an occulting disk is used to reject the bright light from the lunar disk while passing the surrounding light. A Lyot stop is placed at the pupil image to minimize the diffracted light from around the edge of the entrance pupil. The Lunar Coronagraph is remotely operated nearly autonomously and can observe

  17. External occulter laboratory demonstrator for the forthcoming formation flying coronagraphs.

    PubMed

    Landini, Federico; Vives, Sébastien; Venet, Mélanie; Romoli, Marco; Guillon, Christophe; Fineschi, Silvano

    2011-12-20

    The design and optimization of the external occulter geometry is one of the most discussed topics among solar coronagraph designers. To improve the performance of future coronagraphs and to stretch their inner fields of view toward the solar limb, the new concept of coronagraphs in formation flight has been introduced in the scientific debate. Solar coronagraphs in formation flight require several mechanical and technological constraints to be met, mainly due to the large dimension of the occulter and to the spacecraft's reciprocal alignment. The occulter edge requires special attention to minimize diffraction while being compatible with the handling and integrating of large delicate space components. Moreover, it is practically impossible to set up a full-scale model for laboratory tests. This article describes the design and laboratory tests on a demonstrator for a coronagraph to be operated in formation flight. The demonstrator is based on the principle of the linear edge, thus the presented results cannot be directly extrapolated to the case of the flying circular occulter. Nevertheless, we are able to confirm the results of other authors investigating on smaller coronagraphs and provide further information on the geometry and tolerances of the optimization system. The described work is one of the results of the ESA STARTIGER program on formation flying coronagraphs ["The STARTIGER's demonstrators: toward a new generation of formation flying solar coronagraphs," in 2010 International Conference on Space Optics (ICSO) (2010), paper 39].

  18. The WFIRST-AFTA coronagraph design update

    NASA Astrophysics Data System (ADS)

    Goullioud, R.; Zhao, F.; Tang, H.; Wu, J.

    2014-08-01

    The most recent concept for the Wide Field Infrared Survey Telescope (WFIRST) flight mission features a secondary, descopable, instrument that will perform exoplanet detection via coronagraphy of the host star. This observatory is based on the existing Astrophysics Focused Telescope Assets (AFTA) 2.4-meter telescope. The mission will study exoplanets via coronagraphy and gravitational microlensing, probe dark energy, and survey the near infrared sky. Over the past year, the engineering team has been working with the science definition team to refine the mission and payload concepts. We present the current design of the coronagraph instrument point design.

  19. Coronagraphic Notch Filter for Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Cohen, David; Stirbl, Robert

    2004-01-01

    A modified coronagraph has been proposed as a prototype of improved notch filters in Raman spectrometers. Coronagraphic notch filters could offer alternatives to both (1) the large and expensive double or triple monochromators in older Raman spectrometers and (2) holographic notch filters, which are less expensive but are subject to environmental degradation as well as to limitations of geometry and spectral range. Measurement of a Raman spectrum is an exercise in measuring and resolving faint spectral lines close to a bright peak: In Raman spectroscopy, a monochromatic beam of light (the pump beam) excites a sample of material that one seeks to analyze. The pump beam generates a small flux of scattered light at wavelengths slightly greater than that of the pump beam. The shift in wavelength of the scattered light from the pump wavelength is known in the art as the Stokes shift. Typically, the flux of scattered light is of the order of 10 7 that of the pump beam and the Stokes shift lies in the wave-number range of 100 to 3,000 cm 1. A notch filter can be used to suppress the pump-beam spectral peak while passing the nearby faint Raman spectral lines. The basic principles of design and operation of a coronagraph offer an opportunity for engineering the spectral transmittance of the optics in a Raman spectrometer. A classical coronagraph may be understood as two imaging systems placed end to end, such that the first system forms an intermediate real image of a nominally infinitely distant object and the second system forms a final real image of the intermediate real image. If the light incident on the first telescope is collimated, then the intermediate image is a point-spread function (PSF). If an appropriately tailored occulting spot (e.g., a Gaussian-apodized spot with maximum absorption on axis) is placed on the intermediate image plane, then the instrument inhibits transmission of light from an on-axis source. However, the PSFs of off-axis light sources are

  20. Coronagraphic imaging on the VLTI with VIDA

    NASA Astrophysics Data System (ADS)

    Lardière, O.

    In a few years, the VLTI will be able to combine light from 4 to 8 telescopes equipped with adaptive optics. In order to exploit the full VLTI infrastructure, a second generation instrument, based on the densified pupil concept (VIDA), has been proposed for very high resolution direct imaging and coronagraphy. This paper presents some possible coronagraphic devices providing a total star extinction on the VLTI when there are no phase errors. Lastly, the expected performances considering cophasing and adaptive optics residual errors are also presented.

  1. Improved achromatization of phase mask coronagraphs using colored apodization

    NASA Astrophysics Data System (ADS)

    N'diaye, M.; Dohlen, K.; Cuevas, S.; Soummer, R.; Sánchez-Pérez, C.; Zamkotsian, F.

    2012-02-01

    Context. For direct imaging of exoplanets, a stellar coronagraph helps to remove the image of an observed bright star by attenuating the diffraction effects caused by the telescope aperture of diameter D. The dual zone phase mask (DZPM) coronagraph constitutes a promising concept since it theoretically offers a small inner working angle (IWA ~ λ0/D where λ0 denotes the central wavelength of the spectral range Δλ), good achromaticity, and high starlight rejection, typically reaching a 106 contrast at 5 λ0/D from the star over a spectral bandwidth Δλ/λ0 of 25% (similar to H-band). This last value proves to be encouraging for broadband imaging of young and warm Jupiter-like planets. Aims: Contrast levels higher than 106 are, however, required for observing older and/or less massive companions over a finite spectral bandwidth. An achromatization improvement of the DZPM coronagraph is therefore mandatory to reach such good performance. Methods: In its design, the DZPM coronagraph uses a gray (or achromatic) apodization. We replaced it by a colored apodization to increase the performance of this coronagraphic system over a wide spectral range. This innovative concept, called colored apodizer phase mask (CAPM) coronagraph, is defined to reach the highest contrast in the exoplanet search area. Once this has been done, we study the performance of the CAPM coronagraph in the presence of different errors to evaluate the sensitivity of our concept. Results: A 2.5 contrast gain is estimated from the performance provided by the CAPM coronagraph with respect to that of the DZPM coronagraph. A 2.2 × 10-8 intensity level at 5 λ0/D separation is then theoretically achieved with the CAPM coronagraph in the presence of a clear circular aperture and a 25% bandwidth. In addition, our studies show that our concept is less sensitive to low than to high-order aberrations for a given value of rms wavefront errors.

  2. The Gemini Planet Imager coronagraph testbed

    NASA Astrophysics Data System (ADS)

    Soummer, Rémi; Sivaramakrishnan, Anand; Oppenheimer, Ben R.; Roberts, Robin; Brenner, Douglas; Carlotti, Alexis; Pueyo, Laurent; Macintosh, Bruce; Bauman, Brian; Saddlemyer, Les; Palmer, David; Erickson, Darren; Dorrer, Christophe; Caputa, Kris; Marois, Christian; Wallace, Kent; Griffiths, Emily; Mey, Jacob

    2009-08-01

    The Gemini Planet Imager (GPI) is a new facility instrument to be commissioned at the 8-m Gemini South telescope in early 2011. It combines of several subsystems including a 1500 subaperture Extreme Adaptive Optics system, an Apodized Pupil Lyot Coronagraph, a near-infrared high-accuracy interferometric wavefront sensor, and an Integral Field Unit Spectrograph, which serves as the science instrument. GPI's main scientific goal is to detect and characterize relatively young (<2GYr), self luminous planets with planet-star brightness ratios of <= 10-7 in the near infrared. Here we present an overview of the coronagraph subsystem, which includes a pupil apodization, a hard-edged focal plane mask and a Lyot stop. We discuss designs optimization, masks fabrication and testing. We describe a near infrared testbed, which achieved broadband contrast (H-band) below 10-6 at separations > 5λ/D, without active wavefront control (no deformable mirror). We use Fresnel propagation modeling to analyze the testbed results.

  3. Recent developments with the visible nulling coronagraph

    NASA Astrophysics Data System (ADS)

    Hicks, Brian A.; Lyon, Richard G.; Bolcar, Matthew R.; Clampin, Mark; Petrone, Peter; Helmbrecht, Michael A.; Howard, Joseph M.; Miller, Ian J.

    2016-08-01

    A wide array of general astrophysics studies including detecting and characterizing habitable exoplanets could be enabled by a future large segmented telescope with sensitivity in the UV, optical, and infrared bands. When paired with a starshade or coronagraph, such an observatory could enable direct imaging and detailed spectroscopic observations of nearby Earth-like habitable zone planets. Over the past several years, a laboratory-based Visible Nulling Coronagraph (VNC) has evolved to reach requisite contrasts over a 1 nm bandwidth at narrow source angle separation using a segmented deformable mirror in one arm of a Mach-Zehnder layout. More recent efforts targeted broadband performance following the addition of two sets of half-wave Fresnel rhomb achromatic phase shifters (APS) with the goal of reaching 10-9 contrast, at a separation of 2λ/D, using a 40 nm (6%) bandwidth single mode fiber source. Here we present updates on the VNC broadband nulling effort, including approaches to addressing system contrast limitations.

  4. Estimating Coronagraph Visibility Functions - Progress Report

    NASA Astrophysics Data System (ADS)

    St Cyr, O. C.; Xie, H.; Duncan, D.; Webb, D. F.; Howard, R.; Gurman, J. B.

    2015-12-01

    Annual estimates of the coronal mass ejection (CME) rate have been well-documented and are quasi-continuous since the mid-1970s based on both groundbased and spacebased observations. However, coronagraphic observations from a single viewpoint are unable to detect all CMEs because they are limited by the properties of Thomson-scattered photospheric radiation by coronal electrons. To overcome this limitation and to extend the CME rate estimates beyond a single instrument, Webb & Howard (1994) formulated the "visibility function" as an instrument-specific calibration factor. Recently we have begun an investigation comparing visibility functions for SOHO LASCO, STEREO COR1/COR2, and the groundbased Mauna Loa Solar Observatory Mk3/Mk4 coronagraphs in order to extend the historical record of the CME rate. With the launch of the twin STEREO spacecraft in late 2006, we are able to use the combination of multiple instruments viewing from longitudinally-separated locations to obtain new estimates of the global CME rate. We provide a progress report on this activity.

  5. The DLR AsteroidFinder for NEOs

    NASA Astrophysics Data System (ADS)

    Mottola, Stefano; Kuehrt, Ekkehard; Michaelis, Harald; Hoffmann, Harald; Spietz, Peter; Jansen, Frank; Thimo Grundmann, Jan; Hahn, Gerhard; Montenegro, Sergio; Findlay, Ross; Boerner, Anko; Messina, Gabriele; Behnke, Thomas; Tschentscher, Matthias; Scheibe, Karsten; Mertens, Volker; Heidecke, Ansgar

    Potential Earth-impacting asteroids that spend most of their time interior to Earth's orbit are extremely difficult to be observed from the ground and remain largely undetected. Firstly, they are mostly located at small solar elongations, where the sky brightness and their faintness due to the large phase angle prevents their discovery. Secondly, these objects tend to have very long synodic orbital periods, which makes observation opportunities rare and impact warning times short. Because of these limitations, even the advent of next generation ground-based asteroid surveys is not likely to radically improve the situation (Veres et al. Icarus 203, p472, 2009). On the other hand, a small satellite with a suitable design can observe close to the Sun and detect these objects efficiently against a dark sky background. For this reason, DLR, the German Aerospace Center, has selected AsteroidFinder as the first experiment to be launched under its new compact satellite national program. The primary goal of the mission is to detect and characterize Near Earth Objects (NEOs), with a particular focus on the population of objects completely contained within Earth's orbit (IEOs or Inner Earth Objects). Current dynamical models predict the existence of more than 1000 such objects down to a size of 100m, of which, due to the abovementioned observation difficulties, only 10 have been discovered to date. Benefitting from the vantage point of a Low Earth Orbit (LEO), AsteroidFinder makes use of a small optical telescope to scan those regions of the sky that are close to the Sun, and therefore beyond the reach of ground based observatories. By estimating the population, the size and the orbital distribution of IEOs, AsteroidFinder will contribute to our knowledge of the inner Solar System, and to the assessment of the impact hazard for the Earth. A secondary goal of the mission is to demonstrate techniques that enable the space-based detection of space debris in the cm size range

  6. On-Orbit Performance of the NICMOS Coronagraph

    NASA Astrophysics Data System (ADS)

    Schneider, G.

    1997-12-01

    The Near Infrared Camera and Multi-Object Spectrometer (NICMOS) on the Hubble Space Telescope includes a coronagraph in the f/45 camera. Under the HST Guaranteed Time Observing program the NICMOS IDT will be carrying out coronagraphic imaging surveys of selected M-dwarfs, young stars and main sequence stars with IR excesses to search for brown dwarf and giant planet companions, and protoplanetary disks. The performance levels of the NICMOS coronagraph were determined during the on-orbit instrumental calibration carried out the Servicing Mission Observatory Verification phase of the mission. To obtain optimal performance in lowering both the diffracted energy in the regions surrounding bright star, by reducing the high spatial frequency components of the occulted core of the PSF, and down stream scattering a number of adjustments were made to coronagraphic operations. With those improvements in place we will be able to reduce the background from the unocculted wings of a centrally occulted stellar PSF by factors of 1E-5 near the edge of the coronagraphic hole (375 mas radius) to 1E-6 at 1" using a differential imaging strategy. Details of the calibration and performance levels of the NICMOS coronagraph and their implications for our GTO coronagraphic science programs are presented.

  7. A JWST NIRCam Coronagraphic Imaging Survey of Nearby Young M Dwarfs

    NASA Astrophysics Data System (ADS)

    Schlieder, Joshua E.; Meyer, Michael; Beichman, Charles A.; Reggiani, Maddalena; Daemgen, Sebastian; Leisenring, Jarron; Ygouf, Marie

    2017-06-01

    The population of giant planets on wide orbits around low-mass M dwarf stars is poorly understood. Transit, radial velocity and microlensing surveys provide population constraints and occurrence rate estimates within 10 AU, but current ground based imaging struggles to probe below 1 Jupiter mass at larger separations. In the vicinity of the closest, youngest M dwarfs, the unprecedented sensitivity of NIRCam coronagraphic imaging on the JWST provides direct access to lower-mass gas-giants beyond 10 AU. Survey simulations reveal that 3-5 micron imaging is sensitive to sub-Jupiter mass planets and pushes into the ice-giant mass regime around the most favorable targets. Following our simulations, we have designed a NIRCam GTO program to perform deep, dual-band coronagraphic imaging on a sample of the closest youngest M dwarfs. Our program will use the round MASK430R coronagraph with both the F444W and F322W2 filters and include telescope rolls for PSF subtraction. The dual-band imaging approach allows for color-based rejection of stellar and galactic background contaminants. Such observations will provide the first limits on the presence of sub-Jupiter mass planets in the outskirts of these stellar systems, provide constraints on the peak of the planet surface density distribution, and probe the separation of the primordial CO ice line, the hypothesized venue for ice-giant formation.

  8. Astronomical Near-neighbor Detection with a Four-quadrant Phase Mask (FQPM) Coronagraph

    NASA Technical Reports Server (NTRS)

    Haguenauer, Pierre; Serabyn, Eugene; Mennesson, Bertrand; Wallace, James K.; Gappinger, Robert O.; Troy, Mitchell; Bloemhof, Eric E.; Moore, Jim; Koresko, Chris D.

    2006-01-01

    Direct detection of planets around nearby stars requires the development of high-contrast imaging techniques, because of their very different respective fluxes. We thus investigated the innovative coronagraphic approach based on the use of a four-quadrant phase mask (FQPM). Simulations showed that, combined with high-level wavefront correction on an unobscured off-axis section of a large telescope, this method allows high-contrast imaging very close to stars, with detection capability superior to that of a traditional coronagraph. A FQPM instrument was thus built to test the feasibility of near-neighbor observations with our new off-axis approach on a ground-based telescope. In June 2005, we deployed our instrument to the Palomar 200-inch telescope, using existing facilities as much as possible for rapid implementation. In these initial observations, using data processing techniques specific to FQPM coronagraphs, we reached extinction levels of the order of 200:1. Here we discuss our simulations and on-sky results obtained so far.

  9. Analytical expression of long-exposure adaptive-optics-corrected coronagraphic image. First application to exoplanet detection.

    PubMed

    Sauvage, J-F; Mugnier, L M; Rousset, G; Fusco, T

    2010-11-01

    In this paper we derive an analytical model of a long-exposure star image for an adaptive-optics(AO)-corrected coronagraphic imaging system. This expression accounts for static aberrations upstream and downstream of the coronagraphic mask as well as turbulence residuals. It is based on the perfect coronagraph model. The analytical model is validated by means of simulations using the design and parameters of the SPHERE instrument. The analytical model is also compared to a simulated four-quadrant phase-mask coronagraph. Then, its sensitivity to a miscalibration of structure function and upstream static aberrations is studied, and the impact on exoplanet detectability is quantified. Last, a first inversion method is presented for a simulation case using a single monochromatic image with no reference. The obtained result shows a planet detectability increase by two orders of magnitude with respect to the raw image. This analytical model presents numerous potential applications in coronographic imaging, such as exoplanet direct detection, and circumstellar disk observation.

  10. Laboratory validation of the dual-zone phase mask coronagraph in broadband light at the high-contrast imaging THD testbed

    NASA Astrophysics Data System (ADS)

    Delorme, J. R.; N'Diaye, M.; Galicher, R.; Dohlen, K.; Baudoz, P.; Caillat, A.; Rousset, G.; Soummer, R.; Dupuis, O.

    2016-08-01

    Context. Specific high-contrast imaging instruments are mandatory to characterize circumstellar disks and exoplanets around nearby stars. Coronagraphs are commonly used in these facilities to reject the diffracted light of an observed star and enable direct imaging and spectroscopy of its circumstellar environment. One important property of the coronagraph is to be able to work in broadband light. Aims: Among several proposed coronagraphs, the dual-zone phase mask coronagraph is a promising solution for starlight rejection in broadband light. In this paper, we perform the first validation of this concept in laboratory. Methods: First, we consider the principle of the dual-zone phase mask coronagraph. Then, we describe the high-contrast imaging THD testbed, the manufacturing of the components, and the quality control procedures. Finally, we study the sensitivity of our coronagraph to low-order aberrations (inner working angle and defocus) and estimate its contrast performance. Our experimental broadband light results are compared with numerical simulations to check agreement with the performance predictions. Results: With the manufactured prototype and using a dark hole technique based on the self-coherent camera, we obtain contrast levels down to 2 × 10-8 between 5 and 17λ0/D in monochromatic light (640 nm). We also reach contrast levels of 4 × 10-8 between 7 and 17λ0/D in broadband (λ0 = 675 nm, Δλ = 250 and Δλ/λ0 = 40%), which demonstrates the excellent chromatic performance of the dual-zone phase mask coronagraph. Conclusions: The performance reached by the dual-zone phase mask coronagraph is promising for future high-contrast imaging instruments that aim to detect and spectrally characterize old or light gaseous planets.

  11. The design of ultrasonic range finder

    NASA Astrophysics Data System (ADS)

    Na, Yongyi

    2017-03-01

    Electronic rangefinder measurement scope in 0.10˜5.00 m, 1 cm measurement precision, measurement with no direct contact with the object to be tested, able to display measurement results clear and stable. Because ultrasonic directivity is strong, energy consumption is slow, in the medium transmission distance is farther, so ultrasonic often used for distance measurement, such as range finder and level measurement instrument can be done by ultrasound.

  12. Interferometer Designs for the Terrestrial Planet Finder

    NASA Technical Reports Server (NTRS)

    Lawson, P. R.; Dumont, P. J.; Colavita, M. M.

    2000-01-01

    The Terrestrial Planet Finder (TPF) is a space-based infrared interferometer that will combine high sensitivity and spatial resolution to detect and characterize planetary systems within 15 pc of our sun. TPF is a key element in NASA's Origins Program and is currently un- der study in its Pre-Project Phase. We review some of the interferometer designs that have been considered for starlight nulling, with particular attention to the architecture and subsystems of the central beam-combiner.

  13. Interferometer Designs for the Terrestrial Planet Finder

    NASA Technical Reports Server (NTRS)

    Lawson, P. R.; Dumont, P. J.; Colavita, M. M.

    1999-01-01

    The Terrestrial Planet Finder (TPF) is a space-based infrared interferometer that will combine high sensitivity and spatial resolution to detect and characterize planetary systems within 15 pc of our sun. TPF is a key element in NASA's Origins Program and is currently under study in its Pre-Project Phase. We review some of the interferometer designs that have been considered for starlight nulling, with particular attention to the architecture and subsystems of the central beam-combiner.

  14. Wheelchair assisted with laser range finder

    NASA Astrophysics Data System (ADS)

    Kang, Cheol U.; Wang, Hongbo; Ishimatsu, Takakazu; Ochiai, Tsumoru

    1995-12-01

    The paper presents a wheel chair system with the capability of self-localization and obstacle avoidance. Firstly, the approaches of landmark recognition and the self-localization of the wheel chair are described. Then, the principal of the obstacle avoidance using a laser range finder is described. Subsequently, the total system of the wheel chair is introduced. Finally, a navigation experiment is given. Experimental results indicate the effectiveness of our system.

  15. An Overview of WFIRST-AFTA Coronagraph Modelling

    NASA Technical Reports Server (NTRS)

    Krist, John; Nemati, Bijan; Zhou, Hanying; Sidick, Erkin

    2015-01-01

    The WFIRST/AFTA 2.4 m space telescope currently under study includes a stellar coronagraph for the imaging and spectral characterization of extrasolar planets. Based largely on performance predictions from end-to-end optical propagation modeling, promising coronagraphic methods were selected in late 2013 for further consideration for use on AFTA. Since those downselect analyses further modeling work has been done on evaluating refined coronagraph designs, wavefront sensing and control, detector representation, and time-dependent effects. Thermal, structural, ray trace, and diffraction propagation models are used in these studies. Presented here is the progress to date and plans for future analyses.

  16. Basic Testing of the DUCHAMP Source Finder

    NASA Astrophysics Data System (ADS)

    Westmeier, T.; Popping, A.; Serra, P.

    2012-01-01

    This paper presents and discusses the results of basic source finding tests in three dimensions (using spectroscopic data cubes) with DUCHAMP, the standard source finder for the Australian Square Kilometre Array Pathfinder. For this purpose, we generated different sets of unresolved and extended Hi model sources. These models were then fed into DUCHAMP, using a range of different parameters and methods provided by the software. The main aim of the tests was to study the performance of DUCHAMP on sources with different parameters and morphologies and assess the accuracy of DUCHAMP's source parametrisation. Overall, we find DUCHAMP to be a powerful source finder capable of reliably detecting sources down to low signal-to-noise ratios and accurately measuring their position and velocity. In the presence of noise in the data, DUCHAMP's measurements of basic source parameters, such as spectral line width and integrated flux, are affected by systematic errors. These errors are a consequence of the effect of noise on the specific algorithms used by DUCHAMP for measuring source parameters in combination with the fact that the software only takes into account pixels above a given flux threshold and hence misses part of the flux. In scientific applications of DUCHAMP these systematic errors would have to be corrected for. Alternatively, DUCHAMP could be used as a source finder only, and source parametrisation could be done in a second step using more sophisticated parametrisation algorithms.

  17. Phase-space structures - II. Hierarchical Structure Finder

    NASA Astrophysics Data System (ADS)

    Maciejewski, M.; Colombi, S.; Springel, V.; Alard, C.; Bouchet, F. R.

    2009-07-01

    A new multidimensional Hierarchical Structure Finder (HSF) to study the phase-space structure of dark matter in N-body cosmological simulations is presented. The algorithm depends mainly on two parameters, which control the level of connectivity of the detected structures and their significance compared to Poisson noise. By working in six-dimensional phase space, where contrasts are much more pronounced than in three-dimensional (3D) position space, our HSF algorithm is capable of detecting subhaloes including their tidal tails, and can recognize other phase-space structures such as pure streams and candidate caustics. If an additional unbinding criterion is added, the algorithm can be used as a self-consistent halo and subhalo finder. As a test, we apply it to a large halo of the Millennium Simulation, where 19 per cent of the halo mass is found to belong to bound substructures, which is more than what is detected with conventional 3D substructure finders, and an additional 23-36 per cent of the total mass belongs to unbound HSF structures. The distribution of identified phase-space density peaks is clearly bimodal: high peaks are dominated by the bound structures and show a small spread in their height distribution; low peaks belong mostly to tidal streams, as expected. However, the projected (3D) density distribution of the structures shows that some of the streams can have comparable density to the bound structures in position space. In order to better understand what HSF provides, we examine the time evolution of structures, based on the merger tree history. Given the resolution limit of the Millennium Simulation, bound structures typically make only up to six orbits inside the main halo. The number of orbits scales approximately linearly with the redshift corresponding to the moment of merging of the structures with the halo. At fixed redshift, the larger the initial mass of the structure which enters the main halo, the faster it loses mass. The difference in

  18. Technology Advancement of the Visible Nulling Coronagraph

    NASA Technical Reports Server (NTRS)

    Lyon, Richard G.; Clampin, Mark; Petrone, Peter; Thompson, Patrick; Bolcar, Matt; Madison, Timothy; Woodruff, Robert; Noecker, Charley; Kendrick, Steve

    2010-01-01

    The critical high contrast imaging technology for the Extrasolar Planetary Imaging Coronagraph (EPIC) mission concept is the visible nulling coronagraph (VNC). EPIC would be capable of imaging jovian planets, dust/debris disks, and potentially super-Earths and contribute to answering how bright the debris disks are for candidate stars. The contrast requirement for EPIC is 10(exp 9) contrast at 125 milli-arseconds inner working angle. To advance the VNC technology NASA/Goddard Space Flight Center, in collaboration with Lockheed-Martin, previously developed a vacuum VNC testbed, and achieved narrowband and broadband suppression of the core of the Airy disk. Recently our group was awarded a NASA Technology Development for Exoplanet Missions to achieve two milestones: (i) 10(exp 8) contrast in narrowband light, and, (ii) 10(ecp 9) contrast in broader band light; one milestone per year, and both at 2 Lambda/D inner working angle. These will be achieved with our 2nd generation testbed known as the visible nulling testbed (VNT). It contains a MEMS based hex-packed segmented deformable mirror known as the multiple mirror array (MMA) and coherent fiber bundle, i.e. a spatial filter array (SFA). The MMA is in one interferometric arm and works to set the wavefront differences between the arms to zero. Each of the MMA segments is optically mapped to a single mode fiber of the SFA, and the SFA passively cleans the sub-aperture wavefront error leaving only piston, tip and tilt error to be controlled. The piston degree of freedom on each segment is used to correct the wavefront errors, while the tip/tilt is used to simultaneously correct the amplitude errors. Thus the VNT controls both amplitude and wavefront errors with a single MMA in closed-loop in a vacuum tank at approx.20 Hz. Herein we will discuss our ongoing progress with the VNT.

  19. The visible nulling coronagraph -- progress towards mission and technology development

    NASA Technical Reports Server (NTRS)

    Shao, Michael; Levine, B. Martin; Wallace, J. Kent; Serabyn, Eugene; Liu, Duncan T.; Lane, Benjamin F.

    2004-01-01

    This paper describes a space mission for visible direct detection and spectroscopy of Earth like extrasolar planets using a nulling coronagraph instrument behind a moderately sized telescope in space.

  20. The JWST/NIRCam Coronagraph: Mask Design and Fabrication

    NASA Technical Reports Server (NTRS)

    Krista, John E.; Balasubramanian, Kunjithapatha; Beichman, Charles A.; Echternach, Pierre M.; Green, Joseph J.; Liewer, Kurt M.; Muller, Richard E.; Serabyn, Eugene; Shaklan, Stuart B.; Trauger, John T.; hide

    2009-01-01

    The NIRCam instrument on the James Webb Space Telescope will provide coronagraphic imaging from lambda =1-5 microns of high contrast sources such as extrasolar planets and circumstellar disks. A Lyot coronagraph with a variety of circular and wedge-shaped occulting masks and matching Lyot pupil stops will be implemented. The occulters approximate grayscale transmission profiles using halftone binary patterns comprising wavelength-sized metal dots on anti-reflection coated sapphire substrates. The mask patterns are being created in the Micro Devices Laboratory at the Jet Propulsion Laboratory using electron beam lithography. Samples of these occulters have been successfully evaluated in a coronagraphic testbed. In a separate process, the complex apertures that form the Lyot stops will be deposited onto optical wedges. The NIRCam coronagraph flight components are expected to be completed this year.

  1. Laboratory demonstration of a dual-stage vortex coronagraph

    NASA Astrophysics Data System (ADS)

    Serabyn, Eugene; Liewer, Kurt; Mawet, Dimitri

    2016-11-01

    While an ideal optical vortex coronagraph operating behind a clear, circular, unaberrated telescope aperture can theoretically provide perfect rejection of the incident plane wave from an unresolved star, use of a telescope with an on-axis secondary mirror limits the rejection. In theory, a dual-stage vortex coronagraph can provide improved starlight rejection for an on-axis telescope, and here we provide experimental confirmation of the predicted distribution of the residual light in the output pupil plane of a dual-stage vortex coronagraph. In addition, a simple method of further improving the rejection of such a coronagraph is suggested: by slightly oversizing the first Lyot stop and phase-shifting the light within the exposed annulus by half a wave, the residual starlight within the pupil can be canceled to deeper levels.

  2. The JWST/NIRCam Coronagraph: Mask Design and Fabrication

    NASA Technical Reports Server (NTRS)

    Krista, John E.; Balasubramanian, Kunjithapatha; Beichman, Charles A.; Echternach, Pierre M.; Green, Joseph J.; Liewer, Kurt M.; Muller, Richard E.; Serabyn, Eugene; Shaklan, Stuart B.; Trauger, John T.; Wilson, Daniel W.; Horner, Scott D.; Mao, Yalan; Somerstein, Stephen F.; Vasudevan, Gopal; Kelly, Douglas M.; Rieke, Marcia J.

    2009-01-01

    The NIRCam instrument on the James Webb Space Telescope will provide coronagraphic imaging from lambda =1-5 microns of high contrast sources such as extrasolar planets and circumstellar disks. A Lyot coronagraph with a variety of circular and wedge-shaped occulting masks and matching Lyot pupil stops will be implemented. The occulters approximate grayscale transmission profiles using halftone binary patterns comprising wavelength-sized metal dots on anti-reflection coated sapphire substrates. The mask patterns are being created in the Micro Devices Laboratory at the Jet Propulsion Laboratory using electron beam lithography. Samples of these occulters have been successfully evaluated in a coronagraphic testbed. In a separate process, the complex apertures that form the Lyot stops will be deposited onto optical wedges. The NIRCam coronagraph flight components are expected to be completed this year.

  3. Diffraction effects in a giant saw-toothed edge externally occulted solar coronagraph

    NASA Astrophysics Data System (ADS)

    Verroi, E.; Frassetto, F.; Naletto, G.

    2008-07-01

    Typical diffraction and vignetting effects associated to the use of both externally and internally occulted coronagraphs make the innermost solar corona quite unobserved. However, by increasing the distance between the coronagraph telescope and the external occulter to hundred of meters, it is possible to observe the solar corona down to 1.01 solar radii without vignetting. This is the case of ASPIICS (Association de Satellites Pour l'Imagerie et l'Interférométrie Coronographique Solaire), a mission proposed to ESA for the PROBA3 program for formation flying. ASPIICS foresees two satellites: the external occulter is located on one spacecraft, and the telescope on the other. In this work we present the results obtained by a theoretical analysis of the apodization of the external occulter. This technique allows the reduction of the diffracted light contribution. We have developed a code that can simulates the effects of the giant external occulter (1 m diameter) on the photospheric light, and calculates the intensity of the diffracted light on the coronagraph entrance aperture. It is possible, in this way, to analyze various shapes of the occulter edge. In particular, we have focused our attention in the case of the serrated disc with variable number of teeth of different length. We considered the simple occurrence of a point-like monochromatic source at infinity. The results show that, employing a toothed disc, improvement of the S/N ratio of many order of magnitude (whit respect to a simple circular flat disc) can be obtained.

  4. Testbed Demonstration of Low Order Wavefront Sensing and Control Technology for WFIRST Coronagraph

    NASA Astrophysics Data System (ADS)

    Shi, Fang; Balasubramanian, K.; Cady, E.; Kern, B.; Lam, R.; Mandic, M.; Patterson, K.; Poberezhskiy, I.; Shields, J.; Seo, J.; Tang, H.; Truong, T.; Wilson, D.

    2017-01-01

    NASA’s WFIRST-AFTA Coronagraph will be capable of directly imaging and spectrally characterizing giant exoplanets similar to Neptune and Jupiter, and possibly even super-Earths, around nearby stars. To maintain the required coronagraph performance in a realistic space environment, a Low Order Wavefront Sensing and Control (LOWFS/C) subsystem is necessary. The LOWFS/C will use the rejected stellar light to sense and suppress the telescope pointing drift and jitter as well as low order wavefront errors due to the changes in thermal loading of the telescope and the rest of the observatory. The LOWFS/C uses a Zernike phase contrast wavefront sensor with the phase shifting disk combined with the stellar light rejecting occulting mask, a key concept to minimize the non-common path error. Developed as a part of the Dynamic High Contrast Imaging Testbed (DHCIT), the LOWFS/C subsystem also consists of an Optical Telescope Assembly Simulator (OTA-S) to generate the realistic line-of-sight (LoS) drift and jitter as well as low order wavefront error from WFIRST-AFTA telescope’s vibration and thermal drift. The entire LOWFS/C subsystem have been integrated, calibrated, and tested in the Dynamic High Contrast Imaging Testbed. In this presentation we will show the results of LOWFS/C performance during the dynamic coronagraph tests in which we have demonstrated that LOWFS/C is able to maintain the coronagraph contrast with the presence of WFIRST like line-of-sight drift and jitter as well as low order wavefront drifts.

  5. Ames Coronagraph Experiment: Enabling Missions to Directly Image Exoplanets

    NASA Technical Reports Server (NTRS)

    Belikov, Ruslan

    2014-01-01

    Technology to find biomarkers and life on other worlds is rapidly maturing. If there is a habitable planet around the nearest star, we may be able to detect it this decade with a small satellite mission. In the 2030 decade, we will likely know if there is life in our Galactic neighborhood (1000 nearest stars). The Ames Coronagraph Experiment is developing coronagraphic technologies to enable such missions.

  6. Contamination from Skylab as determined from the solar coronagraph data

    NASA Technical Reports Server (NTRS)

    Mcguire, J. P.

    1976-01-01

    The white light solar coronagraph was one of the scientific telescopes flown on Skylab to study the sun. It studied the sun's atmosphere located from 0.5 to 5.0 solar radii above the sun's limb. Such a telescope is so sensitive to contamination around the spacecraft that it caused a major contamination abatement program to be initiated at the conception of Skylab. The coronagraph's data is analyzed showing the successfulness of that abatement program.

  7. Modeling and Implementation of Multi-Position Non-Continuous Rotation Gyroscope North Finder

    PubMed Central

    Luo, Jun; Wang, Zhiqian; Shen, Chengwu; Kuijper, Arjan; Wen, Zhuoman; Liu, Shaojin

    2016-01-01

    Even when the Global Positioning System (GPS) signal is blocked, a rate gyroscope (gyro) north finder is capable of providing the required azimuth reference information to a certain extent. In order to measure the azimuth between the observer and the north direction very accurately, we propose a multi-position non-continuous rotation gyro north finding scheme. Our new generalized mathematical model analyzes the elements that affect the azimuth measurement precision and can thus provide high precision azimuth reference information. Based on the gyro’s principle of detecting a projection of the earth rotation rate on its sensitive axis and the proposed north finding scheme, we are able to deduct an accurate mathematical model of the gyro outputs against azimuth with the gyro and shaft misalignments. Combining the gyro outputs model and the theory of propagation of uncertainty, some approaches to optimize north finding are provided, including reducing the gyro bias error, constraining the gyro random error, increasing the number of rotation points, improving rotation angle measurement precision, decreasing the gyro and the shaft misalignment angles. According them, a north finder setup is built and the azimuth uncertainty of 18” is obtained. This paper provides systematic theory for analyzing the details of the gyro north finder scheme from simulation to implementation. The proposed theory can guide both applied researchers in academia and advanced practitioners in industry for designing high precision robust north finder based on different types of rate gyroscopes. PMID:27657067

  8. Modeling and Implementation of Multi-Position Non-Continuous Rotation Gyroscope North Finder.

    PubMed

    Luo, Jun; Wang, Zhiqian; Shen, Chengwu; Kuijper, Arjan; Wen, Zhuoman; Liu, Shaojin

    2016-09-20

    Even when the Global Positioning System (GPS) signal is blocked, a rate gyroscope (gyro) north finder is capable of providing the required azimuth reference information to a certain extent. In order to measure the azimuth between the observer and the north direction very accurately, we propose a multi-position non-continuous rotation gyro north finding scheme. Our new generalized mathematical model analyzes the elements that affect the azimuth measurement precision and can thus provide high precision azimuth reference information. Based on the gyro's principle of detecting a projection of the earth rotation rate on its sensitive axis and the proposed north finding scheme, we are able to deduct an accurate mathematical model of the gyro outputs against azimuth with the gyro and shaft misalignments. Combining the gyro outputs model and the theory of propagation of uncertainty, some approaches to optimize north finding are provided, including reducing the gyro bias error, constraining the gyro random error, increasing the number of rotation points, improving rotation angle measurement precision, decreasing the gyro and the shaft misalignment angles. According them, a north finder setup is built and the azimuth uncertainty of 18" is obtained. This paper provides systematic theory for analyzing the details of the gyro north finder scheme from simulation to implementation. The proposed theory can guide both applied researchers in academia and advanced practitioners in industry for designing high precision robust north finder based on different types of rate gyroscopes.

  9. The STAR cluster-finder ASIC

    SciTech Connect

    Botlo, M.; LeVine, M.J.; Scheetz, R.A.; Schulz, M.W.; Short, P.; Woods, J.; Crosetto, D.

    1997-12-01

    STAR is a large TPC-based experiment at RHIC, the relativistic heavy ion collider at Brookhaven National Laboratory. The STAR experiment reads out a TPC and an SVT (silicon vertex tracker), both of which require in-line pedestal subtraction, compression of ADC values from 10-bit to 8-bit, and location of time sequences representing responses to charged-particle tracks. The STAR cluster finder ASIC responds to all of these needs. Pedestal subtraction and compression are performed using lookup tables in attached RAM. The authors describe its design and implementation, as well as testing methodology and results of tests performed on foundry prototypes.

  10. Harnessing the Power of the WFIRST-Coronagraph: A Coordinated Plan for Exoplanet and Disk Science

    NASA Astrophysics Data System (ADS)

    Turnbull, Margaret

    We propose to form a WFIRST Coronagraph Science Investigation Team (WFIRST-C SIT) for the purpose of defining the coronagraph scientific performance requirements, designing an exoplanet and debris disk observing program, and developing data analysis techniques including faint source detection and spectral retrieval. Our team will accomplish these tasks by: 1. Providing detailed characterization of the candidate target stars in terms of stellar/substeller companions, circumstellar debris, and astrophysical background in order to inform the final target selection by the community. As part of this effort, we will make a plan for coordination between WFIRST and Large Binocular Telescope Interferometer (LBTI) target selection, to obtain both scattered light and thermal emission observations of exozodiacal dust in the same systems. This will be important precursor science for future exoEarth direct imaging missions. 2. Creating simulated spatial-spectral data cubes representative of what the WFIRST coronagraph may see around the candidate targets, including known and hypothetical exoplanets, dynamically consistent interplanetary dust distributions, and astrophysical background contamination. The code framework to make the high-fidelity input models exists within our team, and we currently have a complete spectral data cube that allows us to generate images at any wavelength between 0.3 microns and 2.5 microns. To generate the simulated datasets for WFIRST, we will make use of instrument simulation tools provided by the coronagraph design team, spanning the range of expected coronagraph performance characteristics. We will also add functionality to these tools, or build our own, as required. 3. Designing and conducting a â€oeblind retrieval challenge― study to distribute these data amongst source detection and spectral modeling teams in the exoplanet and wider astrophysics community. Given the variety of sources expected in each planet-finding field, we expect

  11. A comparison between different coronagraphic data reduction techniques

    NASA Astrophysics Data System (ADS)

    Carolo, E.; Vassallo, D.; Farinato, J.; Bergomi, M.; Bonavita, M.; Carlotti, A.; D'Orazi, V.; Greggio, D.; Magrin, D.; Mesa, D.; Pinna, E.; Puglisi, A.; Stangalini, M.; Verinaud, C.; Viotto, V.

    2016-07-01

    A robust post processing technique is mandatory for analysing the coronagraphic high contrast imaging data. Angular Differential Imaging (ADI) and Principal Component Analysis (PCA) are the most used approaches to suppress the quasi-static structure presents in the Point Spread Function (PSF) for revealing planets at different separations from the host star. In this work, we present the comparison between ADI and PCA applied to System of coronagraphy with High order Adaptive optics from R to K band (SHARK-NIR), which will be implemented at Large Binocular Telescope (LBT). The comparison has been carried out by using as starting point the simulated wavefront residuals of the LBT Adaptive Optics (AO) system, in different observing conditions. Accurate tests for tuning the post processing parameters to obtain the best performance from each technique were performed in various seeing conditions (0:4"-1") for star magnitude ranging from 8 to 12, with particular care in finding the best compromise between quasi static speckle subtraction and planets detection.

  12. The Four Quadrant Phase Mask Coronagraph and its avatars

    NASA Astrophysics Data System (ADS)

    Rouan, Daniel; Baudrand, Jacques; Boccaletti, Anthony; Baudoz, Pierre; Mawet, Dimitri; Riaud, Pierre

    2007-04-01

    A renewal of interest into Lyot coronagraphy began about 10 years ago with the advent of the new and very demanding goal of detecting directly extrasolar planets. Among the new ideas, the Four Quadrant Phase Mask (4QPMC) has been rather prolific. The 4QPM coronagraph is based the peculiar design of binary phase mask (0,π) dividing the full field of view at the focal plane in four quadrants. The mutual destructive interferences of the coherent light of a source perfectly centered on the mask, produce a total nulling within the pupil image, as is demonstrated analytically. We first recall the concept and performance of the 4QPMC. We then analyse the different limitations in space or ground-based observations from simulations. We then address the issue of device manufacturing and give the status of the actual performance in laboratory. A section reviews the various instruments under development that are equipped with this component. We conclude with a panorama of the rest of the family of the 4QPMC, which comprises several variants proposed by different teams. More specifically we address the important question of the achromatization by describing the various ideas which are currently explored to solve this problem. Among them, some genuine ones, not yet published, are presented. To cite this article: D. Rouan et al., C. R. Physique 8 (2007).

  13. misFinder: identify mis-assemblies in an unbiased manner using reference and paired-end reads.

    PubMed

    Zhu, Xiao; Leung, Henry C M; Wang, Rongjie; Chin, Francis Y L; Yiu, Siu Ming; Quan, Guangri; Li, Yajie; Zhang, Rui; Jiang, Qinghua; Liu, Bo; Dong, Yucui; Zhou, Guohui; Wang, Yadong

    2015-11-16

    Because of the short read length of high throughput sequencing data, assembly errors are introduced in genome assembly, which may have adverse impact to the downstream data analysis. Several tools have been developed to eliminate these errors by either 1) comparing the assembled sequences with some similar reference genome, or 2) analyzing paired-end reads aligned to the assembled sequences and determining inconsistent features alone mis-assembled sequences. However, the former approach cannot distinguish real structural variations between the target genome and the reference genome while the latter approach could have many false positive detections (correctly assembled sequence being considered as mis-assembled sequence). We present misFinder, a tool that aims to identify the assembly errors with high accuracy in an unbiased way and correct these errors at their mis-assembled positions to improve the assembly accuracy for downstream analysis. It combines the information of reference (or close related reference) genome and aligned paired-end reads to the assembled sequence. Assembly errors and correct assemblies corresponding to structural variations can be detected by comparing the genome reference and assembled sequence. Different types of assembly errors can then be distinguished from the mis-assembled sequence by analyzing the aligned paired-end reads using multiple features derived from coverage and consistence of insert distance to obtain high confident error calls. We tested the performance of misFinder on both simulated and real paired-end reads data, and misFinder gave accurate error calls with only very few miscalls. And, we further compared misFinder with QUAST and REAPR. misFinder outperformed QUAST and REAPR by 1) identified more true positive mis-assemblies with very few false positives and false negatives, and 2) distinguished the correct assemblies corresponding to structural variations from mis-assembled sequence. misFinder can be freely downloaded

  14. NICMOS Coronagraphic Surveys-Preliminary Results

    NASA Astrophysics Data System (ADS)

    Schneider, G.

    1998-07-01

    A search for previously unknown low-mass (giant planet and brown dwarf) companions to stars in the solar neighborhood, and circumstellar dust disks around main sequence stars by direct coronagraphic imaging has been undertaken by the NICMOS Instrument Definition Team (IDT). Observations of a carefully selected candidate list of ~100 stars began on February 28, 1998, more than a year after the start of the NICMOS mission. Using a differential imaging strategy, as originally demonstrated in the second Servicing Mission/Observatory Verification (SMOV) program, we were able to achieve statistically significant detections of substellar companions at 1.6 micron with a Delta H of ~10 at separations as close as 0.5" (corresponding to 2.5 AU at 5 pc), with increasingly better performance at increasing radii. With nearly two dozen candidates now observed, and a better understanding of the focal plane stability and target acquisition precision we report on the efficacy of the program for detecting transitional objects into the 3 to 5 Jupiter mass regime.

  15. Coronagraph instrument for WFIRST-AFTA

    NASA Astrophysics Data System (ADS)

    Noecker, M. Charley; Zhao, Feng; Demers, Rick; Trauger, John; Guyon, Olivier; Jeremy Kasdin, N.

    2016-01-01

    The Wide-Field Infrared Survey Telescope (WFIRST) is a NASA observatory concept, now in phase A study, which is designed to perform wide-field imaging and slitless spectroscopic surveys for dark energy research and other astrophysical studies. It will also perform microlensing surveys to look for distant exoplanets in our galaxy, and direct imaging studies of some of the very nearest exoplanets. The current astrophysics focused telescope assets (AFTA) design of the mission makes use of an existing 2.4-m telescope, which yields enhanced sensitivity and imaging performance in all these science programs. AFTA also enables the addition of a coronagraph instrument (CGI) for direct imaging and spectroscopy of nearby giant exoplanets (including some that were discovered by radial velocity and other methods), and also for observing debris disks around the candidate host stars. This paper outlines the context for the other papers in this special volume on the WFIRST-AFTA CGI, covering the science, design, engineering, and technology development of the observatory and its CGI.

  16. 47 CFR 80.289 - Requirements for radio direction finder.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Requirements for radio direction finder. 80.289 Section 80.289 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO... Requirements for radio direction finder. (a) The radio direction finding apparatus must: (1) Be capable of...

  17. 47 CFR 80.289 - Requirements for radio direction finder.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Requirements for radio direction finder. 80.289 Section 80.289 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO... Requirements for radio direction finder. (a) The radio direction finding apparatus must: (1) Be capable of...

  18. 47 CFR 80.289 - Requirements for radio direction finder.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Requirements for radio direction finder. 80.289 Section 80.289 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO... Requirements for radio direction finder. (a) The radio direction finding apparatus must: (1) Be capable of...

  19. 47 CFR 80.289 - Requirements for radio direction finder.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Requirements for radio direction finder. 80.289 Section 80.289 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO... Requirements for radio direction finder. (a) The radio direction finding apparatus must: (1) Be capable of...

  20. 47 CFR 80.289 - Requirements for radio direction finder.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Requirements for radio direction finder. 80.289 Section 80.289 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO... Requirements for radio direction finder. (a) The radio direction finding apparatus must: (1) Be capable of...

  1. Humanitarian Mine Finder Experiment for Humanitarian Demining (HD)

    DTIC Science & Technology

    2009-06-01

    surface and buried Airborne techniques offer safety and speed over traditional HD th d UHF Band 2-D SAR L-band 2 D SAR me o s underground ...Backup Slides 20 Mine Finder Phase 1 •Design Mine Finder Rader •Determine which frequency bands (VHF, UHF, L, S, C, X, K) will provide greatest

  2. Comparison of Potential ASKAP HI Survey Source Finders

    NASA Astrophysics Data System (ADS)

    Popping, A.; Jurek, R.; Westmeier, T.; Serra, P.; Flöer, L.; Meyer, M.; Koribalski, B.

    2012-02-01

    The large size of the ASKAP HI surveys DINGO and WALLABY necessitates automated 3D source finding. A performance difference of a few percent corresponds to a significant number of galaxies being detected or undetected. As such, the performance of the automated source finding is of paramount importance to both of these surveys. We have analysed the performance of various source finders to determine which will allow us to meet our survey goals during the DINGO and WALLABY design studies. Here we present a comparison of the performance of five different methods of automated source finding. These source finders are duchamp, gamma-finder, a CNHI finder, a 2d-1d wavelet reconstruction finder and a sigma clipping method (s+c finder). Each source finder was applied to the same three-dimensional data cubes containing (a) point sources with a Gaussian velocity profile and (b) spatially extended model-galaxies with inclinations and rotation profiles. We focus on the completeness and reliability of each algorithm when comparing the performance of the different source finders.

  3. 2. VIEW SOUTHWEST, prime search radar tower, height finder radar ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. VIEW SOUTHWEST, prime search radar tower, height finder radar towards, height finder radar towers, and radar tower (unknown function) - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

  4. Terrestrial Planet Finder space vehicle architecture trades

    NASA Astrophysics Data System (ADS)

    Wehner, Michael J.; Moses, Stewart L.; Kroening, Keith; Johnson, Elizabeth D.

    1998-07-01

    THe goal of NASA's Terrestrial PLanet Finder program is to detect Earth-size planets orbiting other stars and evaluate their ability to sustain life. This will be accomplished through spaced-based IR interferometry using baselines much longer than previously flown. This paper presents the technical trades being evaluated by TRW to implement this investigation. Two primary concepts are considered: a single monolithic deployed interferometer with a baseline of up to approximately 100 meters and a free-flying constellation of interferometer components featuring precision station- keeping over baselines of up to several kilometers. Exo- planet detection is best performed at approximately 10 micron wavelength requiring the instrument to operate at cryogenic temperatures to minimize the effects of telescope thermal emissions. Further improvements in sensitivity can be facilitated by flying on a deep space trajectory away from the Sun to reduce zodiacal background emissions. Numerous technical innovations are necessary to enable such a system; however, most of these technologies are being developed by existing programs and there should be no roadblocks to fielding such a terrestrial planet finder in the 2010-2020 time frame.

  5. CellFinder: a cell data repository

    PubMed Central

    Stachelscheid, Harald; Seltmann, Stefanie; Lekschas, Fritz; Fontaine, Jean-Fred; Mah, Nancy; Neves, Mariana; Andrade-Navarro, Miguel A.; Leser, Ulf; Kurtz, Andreas

    2014-01-01

    CellFinder (http://www.cellfinder.org) is a comprehensive one-stop resource for molecular data characterizing mammalian cells in different tissues and in different development stages. It is built from carefully selected data sets stemming from other curated databases and the biomedical literature. To date, CellFinder describes 3394 cell types and 50 951 cell lines. The database currently contains 3055 microscopic and anatomical images, 205 whole-genome expression profiles of 194 cell/tissue types from RNA-seq and microarrays and 553 905 protein expressions for 535 cells/tissues. Text mining of a corpus of >2000 publications followed by manual curation confirmed expression information on ∼900 proteins and genes. CellFinder’s data model is capable to seamlessly represent entities from single cells to the organ level, to incorporate mappings between homologous entities in different species and to describe processes of cell development and differentiation. Its ontological backbone currently consists of 204 741 ontology terms incorporated from 10 different ontologies unified under the novel CELDA ontology. CellFinder’s web portal allows searching, browsing and comparing the stored data, interactive construction of developmental trees and navigating the partonomic hierarchy of cells and tissues through a unique body browser designed for life scientists and clinicians. PMID:24304896

  6. Automated scheduler improvements and generalizations for the Automated Planet Finder

    NASA Astrophysics Data System (ADS)

    Holden, Bradford P.; Burt, Jennifer A.; Deich, William T. S.

    2016-07-01

    The Automated Planet Finder (APF) was originally designed as a single purpose facility to search for exoplanets. The APF, however, has become a general use observatory that is used by astronomers the world over. We describe the improvements to our software for operations that both optimize finding planets with known periods and supporting a much broader community of astronomers with a variety of interests and requirements. These include a variety of observing modes beyond the originally envisioned fixed target lists, such as time dependent priorities to meet the needs of rapid varying targets, and improved tools for simulating observing cadence for the planet hunting teams. We discuss the underlying software for the APF, illustrating why its simplicity of use allows users to write software that focuses on scientific productivity. Because of this simplicity, we can then develop scheduling software, which is easily integrated into the APF operations suite. We test these new scheduling modes using a nightly simulator which uses historical weather and seeing data. After discussing this new simulation tool, we measure how well the methods work after a 36 month simulated campaign to follow-up transiting targets. We find that the data yield of each of the tested schemes is similar. Therefore, we can focus on the best potential scientific return with little concern about the impact on the number or duration of observations.

  7. Fiber optic gyroscope dynamic north-finder algorithm modeling and analysis based on Simulink

    NASA Astrophysics Data System (ADS)

    Zhang, Zhengyi; Liu, Chuntong

    2017-09-01

    In view of the problems such as the lower automation level and the insufficient precision of the traditional fiber optic gyroscope (FOG) static north-finder, this paper focuses on the in-depth analysis of the FOG dynamic north-finder principle and algorithm. The simulation model of the FOG dynamic north found algorithm with the least square method by points is established using Simulink toolbox, and then the platform rotation speed and sampling frequency, which affect FOG dynamic north found precision obviously, are simulated and calculated, and the optimization analysis is carried out as a key consideration. The simulation results show that, when the platform rotation speed is between 4.5 °/s and 8.5 °/s and the sampling frequency is at about 50 Hz in the case of using the parameters of this paper, the FOG dynamic north finding system can reach the higher precision. And the conclusions can provide the reference and validation for the engineering and practical of FOG dynamic north-finder.

  8. Spacelab Lyman Alpha-White Light Coronagraph Program

    NASA Astrophysics Data System (ADS)

    Kohl, J. L.

    1986-06-01

    The Spacelab Lyman Alpha Coronagraph (SLAC) of the Smithsonian Astrophysical Observatory (SAO) and the White Light Coronagraph (WLC) to be provided by the High Altitude Observatory (HAO) are two separate coronagraphs which would be operated in a joint fashion during Spacelab missions to be flown by the Space Shuttle. The two instruments would be used to perform joint observations of solar coronal structures from 1.2 to 8.0 solar radii from sun-center in vacuum ultraviolet and visible radiations. Temperatures, densities, and flow velocities throughout the solar wing acceleration region of the inner solar corona were measured. The Phase I Definition activity resulted in the successful definition and preliminary design of the experiment/instrumentation subsystem and associated software, ground support equipment and interfaces to the extended required to accurately estimate the scope of the investigation and prepare an Investigational Development Plan; the performance of the necessary functional, operations, and safety analyses necessary to complete the Experiment Requirements document.

  9. Spacelab Lyman Alpha-White Light Coronagraph Program

    NASA Technical Reports Server (NTRS)

    Kohl, J. L.

    1986-01-01

    The Spacelab Lyman Alpha Coronagraph (SLAC) of the Smithsonian Astrophysical Observatory (SAO) and the White Light Coronagraph (WLC) to be provided by the High Altitude Observatory (HAO) are two separate coronagraphs which would be operated in a joint fashion during Spacelab missions to be flown by the Space Shuttle. The two instruments would be used to perform joint observations of solar coronal structures from 1.2 to 8.0 solar radii from sun-center in vacuum ultraviolet and visible radiations. Temperatures, densities, and flow velocities throughout the solar wing acceleration region of the inner solar corona were measured. The Phase I Definition activity resulted in the successful definition and preliminary design of the experiment/instrumentation subsystem and associated software, ground support equipment and interfaces to the extended required to accurately estimate the scope of the investigation and prepare an Investigational Development Plan; the performance of the necessary functional, operations, and safety analyses necessary to complete the Experiment Requirements document.

  10. ASPIICS: an externally occulted coronagraph for PROBA-3: Design evolution

    NASA Astrophysics Data System (ADS)

    Renotte, Etienne; Baston, Elena Carmen; Bemporad, Alessandro; Capobianco, Gerardo; Cernica, Ileana; Darakchiev, Radoslav; Denis, François; Desselle, Richard; De Vos, Lieve; Fineschi, Silvano; Focardi, Mauro; Górski, Tomasz; Graczyk, Rafał; Halain, Jean-Philippe; Hermans, Aline; Jackson, Carl; Kintziger, Christian; Kosiec, Jacek; Kranitis, Nektarios; Landini, Federico; Lédl, Vít.; Massone, Giuseppe; Mazzoli, Alexandra; Melich, Radek; Mollet, Dominique; Mosdorf, Michał; Nicolini, Gianalfredo; Nicula, Bogdan; Orleański, Piotr; Palau, Marie-Catherine; Pancrazzi, Maurizio; Paschalis, Antonis; Peresty, Radek; Plesseria, Jean-Yves; Rataj, Miroslaw; Romoli, Marco; Thizy, Cédric; Thomé, Michel; Tsinganos, Kanaris; Wodnicki, Ryszard; Walczak, Tomasz; Zhukov, Andrei

    2014-08-01

    PROBA-3 is a mission devoted to the in-orbit demonstration of precise formation flying techniques and technologies for future ESA missions. PROBA-3 will fly ASPIICS (Association de Satellites pour l'Imagerie et l'Interferométrie de la Couronne Solaire) as primary payload, which makes use of the formation flying technique to form a giant coronagraph capable of producing a nearly perfect eclipse allowing to observe the sun corona closer to the rim than ever before. The coronagraph is distributed over two satellites flying in formation (approx. 150m apart). The so called Coronagraph Satellite carries the camera and the so called Occulter Satellite carries the sun occulter disc. This paper is reviewing the design and evolution of the ASPIICS instrument as at the beginning of Phase C/D.

  11. SDC: a multistage coronagraphic platform at Palomar observatory

    NASA Astrophysics Data System (ADS)

    Bottom, Michael; Serabyn, Eugene; Shelton, Chris; Wallace, J. Kent; Bartos, Randall D.; Kuhn, Jonas; Mawet, Dimitri; Mennesson, Bertrand; Burruss, Rick

    2016-01-01

    Direct imaging of planets is challenging for two main reasons: first, stars are brighter than their planets by many orders of magnitude (requiring high contrast), and second, planets and their host stars are close to each other (require a low inner working angle instrument). Many exciting new technologies are attempting to address these challenges to enable imaging and spectroscopy of exoplanets. To this end, we present a new instrument, the "Stellar Double Coronagraph" (SDC), a flexible coronagraphic platform. Situated at Palomar Observatory's 200" Hale telescope, it supports a number of interchangeable observing configurations. These include multiple vortex coronagraphs in series, hybrid pupil/phase masks, and novel focal-plane wavefront sensing and control schemes for improved contrast and inner working angles. We describe the motivation, design, observing modes, wavefront control strategies, and data reduction pipeline. We also present early science results, demonstrating the capabilities and potential of these approaches.

  12. Apodized vortex coronagraph designs for segmented aperture telescopes

    NASA Astrophysics Data System (ADS)

    Ruane, Garreth; Jewell, Jeffery; Mawet, Dimitri; Pueyo, Laurent; Shaklan, Stuart

    2016-07-01

    Current state-of-the-art high contrast imaging instruments take advantage of a number of elegant coronagraph designs to suppress starlight and image nearby faint objects, such as exoplanets and circumstellar disks. The ideal performance and complexity of the optical systems depends strongly on the shape of the telescope aperture. Unfortunately, large primary mirrors tend to be segmented and have various obstructions, which limit the performance of most conventional coronagraph designs. We present a new family of vortex coronagraphs with numerically-optimized gray-scale apodizers that provide the sensitivity needed to directly image faint exoplanets with large, segmented aperture telescopes, including the Thirty Meter Telescope (TMT) as well as potential next-generation space telescopes.

  13. The Spacelab Lyman alpha and white light coronagraphs program

    NASA Technical Reports Server (NTRS)

    Kohl, J. L.; Withbroe, G. L.; Weiser, H.; Macqueen, R. M.; Munro, R. H.

    1981-01-01

    The Harvard-Smithsonian Center for Astrophysics and the High Altitude Observatory have defined a joint coronagraphs experiment for a future Spacelab mission. The instrumentation package would include an ultraviolet light coronagraph to measure the intensity and profiles of spectral lines formed between 1.2 and 8 solar radii from sun center and a white light coronagraph to measure the intensity and polarization of visible light. The overall goals of the joint program are to use new coronal plasma diagnostic techniques to understand the physical processes and mechanisms operating in the solar corona, to understand the acceleration of high-speed and low-speed solar wind streams and to extrapolate this knowledge to other stars in order to help understand the physics of stellar coronae and stellar mass loss.

  14. Statechart Analysis with Symbolic PathFinder

    NASA Technical Reports Server (NTRS)

    Pasareanu, Corina S.

    2012-01-01

    We report here on our on-going work that addresses the automated analysis and test case generation for software systems modeled using multiple Statechart formalisms. The work is motivated by large programs such as NASA Exploration, that involve multiple systems that interact via safety-critical protocols and are designed with different Statechart variants. To verify these safety-critical systems, we have developed Polyglot, a framework for modeling and analysis of model-based software written using different Statechart formalisms. Polyglot uses a common intermediate representation with customizable Statechart semantics and leverages the analysis and test generation capabilities of the Symbolic PathFinder tool. Polyglot is used as follows: First, the structure of the Statechart model (expressed in Matlab Stateflow or Rational Rhapsody) is translated into a common intermediate representation (IR). The IR is then translated into Java code that represents the structure of the model. The semantics are provided as "pluggable" modules.

  15. Analysis of Random Segment Errors on Coronagraph Performance

    NASA Technical Reports Server (NTRS)

    Stahl, Mark T.; Stahl, H. Philip; Shaklan, Stuart B.; N'Diaye, Mamadou

    2016-01-01

    At 2015 SPIE O&P we presented "Preliminary Analysis of Random Segment Errors on Coronagraph Performance" Key Findings: Contrast Leakage for 4thorder Sinc2(X) coronagraph is 10X more sensitive to random segment piston than random tip/tilt, Fewer segments (i.e. 1 ring) or very many segments (> 16 rings) has less contrast leakage as a function of piston or tip/tilt than an aperture with 2 to 4 rings of segments. Revised Findings: Piston is only 2.5X more sensitive than Tip/Tilt

  16. Experimental study of a low-order wavefront sensor for high-contrast coronagraphic imagers

    NASA Astrophysics Data System (ADS)

    Lozi, Julien; Belikov, R.; Schneider, G.; Guyon, O.; Thomas, S.; Pluzhnik, E.; EXCEDE Project Technology Development Team

    2014-01-01

    For the technology development of the mission EXCEDE (EXoplanetary Circumstellar Environments and Disk Explorer) - a 0.7 m telescope equipped with a Phase-Induced Amplitude Apodization Coronagraph (PIAA-C) and a 2000-element MEMS deformable mirror, capable of raw contrasts of 1e-6 at 1.2 λ/D and 1e-7 above 2 λ/D - we developed a test bench simulating it’s key components. To achieve this level of contrast, one of the main goals is to remove low-order aberrations, using a Low-Order WaveFront Sensor (LOWFS). An experiment simulating the starlight suppression system is currently developed at NASA Ames Research Center, and includes a LOWFS controlling tip/tilt modes in real time at 1 kHz. The LOWFS allowed us to reduce the tip/tilt disturbances to 1e-3 λ/D rms, letting us achieve a contrast of 4e-7 between 1.2 and 2 λ/D. Also by studying accurately this system, and by comparing it to simulations, we are able to deduce its performances on different coronagraphs - different sizes of telescopes, inner working angles, contrasts, etc. - and therefore study its contribution beyond EXCEDE.

  17. Parallel HOP: A Scalable Halo Finder for Massive Cosmological Data Sets

    NASA Astrophysics Data System (ADS)

    Skory, Stephen; Turk, Matthew J.; Norman, Michael L.; Coil, Alison L.

    2010-11-01

    Modern N-body cosmological simulations contain billions (109) of dark matter particles. These simulations require hundreds to thousands of gigabytes of memory and employ hundreds to tens of thousands of processing cores on many compute nodes. In order to study the distribution of dark matter in a cosmological simulation, the dark matter halos must be identified using a halo finder, which establishes the halo membership of every particle in the simulation. The resources required for halo finding are similar to the requirements for the simulation itself. In particular, simulations have become too extensive to use commonly employed halo finders, such that the computational requirements to identify halos must now be spread across multiple nodes and cores. Here, we present a scalable-parallel halo finding method called Parallel HOP for large-scale cosmological simulation data. Based on the halo finder HOP, it utilizes message passing interface and domain decomposition to distribute the halo finding workload across multiple compute nodes, enabling analysis of much larger data sets than is possible with the strictly serial or previous parallel implementations of HOP. We provide a reference implementation of this method as a part of the toolkit "yt", an analysis toolkit for adaptive mesh refinement data that include complementary analysis modules. Additionally, we discuss a suite of benchmarks that demonstrate that this method scales well up to several hundred tasks and data sets in excess of 20003 particles. The Parallel HOP method and our implementation can be readily applied to any kind of N-body simulation data and is therefore widely applicable.

  18. Parallel HOP: A Scalable Halo Finder for Massive Cosmological Data Sets

    NASA Astrophysics Data System (ADS)

    Skory, Stephen; Turk, Matthew J.; Norman, Michael L.; Coil, Alison L.

    2011-03-01

    Modern N-body cosmological simulations contain billions (10(9) ) of dark matter particles. These simulations require hundreds to thousands of gigabytes of memory, and employ hundreds to tens of thousands of processing cores on many compute nodes. In order to study the distribution of dark matter in a cosmological simulation, the dark matter halos must be identified using a halo finder, which establishes the halo membership of every particle in the simulation. The resources required for halo finding are similar to the requirements for the simulation itself. In particular, simulations have become too extensive to use commonly-employed halo finders, such that the computational requirements to identify halos must now be spread across multiple nodes and cores. Here we present a scalable-parallel halo finding method called Parallel HOP for large-scale cosmological simulation data. Based on the halo finder HOP, it utilizes MPI and domain decomposition to distribute the halo finding workload across multiple compute nodes, enabling analysis of much larger datasets than is possible with the strictly serial or previous parallel implementations of HOP. We provide a reference implementation of this method as a part of the toolkit yt, an analysis toolkit for Adaptive Mesh Refinement (AMR) data that includes complementary analysis modules. Additionally, we discuss a suite of benchmarks that demonstrate that this method scales well up to several hundred tasks and datasets in excess of 2000(3) particles. The Parallel HOP method and our implementation can be readily applied to any kind of N-body simulation data and is therefore widely applicable. Parallel HOP is part of yt.

  19. PARALLEL HOP: A SCALABLE HALO FINDER FOR MASSIVE COSMOLOGICAL DATA SETS

    SciTech Connect

    Skory, Stephen; Turk, Matthew J.; Norman, Michael L.; Coil, Alison L. E-mail: mjturk@ucsd.ed E-mail: acoil@ucsd.ed

    2010-11-15

    Modern N-body cosmological simulations contain billions (10{sup 9}) of dark matter particles. These simulations require hundreds to thousands of gigabytes of memory and employ hundreds to tens of thousands of processing cores on many compute nodes. In order to study the distribution of dark matter in a cosmological simulation, the dark matter halos must be identified using a halo finder, which establishes the halo membership of every particle in the simulation. The resources required for halo finding are similar to the requirements for the simulation itself. In particular, simulations have become too extensive to use commonly employed halo finders, such that the computational requirements to identify halos must now be spread across multiple nodes and cores. Here, we present a scalable-parallel halo finding method called Parallel HOP for large-scale cosmological simulation data. Based on the halo finder HOP, it utilizes message passing interface and domain decomposition to distribute the halo finding workload across multiple compute nodes, enabling analysis of much larger data sets than is possible with the strictly serial or previous parallel implementations of HOP. We provide a reference implementation of this method as a part of the toolkit {sup yt}, an analysis toolkit for adaptive mesh refinement data that include complementary analysis modules. Additionally, we discuss a suite of benchmarks that demonstrate that this method scales well up to several hundred tasks and data sets in excess of 2000{sup 3} particles. The Parallel HOP method and our implementation can be readily applied to any kind of N-body simulation data and is therefore widely applicable.

  20. 3. VIEW NORTHWEST, height finder radar towers, and radar tower ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. VIEW NORTHWEST, height finder radar towers, and radar tower (unknown function) - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

  1. 1. VIEW NORTHWEST, operations building, height finder radar tower, and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. VIEW NORTHWEST, operations building, height finder radar tower, and radar tower (unknown function) - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

  2. Imaging exoplanets with the WFIRST Coronagraph: A background check of high priority targets

    NASA Astrophysics Data System (ADS)

    Fu, Guangwei; Turnbull, Margaret C.; Gallagher, John S.; Kotulla, Ralf C.; Merrelli, Aronne; L'Ecuyer, Tristan; Hu, Renyu

    2016-01-01

    The WFIRST coronagraph is envisioned to achieve a limiting contrast for exoplanet detection of 10e-9. This revolutionary mission will enable the direct detection of known and newly discovered exoplanets amongst the nearest stars, from super-Earths to giants. However, at this contrast the coronagraph will essentially see a Hubble Ultra Deep Field (HUDF) in every image. For targets near the Galactic Plane on the sky, distant stars with varying levels of extinction and reddening will dominate the background. Away from the plane, we then expect extragalactic sources to dominate. What impact will these background sources have on the WFIRST exoplanet imaging program? How can we efficiently distinguish background sources from exoplanet targets in a single image? To have a comprehensive understanding of the distribution of background sources across the sky, we have used the HUDF to model extragalactic faint sources, and "Trilegal" simulations to model galactic background sources. Through some preliminary color and point source analysis, we offer a statistical estimation of expected background contamination and the probability of false positive background sources. In this poster we show plots relating number of extragalactic sources versus magnitude in HUDF and "Trilegal" simulation. We present a table of high priority WFIRST exoplanet imaging targets, with an assessment of the "background threat" due to background stars, galaxies, and binary companions.

  3. Characterizing edge-generated stray light sources for TPF Coronagraph pupil masks

    NASA Astrophysics Data System (ADS)

    Ceperley, Daniel; Neureuther, Andrew; Lieber, Michael; Kasdin, Jeremy

    2005-08-01

    The edge generated stray-light from corner boundary conditions, interactions with the lower mask structure, and surface plasmon polaritons that may limit Terrestrial Planet Finder Coronagraph performance are characterized. Previously a number of stray light sources, unaccounted for by the ideal thin mask theory used to design the pupil-plane masks, were identified. In this paper we illustrate and quantify the most important outstanding stray-light sources in the near-field in order to improve the model of pupil-plane mask transmission used by the Integrated Telescope Model. Corner spikes, caused by the need to bring the ideal top-hat field into compliance with the boundary conditions set forth by Maxwell's equations, form the strongest source of stray-light, accounting for up to a 1λ shift in the effective opening width per edge. Undercutting mask edges by 20° reduces this source of stray-light by more than a factor of five. Interactions between light and the lower mask structure, a secondary effect, account for only a few percent of the stray-light in the TE polarization but account for up to 50% of the stray-light in the TM polarization due to surface plasmon polaritons. Surface plasmon polaritons, surface waves that run for tens of microns and radiate at corners, form the final stray-light source. On thin masks they may account for up to a 1λ shift in the effective opening width; however, their effects can be easily mitigated by choosing a poor surface plasmon material, such as Chrome. The results presented here are being used to facilitate end-to-end system modeling through the Integrated Telescope Model.

  4. The COR1 Inner Coronagraph for STEREO-SECCHI

    NASA Technical Reports Server (NTRS)

    Thompson, William T.; Davila, Joseph M.; Fisher, Richard R.; Orwig, Larry E.; Mentzell, John E.; Hetherington, Samuel E.; Derro, Rebecca J.; Ferderline, Robert E.; Clark, David C.; Chen, Philip T.

    2004-01-01

    The Solar Terrestrial Relations Observatory (STEREO) is a pair of identical satellites that will orbit the Sun so as to drift ahead of and behind Earth respectively, to give a stereo view of the Sun. STEREO is currently scheduled for launch in November 2005. One of the instrument packages that will be own on each of the STEREO spacecrafts is the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI), which consists of an extreme ultraviolet imager, two coronagraphs, and two side-viewing heliospheric imagers to observe solar coronal mass ejections all the way from the Sun to Earth. We report here on the inner coronagraph, labeled COR1. COR1 is a classic Lyot internally occulting refractive coronagraph, adapted for the first time to be used in space. The field of view is from 1.3 to 4 solar radii. A linear polarizer is used to suppress scattered light, and to extract the polarized brightness signal from the solar corona. The optical scattering performance of the coronagraph was first modeled using both the ASAP and APART numerical modeling codes, and then tested at the Vacuum Tunnel Facility at the National Center for Atmospheric Research in Boulder, Colorado. In this report, we will focus on the COR1 optical design, the predicted optical performance, and the observed performance in the lab. We will also discuss the mechanical and thermal design, and the cleanliness requirements needed to achieve the optical performance.

  5. MiniCOR: A miniature coronagraph for an interplanetary CUBESAT

    NASA Astrophysics Data System (ADS)

    Vourlidas, A.; Korendyke, C.; Liewer, P. C.; Cutler, J.; Howard, R.; Plunkett, S. P.; Thernisien, A. F.

    2015-12-01

    Coronagraphs occupy a unique place in Heliophysics, critical to both NAA and NOAA programs. They are the primary means for the study of the extended solar coorna and its short/long term activity. In addition coronagraphs are the only instrument that can image coronal mass ejections (CMEs) leaving the Sun and provide ciritical information for space weather forecasting. We descirbe a low cost miniaturzied CubeSat coronagraph, MiniCOR, designed to operate in deep space which will returndata with higher cadence and sensitivity than that from the SOHO/LASCO coronagraphs. MiniCOR is a six unit (6U) science craft with a tightly integrated, single instrument interplanetary flight system optiized for science. MiniCOR fully exploits recent technology advance in CubeSat technology and active pixel sensors. With a factor of 2.9 improvement in light gathering power over SOHO and quasi-continuous data collection, MiniCOR can observe the slow solar wind, CMEs and shocks with sufficient signal-to-noise ratio (SNR) to open new windows on our understanding of the inner Heliosphere. An operating Minic'OR would prvide coornagraphic observations in support of the upcoming Solar Probe Plus (SPP) and Solar Orbiter (SO) missions.

  6. Low order wavefront sensing and control for WFIRST coronagraph

    NASA Astrophysics Data System (ADS)

    Shi, Fang; Balasubramanian, Kunjithapatham; Bartos, Randall; Hein, Randall; Lam, Raymond; Mandic, Milan; Moore, Douglas; Moore, James; Patterson, Keith; Poberezhskiy, Ilya; Shields, Joel; Sidick, Erkin; Tang, Hong; Truong, Tuan; Wallace, James K.; Wang, Xu; Wilson, Daniel W.

    2016-07-01

    To maintain the required WFIRST Coronagraph starlight suppression performance in a realistic space environment, a low order wavefront sensing and control (LOWFS/C) subsystem is necessary. The LOWFS/C uses the rejected stellar light from coronagraph to sense and suppress the telescope pointing drift and jitter as well as the low order wavefront errors due to changes in thermal loading on the telescope and the rest of the observatory. In this paper we will present an overview of the low order wavefront sensing and control subsystem for the WFIRST Coronagraph and describe the WFIRST Coronagraph LOWFS function, its design, and modeled performance. We will present experimental results on a dedicated LOWFS/C testbed that show that the LOWFS/C subsystem not only can sense pointing errors better than 0.2 mas but has also experimentally demonstrated closed loop pointing error suppression with residuals better than 0.4 mas rms per axis for the vast majority of observatory reaction wheel speeds.

  7. Prospects for Observing Space Debris with Solar Coronagraphs

    DTIC Science & Technology

    1994-04-07

    mode designed to detect orbital debris . II 4- Coronagraph -2or -2- /• -. 0.001 s -4- -6. . . . . . -3 -2 -1 0 1 Log a (cm) Figure 1. Per-pixel signal...velocities of orbital debris and the typical direction and fast transit times of nearby particles under strong wind conditions, or random and nonlinear

  8. CoCo: an infrared cold coronagraph for astronomical observations

    NASA Astrophysics Data System (ADS)

    Wang, Shu-I.; Owensby, Pamela D.; Toomey, Douglas W.; Brown, Robert H.; Stahlberger, Werner E.; Cavedoni, Charles P.; Hua, Rong; Ftaclas, Christ

    1994-06-01

    This paper describes the design of an IR cold coronagraph (CoCo) built by SETS Technology, Inc., for use at the NASA 3 m IR Telescope Facility (IRTF) at Mauna Kea Observatory, for the imaging of faint IR sources in proximity to bright sources. The coronagraph is designed to obtain high contrast photometric images by use of an occulting mask and a pupil mask. The coronagraph is to be used in combination with the IRTF NSFCAM, which covers 1-5 micrometers and uses a 256x256 InSb array. The platescale can be varied from 0.06'/pixel to 0.15'/pixel, covering a field of view of 14' and 38', respectively. Selectable apodized and hard occulting masks are mounted on a wheel as the first element in the system to reduce scattered light. Selectable pupil masks are cooled to 77K within the CoCo cryostat. The cryostat consists of a liquid nitrogen can for cooling the optics, masks, and baffles. The CoCo dewar is mounted on a slide in a housing to allow it to move out of the beam path so that the NSFCAM may be used with or without the coronagraph during the same observing period.

  9. Common-Path Wavefront Sensing for Advanced Coronagraphs

    NASA Technical Reports Server (NTRS)

    Wallace, J. Kent; Serabyn, Eugene; Mawet, Dimitri

    2012-01-01

    Imaging of faint companions around nearby stars is not limited by either intrinsic resolution of a coronagraph/telescope system, nor is it strictly photon limited. Typically, it is both the magnitude and temporal variation of small phase and amplitude errors imparted to the electric field by elements in the optical system which will limit ultimate performance. Adaptive optics systems, particularly those with multiple deformable mirrors, can remove these errors, but they need to be sensed in the final image plane. If the sensing system is before the final image plane, which is typical for most systems, then the non-common path optics between the wavefront sensor and science image plane will lead to un-sensed errors. However, a new generation of high-performance coronagraphs naturally lend themselves to wavefront sensing in the final image plane. These coronagraphs and the wavefront sensing will be discussed, as well as plans for demonstrating this with a high-contrast system on the ground. Such a system will be a key system-level proof for a future space-based coronagraph mission, which will also be discussed.

  10. Micro-Laser Range Finder Development: Using the Monolithic Approach

    DTIC Science & Technology

    1999-02-01

    Approved for public release; distribution is unlimited. Micro- Laser Range Finder Development: Using the Monolithic Approach February 1999 John... Nettleton , Dallas Barr, Brad Schilling & Jonathan Lei US ARMY CECOM RDEC NVESD Fort Belvoir, VA Samuel M. Goldwasser Engineering Consultant Bala-Cynwyd, PA...ABSTRACT Laser range finders are a vital component of high precision targeting engagements. The precise and accurate range-to-target information is

  11. Introduction to Searching with SciFinder Scholar

    NASA Astrophysics Data System (ADS)

    Ridley, Damon D.

    2001-04-01

    With SciFinder Scholar now one of the preferred access routes to information in the sciences, many college information retrieval courses that dealt with online networks need to be redesigned. Although one of the basic assumptions within the design of SciFinder Scholar is that staff and students may retrieve valuable answers with little training, nevertheless, with a little instruction improved search results may be obtained. We present here our basic teaching program for senior undergraduate and postgraduate classes.

  12. ACCESS - A Science and Engineering Assessment of Space Coronagraph Concepts for the Direct Imaging and Spectroscopy of Exoplanetary Systems

    NASA Technical Reports Server (NTRS)

    Trauger, John

    2008-01-01

    Topics include and overview, science objectives, study objectives, coronagraph types, metrics, ACCESS observatory, laboratory validations, and summary. Individual slides examine ACCESS engineering approach, ACCESS gamut of coronagraph types, coronagraph metrics, ACCESS Discovery Space, coronagraph optical layout, wavefront control on the "level playing field", deformable mirror development for HCIT, laboratory testbed demonstrations, high contract imaging with the HCIT, laboratory coronagraph contrast and stability, model validation and performance predictions, HCIT coronagraph optical layout, Lyot coronagraph on the HCIT, pupil mapping (PIAA), shaped pupils, and vortex phase mask experiments on the HCIT.

  13. ACCESS - A Science and Engineering Assessment of Space Coronagraph Concepts for the Direct Imaging and Spectroscopy of Exoplanetary Systems

    NASA Technical Reports Server (NTRS)

    Trauger, John

    2008-01-01

    Topics include and overview, science objectives, study objectives, coronagraph types, metrics, ACCESS observatory, laboratory validations, and summary. Individual slides examine ACCESS engineering approach, ACCESS gamut of coronagraph types, coronagraph metrics, ACCESS Discovery Space, coronagraph optical layout, wavefront control on the "level playing field", deformable mirror development for HCIT, laboratory testbed demonstrations, high contract imaging with the HCIT, laboratory coronagraph contrast and stability, model validation and performance predictions, HCIT coronagraph optical layout, Lyot coronagraph on the HCIT, pupil mapping (PIAA), shaped pupils, and vortex phase mask experiments on the HCIT.

  14. cFinder: definition and quantification of multiple haplotypes in a mixed sample.

    PubMed

    Niklas, Norbert; Hafenscher, Julia; Barna, Agnes; Wiesinger, Karin; Pröll, Johannes; Dreiseitl, Stephan; Preuner-Stix, Sandra; Valent, Peter; Lion, Thomas; Gabriel, Christian

    2015-09-07

    Next-generation sequencing allows for determining the genetic composition of a mixed sample. For instance, when performing resistance testing for BCR-ABL1 it is necessary to identify clones and define compound mutations; together with an exact quantification this may complement diagnosis and therapy decisions with additional information. Moreover, that applies not only to oncological issues but also determination of viral, bacterial or fungal infection. The efforts to retrieve multiple haplotypes (more than two) and proportion information from data with conventional software are difficult, cumbersome and demand multiple manual steps. Therefore, we developed a tool called cFinder that is capable of automatic detection of haplotypes and their accurate quantification within one sample. BCR-ABL1 samples containing multiple clones were used for testing and our cFinder could identify all previously found clones together with their abundance and even refine some results. Additionally, reads were simulated using GemSIM with multiple haplotypes, the detection was very close to linear (R(2) = 0.96). Our aim is not to deduce haploblocks over statistics, but to characterize one sample's composition precisely. As a result the cFinder reports the connections of variants (haplotypes) with their readcount and relative occurrence (percentage). Download is available at http://sourceforge.net/projects/cfinder/. Our cFinder is implemented in an efficient algorithm that can be run on a low-performance desktop computer. Furthermore, it considers paired-end information (if available) and is generally open for any current next-generation sequencing technology and alignment strategy. To our knowledge, this is the first software that enables researchers without extensive bioinformatic support to designate multiple haplotypes and how they constitute to a sample.

  15. The automated planet finder at Lick Observatory

    NASA Astrophysics Data System (ADS)

    Radovan, Matt V.; Lanclos, Kyle; Holden, Bradford P.; Kibrick, Robert I.; Allen, S. L.; Deich, William T. S.; Rivera, Eugenio; Burt, Jennifer; Fulton, Benjamin; Butler, Paul; Vogt, Steven S.

    2014-07-01

    By July 2014, the Automated Planet Finder (APF) at Lick Observatory on Mount Hamilton will have completed its first year of operation. This facility combines a modern 2.4m computer-controlled telescope with a flexible development environment that enables efficient use of the Levy Spectrometer for high cadence observations. The Levy provides both sub-meter per second radial velocity precision and high efficiency, with a peak total system throughput of 24%. The modern telescope combined with efficient spectrometer routinely yields over 100 observations of 40 stars in a single night, each of which has velocity errors of 0.7 to 1.4 meters per second, all with typical seeing of < 1 arc second full-width-half-maximum (FWHM). The whole observing process is automated using a common application programming interface (API) for inter-process communication which allows scripting to be done in a variety of languages (Python, Tcl, bash, csh, etc.) The flexibility and ease-of-use of the common API allowed the science teams to be directly involved in the automation of the observing process, ensuring that the facility met their requirements. Since November 2013, the APF has been routinely conducting autonomous observations without human intervention.

  16. Development of PIAA Complex Mask Coronagraphs for large aperture ground-based telescopes

    NASA Astrophysics Data System (ADS)

    Newman, Kevin; Sirbu, Dan; Belikov, Ruslan; Guyon, Olivier

    2016-07-01

    The Phase Induced Amplitude Apodization Complex Mask Coronagraph (PIAACMC) is an architecture for directly observing extra-solar planets, and can achieve performance near the theoretical limits for any direct-detection instrument. The PIAACMC architecture includes aspheric PIAA optics, and a complex phase-shifting focal plane mask that provides a pi phase shift to a portion of the on-axis starlight. The phase-shifted starlight is forced to interfere destructively with the un-shifted starlight, causing the starlight to be eliminated, and allowing a region for high-contrast imaging near the star. The PIAACMC architecture can be designed for segmented and obscured apertures, so it is particularly well suited for ground-based observing with the next generation of large telescopes. There will be unique scientific opportunities for directly observing Earth-like planets around nearby low-mass stars. We will discuss design strategies for adapting PIAACMC for the next generation of large ground-based telescopes, and present progress on the development of the focal plane mask technology. We also present simulations of wave-front control with PIAACMC, and suggest directions to apply the coronagraph architecture to future telescopes.

  17. Optimization of the occulter for the Solar Orbiter/METIS coronagraph

    NASA Astrophysics Data System (ADS)

    Landini, Federico; Vivès, Sébastien; Romoli, Marco; Guillon, Christophe; Pancrazzi, Maurizio; Escolle, Clement; Focardi, Mauro; Antonucci, Ester; Fineschi, Silvano; Naletto, Giampiero; Nicolini, Gianalfredo; Nicolosi, Piergiorgio; Spadaro, Daniele

    2012-09-01

    METIS (Multi Element Telescope for Imaging and Spectroscopy investigation), selected to fly aboard the Solar Orbiter ESA/NASA mission, is conceived to perform imaging (in visible, UV and EUV) and spectroscopy (in EUV) of the solar corona, by means of an integrated instrument suite located on a single optical bench and sharing the same aperture on the satellite heat shield. As every coronagraph, METIS is highly demanding in terms of stray light suppression. Coronagraphs history teaches that a particular attention must be dedicated to the occulter optimization. The METIS occulting system is of particular interest due to its innovative concept. In order to meet the strict thermal requirements of Solar Orbiter, METIS optical design has been optimized by moving the entrance pupil at the level of the external occulter on the S/C thermal shield, thus reducing the size of the external aperture. The scheme is based on an inverted external-occulter (IEO). The IEO consists of a circular aperture on the Solar Orbiter thermal shield. A spherical mirror rejects back the disk-light through the IEO. A breadboard of the occulting assembly (BOA) has been manufactured in order to perform stray light tests in front of two solar simulators (in Marseille, France and in Torino, Italy). A first measurement campaign has been carried on at the Laboratoire d'Astrophysique de Marseille. In this paper we describe the BOA design, the laboratory set-up and the preliminary results.

  18. A neural network gravitational arc finder based on the Mediatrix filamentation method

    NASA Astrophysics Data System (ADS)

    Bom, C. R.; Makler, M.; Albuquerque, M. P.; Brandt, C. H.

    2017-01-01

    Context. Automated arc detection methods are needed to scan the ongoing and next-generation wide-field imaging surveys, which are expected to contain thousands of strong lensing systems. Arc finders are also required for a quantitative comparison between predictions and observations of arc abundance. Several algorithms have been proposed to this end, but machine learning methods have remained as a relatively unexplored step in the arc finding process. Aims: In this work we introduce a new arc finder based on pattern recognition, which uses a set of morphological measurements that are derived from the Mediatrix filamentation method as entries to an artificial neural network (ANN). We show a full example of the application of the arc finder, first training and validating the ANN on simulated arcs and then applying the code on four Hubble Space Telescope (HST) images of strong lensing systems. Methods: The simulated arcs use simple prescriptions for the lens and the source, while mimicking HST observational conditions. We also consider a sample of objects from HST images with no arcs in the training of the ANN classification. We use the training and validation process to determine a suitable set of ANN configurations, including the combination of inputs from the Mediatrix method, so as to maximize the completeness while keeping the false positives low. Results: In the simulations the method was able to achieve a completeness of about 90% with respect to the arcs that are input into the ANN after a preselection. However, this completeness drops to 70% on the HST images. The false detections are on the order of 3% of the objects detected in these images. Conclusions: The combination of Mediatrix measurements with an ANN is a promising tool for the pattern-recognition phase of arc finding. More realistic simulations and a larger set of real systems are needed for a better training and assessment of the efficiency of the method.

  19. Demonstration of Broadband Contrast at 1.2 Lambda/D for the EXCEDE Phase-Induced Amplitude Apodization Coronagraph

    NASA Technical Reports Server (NTRS)

    Sirbu, Dan; Thomas, Sandrine J.; Belikov, Ruslan; Lozi, Julien; Bendek, Eduardo; Pluzhnik, Eugene; Lynch, Dana H.; Hix, Troy; Zell, Peter; Schneider, Glenn; hide

    2015-01-01

    The proposed coronagraph instrument on the EXCEDE (EXoplanetary Circumstellar Environments and Disk Explorer) mission study uses a Phase-Induced Amplitude Apodization (PIAA) coronagraph architecture to enable high-contrast imaging of circumstellar debris disks and giant planets at angular separations as close in as the habitable zone of nearby host stars. We report on the experimental results obtained in the vacuum chamber at the Lockheed Martin Advanced Technology Center in 10 percent broadband light centered about 650 nanometers, with a median contrast of 1 x 10 (sup -5) between 1.2 and 2.0 lambda /D simultaneously with 3 x 10 (sup -7) contrast between 2 and 11 =D between 2 and 11 lambda/D for a single-sided dark hole using a deformable mirror (DM) upstream of the PIAA coronagraph. The results are stable and repeatable as demonstrated by three measurements runs with DM settings set from scratch and maintained on the best 90 percent out of the 1000 collected frames. We compare the reduced experimental data with simulation results from modeling observed experimental limits; performance is consistent with uncorrected low-order modes not estimated by the Low Order Wavefront Sensor (LOWFS). Modeled sensitivity to bandwidth and residual tip/tilt modes is well-matched to the experiment.

  20. Optimization of Planet Finder Observing Strategy

    NASA Astrophysics Data System (ADS)

    Sinukoff, E.

    2014-03-01

    We evaluate radial velocity observing strategies to be considered for future planethunting surveys with the Automated Planet Finder, a new 2.4-m telescope at Lick Observatory. Observing strategies can be optimized to mitigate stellar noise, which can mask and imitate the weak Doppler signals of low-mass planets. We estimate and compare sensitivities of 5 different observing strategies to planets around G2-M2 dwarfs, constructing RV noise models for each stellar spectral type, accounting for acoustic, granulation, and magnetic activity modes. The strategies differ in exposure time, nightly and monthly cadence, and number of years. Synthetic RV time-series are produced by injecting a planet signal onto the stellar noise, sampled according to each observing strategy. For each star and each observing strategy, thousands of planet injection recovery trials are conducted to determine the detection efficiency as a function of orbital period, minimum mass, and eccentricity. We find that 4-year observing strategies of 10 nights per month are sensitive to planets ~25-40% lower in mass than the corresponding 1 year strategies of 30 nights per month. Three 5-minute exposures spaced evenly throughout each night provide a 10% gain in sensitivity over the corresponding single 15-minute exposure strategies. All strategies are sensitive to planets of lowest mass around the modeled K7 dwarf. This study indicates that APF surveys adopting the 4-year strategies should detect Earth-mass planets on < 10-day orbits around quiet late-K dwarfs as well as > 1.6 Earth-mass planets in their habitable zones.

  1. Control design for momentum-compensated fast steering mirror for WFIRST-AFTA coronagraph instrument

    NASA Astrophysics Data System (ADS)

    Patterson, Keith; Shields, Joel; Wang, Xu; Tang, Hong; Azizi, Ali; Brugarolas, Paul; Mandic, Milan; Shi, Fang

    2015-09-01

    This paper presents results of the feedback control design for JPL's Fast Steering Mirror (FSM) for the WFIRST- AFTA coronagraph instrument. The objective of this controller is to cancel jitter disturbances in the beam from the spacecraft to a pointing stability of 0.4 masec over the duration of the observation using a momentum- compensated FSM. The plant model for the FSM was characterized experimentally, and the sensor model is based on simulated modeling. The control approach is divided between feedback compensation of low frequency attitude control system (ACS) drift, and feedforward cancellation of high frequency tonal disturbances originating from reaction wheel excitation of the telescope structure. This paper will present various aspects of the controller design, plant characterization, sensor modeling, disturbance estimation, performance simulation, and preliminary experimental testing results.

  2. Electric field conjugation with the project 1640 coronagraph

    NASA Astrophysics Data System (ADS)

    Cady, Eric; Baranec, Christoph; Beichman, Charles; Brenner, Douglas; Burruss, Rick; Crepp, Justin; Dekany, Richard; Hale, David; Hillenbrand, Lynne; Hinkley, Sasha; Ligon, E. Robert; Lockhart, Thomas; Oppenheimer, Ben; Parry, Ian; Pueyo, Laurent; Rice, Emily; Roberts, Lewis C.; Roberts, Jennifer; Shao, Michael; Sivaramakrishnan, Anand; Soummer, Remi; Tang, Hong; Truong, Tuan; Vasisht, Gautam; Vescelus, Fred; Wallace, J. Kent; Zhai, Chengxing; Zimmerman, Neil

    2013-09-01

    The Project 1640 instrument on the 200-inch Hale telescope at Palomar Observatory is a coronagraphic instru- ment with an integral eld spectrograph at the back end, designed to nd young, self-luminous planets around nearby stars. To reach the necessary contrast for this, the PALM-3000 adaptive optics system corrects for fast atmospheric speckles, while CAL, a phase-shifting interferometer in a Mach-Zehnder con guration, measures the quasistatic components of the complex electric eld in the pupil plane following the coronagraphic stop. Two additional sensors measure and control low-order modes. These eld measurements may then be combined with a system model and data taken separately using a white-light source internal to the AO system to correct for both phase and amplitude aberrations. Here, we discuss and demonstrate the procedure to maintain a half-plane dark hole in the image plane while the spectrograph is taking data, including initial on-sky performance.

  3. The COSMO coronagraph optical design and stray light analysis

    NASA Astrophysics Data System (ADS)

    Gallagher, Dennis; Wu, Zhen; Larson, Brandon; Nelson, Peter G.; Oakley, Phil; Sewell, Scott; Tomczyk, Steven

    2016-07-01

    The Coronal Solar Magnetism Observatory Large Coronagraph (COSMO-LC) is a 1.5 meter Lyot coronagraph dedicated to measuring magnetic fields and plasma properties in the solar corona. The COSMO-LC will be able to observe coronal emissions lines from 530-1100 nm using a filtergraph instrument. COSMO-LC will have a 1 degree field of view to observe the full solar corona out to 1 solar radius beyond the limb of the sun. This presented challenges due to the large Etendue of the system. The COSMO-LC spatial resolution is 2 arc-seconds per pixel (4k X 4k). The most critical part of the coronagraph is the objective lens that is exposed to direct sunlight that is five orders of magnitude brighter than the corona. Therefore, it is key to the operation of a coronagraph that the objective lens (O1) scatter as little light as possible, on order a few parts per million. The selection of the material and the polish applied to the O1 are critical in reducing scattered light. In this paper we discuss the design of the COSMO-LC and the detailed design of the O1 and other key parts of the COSMO-LC that keep stray light to a minimum. The result is an instrument with stray light below 5 millionths the brightness of the sun 50 arc-seconds from the sun. The COSMO-LC has just had a Preliminary Design Review (PDR) and the PDR design is presented.

  4. Coronagraph particulate measurements. Skylab flight experiment T025

    NASA Technical Reports Server (NTRS)

    Greenberg, J. M.; Schuerman, D. W.; Giovane, F.; Wang, R. T.; Hardy, D. C.

    1975-01-01

    Major results of the Skylab T025 Coronagraph experiment designed to monitor the particulate contamination about the spacecraft and to study the earth's atmospheric aerosol distribution are presented. A model for comet outbursts based on the properties of amorphous ice and ground based narrow-band and white light photography of comet Kohoutek ten days to perihelion are included. The effect of atmospheric refraction on the analysis of the T025 atmospheric data was also investigated.

  5. Respective capabilities of affordable Coronagraphs and Interferometers searching for Biosignatures

    NASA Astrophysics Data System (ADS)

    Leger, Alain M.

    2015-12-01

    We describe an analytic model to estimate the capabilities of space missions dedicated to the search for biosignatures in the atmosphere of rocky planets located in the Habitable Zone of nearby stars. Relations between performance and parameters such as mirror diameter, distance to target, stellar properties, are obtained.Two types of instruments are considered: Coronagraphs observing in the visible, and Nulling Interferometers observing in the thermal infrared. Missions considered as affordable are single-pupil coronagraphs with a 2.4 m primary mirror, and formation flying interferometers with 4 x 0.75 m collecting mirrors with baselines ranging from a few decameters to a few hectometers.The numbers of accessible planets are calculated as a function of ηearth, the mean number of Earth analogues and super-Earths in stellar Habitable Zones.Based on current estimates, ηearth=10% around FGK stars and 20% around M stars, the built-in coronagraph and starshade could study only ~2.0 relevant planets, and the interferometer ~14. These numbers are obtained under the major assumption that the exozodiacal light around the target stars is not an issue for any of these instruments.For the coronagraphs, our estimates are in agreement with the values recently published by Stark et al. (2014), but these authors did not consider the case of interferometers.For the long-term future, building both types of spectroscopic instruments, and using them on the same targets, will be the optimal solution because they provide complementary information. But as a first affordable space mission, the interferometer looks the more promising in term of biosignature harvest.

  6. CME dynamics using coronagraph and interplanetary ejecta observations

    NASA Astrophysics Data System (ADS)

    Dal Lago, Alisson; Demítrio Gonzalez Alarcon, Walter; da Silva, Marlos; de Lucas, Aline; Braga, Carlos Roberto; Ramos Vieira, Lucas

    One of the key issues of Space Weather is the dynamics of coronal mass ejections, from their release from the Sun, their propagation throughout the interplanetary space, eventually im-pacting the earth and other planets. These impacts of CMEs are the most important drivers of space weather phenomena. A number of empirical and analytical studies have addressed this point so far, using observations from coronagraphs and interplanetary monitors, in order to correlate CMEs observed near the Sun and in situ (e.g. earth vincity). However, results are far from conclusive. Error bars in CME travel time predictions from the Sun to earth, are of the order of 1 day, which is considerably big for the typical time scale of 1 to 3 days of their travel time. After many years of intensive investigations of CMEs observed with the Large An-gle and Spectrometric Coronagraph (LASCO), abord the Solar and Heliospheric Observatory (SOHO), we found that the subset of interplanetary counterparts of CMEs, the ICMEs, with a well defined ejecta structure are those with best predictable behaviour. The prediction of these interplanetary ejecta travel time to earth, using coronagraph observations is the one with lowest error bar among other sets of events, such as interplanetary shock. We present a statistic study of all the CME-ejecta events observed by SOHO and by the Advanced Composition Explorer (ACE) satellite since 1997.

  7. Direct Imaging Searches with the Apodizing Phase Plate Coronagraph

    NASA Astrophysics Data System (ADS)

    Kenworthy, M.; Meshkat, T.; Otten, , G.; Codona, J.

    2014-03-01

    The sensitivity of direct imaging searches for extrasolar planets is limited by the presence of diffraction rings from the primary star. Coronagraphs are angular filters that minimise these diffraction structures whilst allowing light from faint companions to shine through. The Apodizing Phase Plate (APP; Kenworthy 2007) coronagraph is a simple pupil plane optic that suppresses diffraction over a 180 degree region around each star simultaneously, providing easy beam switching observations and requiring no time consuming optical alignment at the telescope. We will present our results on using the APP at the Very Large Telescope in surveys for extrasolar planets around A/F and debris disk hosting stars in the L' band (3.8 microns) in the Southern Hemisphere, where we reach a contrast of 12 magnitudes at 0.5 arcseconds (Meshkat 2013). In Leiden, we are also developing the next generation of broadband achromatic coronagraphs that can simultaneously image both sides of the star using Vector APPs (Snik 2012, Otten 2012). Recent laboratory results showing the potential of this technology for future ELTs will also be presented.

  8. Automatic analysis of double coronal mass ejections from coronagraph images

    NASA Astrophysics Data System (ADS)

    Jacobs, Matthew; Chang, Lin-Ching; Pulkkinen, Antti; Romano, Michelangelo

    2015-11-01

    Coronal mass ejections (CMEs) can have major impacts on man-made technology and humans, both in space and on Earth. These impacts have created a high interest in the study of CMEs in an effort to detect and track events and forecast the CME arrival time to provide time for proper mitigation. A robust automatic real-time CME processing pipeline is greatly desired to avoid laborious and subjective manual processing. Automatic methods have been proposed to segment CMEs from coronagraph images and estimate CME parameters such as their heliocentric location and velocity. However, existing methods suffered from several shortcomings such as the use of hard thresholding and an inability to handle two or more CMEs occurring within the same coronagraph image. Double-CME analysis is a necessity for forecasting the many CME events that occur within short time frames. Robust forecasts for all CME events are required to fully understand space weather impacts. This paper presents a new method to segment CME masses and pattern recognition approaches to differentiate two CMEs in a single coronagraph image. The proposed method is validated on a data set of 30 halo CMEs, with results showing comparable ability in transient arrival time prediction accuracy and the new ability to automatically predict the arrival time of a double-CME event. The proposed method is the first automatic method to successfully calculate CME parameters from double-CME events, making this automatic method applicable to a wider range of CME events.

  9. NIRCam Coronagraphic Observations of Disks and Planetary Systems

    NASA Astrophysics Data System (ADS)

    Beichman, Charles A.; Ygouf, Marie; Gaspar, Andras; NIRCam Science Team

    2017-06-01

    The NIRCam coronagraph offers a dramatic increase in sensitivity at wavelengths of 3-5 um where young planets are brightest. While large ground-based telescopes with Extreme Adaptive Optics have an advantage in inner working angle, NIRCam's sensitivity will allow high precision photometry for known planets and searches for planets with masses below that of Saturn. For debris disk science NIRCam observations will address the scattering properties of dust, look for evidence of ices and tholins, and search for planets which affect the structure of the disk itself.The NIRCam team's GTO program includes medium-band filter observations of known young planets having 1-5 Jupiter masses. A collaborative program with the MIRI team will provide coronagraphic observations at longer wavelengths. The combined dataset will yield the exoplanet’s total luminosity and effective temperature, an estimate of the initial entropy of the newly-formed planet, and the retrieval of atmospheric properties.The program will also make deep searches for lower mass planets toward known planetary systems, nearby young M stars and debris disk systems. Achievable mass limits range from ~1 Jupiter mass beyond 20 AU for the brightest A stars to perhaps a Uranus mass within 10 AU for the closest M stars.We will discuss details of the coronagraphic program for both the exoplanet and debris disk cases with an emphasis on using APT to optimize the observations of target and reference stars.

  10. Oblique Sounding of the Ionosphere by Means of an Ionosonde-Direction Finder with Chirp Signal

    NASA Astrophysics Data System (ADS)

    Vertogradov, G. G.; Uryadov, V. P.; Sklyarevsky, M. S.; Valov, V. A.

    2017-04-01

    We give a mathematical rationale, an algorithm, and hardware implementation for a multichannel ionosonde-direction finder with chirp signal. The results of experimental studies of twodimensional angle-frequency characteristics on the Cyprus—Rostov-on-Don meridional obliquesounding path are presented. It is shown that both regular (terminator-related) and irregular (caused by the passage of a traveling ionospheric disturbance through the propagation path) transverse (with respect to the propagation path) horizontal gradients of the electron number density lead to a deviation of the azimuth of the high-angle ray in the direction of the Ne gradient. The experimental data are compared with the simulation results.

  11. Tracking of Humans and Robots Using Laser Range Finders

    NASA Astrophysics Data System (ADS)

    Bršcic, Drazen; Sasaki, Takeshi; Hashimoto, Hideki

    There exist various applications where tracking of humans or robots in an area is needed. An example of such applications are Intelligent Spaces, where humans and robots share a common space and their positions are tracked by a system of sensors in the space. In this paper a system for tracking both humans and robots that utilizes laser range finders as sensing devices is described. The details of the extraction of objects from the laser scan, data association and estimation are given, and results of tracking humans and robots are described. Calibration of the distributed laser range finders, which is important for the operation of the tracking system is also described, both in a manual and automated variant and experimental results are given. Finally, the inclusion of a laser range finder onboard the mobile robot in the tracking process is described and accompanied with experimental results. The distributed fusion of static and onboard sensors is also discussed.

  12. Laboratory Demonstration of Phase Induced Amplitude Apodization (PIAA) Coronagraph with Better than 10(exp -9) Contrast

    NASA Technical Reports Server (NTRS)

    Kern, Brian; Guyon, Olivier; Kuhnert, Andreas; Niessner, Albert; Martinache, Frantz; Balasubramanian, Kunjithapatham

    2013-01-01

    We present coronagraphic images from the Phase Induced Amplitude Apodization (PIAA) coronagraph on NASA's High Contrast Imaging Testbed (HCIT) at the Jet Propulsion Lab, showing contrasts of 5x10(exp -1) averaged from 2-4 lambda/D, in monochromatic light at 808 nm. In parallel with the coronagraph and its deformable mirror and coronagraphic wavefront control, we also demonstrate a low-order wavefront control system, giving 100 x rms suppression of introduced tip/tilt disturbances down to residual levels of 10(exp -3) lambda/D. Current limitations, as well as broadband (10% fractional bandpass) preliminary results are discussed.

  13. FilFinder: Filamentary structure in molecular clouds

    NASA Astrophysics Data System (ADS)

    Koch, Eric W.; Rosolowsky, Erik W.

    2016-08-01

    FilFinder extracts and analyzes filamentary structure in molecular clouds. In particular, it is capable of uniformly extracting structure over a large dynamical range in intensity. It returns the main filament properties: local amplitude and background, width, length, orientation and curvature. FilFinder offers additional tools to, for example, create a filament-only image based on the properties of the radial fits. The resulting mask and skeletons may be saved in FITS format, and property tables may be saved as a CSV, FITS or LaTeX table.

  14. Terrestrial Planet Finder, Planet Detection Test-Bed: Latest Results of Planet Light Detection in the Presence of Starlight

    NASA Technical Reports Server (NTRS)

    Martin, Stefan R.; Booth, Andrew J.

    2008-01-01

    The Terrestrial Planet Finder, Planet Detection Test-bed is a lab based simulation of the optics and control systems for the Terrestrial Planet Finder Interferometer mission. The test-bed supports starlight nulling at 10um infrared wavelengths, with fringe tracking at 2um wavelengths and angle and shear tracking at visible wavelengths. It further allows injection of simulated planet light in the presence of the nulled star light, to allow testing of planet detection methods. We will describe the detailed construction and operation of the test-bed from an optical and control system perspective. We will also report the latest results for narrow band nulls, and the detection of broad band planet light in the presence of nulled starlight.

  15. The coronagraphic Modal Wavefront Sensor: a hybrid focal-plane sensor for the high-contrast imaging of circumstellar environments

    NASA Astrophysics Data System (ADS)

    Wilby, M. J.; Keller, C. U.; Snik, F.; Korkiakoski, V.; Pietrow, A. G. M.

    2017-01-01

    The raw coronagraphic performance of current high-contrast imaging instruments is limited by the presence of a quasi-static speckle (QSS) background, resulting from instrumental Non-Common Path Errors (NCPEs). Rapid development of efficient speckle subtraction techniques in data reduction has enabled final contrasts of up to 10-6 to be obtained, however it remains preferable to eliminate the underlying NCPEs at the source. In this work we introduce the coronagraphic Modal Wavefront Sensor (cMWS), a new wavefront sensor suitable for real-time NCPE correction. This combines the Apodizing Phase Plate (APP) coronagraph with a holographic modal wavefront sensor to provide simultaneous coronagraphic imaging and focal-plane wavefront sensing with the science point-spread function. We first characterise the baseline performance of the cMWS via idealised closed-loop simulations, showing that the sensor is able to successfully recover diffraction-limited coronagraph performance over an effective dynamic range of ±2.5 radians root-mean-square (rms) wavefront error within 2-10 iterations, with performance independent of the specific choice of mode basis. We then present the results of initial on-sky testing at the William Herschel Telescope, which demonstrate that the sensor is capable of NCPE sensing under realistic seeing conditions via the recovery of known static aberrations to an accuracy of 10 nm (0.1 radians) rms error in the presence of a dominant atmospheric speckle foreground. We also find that the sensor is capable of real-time measurement of broadband atmospheric wavefront variance (50% bandwidth, 158 nm rms wavefront error) at a cadence of 50 Hz over an uncorrected telescope sub-aperture. When combined with a suitable closed-loop adaptive optics system, the cMWS holds the potential to deliver an improvement of up to two orders of magnitude over the uncorrected QSS floor. Such a sensor would be eminently suitable for the direct imaging and spectroscopy of

  16. Coronagraphic phase diversity: a simple focal plane sensor for high-contrast imaging.

    PubMed

    Sauvage, J-F; Mugnier, L; Paul, B; Villecroze, R

    2012-12-01

    Exoplanet direct imaging is a challenging goal of today's astronomical instrumentation. Several high-contrast imaging instruments dedicated to this task are currently being integrated; they are ultimately limited by the presence of quasi-static speckles in the imaging focal plane. These speckles originate in residual quasi-static optical aberrations, which must be measured and compensated for, typically at a nanometric level. We present a novel focal plane wavefront sensor (WFS) designed for this particular application. It is an extension of the phase diversity technique to coronagraphic imaging. This sensor requires no dedicated hardware and uses only two scientific images differing from a known aberration, which can be conveniently introduced by the adaptive optics subsystem. The aberrations are therefore calibrated all the way down to the scientific camera, without any differential aberrations between the sensor and the scientific camera. We show the potential of this WFS by means of simulations, and we perform a preliminary experimental validation.

  17. NASA's Terrestrial Planet Finder: The Search for (Habitable) Planets

    NASA Technical Reports Server (NTRS)

    Beichman, C.

    1999-01-01

    One of the primary goals of NASA's Origins program is the search for habitable planets. I will describe how the Terrestrial Planet Finder (TPF) will revolutionize our understanding of the origin and evolution of planetary systems, and possibly even find signs of life beyond the Earth.

  18. NASA's terrestial planet finder: the search for (habitable) planets

    NASA Technical Reports Server (NTRS)

    Beichman, C. A.

    2000-01-01

    One of the primary goals of NASA's Origins program is the search for hospitable planets. I will describe how the Terrestrial Planet Finder (TPF) will revolutionize our understanding of the origin and evolution of planetary systems, and possibly even find signs of life beyond Earth.

  19. 5. VIEW EAST, height finder radar towers, radar tower (unknown ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. VIEW EAST, height finder radar towers, radar tower (unknown function), prime search radar tower, operations building, and central heating plant - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

  20. 12 CFR 7.1002 - National bank acting as finder.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... OPERATIONS Bank Powers § 7.1002 National bank acting as finder. (a) General. It is part of the business of... and terms to potential markets for these products and services; (2) Communicating to the seller an... sellers, and conducting market research to identify potential new customers for retailers; (5)...

  1. FACTOR FINDER CD-ROM | Science Inventory | US EPA

    EPA Pesticide Factsheets

    The Factor Finder CD-ROM is a user-friendly, searchable tool used to locate exposure factors and sociodemographic data for user-defined populations. Factor Finder improves the exposure assessors and risk assessors (etc.) ability to efficiently locate exposure-related information for a population of concern. Users can either enter keywords into a user-defined search box or use pull-down menus to help pinpoint specific information. The pull-down menu features general categories such as chemicals of concern, contaminated media, geographic region, exposure pathways and routes, age, food categories, and activities to name just a few. Numerous subcategories are available for selection from the pull down menu as well. Factor Finder searches both documents to retrieve the specified data and displays the information on the user's personal computer (PC) screen. Factor Finder is used by exposure assessors, risk assessors, and other concerned communities to locate exposure-related data contained within the Exposure Factors Handbook (EFH) and Sociodemographic Data Used in Identifying Potentially Highly Exposed Populations (HEP). The EFH and the HEP are companion guidance documents produced by the National Center for Environmental Assessment (NCEA) within EPA's Office of Research and Development. The Exposure Factors Handbook (EFH) summarizes data on exposure factors (values that describe human behaviors and characteristics that affect exposure to environmental cont

  2. Ortholog-Finder: A Tool for Constructing an Ortholog Data Set

    PubMed Central

    Horiike, Tokumasa; Minai, Ryoichi; Miyata, Daisuke; Nakamura, Yoji; Tateno, Yoshio

    2016-01-01

    Orthologs are widely used for phylogenetic analysis of species; however, identifying genuine orthologs among distantly related species is challenging, because genes obtained through horizontal gene transfer (HGT) and out-paralogs derived from gene duplication before speciation are often present among the predicted orthologs. We developed a program, “Ortholog-Finder,” to obtain ortholog data sets for performing phylogenetic analysis by using all open-reading frame data of species. The program includes five processes for minimizing the effects of HGT and out-paralogs in phylogeny construction: 1) HGT filtering: Genes derived from HGT could be detected and deleted from the initial sequence data set by examining their base compositions. 2) Out-paralog filtering: Out-paralogs are detected and deleted from the data set based on sequence similarity. 3) Classification of phylogenetic trees: Phylogenetic trees generated for ortholog candidates are classified as monophyletic or polyphyletic trees. 4) Tree splitting: Polyphyletic trees are bisected to obtain monophyletic trees and remove HGT genes and out-paralogs. 5) Threshold changing: Out-paralogs are further excluded from the data set based on the difference in the similarity scores of genuine orthologs and out-paralogs. We examined how out-paralogs and HGTs affected phylogenetic trees constructed for species based on ortholog data sets obtained by Ortholog-Finder with the use of simulation data, and we determined the effects of confounding factors. We then used Ortholog-Finder in phylogeny construction for 12 Gram-positive bacteria from two phyla and validated each node of the constructed tree by comparison with individually constructed ortholog trees. PMID:26782935

  3. Ortholog-Finder: A Tool for Constructing an Ortholog Data Set.

    PubMed

    Horiike, Tokumasa; Minai, Ryoichi; Miyata, Daisuke; Nakamura, Yoji; Tateno, Yoshio

    2016-01-18

    Orthologs are widely used for phylogenetic analysis of species; however, identifying genuine orthologs among distantly related species is challenging, because genes obtained through horizontal gene transfer (HGT) and out-paralogs derived from gene duplication before speciation are often present among the predicted orthologs. We developed a program, "Ortholog-Finder," to obtain ortholog data sets for performing phylogenetic analysis by using all open-reading frame data of species. The program includes five processes for minimizing the effects of HGT and out-paralogs in phylogeny construction: 1) HGT filtering: Genes derived from HGT could be detected and deleted from the initial sequence data set by examining their base compositions. 2) Out-paralog filtering: Out-paralogs are detected and deleted from the data set based on sequence similarity. 3) Classification of phylogenetic trees: Phylogenetic trees generated for ortholog candidates are classified as monophyletic or polyphyletic trees. 4) Tree splitting: Polyphyletic trees are bisected to obtain monophyletic trees and remove HGT genes and out-paralogs. 5) Threshold changing: Out-paralogs are further excluded from the data set based on the difference in the similarity scores of genuine orthologs and out-paralogs. We examined how out-paralogs and HGTs affected phylogenetic trees constructed for species based on ortholog data sets obtained by Ortholog-Finder with the use of simulation data, and we determined the effects of confounding factors. We then used Ortholog-Finder in phylogeny construction for 12 Gram-positive bacteria from two phyla and validated each node of the constructed tree by comparison with individually constructed ortholog trees. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  4. Computer vision applications for coronagraphic optical alignment and image processing.

    PubMed

    Savransky, Dmitry; Thomas, Sandrine J; Poyneer, Lisa A; Macintosh, Bruce A

    2013-05-10

    Modern coronagraphic systems require very precise alignment between optical components and can benefit greatly from automated image processing. We discuss three techniques commonly employed in the fields of computer vision and image analysis as applied to the Gemini Planet Imager, a new facility instrument for the Gemini South Observatory. We describe how feature extraction and clustering methods can be used to aid in automated system alignment tasks, and also present a search algorithm for finding regular features in science images used for calibration and data processing. Along with discussions of each technique, we present our specific implementation and show results of each one in operation.

  5. Coronagraphic Amplitude and Phase Correction for Detecting Planets

    NASA Technical Reports Server (NTRS)

    Woodgate, Bruce E.; Bowers, Charles W.

    2003-01-01

    Detection of earth-like planets around other stars using coronagraphy requires the optical beam into the coronagraph to be extremely uniform in both phase and amplitude. Errors in phase can be corrected using a deformable mirror, and error in amplitude can be corrected using a spatial light modulator, both in the pupil plan,a. These corrections can be combined using a Michelson interferometer. If amplitude corrections of only a few percent range are needed, the required accuracy of 10 (circumflex) -4 can be obtained with spatial light modulators with the modest dynamic range of 8 bits.

  6. Design and experimental test of an optical vortex coronagraph

    NASA Astrophysics Data System (ADS)

    Liu, Cheng-Chao; Ren, De-Qing; Zhu, Yong-Tian; Dou, Jiang-Pei

    2017-05-01

    Using an optical vortex coronagraph (OVC) is one of the most promising techniques for directly imaging exoplanets because of its small inner working angle and high throughput. This paper presents the design and laboratory demonstration performance of an OVC based on liquid crystal polymers (LCPs) at 633 nm and 1520 nm. The OVC can deliver good performance in laboratory tests and achieve a contrast of 10-6 at an angular distance of 3λ/D, which can be implemented for imaging young giant exoplanets in combination with extreme adaptive optics.

  7. Post-Coronagraph Wavefront Sensor for Gemini Planet Imager

    NASA Technical Reports Server (NTRS)

    Wallace, J. Kent; Burruss, Rick; Pueyo, Laurent; Soummer, Remi; Shelton, Chris; Bartos, Randall; Fregoso, Felipe; Nemati, Bijan; Best, Paul; Angione, John

    2009-01-01

    The calibration wavefront system for the Gemini Planet Imager (GPI) will measure the complex wavefront at the apodized pupil and provide slow phase errors to the AO system to mitigate against image plane speckles that would cause a loss in contrast. This talk describes both the low-order and high-order sensors in the calibration wavefront sensor and how the information is combined to form the wavefront estimate before the coronagraph. We will show laboratory results from our calibration testbed that demonstrate the subsystem performance at levels commensurate with those required on the final instrument.

  8. Post-Coronagraph Wavefront Sensor for Gemini Planet Imager

    NASA Technical Reports Server (NTRS)

    Wallace, J. Kent; Burruss, Rick; Pueyo, Laurent; Soummer, Remi; Shelton, Chris; Bartos, Randall; Fregoso, Felipe; Nemati, Bijan; Best, Paul; Angione, John

    2009-01-01

    The calibration wavefront system for the Gemini Planet Imager (GPI) will measure the complex wavefront at the apodized pupil and provide slow phase errors to the AO system to mitigate against image plane speckles that would cause a loss in contrast. This talk describes both the low-order and high-order sensors in the calibration wavefront sensor and how the information is combined to form the wavefront estimate before the coronagraph. We will show laboratory results from our calibration testbed that demonstrate the subsystem performance at levels commensurate with those required on the final instrument.

  9. Performance characterization of a broadband vector Apodizing Phase Plate coronagraph.

    PubMed

    Otten, Gilles P P L; Snik, Frans; Kenworthy, Matthew A; Miskiewicz, Matthew N; Escuti, Michael J

    2014-12-01

    One of the main challenges for the direct imaging of planets around nearby stars is the suppression of the diffracted halo from the primary star. Coronagraphs are angular filters that suppress this diffracted halo. The Apodizing Phase Plate coronagraph modifies the pupil-plane phase with an anti-symmetric pattern to suppress diffraction over a 180 degree region from 2 to 7 λ/D and achieves a mean raw contrast of 10(-4) in this area, independent of the tip-tilt stability of the system. Current APP coronagraphs implemented using classical phase techniques are limited in bandwidth and suppression region geometry (i.e. only on one side of the star). In this paper, we introduce the vector-APP (vAPP) whose phase pattern is implemented through the vector phase imposed by the orientation of patterned liquid crystals. Beam-splitting according to circular polarization states produces two, complementary PSFs with dark holes on either side. We have developed a prototype vAPP that consists of a stack of three twisting liquid crystal layers to yield a bandwidth of 500 to 900 nm. We characterize the properties of this device using reconstructions of the pupil-plane pattern, and of the ensuing PSF structures. By imaging the pupil between crossed and parallel polarizers we reconstruct the fast axis pattern, transmission, and retardance of the vAPP, and use this as input for a PSF model. This model includes aberrations of the laboratory set-up, and matches the measured PSF, which shows a raw contrast of 10(-3.8) between 2 and 7 λ/D in a 135 degree wedge. The vAPP coronagraph is relatively easy to manufacture and can be implemented together with a broadband quarter-wave plate and Wollaston prism in a pupil wheel in high-contrast imaging instruments. The liquid crystal patterning technique permits the application of extreme phase patterns with deeper contrasts inside the dark holes, and the multilayer liquid crystal achromatization technique enables unprecedented spectral bandwidths

  10. Stray-light analyses of the METIS coronagraph on Solar Orbiter

    NASA Astrophysics Data System (ADS)

    Fineschi, S.; Sandri, P.; Landini, F.; Romoli, M.; DaDeppo, V.; Frassetto, F.; Verroi, E.; Naletto, G.; Morea, D.; Antonucci, E.; Spadaro, D.; Andretta, V.

    2015-09-01

    The METIS coronagraph on board the Solar Orbiter mission will have the unique opportunity of observing the solar outer atmosphere as close to the Sun as 0.28 A.U., and from up to 35° out-of-ecliptic. The telescope design of the METIS coronagraph includes two optical paths: i) broad-band imaging of the full corona in linearly polarized visible-light (VL: 580-640 nm), ii) narrow-band imaging of the full corona in the ultraviolet (UV) Lyman α (121.6 nm). This paper describes the stray-light analyses performed on the UV and VL channels of the METIS Telescope with the nonsequential modality of Zemax OpticStudio. A detailed opto-mechanical model of the METIS Telescope is simulated by placing the CAD parts of all the sub-assemblies at the nominal position. Each surface, mechanical and optical, is provided with a modelled coating and BSDF reproducing the optical and the diffusing properties. The geometric model allows for the verification of the correct functioning of the blocking elements inside the telescope and for an evaluation of the stray-light level due to surface roughness. The diffraction off the inner edge of the IEO on the plane of the IO is modelled separately from the contributor of the surface micro-roughness. The contributors due to particle contamination and cosmetic defects are also analysed. The results obtained are merged together and compared to the requirements of stray-light. The results of this analysis together with those from two different analyses based on a Montecarlo ray-trace and a semi-analytical model are consistent with each other and indicate that the METIS design meets the stray-light level requirements

  11. Testing the Apodized Pupil Lyot Coronagraph on the Laboratory for Adaptive Optics Extreme Adaptive Optics Testbed

    NASA Astrophysics Data System (ADS)

    Thomas, Sandrine J.; Soummer, Rémi; Dillon, Daren; Macintosh, Bruce; Gavel, Donald; Sivaramakrishnan, Anand

    2011-10-01

    We present testbed results of the Apodized Pupil Lyot Coronagraph (APLC) at the Laboratory for Adaptive Optics (LAO). These results are part of the validation and tests of the coronagraph and of the Extreme Adaptive Optics (ExAO) for the Gemini Planet Imager (GPI). The apodizer component is manufactured with a halftone technique using black chrome microdots on glass. Testing this APLC (like any other coronagraph) requires extremely good wavefront correction, which is obtained to the 1 nm rms level using the microelectricalmechanical systems (MEMS) technology, on the ExAO visible testbed of the LAO at the University of Santa Cruz. We used an APLC coronagraph without central obstruction, both with a reference super-polished flat mirror and with the MEMS to obtain one of the first images of a dark zone in a coronagraphic image with classical adaptive optics using a MEMS deformable mirror (without involving dark hole algorithms). This was done as a complementary test to the GPI coronagraph testbed at American Museum of Natural History, which studied the coronagraph itself without wavefront correction. Because we needed a full aperture, the coronagraph design is very different from the GPI design. We also tested a coronagraph with central obstruction similar to that of GPI. We investigated the performance of the APLC coronagraph and more particularly the effect of the apodizer profile accuracy on the contrast. Finally, we compared the resulting contrast to predictions made with a wavefront propagation model of the testbed to understand the effects of phase and amplitude errors on the final contrast.

  12. TESTING THE APODIZED PUPIL LYOT CORONAGRAPH ON THE LABORATORY FOR ADAPTIVE OPTICS EXTREME ADAPTIVE OPTICS TESTBED

    SciTech Connect

    Thomas, Sandrine J.; Dillon, Daren; Gavel, Donald; Macintosh, Bruce; Sivaramakrishnan, Anand E-mail: dillon@ucolick.org E-mail: soummer@stsci.edu E-mail: anand@amnh.org

    2011-10-15

    We present testbed results of the Apodized Pupil Lyot Coronagraph (APLC) at the Laboratory for Adaptive Optics (LAO). These results are part of the validation and tests of the coronagraph and of the Extreme Adaptive Optics (ExAO) for the Gemini Planet Imager (GPI). The apodizer component is manufactured with a halftone technique using black chrome microdots on glass. Testing this APLC (like any other coronagraph) requires extremely good wavefront correction, which is obtained to the 1 nm rms level using the microelectricalmechanical systems (MEMS) technology, on the ExAO visible testbed of the LAO at the University of Santa Cruz. We used an APLC coronagraph without central obstruction, both with a reference super-polished flat mirror and with the MEMS to obtain one of the first images of a dark zone in a coronagraphic image with classical adaptive optics using a MEMS deformable mirror (without involving dark hole algorithms). This was done as a complementary test to the GPI coronagraph testbed at American Museum of Natural History, which studied the coronagraph itself without wavefront correction. Because we needed a full aperture, the coronagraph design is very different from the GPI design. We also tested a coronagraph with central obstruction similar to that of GPI. We investigated the performance of the APLC coronagraph and more particularly the effect of the apodizer profile accuracy on the contrast. Finally, we compared the resulting contrast to predictions made with a wavefront propagation model of the testbed to understand the effects of phase and amplitude errors on the final contrast.

  13. First Year of WFIRST/AFTA Coronagraph Technology Development: Testbed Progress Update

    NASA Astrophysics Data System (ADS)

    Poberezhskiy, Ilya; Poberezhskiy, Ilya; Zhao, Feng; An, Xin; Balasubramanian, Kunjithapatham; Belikov, Rus; Cady, Eric; Diaz, Rosemary; Gordon, Brian; Guyon, Olivier; Kasdin, N. Jeremy; Kern, Brian; Kuhnert, Andreas; Moody, Dwight; Muller, Richard; Nemati, Bijan; Patterson, Keith; Riggs, A. J.; Ryan, Daniel; Seo, Byoung-Joon; Sidick, Erkin; Shi, Fang; Tang, Hong; Trauger, John; Wallace, Kent; Wang, Xu; Wilson, Daniel; White, Victor; Yee, Karl; Zhou, Hanying; Zimmerman, Neil

    2015-01-01

    NASA's WFIRST/AFTA mission study includes the first high-contrast stellar coronagraph in space. This coronagraph will be capable of imaging and spectrally characterizing giant exoplanets similar to Neptune and Jupiter and possibly super-Earths, as well as circumstellar disks. After a transparent and rigorous downselect process, NASA chose in December of 2013 a primary design called an Occulting Mask Coronagraph (OMC) that combines two technical approaches, Shaped Pupil and Hybrid Lyot, in one instrument. The Phase-Induced Amplitude Apodization Complex Mask Coronagraph was selected as the backup design.The OMC coronagraph technologies were assessed to have the highest likelihood of passing the WFIRST/AFTA flight readiness gates and the ability to produce compelling science by working with the existing 2.4-meter telescope 'as is,' including its central obscuration, expected thermal drift, and the observatory pointing jitter. NASA set us the objective of maturing the WFIRST/AFTA coronagraph to Technology Readiness Level (TRL) 5 by October 1, 2016. A set of technical milestones was agreed upon to track the progress toward achieving TRL 5.Substantial advances in WFIRST/AFTA coronagraph technology have been made during 2014, and the OMC progress is currently running ahead of the schedule laid out by the milestones. Our poster will present some of these key recent results to the community, including:(1) Fabrication and characterization of WFIRST/AFTA coronagraph pupil plane and focal plane masks designed to work with the existing 2.4 telescope.(2) Experimental results demonstrating high contrast achieved on a coronagraph testbed in narrowband and broadband light - first such results obtained with an obscured pupil.(3) Progress in the development of the low-order wavefront sensing and control subsystem that will use rejected starlight to sense and correct both high frequency pointing jitter and slow varying low order aberrations. This subsystem will be integrated with the

  14. CIAXE: co-axial achromatic interferential coronagraph: first laboratory results

    NASA Astrophysics Data System (ADS)

    Allouche, Fatmé; Gay, Jean; Rabbia, Yves; Assus, Pierre

    2010-07-01

    In 1996, Jean Gay and Yves Rabbia presented their Achromatic Interferential Coronagraph (AIC) for detecting and imaging faint companions (ultimately exoplanets) in the neighboring of a star. As presented then, the Michleson-like Interferometer configuration of the AIC hardens its insertion into an existing (coaxial) optical train, the output beam of the AIC being delivered at right angle from the input beam. To overcome this, they reconfigured the AIC into a compact and fully axial coronagraph, the CIAXE, which main feature consists of using two thick lenses machined in the same optical material. For the CIAXE to deliver the output beam along the same axis as the input beam, the two lenses are coaxially disposed on the optical axis and are separated, at their common spherical contact surface by a thin air gap acting like a beam splitter. We have set up a laboratory experiment aiming at validating the principle of the concept. Our first step was to equalize the thicknesses of the two lenses, so as to make zero the optical path difference between both arms. For this, the (residual) value of the OPD has been evaluated and then the lenses have been re-machined so as to decrease as far as technologically possible, the thicknesses mismatch. As a second step, a micro-controlled rotation around the common curvature center of the spherical surfaces of the lenses is applied. This allows a fine tuning of the residual OPD at the required accuracy level. Are presented here test bench, steps and results.

  15. High Contrast Imaging with the JWST NIRCAM Coronagraph

    NASA Technical Reports Server (NTRS)

    Green, Joseph J.; Beichman, Charles; Basinger, Scott A.; Horner, Scott; Meyer, Michael; Redding, David C.; Rieke, Marcia; Trauger, John T.

    2005-01-01

    Relative to ground-based telescopes, the James Webb Space Telescope (JWST) will have a substantial sensitivity advantage in the 2.2-5pm wavelength range where brown dwarfs and hot Jupiters are thought to have significant brightness enhancements. To facilitate high contrast imaging within this band, the Near-Infrared Camera (NIRCAM) will employ a Lyot coronagraph with an array of band-limited image-plane occulting spots. In this paper, we provide the science motivation for high contrast imaging with NIRCAM, comparing its expected performance to that of the Keck, Gemini and 30 m (TMT) telescopes equipped with Adaptive Optics systems of different capabilities. We then describe our design for the NIRCAM coronagraph that enables imaging over the entire sensitivity range of the instrument while providing significant operational flexibility. We describe the various design tradeoffs that were made in consideration of alignment and aberration sensitivities and present contrast performance in the presence of JWST's expected optical aberrations. Finally we show an example of a that can provide 10-5 companion sensitivity at sub-arcsecond separations.

  16. Development of KASI Geomagnetic Storm Forecast System using Coronagraph Data

    NASA Astrophysics Data System (ADS)

    Baek, Ji-Hye; Choi, SeongHwan; Park, Jongyeob; Kim, Roksoon; Kim, Sujin; Kim, Jihun

    2017-08-01

    We present Korea Astronomy and Space Science Institute (KASI) Geomagnetic Storm Forecast System. The aim of the system is to calculate the CME arrival time and predict the geoeffectiveness of the CME. To implement the system, we use the Large Angle and Spectrometric Coronagraph (LASCO) C2 and C3 data, the HMI magnetogram data of Solar Dynamics Observatory(SDO), and CACTUS CME list. The system consists of servers, which are to download, process, and publish data, data handling programs and web service. We apply an image differencing technique on LASCO data to determine speed and earthward direction parameters of CMEs. KASI Geomagnetic Storm Forecast Model has installed and being tested at Community Coordinated Modeling Center (CCMC) of NASA/GSFC. We expect that users can predict CME arrival time and geoeffectiveness of the CME easily and fast using the system. In order to improve the forecast performance of the system, we plan to incorporate advanced coronagraph data which will be developed and installed on ISS by KASI and NASA in collaboration.

  17. Experimental Progress and Results of a Visible Nulling Coronagraph

    NASA Technical Reports Server (NTRS)

    Samuele, Rocco; Wallace, J. Kent; Schmidtlin, Edouard; Shao, Mike; Levine, B. Martin; Fregoso, Santos

    2007-01-01

    The crux of visible exoplanet detection is overcoming significant star-planet contrast ratios on the order of 10(exp -7) to 10(exp -10)-at very small angular separations. We are developing an interferometric nulling coronagraph designed to achieve a 10(exp -6) contrast ratio at a working science bandpass of 20% visible light. Achieving large, broadband suppression requires a pseudo-achromatic phase flip, while maintaining a strict error budget. Recent results from our nulling interferometer testbed yield contrast ratios at the 1.05x10(exp -6) level, with a 15% visible bandpass. This result is at 65% of our final bandpass requirement, although limitations of our current configuration make major hardware changes essential to broadening the bandpass. We make the argument that broadening the bandpass should not necessarily adversely affect the null depth until beyond the 20% visible light level. Using the same setup we are able to reach monochromatic null depths of 1.11x10(exp -7) (?= 638 nm)averaged over three seconds. This paper will describe our experimental approach for achieving deep broadband nulls, as well as error considerations and limitations, and the most recent results for our nulling coronagraph testbed.

  18. Stop-less Lyot coronagraph for exoplanet characterization

    NASA Astrophysics Data System (ADS)

    Vigan, A.; N'Diaye, M.; Dohlen, K.

    2012-09-01

    The characterization of directly-imaged exoplanets at very small angular separations requires high-contrast spec-troscopic capabilities. For this purpose, the new generation of instruments dedicated to direct imaging of massive exoplanets at large orbital radii, such as VLT/SPHERE and Gemini/GPI, includes integral field spectroscopy (IFS) and/or long slit spectroscopy (LSS) coupled with coronography. LSS is particularly challenging since observations will be stronly limited by quasi-static speckles and diffraction residuals that need to be removed with a posteriori data analysis methods. It is therefore necessary to limit as much as possible the influence of diffraction in the data. In this work we compare the use of the classical Lyot coronagraph (CLC) and the stop- less Lyot coronagraph (SLLC) with LSS for the characterization of exoplanets. SLLC uses a grey apodization to suppress the diffraction above 4.53 λ/D and does not require the use of any Lyot stop, offering a convenient implementation. We show that this apodized long slit spectroscopy (ALSS) improves notably the performance at small angular separations (0.3"-0.4"), allowing the spectral analysis of colder planets.

  19. Lyot coronagraph design study for large, segmented space telescope apertures

    NASA Astrophysics Data System (ADS)

    Zimmerman, Neil T.; N'Diaye, Mamadou; St. Laurent, Kathryn E.; Soummer, Rémi; Pueyo, Laurent; Stark, Christopher C.; Sivaramakrishnan, Anand; Perrin, Marshall; Vanderbei, Robert J.; Kasdin, N. J.; Shaklan, Stuart; Carlotti, Alexis

    2016-07-01

    Recent efforts combining the optimization techniques of apodized pupil Lyot coronagraphs (APLC) and shaped pupils have demonstrated the viability of a binary-transmission mask architecture for extremely high contrast (10-10) exoplanet imaging. We are now building on those innovations to carry out a survey of Lyot coronagraph performance for large, segmented telescope apertures. These apertures are of the same kind under considera- tion for NASA's Large UV/Optical/IR (LUVOIR) observatory concept. To map the multi-dimensional design parameter space, we have developed a software toolkit to manage large sets of mask optimization programs and execute them on a computing cluster. Here we summarize a preliminary survey of 500 APLC solutions for 4 reference hexagonal telescope apertures. Several promising designs produce annular, 10-10 contrast dark zones down to inner working angle 4λ0=D over a 15% bandpass, while delivering a half-max PSF core throughput of 18%. We also report our progress on devising solutions to the challenges of Lyot stop alignment/fabrication tolerance that arise in this contrast regime.

  20. The Subaru Coronagraphic Extreme AO Project: Progress and Upgrades

    NASA Astrophysics Data System (ADS)

    Jovanovic, Nemanja; Martinache, F.; Guyon, O.; Clergeon, C.; Garrel, V.

    2013-01-01

    The Subaru Coronagraphic Extreme AO (SCExAO) instrument consists of a high performance Phase Induced Amplitude Apodisation (PIAA) coronagraph combined with an extreme Adaptive Optics (AO) system operating in the near-infrared (H band). The extreme AO system driven by the 2000 element deformable mirror will allow for Strehl ratios>90% to be achieved in the H-band when it goes closed loop. This makes the SCExAO instrument a powerful platform for high contrast imaging down to angular separations of the order of 1 λ/D. In this paper we report on the recent progress in regards to the development of the instrument, which includes the addition of a visible bench that makes use of the light at shorter wavelengths not currently utilized by SCExAO and closing the loop on the tip/tilt wavefront sensor. We will also discuss two exciting guest instruments which will expand the capabilities of SCExAO over the next few years; namely CHARIS which is a integral field spectrograph as well as VAMPIRES, a visible aperture masking experiment based on polarimetric analysis of circumstellar disks.

  1. The mounting system of lenses in ASPIICS coronagraph

    NASA Astrophysics Data System (ADS)

    Veselý, Martin; Vít, Tomáš; Pleštil, Jan

    2016-11-01

    This article describes the mounting system of lenses in a coronagraph ASPIICS (Association of Spacecraft for Polarimetric Imaging Investigation of the Corona of the Sun). ASPIICS is developed and produced in cooperation of twenty partners from seven countries. It is a part of the ESA's PROBA-3 mission, which includes a formation flight of a pair of satellites at orbit. Coronagraph itself consists of three objectives, where the last one is composed by one objective tube for each lens plus holder and Lyot stop. To achieve high accuracy of mounting of the individual lenses, it was necessary to achieve tight geometric and dimensional tolerances for manufacturing of the objectives barrels. In order to minimize the stress and to prevent the displacement of the lens from ideal position during a temperature change on orbit, an athermal solution was proposed. This is achieved by inserting a Teflon ring of a suitable thickness between the lens surface, objective barrel and the spring washer with a precisely defined contact force. It was necessary to find a suitable technological process of manufacturing, because of the specific behavior of PTFE during turning and complex design of other parts. All parameters of mounting system were repeatedly verified by a thermomechanical analysis in FEM software, based on tests of real parts.

  2. Curved track segment finding using Tiny Triplet Finder (TTF)

    SciTech Connect

    Wu, Jin-Yuan; Wang, M.; Gottschalk, E.; Shi, Z.; /Fermilab

    2006-11-01

    We describe the applications of a track segment recognition scheme called the Tiny Triplet Finder (TTF) that involves the grouping of three hits satisfying a constraint forming of a track segment. The TTF was originally developed solving straight track segment finding problem, however, it is also suitable in many curved track segment finding problems. The examples discussed in this document are among popular detector layouts in high-energy/nuclear physics experiments. Although it is not practical to find a universal recipe for arbitrary detector layouts, the method of the TTF application is illustrated via the discussion of the examples. Generally speaking, whenever the data item to be found in a pattern recognition problem contains two free parameters, and if the constraint connecting the measurements and the two free parameters has an approximate shift invariant property, the Tiny Triplet Finder can be used.

  3. Detectability of active triangulation range finder: a solar irradiance approach.

    PubMed

    Liu, Huizhe; Gao, Jason; Bui, Viet Phuong; Liu, Zhengtong; Lee, Kenneth Eng Kian; Peh, Li-Shiuan; Png, Ching Eng

    2016-06-27

    Active triangulation range finders are widely used in a variety of applications such as robotics and assistive technologies. The power of the laser source should be carefully selected in order to satisfy detectability and still remain eye-safe. In this paper, we present a systematic approach to assess the detectability of an active triangulation range finder in an outdoor environment. For the first time, we accurately quantify the background noise of a laser system due to solar irradiance by coupling the Perez all-weather sky model and ray tracing techniques. The model is validated with measurements with a modeling error of less than 14.0%. Being highly generic and sufficiently flexible, the proposed model serves as a guide to define a laser system for any geographical location and microclimate.

  4. Terrestrial Planet Finder Interferometer: 2007-2008 Progress and Plans

    NASA Technical Reports Server (NTRS)

    Lawson, P. R.; Lay, O. P.; Martin, S. R.; Peters, R. D.; Gappinger, R. O.; Ksendzov, A.; Scharf, D. P.; Booth, A. J.; Beichman, C. A.; Serabyn, E.; hide

    2008-01-01

    This paper provides an overview of technology development for the Terrestrial Planet Finder Interferometer (TPF-I). TPF-I is a mid-infrared space interferometer being designed with the capability of detecting Earth-like planets in the habitable zones around nearby stars. The overall technology roadmap is presented and progress with each of the testbeds is summarized. The current interferometer architecture, design trades, and the viability of possible reduced-scope mission concepts are also presented.

  5. Terrestrial Planet Finder Interferometer: Architecture, Mission Design, and Technology Development

    NASA Technical Reports Server (NTRS)

    Henry, Curt

    2004-01-01

    This slide presentation represents an overview progress report about the system design and technology development of two interferometer concepts studied for the Terrestrial Planet Finder (TPF) project. The two concepts are a structurally-connected interferometer (SCI) intended to fulfill minimum TPF science goals and a formation-flying interferometer (FFI) intended to fulfill full science goals. Described are major trades, analyses, and technology experiments completed. Near term plans are also described. This paper covers progress since August 2003

  6. Terrestrial Planet Finder Interferometer: 2007-2008 Progress and Plans

    NASA Technical Reports Server (NTRS)

    Lawson, P. R.; Lay, O. P.; Martin, S. R.; Peters, R. D.; Gappinger, R. O.; Ksendzov, A.; Scharf, D. P.; Booth, A. J.; Beichman, C. A.; Serabyn, E.; Johnston, K. J.; Danchi, W. C.

    2008-01-01

    This paper provides an overview of technology development for the Terrestrial Planet Finder Interferometer (TPF-I). TPF-I is a mid-infrared space interferometer being designed with the capability of detecting Earth-like planets in the habitable zones around nearby stars. The overall technology roadmap is presented and progress with each of the testbeds is summarized. The current interferometer architecture, design trades, and the viability of possible reduced-scope mission concepts are also presented.

  7. Adaptive Nulling for the Terrestrial Planet Finder Interferometer

    NASA Technical Reports Server (NTRS)

    Peters, Robert D.; Lay, Oliver P.; Jeganathan, Muthu; Hirai, Akiko

    2006-01-01

    A description of adaptive nulling for Terrestrial Planet Finder Interferometer (TPFI) is presented. The topics include: 1) Nulling in TPF-I; 2) Why Do Adaptive Nulling; 3) Parallel High-Order Compensator Design; 4) Phase and Amplitude Control; 5) Development Activates; 6) Requirements; 7) Simplified Experimental Setup; 8) Intensity Correction; and 9) Intensity Dispersion Stability. A short summary is also given on adaptive nulling for the TPFI.

  8. Fusion of a Variable Baseline System and a Range Finder

    PubMed Central

    Hernández-Aceituno, Javier; Acosta, Leopoldo; Arnay, Rafael

    2012-01-01

    One of the greatest difficulties in stereo vision is the appearance of ambiguities when matching similar points from different images. In this article we analyze the effectiveness of using a fusion of multiple baselines and a range finder from a theoretical point of view, focusing on the results of using both prismatic and rotational articulations for baseline generation, and offer a practical case to prove its efficiency on an autonomous vehicle. PMID:22368469

  9. Efficient decoding algorithms for generalized hidden Markov model gene finders

    PubMed Central

    Majoros, William H; Pertea, Mihaela; Delcher, Arthur L; Salzberg, Steven L

    2005-01-01

    Background The Generalized Hidden Markov Model (GHMM) has proven a useful framework for the task of computational gene prediction in eukaryotic genomes, due to its flexibility and probabilistic underpinnings. As the focus of the gene finding community shifts toward the use of homology information to improve prediction accuracy, extensions to the basic GHMM model are being explored as possible ways to integrate this homology information into the prediction process. Particularly prominent among these extensions are those techniques which call for the simultaneous prediction of genes in two or more genomes at once, thereby increasing significantly the computational cost of prediction and highlighting the importance of speed and memory efficiency in the implementation of the underlying GHMM algorithms. Unfortunately, the task of implementing an efficient GHMM-based gene finder is already a nontrivial one, and it can be expected that this task will only grow more onerous as our models increase in complexity. Results As a first step toward addressing the implementation challenges of these next-generation systems, we describe in detail two software architectures for GHMM-based gene finders, one comprising the common array-based approach, and the other a highly optimized algorithm which requires significantly less memory while achieving virtually identical speed. We then show how both of these architectures can be accelerated by a factor of two by optimizing their content sensors. We finish with a brief illustration of the impact these optimizations have had on the feasibility of our new homology-based gene finder, TWAIN. Conclusions In describing a number of optimizations for GHMM-based gene finders and making available two complete open-source software systems embodying these methods, it is our hope that others will be more enabled to explore promising extensions to the GHMM framework, thereby improving the state-of-the-art in gene prediction techniques. PMID:15667658

  10. Location Of A Vehicle With A Laser Range Finder

    NASA Astrophysics Data System (ADS)

    Zhao, C. J.; Monchaud, S.; Marce, L.; Julliere, M.

    1984-02-01

    Absolute location of a mobile robot is necessary to improve the autonomy of vehicle built for hostile environments. We are developing a scanning laser range finder based on triangulation to get range data about the edges of a cylindrical polyhedral world. From the matching between the measurements and data computed from a model of the a priori known environment, the position of the robot is deduced accurately.

  11. Terrestrial Planet Finder Interferometer: Architecture, Mission Design, and Technology Development

    NASA Technical Reports Server (NTRS)

    Henry, Curt

    2004-01-01

    This slide presentation represents an overview progress report about the system design and technology development of two interferometer concepts studied for the Terrestrial Planet Finder (TPF) project. The two concepts are a structurally-connected interferometer (SCI) intended to fulfill minimum TPF science goals and a formation-flying interferometer (FFI) intended to fulfill full science goals. Described are major trades, analyses, and technology experiments completed. Near term plans are also described. This paper covers progress since August 2003

  12. Adaptive Nulling for the Terrestrial Planet Finder Interferometer

    NASA Technical Reports Server (NTRS)

    Peters, Robert D.; Lay, Oliver P.; Jeganathan, Muthu; Hirai, Akiko

    2006-01-01

    A description of adaptive nulling for Terrestrial Planet Finder Interferometer (TPFI) is presented. The topics include: 1) Nulling in TPF-I; 2) Why Do Adaptive Nulling; 3) Parallel High-Order Compensator Design; 4) Phase and Amplitude Control; 5) Development Activates; 6) Requirements; 7) Simplified Experimental Setup; 8) Intensity Correction; and 9) Intensity Dispersion Stability. A short summary is also given on adaptive nulling for the TPFI.

  13. Utilization of SciFinder Scholar at an Undergraduate Institution

    NASA Astrophysics Data System (ADS)

    O'Reilly, Stacy A.; Wilson, Anne M.; Howes, Barbara

    2002-04-01

    The use of tools to search chemical information databases continues to be important to science educators. The ability to perform online searches of Chemical Abstracts Service can have a significant impact on teaching and research. The implementation of SciFinder Scholar at Butler University has resulted in significant changes in teaching, student-based research, and faculty development in the Chemistry Department. Details of these changes in courses, student research projects and proposals, and the professional growth of the faculty are discussed.

  14. A new active method to correct for the effects of complex apertures on coronagraph performance

    NASA Astrophysics Data System (ADS)

    Mazoyer, Johan; Pueyo, Laurent; N'Diaye, Mamadou; Fogarty, Kevin; Perrin, Marshall D.; Soummer, Remi; Norman, Colin Arthur

    2017-01-01

    The increasing complexity of the aperture geometry of the future space (WFIRST, LUVOIR) and ground based-telescope (E-ELT, TMT) will limit the performance of the next generation of coronagraphic instruments for high contrast imaging of exoplanets.We propose here a new closed-loop optimization technique to use the deformable mirrors to correct for the effects of complex apertures on coronagraph performance. This method is a new alternative to the ACAD technique previously developed by our group. This technique allows the use of any coronagraph designed for continuous apertures, with complex, segmented, apertures, maintaining high performance in contrast and throughput. Finally, this closed loop technique allows flexibility to adapt for changing pupil geometries (e.g. in case of segment failure or maintenance for ground-based telescopes), or "manufacturing imperfections in the coronagraph assembly and alignment.We present a numerical study on several pupil geometries (segmented LUVOIR type aperture, WFIRST, ELTs) for which we obtained high contrast levels with several deformable mirror setups (size, number of actuators, separation between them), coronagraphs (apodized pupil lyot and vortex coronagraphs) and spectral bandwidths. Finally, using the results of this study, we will present recommendations for future coronagraphic instruments.

  15. Requirements and design reference mission for the WFIRST/AFTA coronagraph instrument

    NASA Astrophysics Data System (ADS)

    Demers, Richard T.; Dekens, Frank; Calvet, Rob; Chang, Zensheu; Effinger, Robert; Ek, Eric; Hovland, Larry; Jones, Laura; Loc, Anthony; Nemati, Bijan; Noecker, Charley; Neville, Timothy; Pham, Hung; Rud, Mike; Tang, Hong; Villalvazo, Juan

    2015-09-01

    The WFIRST-AFTA coronagraph instrument takes advantage of AFTAs 2.4-meter aperture to provide novel exoplanet imaging science at approximately the same instrument cost as an Explorer mission. The AFTA coronagraph also matures direct imaging technologies to high TRL for an Exo-Earth Imager in the next decade. The coronagraph Design Reference Mission (DRM) optical design is based on the highly successful High Contrast Imaging Testbed (HCIT), with modifications to accommodate the AFTA telescope design, service-ability, volume constraints, and the addition of an Integral Field Spectrograph (IFS). In order to optimally satisfy the three science objectives of planet imaging, planet spectral characterization and dust debris imaging, the coronagraph is designed to operate in two different modes: Hybrid Lyot Coronagraph or Shaped Pupil Coronagraph. Active mechanisms change pupil masks, focal plane masks, Lyot masks, and bandpass filters to shift between modes. A single optical beam train can thus operate alternatively as two different coronagraph architectures. Structural Thermal Optical Performance (STOP) analysis predicts the instrument contrast with the Low Order Wave Front Control loop closed. The STOP analysis was also used to verify that the optical/structural/thermal design provides the extreme stability required for planet characterization in the presence of thermal disturbances expected in a typical observing scenario. This paper describes the instrument design and the flow down from science requirements to high level engineering requirements.

  16. The Large Angle Spectroscopic Coronagraph (LASCO): Visible light coronal imaging and spectroscopy

    NASA Technical Reports Server (NTRS)

    Brueckner, Guenter E.; Howard, Russell A.; Koomen, Martin J.; Korendyke, C.; Michels, D. J.; Socker, D. G.; Lamy, Philippe; Llebaria, Antoine; Maucherat, J.; Schwenn, Rainer

    1992-01-01

    The Large Angle Spectroscopic Coronagraph (LASCO) is a triple coronagraph being jointly developed for the Solar and Heliospheric Observatory (SOHO) mission. LASCO comprises three nested coronagraphs (C1, C2, and C3) that image the solar corona for 1.1 to 30 solar radii (C1: 1.1 to 3 solar radii, C2: 1.5 to 6 solar radii, and C3: 3 to 30.0 solar radii). The inner coronagraph (C1) is a newly developed mirror version of the classic Lyot coronagraph without an external occultor, while the middle coronagraph (C2) and the outer coronagraph (C3) are externally occulted instruments. High resolution coronal spectroscopy from 1.1 to 3 R solar radii can be performed by using a Fabry-Perot interferometer, which is part of C1. High volume memories and a high speed microprocessor enable extensive onboard image processing. Image compression by factors of 10 to 20 will result in the transmission of 10 to 20 full images per hour.

  17. The Large Angle Spectroscopic Coronagraph (LASCO): Visible light coronal imaging and spectroscopy

    NASA Technical Reports Server (NTRS)

    Brueckner, Guenter E.; Howard, Russell A.; Koomen, Martin J.; Korendyke, C.; Michels, D. J.; Socker, D. G.; Lamy, Philippe; Llebaria, Antoine; Maucherat, J.; Schwenn, Rainer

    1992-01-01

    The Large Angle Spectroscopic Coronagraph (LASCO) is a triple coronagraph being jointly developed for the Solar and Heliospheric Observatory (SOHO) mission. LASCO comprises three nested coronagraphs (C1, C2, and C3) that image the solar corona for 1.1 to 30 solar radii (C1: 1.1 to 3 solar radii, C2: 1.5 to 6 solar radii, and C3: 3 to 30.0 solar radii). The inner coronagraph (C1) is a newly developed mirror version of the classic Lyot coronagraph without an external occultor, while the middle coronagraph (C2) and the outer coronagraph (C3) are externally occulted instruments. High resolution coronal spectroscopy from 1.1 to 3 R solar radii can be performed by using a Fabry-Perot interferometer, which is part of C1. High volume memories and a high speed microprocessor enable extensive onboard image processing. Image compression by factors of 10 to 20 will result in the transmission of 10 to 20 full images per hour.

  18. Requirements and Design Reference Mission for the WFIRST-AFTA Coronagraph Instrument

    NASA Technical Reports Server (NTRS)

    Demers, Richard T.; Dekens, Frank; Calvet, Rob; Chang, Zensheu; Effinger, Robert; Ek, Eric; Hovland, Larry; Jones, Laura; Loc, Anthony; Nemati, Bijan; hide

    2015-01-01

    The WFIRST-AFTA coronagraph instrument take s advantage of AFTA s 2.4 -meter aperture to provide novel exoplanet imaging science at approximately the same instrument cost as an Explorer mission. The AFTA coronagraph also matures direct imaging technologies to high TRL for an Exo-Earth Imager in the next decade. The coronagraph Design Reference Mission (DRM) optical design is based on the highly successful High Contrast Imaging Testbed (HCIT), with modifications to accommodate the AFTA telescope design, service-ability, volume constraints, and the addition of an Integral Field Spectrograph (IFS). In order to optimally satisfy the three science objectives of planet imaging, planet spectral characterization and dust debris imaging, the coronagraph is designed to operate in two different modes : Hybrid Lyot Coronagraph or Shaped Pupil Coronagraph. Active mechanisms change pupil masks, focal plane masks, yot masks, and bandpass filters to shift between modes. A single optical beam train can thus operate alternatively as two different coronagraph architecture s. Structural Thermal Optical Performance (STOP) analysis predict s the instrument contrast with the Low Order Wave Front Control loop closed. The STOP analysis was also used to verify that the optical/structural/thermal design provides the extreme stability required for planet characterization in the presence of thermal disturbances expected in a typical observing scenario. This paper describes the instrument design and the flow down from science requirements to high level engineering requirements.

  19. The Voronoi Tessellation Cluster Finder in 2 1 Dimensions

    SciTech Connect

    Soares-Santos, Marcelle; de Carvalho, Reinaldo R.; Annis, James; Gal, Roy R.; La Barbera, Francesco; Lopes, Paulo A.A.; Wechsler, Risa H.; Busha, Michael T.; Gerke, Brian F.; /SLAC /KIPAC, Menlo Park

    2011-06-23

    We present a detailed description of the Voronoi Tessellation (VT) cluster finder algorithm in 2+1 dimensions, which improves on past implementations of this technique. The need for cluster finder algorithms able to produce reliable cluster catalogs up to redshift 1 or beyond and down to 10{sup 13.5} solar masses is paramount especially in light of upcoming surveys aiming at cosmological constraints from galaxy cluster number counts. We build the VT in photometric redshift shells and use the two-point correlation function of the galaxies in the field to both determine the density threshold for detection of cluster candidates and to establish their significance. This allows us to detect clusters in a self-consistent way without any assumptions about their astrophysical properties. We apply the VT to mock catalogs which extend to redshift 1.4 reproducing the ?CDM cosmology and the clustering properties observed in the Sloan Digital Sky Survey data. An objective estimate of the cluster selection function in terms of the completeness and purity as a function of mass and redshift is as important as having a reliable cluster finder. We measure these quantities by matching the VT cluster catalog with the mock truth table. We show that the VT can produce a cluster catalog with completeness and purity >80% for the redshift range up to {approx}1 and mass range down to {approx}10{sup 13.5} solar masses.

  20. The Voronoi Tessellation cluster finder in 2+1 dimensions

    SciTech Connect

    Soares-Santos, Marcelle; de Carvalho, Reinaldo R.; Annis, James; Gal, Roy R.; La Barbera, Francesco; Lopes, Paulo A.A.; Wechsler, Risa H.; Busha, Michael T.; Gerke, Brian F.; /SLAC /KIPAC, Menlo Park

    2010-11-01

    We present a detailed description of the Voronoi Tessellation (VT) cluster finder algorithm in 2+1 dimensions, which improves on past implementations of this technique. The need for cluster finder algorithms able to produce reliable cluster catalogs up to redshift 1 or beyond and down to 10{sup 13.5} solar masses is paramount especially in light of upcoming surveys aiming at cosmological constraints from galaxy cluster number counts. We build the VT in photometric redshift shells and use the two-point correlation function of the galaxies in the field to both determine the density threshold for detection of cluster candidates and to establish their significance. This allows us to detect clusters in a self-consistent way without any assumptions about their astrophysical properties. We apply the VT to mock catalogs which extend to redshift 1.4 reproducing the {Lambda}CDM cosmology and the clustering properties observed in the Sloan Digital Sky Survey data. An objective estimate of the cluster selection function in terms of the completeness and purity as a function of mass and redshift is as important as having a reliable cluster finder. We measure these quantities by matching the VT cluster catalog with the mock truth table. We show that the VT can produce a cluster catalog with completeness and purity >80% for the redshift range up to {approx}1 and mass range down to {approx}10{sup 13.5} solar masses.

  1. Small-grid dithering strategy for improved coronagraphic performance with JWST

    NASA Astrophysics Data System (ADS)

    Soummer, Rémi; Lajoie, Charles-Philippe; Pueyo, Laurent; Hines, Dean C.; Isaacs, John C.; Nelan, Edmund P.; Clampin, Mark; Perrin, Marshall

    2014-08-01

    Coronagraphic Target Acquisition (TA) is an important factor that contributes to the contrast performance and typically depends on the coronagraph design. In the case of JWST, coronagraphic TAs rely on measuring the centroid of the star's point spread function away from the focal plane mask, and performing a small angle ma- neuver (SAM), to place the star behind the coronagraphic mask. Therefore, the accuracy of the TA is directly limited by the SAM accuracy. Typically JWST coronagraphic observations will include the subtraction of a reference (either a reference star, or a self-reference after a telescope roll). With such differential measurement, the reproducibility of the TA is a very important factor. We propose a novel coronagraphic observation concept whereby the reference PSF is first acquired using a standard TA, followed by coronagraphic observations of a reference star on a small grid of dithered positions. Sub-pixel dithers (5-10 mas each) provide a small reference PSF library that samples the variations in the PSF as a function of position relative to the mask, thus compen- sating for errors in the TA process. This library can be used for PSF subtraction with a variety of algorithms (e.g; LOCI or KLIP algorithms, Lafrenière et al. 2007; Soummer, Pueyo and Larkin 2012). These sub-pixel dithers are executed under closed-loop fine guidance, unlike a standard SAM that executes the maneuver in coarse point mode, which can result in a temporary target offset of 1 arcsecond and would bring the star out from behind the coronagraphic mask. We discuss and evaluate the performance gains from this observation scenario compared to the standard TA both for MIRI coronagraphs.

  2. PISCES: an integral field spectrograph technology demonstration for the WFIRST coronagraph

    NASA Astrophysics Data System (ADS)

    McElwain, Michael W.; Mandell, Avi M.; Gong, Qian; Llop-Sayson, Jorge; Brandt, Timothy; Chambers, Victor J.; Grammer, Bryan; Greeley, Bradford; Hilton, George; Perrin, Marshall D.; Stapelfeldt, Karl R.; Demers, Richard; Tang, Hong; Cady, Eric

    2016-07-01

    We present the design, integration, and test of the Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (PISCES) integral field spectrograph (IFS). The PISCES design meets the science requirements for the Wide-Field InfraRed Survey Telescope (WFIRST) Coronagraph Instrument (CGI). PISCES was integrated and tested in the integral field spectroscopy laboratory at NASA Goddard. In June 2016, PISCES was delivered to the Jet Propulsion Laboratory (JPL) where it was integrated with the Shaped Pupil Coronagraph (SPC) High Contrast Imaging Testbed (HCIT). The SPC/PISCES configuration will demonstrate high contrast integral field spectroscopy as part of the WFIRST CGI technology development program.

  3. PISCES: An Integral Field Spectrograph Technology Demonstration for the WFIRST Coronagraph

    NASA Technical Reports Server (NTRS)

    McElwain, Michael W.; Mandell, Avi M.; Gong, Qian; Llop-Sayson, Jorge; Brandt, Timothy; Chambers, Victor J.; Grammer, Bryan; Greeley, Bradford; Hilton, George; Perrin, Marshall D.; hide

    2016-01-01

    We present the design, integration, and test of the Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (PISCES) integral field spectrograph (IFS). The PISCES design meets the science requirements for the Wide-Field Infra Red Survey Telescope (WFIRST) Coronagraph Instrument (CGI). PISCES was integrated and tested in the integral field spectroscopy laboratory at NASA Goddard. In June 2016, PISCES was delivered to the Jet Propulsion Laboratory (JPL) where it was integrated with the Shaped Pupil Coronagraph (SPC) High Contrast Imaging Testbed (HCIT). The SPC/PISCES configuration will demonstrate high contrast integral field spectroscopy as part of the WFIRST CGI technology development program.

  4. CONSTRUCTION OF A SMALL AUTOMATED CORONAGRAPH FOR OBSERVATIONS OF THE LUNAR Na EXOSPHERE

    NASA Astrophysics Data System (ADS)

    Tucker, Roy; Morgan, T. H.; Killen, R. M.

    2013-10-01

    We report on the final optical and mechanical design and the construction and initial testing of a small coronagraph at the Winer Observatory, near Sonoita, Arizona. The coronagraph includes a narrow band filter and low-light level camera to observe lunar exospheric sodium in the resonance lines of that element near 590 nm. Without the use of a coronagraph, the signal from sodium would be lost against light scattered by the Earth’s atmosphere and scattered light in the telescope. The design uses Commercial Off the Shelf Technology (COTS), and our goal is to obtain observations while the Lunar Atmosphere and Dust Environment Explorer (LADEE) mission is still in orbit.

  5. CORONAGRAPHIC OBSERVATIONS OF FOMALHAUT AT SOLAR SYSTEM SCALES

    SciTech Connect

    Kenworthy, Matthew A.; Meshkat, Tiffany; Quanz, Sascha P.; Meyer, Michael R.; Girard, Julien H.; Kasper, Markus

    2013-02-10

    We report on a search for low mass companions within 10 AU of the star Fomalhaut, using narrowband observations at 4.05 {mu}m obtained with the Apodizing Phase Plate coronagraph on the VLT/NaCo. Our observations place a model-dependent upper mass limit of 12-20 M {sub jup} from 4 to 10 AU, covering the semimajor axis search space between interferometric imaging measurements and other direct imaging non-detections. These observations rule out models where the large semimajor axis for the putative candidate companion Fomalhaut b is explained by dynamical scattering from a more massive companion in the inner stellar system, where such giant planets are thought to form.

  6. The Visible Nulling Coronagraph--Architecture Definition and Technology Development

    NASA Technical Reports Server (NTRS)

    Shao, Michael; Levine, B. Martin; Wallace, J. Kent; Liu, Duncan T.; Schmidtlin, Edouard; Serabyn, Eugene; Mennesson, Bertrand; Green, Joseph J.; Aguayo, Francisco; Fregoso, S. Felipe; Lane, Benjamin F.; Samuele, Rocco; Tuttle, Carl

    2005-01-01

    This paper describes the advantages of visible direct detection and spectroscopy of Earth-like extrasolar planets using a nulling coronagraph instrument behind a moderately sized single aperture space telescope. Our concept synthesizes a nulling interferometer by shearing the telescope pupil, with the resultant producing a deep null. We describe nulling configurations that also include methods to mitigate stellar leakage, such as spatial filtering by a coherent array of single mode fibers, and post-starlight suppression wavefront sensing and control. With diffraction limited telescope optics and similar quality components in the optical train (lambda/20), suppression of the starlight to 1e-10 is readily achievable. We describe key features of the architecture and analysis, present latest results of laboratory measurements demonstrating achievable null depth and component development, and discuss future key technical milestones.

  7. The Visible Nulling Coronagraph--Architecture Definition and Technology Development

    NASA Technical Reports Server (NTRS)

    Shao, Michael; Levine, B. Martin; Wallace, J. Kent; Liu, Duncan T.; Schmidtlin, Edouard; Serabyn, Eugene; Mennesson, Bertrand; Green, Joseph J.; Aguayo, Francisco; Fregoso, S. Felipe; hide

    2005-01-01

    This paper describes the advantages of visible direct detection and spectroscopy of Earth-like extrasolar planets using a nulling coronagraph instrument behind a moderately sized single aperture space telescope. Our concept synthesizes a nulling interferometer by shearing the telescope pupil, with the resultant producing a deep null. We describe nulling configurations that also include methods to mitigate stellar leakage, such as spatial filtering by a coherent array of single mode fibers, and post-starlight suppression wavefront sensing and control. With diffraction limited telescope optics and similar quality components in the optical train (lambda/20), suppression of the starlight to 1e-10 is readily achievable. We describe key features of the architecture and analysis, present latest results of laboratory measurements demonstrating achievable null depth and component development, and discuss future key technical milestones.

  8. The Gemini Planet Imager Coronagraph Testbed Preliminary Performance Results

    NASA Astrophysics Data System (ADS)

    Roberts, Robin

    2010-01-01

    The Gemini Planet Imager (GPI) is a new science instrument being developed and slated for first light early 2011 on the twin 8m Gemini telescopes. Operating in the near infrared, this ground-based, extreme Adaptive Optics (ExAO) coronographic instrument will provide the ability to detect, characterize and analyze young (< 2GYr), self-luminous, extrasolar planets with brightness contrast ratios ≤ 10-7 when compared to their parent star. The coronagraph subsystem includes a pupil apodization, a hard-edged focal plane mask as well as a Lyot stop. Preliminary results indicate that the testbed is performing at very high contrast, having achieved broadband contrasts (H-band) below 10-6 at separations > 5λ/D. Fraunhoffer and Fresnel propagation modeling were used to analyze the testbed results.

  9. SOHO Ultraviolet Coronagraph Spectrometer (UVCS) Mission Operations and Data Analysis

    NASA Technical Reports Server (NTRS)

    Kohl, John L.; Gurman, Joseph B. (Technical Monitor)

    2001-01-01

    The scientific goal of Ultraviolet Coronagraph Spectrometer (UVCS) is to obtain detailed empirical descriptions of the extended solar corona as it evolves through the solar activity cycle and to use those descriptions to identify and understand the physical processes responsible for coronal heating, solar wind acceleration, coronal mass ejections (CMEs), and the phenomena that establish the plasma properties of the solar wind as measured by 'in situ' solar wind instruments. The UVCS on the Solar and Heliospheric Observatory (SOHO) has made major advances in identifying the physical processes responsible for solar wind acceleration, and it has made the first high resolution ultraviolet spectroscopic measurements of CMEs. The UVCS has resulted in over 220 scientific publications.

  10. OSCA, an optimised stellar coronagraph for adaptive optics

    NASA Astrophysics Data System (ADS)

    Thompson, Samantha Jayne

    Described here is the design, manufacturing, testing and commissioning of a coronagraph facility for the 4.2 metre William Herschel Telescope (WHT) and its adaptive optics system (NAOMI). The use of the NAOMI adaptive optics system gives an improved image resolution of ~ 0.15 arcseconds at a wavelength of 2.2?m. This enables the Optimised Stellar Coronagraph for Adaptive optics (OSCA) to null stellar light with smaller occulting masks and thus allows regions closer to bright astronomical objects to be imaged. OSCA is a fully deployable instrument which when in use leaves the focus of the NAOMI beam unchanged. This enables OSCA to be used in conjunction with a number of instruments that have already been commissioned at the WHT. The main imaging camera used with OSCA is INGRID; a 1024 x 1024 pixel HgCdTe cooled short-wave infra-red (SWIR) detector at the NAOMI focus. OSCA also has the option of being used in conjunction with an integral field spectrograph for imaging at visible wavelengths. OSCA provides a selection of 10 different occulting masks with sizes of 0.25 - 2.0 arcseconds in diameter, including two with novel gaussian profiles. There is also a choice of two different sized Lyot stops (pupil plane masks). A dichroic placed before the AO system can give improved suppression performance when occulting masks larger than the seeing disk are used. Also presented are results from observing time with the OSCA system, which highlight the challenges faced by astronomers to obtain high contrast, high resolution images from ground based telescopes. At a time during which there is much activity towards terrestrial planet finding, questions as to the system requirements required for such a task are discussed.

  11. Fabrication of Soft-Edged Occulting Masks for Coronagraphs

    NASA Astrophysics Data System (ADS)

    Tolls, Volker; Aziz, M. J.; Raja, S.

    2009-01-01

    Direct imaging of extra-solar planets is important for determining the properties of individual planets and to study multi-planet systems. Obtaining spectra of extra-solar planets enables us to constrain the composition of planetary atmospheres and surfaces, their climates, their evolution, and their rotation periods. The Lyot coronagraph is one of the important techniques to acquire these spectra. In its simplest design it consists of a telescope, an occulter mask in the first focal plane, a Lyot stop in the following pupil plane, and the detector in the final focal plane. The goal of ongoing research is to achieve the best possible performance from a Lyot coronagraph. Among the study objects is the occulter mask. We are studying a new manufacturing method to overcome the main problems of occulter masks: undesired chromatic effects and intolerable phase distortions. Our method utilizes substrates covered with highly absorbing dye mixtures (optical density of 1 per micron) and focused ion beam (FIB) milling of the mask profiles into these dyes. By combining several dyes with pre-determined mixing ratios, we are able to control the chromaticity of the mask from decreasing to flat to increasing absorptivity with wavelengths. Phase effects occur in these masks only at the transition from the dye to its surrounding medium. The idea is to control these phase effects by embedding the masks in clear, phase-matching glass. This poster will present the progress we made in finding and characterizing suitable materials and the results of first optical tests of FIB machined mask-like structures in dye-doped PMMA. This work was supported by NASA through grant NNG04GC57G and NSF through grant AST-0750222, through SAO IR&D funding and by Harvard University. Central facilities were provided by Harvard's Center for Nanoscale Systems.

  12. A coronagraphic search for brown dwarfs around nearby stars

    NASA Technical Reports Server (NTRS)

    Nakajima, T.; Durrance, S. T.; Golimowski, D. A.; Kulkarni, S. R.

    1994-01-01

    Brown dwarf companions have been searched for around stars within 10 pc of the Sun using the Johns-Hopkins University Adaptive Optics Coronagraph (AOC), a stellar coronagraph with an image stabilizer. The AOC covers the field around the target star with a minimum search radius of 1 sec .5 and a field of view of 1 arcmin sq. We have reached an unprecedented dynamic range of Delta m = 13 in our search for faint companions at I band. Comparison of our survey with other brown dwarf searches shows that the AOC technique is unique in its dynamic range while at the same time just as sensitive to brown dwarfs as the recent brown dwarf surveys. The present survey covered 24 target stars selected from the Gliese catalog. A total of 94 stars were detected in 16 fields. The low-latitude fields are completely dominated by background star contamination. Kolmogorov-Smirnov tests were carried out for a sample restricted to high latitudes and a sample with small angular separations. The high-latitude sample (b greater than or equal to 44 deg) appears to show spatial concentration toward target stars. The small separation sample (Delta Theta less than 20 sec) shows weaker dependence on Galactic coordinates than field stars. These statistical tests suggest that both the high-latitude sample and the small separation sample can include a substantial fraction of true companions. However, the nature of these putative companions is mysterious. They are too faint to be white dwarfs and too blue for brown dwarfs. Ignoring the signif icance of the statistical tests, we can reconcile most of the detections with distant main-sequence stars or white dwarfs except for a candidate next to GL 475. Given the small size of our sample, we conclude that considerably more targets need to be surveyed before a firm conclusion on the possibility of a new class of companions can be made.

  13. A coronagraphic search for brown dwarfs around nearby stars

    NASA Astrophysics Data System (ADS)

    Nakajima, T.; Durrance, S. T.; Golimowski, D. A.; Kulkarni, S. R.

    1994-06-01

    Brown dwarf companions have been searched for around stars within 10 pc of the Sun using the Johns-Hopkins University Adaptive Optics Coronagraph (AOC), a stellar coronagraph with an image stabilizer. The AOC covers the field around the target star with a minimum search radius of 1 sec .5 and a field of view of 1 arcmin sq. We have reached an unprecedented dynamic range of Delta m = 13 in our search for faint companions at I band. Comparison of our survey with other brown dwarf searches shows that the AOC technique is unique in its dynamic range while at the same time just as sensitive to brown dwarfs as the recent brown dwarf surveys. The present survey covered 24 target stars selected from the Gliese catalog. A total of 94 stars were detected in 16 fields. The low-latitude fields are completely dominated by background star contamination. Kolmogorov-Smirnov tests were carried out for a sample restricted to high latitudes and a sample with small angular separations. The high-latitude sample (b greater than or equal to 44 deg) appears to show spatial concentration toward target stars. The small separation sample (Delta Theta less than 20 sec) shows weaker dependence on Galactic coordinates than field stars. These statistical tests suggest that both the high-latitude sample and the small separation sample can include a substantial fraction of true companions. However, the nature of these putative companions is mysterious. They are too faint to be white dwarfs and too blue for brown dwarfs. Ignoring the significance of the statistical tests, we can reconcile most of the detections with distant main-sequence stars or white dwarfs except for a candidate next to GL 475. Given the small size of our sample, we conclude that considerably more targets need to be surveyed before a firm conclusion on the possibility of a new class of companions can be made.

  14. A coronagraphic search for brown dwarfs around nearby stars

    NASA Technical Reports Server (NTRS)

    Nakajima, T.; Durrance, S. T.; Golimowski, D. A.; Kulkarni, S. R.

    1994-01-01

    Brown dwarf companions have been searched for around stars within 10 pc of the Sun using the Johns-Hopkins University Adaptive Optics Coronagraph (AOC), a stellar coronagraph with an image stabilizer. The AOC covers the field around the target star with a minimum search radius of 1 sec .5 and a field of view of 1 arcmin sq. We have reached an unprecedented dynamic range of Delta m = 13 in our search for faint companions at I band. Comparison of our survey with other brown dwarf searches shows that the AOC technique is unique in its dynamic range while at the same time just as sensitive to brown dwarfs as the recent brown dwarf surveys. The present survey covered 24 target stars selected from the Gliese catalog. A total of 94 stars were detected in 16 fields. The low-latitude fields are completely dominated by background star contamination. Kolmogorov-Smirnov tests were carried out for a sample restricted to high latitudes and a sample with small angular separations. The high-latitude sample (b greater than or equal to 44 deg) appears to show spatial concentration toward target stars. The small separation sample (Delta Theta less than 20 sec) shows weaker dependence on Galactic coordinates than field stars. These statistical tests suggest that both the high-latitude sample and the small separation sample can include a substantial fraction of true companions. However, the nature of these putative companions is mysterious. They are too faint to be white dwarfs and too blue for brown dwarfs. Ignoring the signif icance of the statistical tests, we can reconcile most of the detections with distant main-sequence stars or white dwarfs except for a candidate next to GL 475. Given the small size of our sample, we conclude that considerably more targets need to be surveyed before a firm conclusion on the possibility of a new class of companions can be made.

  15. RxnFinder: biochemical reaction search engines using molecular structures, molecular fragments and reaction similarity.

    PubMed

    Hu, Qian-Nan; Deng, Zhe; Hu, Huanan; Cao, Dong-Sheng; Liang, Yi-Zeng

    2011-09-01

    Biochemical reactions play a key role to help sustain life and allow cells to grow. RxnFinder was developed to search biochemical reactions from KEGG reaction database using three search criteria: molecular structures, molecular fragments and reaction similarity. RxnFinder is helpful to get reference reactions for biosynthesis and xenobiotics metabolism. RxnFinder is freely available via: http://sdd.whu.edu.cn/rxnfinder. qnhu@whu.edu.cn.

  16. Test technology on divergence angle of laser range finder based on CCD imaging fusion

    NASA Astrophysics Data System (ADS)

    Shi, Sheng-bing; Chen, Zhen-xing; Lv, Yao

    2016-09-01

    Laser range finder has been equipped with all kinds of weapons, such as tank, ship, plane and so on, is important component of fire control system. Divergence angle is important performance and incarnation of horizontal resolving power for laser range finder, is necessary appraised test item in appraisal test. In this paper, based on high accuracy test on divergence angle of laser range finder, divergence angle test system is designed based on CCD imaging, divergence angle of laser range finder is acquired through fusion technology for different attenuation imaging, problem that CCD characteristic influences divergence angle test is solved.

  17. Technology and design of an infrared interferometer for the Terrestrial Planet Finder

    NASA Technical Reports Server (NTRS)

    Blackwood, G.; Henry, C.; Serabyn, E.; Aung, M.; Gunter, S. M.

    2003-01-01

    This paper describes the architecture studies, technology studies, and testbeds that demonstrate the viability of an infrared interferometer mission architecture for the Terrestrial Planet Finder project.

  18. An innovative concept for the AsteroidFinder/SSB focal plane assembly

    NASA Astrophysics Data System (ADS)

    Schindler, Karsten; Tschentscher, Matthias; Koncz, Alexander; Solbrig, Michael; Michaelis, Harald

    2012-06-01

    This paper gives a summary on the system concept and design of the focal plane assembly of AsteroidFinder/SSB, a small satellite mission which is currently under development at the German Aerospace Center (DLR). An athermal design concept has been developed in accordance to the requirements of the instrument and spacecraft. Key aspects leading to this approach have been a trade-off study of the mechanical telescope interface, the definition of electrical and thermal interfaces and a material selection which minimizes thermally induced stresses. As a novelty, the structure will be manufactured from a machinable AlN-BN composite ceramic. To enable rapid design iterations and development, an integrated modeling approach has been used to conduct a thermo-mechanical analysis of the proposed concept in order to proof its feasibility. The steady-state temperature distribution for various load cases and the resulting stress and strain within the assembly have both been computed using a finite element simulation.

  19. Demonstration of high contrast with an obscured aperture with the WFIRST-AFTA shaped pupil coronagraph

    NASA Astrophysics Data System (ADS)

    Cady, Eric; Prada, Camilo Mejia; An, Xin; Balasubramanian, Kunjithapatham; Diaz, Rosemary; Kasdin, N. Jeremy; Kern, Brian; Kuhnert, Andreas; Nemati, Bijan; Poberezhskiy, Ilya; Eldorado Riggs, A. J.; Zimmer, Robert; Zimmerman, Neil

    2016-01-01

    The coronagraph instrument on the Wide-Field Infrared Survey Telescope-Astrophysics-Focused Telescope Asset (WFIRST-AFTA) mission study has two coronagraphic architectures, shaped pupil and hybrid Lyot, which may be interchanged for use in different observing scenarios. Each architecture relies on newly developed mask components to function in the presence of the AFTA aperture, and so both must be matured to a high technology readiness level in advance of the mission. A series of milestones were set to track the development of the technologies required for the instrument; we report on completion of WFIRST-AFTA coronagraph milestone 2-a narrowband 10-8 contrast test with static aberrations for the shaped pupil-and the plans for the upcoming broadband coronagraph milestone 5.

  20. The W. M. Keck Observatory Infrared Vortex Coronagraph and a First Image of HIP 79124 B

    NASA Astrophysics Data System (ADS)

    Serabyn, E.; Huby, E.; Matthews, K.; Mawet, D.; Absil, O.; Femenia, B.; Wizinowich, P.; Karlsson, M.; Bottom, M.; Campbell, R.; Carlomagno, B.; Defrère, D.; Delacroix, C.; Forsberg, P.; Gomez Gonzalez, C.; Habraken, S.; Jolivet, A.; Liewer, K.; Lilley, S.; Piron, P.; Reggiani, M.; Surdej, J.; Tran, H.; Vargas Catalán, E.; Wertz, O.

    2017-01-01

    An optical vortex coronagraph has been implemented within the NIRC2 camera on the Keck II telescope and used to carry out on-sky tests and observations. The development of this new L‧-band observational mode is described, and an initial demonstration of the new capability is presented: a resolved image of the low-mass companion to HIP 79124, which had previously been detected by means of interferometry. With HIP 79124 B at a projected separation of 186.5 mas, both the small inner working angle of the vortex coronagraph and the related imaging improvements were crucial in imaging this close companion directly. Due to higher Strehl ratios and more relaxed contrasts in L‧ band versus H band, this new coronagraphic capability will enable high-contrast, small-angle observations of nearby young exoplanets and disks on a par with those of shorter-wavelength extreme adaptive optics coronagraphs.

  1. Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (PISCES) for WFIRST/AFTA

    NASA Technical Reports Server (NTRS)

    Gong, Qian; McElwain, Michael; Greeley, Bradford; Grammer, Bryan; Marx, Catherine; Memarsadeghi, Nargess; Hilton, George; Perrin, Marshall; Sayson, Llop; Domingo, Jorge; hide

    2015-01-01

    Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (PISCES) is a prototype lenslet array based integral field spectrometer (IFS) designed for high contrast imaging of extrasolar planets. PISCES will be used to advance the technology readiness of the high contrast IFS baselined on the Wide-Field InfraRed Survey TelescopeAstrophysics Focused Telescope Assets (WFIRSTAFTA) coronagraph instrument. PISCES will be integrated into the high contrast imaging testbed (HCIT) at the Jet Propulsion Laboratory and will work with both the Hybrid Lyot Coronagraph (HLC) and the Shaped Pupil Coronagraph (SPC). We will present the PISCES optical design, including the similarities and differences of lenslet based IFSs to normal spectrometers, the trade-off between a refractive design and reflective design, as well as the compatibility to upgrade from the current 1k x 1k detector array to 4k x 4k detector array. The optical analysis, alignment plan, and mechanical design of the instrument will be discussed.

  2. Polarization compensating protective coatings for TPF-Coronagraph optics to control contrast degrading cross polarization leakage

    NASA Technical Reports Server (NTRS)

    Balasubramanian, Kunjithapatham; Hoppe, Daniel J.; Mouroulis, Pantazis Z.; Marchen, Luis F.; Shaklan, Stuart B.

    2005-01-01

    We describe here the design approaches and performance analysis of the OTA in the wavelength band of interest. Coronagraph performance at 600nm wavelength based on a particular coating and occulting focal plane mask is also presented.

  3. Detecting protostellar jets with the Goddard Fabry-Perot coronagraph, and modification for adaptive optics

    NASA Technical Reports Server (NTRS)

    Woodgate, Bruce E.; Bowers, Charles W.; Grady, Carol A.; Wassell, Edward J.; Palunas, Povilas

    2003-01-01

    The Goddard Fabry-Perot has been used at the Apache Point Observatory 3.5-m telescope to diagnose jets from young Herbig Ae (HD163296) and T Tauri stars (DL Tau and CW Tau), detected by the Space Telescope Imaging Spectrograph coronagraph on the Hubble Space Telescope. The additional spectral discrimination of the Fabry-Perot allows these faint jets to be detected from the ground, to obtain velocities and densities, and to find further extensions. In order to plan what measurements require space coronagraphs, we need to explore the extent to which coronagraphic detections can be made from the ground, including using adaptive optics. Modifications to the Fabry-Perot tunable narrow band coronagraph for possible use with the AEOS 3.65-m telescope will be described.

  4. Detecting Protostellar Jets with the Goddard Fabry-Perot Coronagraph, and Modification for Adaptive Optics

    NASA Technical Reports Server (NTRS)

    Woodgate, Bruce E.; Bowers, Charles W.; Grady, Carol A.; Wassell, Edward J.; Palunas, Povilas

    2003-01-01

    The Goddard Fabry-Perot has been used at the Apache Point Observatory 3.5-m telescope to diagnose jets from young Herbig Ae (HD163296) and T Tauri stars (DL Tau and CW Tau), detected by the Space Telescope Imaging Spectrograph coronagraph on the Hubble Space Telescope. The additional spectral discrimination of the Fabry-Perot allows these faint jets to be detected from the ground, to obtain velocities and densities, and to find further extensions. In order to plan what measurements require space coronagraphs, we need to explore the extent to which coronagraphic detections can be made from the ground, including using adaptive optics. Modifications to the Fabry-Perot tunable narrow band coronagraph for possible use with the AEOS 3.65-m telescope will be described.

  5. WFIRST-AFTA coronagraph shaped pupil masks: design, fabrication, and characterization

    NASA Astrophysics Data System (ADS)

    Balasubramanian, Kunjithapatham; White, Victor; Yee, Karl; Echternach, Pierre; Muller, Richard; Dickie, Matthew; Cady, Eric; Prada, Camilo Mejia; Ryan, Daniel; Poberezhskiy, Ilya; Kern, Brian; Zhou, Hanying; Krist, John; Nemati, Bijan; Eldorado Riggs, A. J.; Zimmerman, Neil T.; Kasdin, N. Jeremy

    2016-01-01

    NASA WFIRST-AFTA mission study includes a coronagraph instrument to find and characterize exoplanets. Various types of masks could be employed to suppress the host starlight to about 10-9 level contrast over a broad spectrum to enable the coronagraph mission objectives. Such masks for high-contrast internal coronagraphic imaging require various fabrication technologies to meet a wide range of specifications, including precise shapes, micron scale island features, ultralow reflectivity regions, uniformity, wave front quality, and achromaticity. We present the approaches employed at JPL to produce pupil plane and image plane coronagraph masks by combining electron beam, deep reactive ion etching, and black silicon technologies with illustrative examples of each, highlighting milestone accomplishments from the High Contrast Imaging Testbed at JPL and from the High Contrast Imaging Lab at Princeton University.

  6. Managing the optical wavefront for high contrast exoplanet imaging with the WFIRST-AFTA coronagraph

    NASA Astrophysics Data System (ADS)

    Trauger, John T.; Krist, John E.; Moody, Dwight

    2016-01-01

    The prospect of extreme high contrast astronomical imaging from space has inspired developments of new coronagraph methods for exoplanet imaging and spectroscopy. However, the requisite contrast, at levels of a billion to one or better for the direct imaging of cool mature exoplanets in reflected visible starlight, leads to challenging new requirements on the stability and control of the optical wavefront at levels currently beyond the reach of ground based telescopes. We briefly review the designs, laboratory validations, and science prospects for direct imaging and spectroscopic characterization of exoplanet systems with an actively corrected Lyot coronagraph. We review exoplanet science performance predicted for NASA's WFIRST-AFTA coronagraph. Together with a pair of deformable mirrors for optical wavefront control, the Lyot coronagraph creates high contrast dark fields of view extending to angular separations within 0.1 arcsec from the central star at visible wavelengths. Performance metrics are presented, including image contrast and spectral bandwidth, and laboratory validation experience.

  7. Improved high-contrast imaging with on-axis telescopes using a multistage vortex coronagraph.

    PubMed

    Mawet, Dimitri; Serabyn, Eugene; Wallace, J Kent; Pueyo, Laurent

    2011-04-15

    The vortex coronagraph is one of the most promising coronagraphs for high-contrast imaging because of its simplicity, small inner working angle, high throughput, and clear off-axis discovery space. However, as with most coronagraphs, centrally obscured on-axis telescopes degrade contrast. Based on the remarkable ability of vortex coronagraphs to move light between the interior and exterior of pupils, we propose a method based on multiple vortices, that without sacrificing throughput, reduces the residual light leakage to (a/A)(n), with n ≥ 4, and a and A being the radii of the central obscuration and primary mirror, respectively. This method thus enables high contrasts to be reached even with an on-axis telescope.

  8. Achromatic interfero-coronagraph with variable rotational shear in laboratory experiments

    NASA Astrophysics Data System (ADS)

    Frolov, Pavel; Kiselev, Alexander; Tavrov, Alexander

    2016-07-01

    Direct imaging of earth-like extrasolar planets in the habitable zone and the search for possible biological signatures are among the key scientific objectives in the modern astronomy. Stellar coronagraph such as achromatic interfero coronagraph (AIC) with a small inner working angle has limited possibilities to detect and characterize planets around nearby stars due to the star leakage effect caused by incomplete suppression of the star of finite angular size. We report on an improved instrument for direct imaging of exoplanets and the study of stellar environment - common-path achromatic interfero-coronagraph with variable rotational shear (common-path achromatic rotation-shearing coronagraph, CP-ARC) - a common path implementation of rotation shearing interferometer. We detail CP-ARC approach and discuss its optical configuration, laboratory prototype and experimental results.

  9. Lyot-based low order wavefront sensor: implementation on the Subaru Coronagraphic Extreme Adaptive Optics System and its laboratory performance

    NASA Astrophysics Data System (ADS)

    Singh, Garima; Guyon, Olivier; Baudoz, Pierre; Jovanovich, Nemanja; Martinache, Frantz; Kudo, Tomoyuki; Serabyn, Eugene; Kuhn, Jonas G.

    2014-08-01

    High throughput, low inner working angle (IWA) phase masks coronagraphs are essential to directly image and characterize (via spectroscopy) earth-like planets. However, the performance of low-IWA coronagraphs is limited by residual pointing errors and other low-order modes. The extent to which wavefront aberrations upstream of the coronagraph are corrected and calibrated drives coronagraphic performance. Addressing this issue is essential for preventing coronagraphic leaks, thus we have developed a Lyot-based low order wave front sensor (LLOWFS) to control the wavefront aberrations in a coronagraph. The LLOWFS monitors the starlight rejected by the coronagraphic mask using a reflective Lyot stop in the downstream pupil plane. The early implementation of LLOWFS at LESIA, Observatoire de Paris demonstrated an open loop measurement accuracy of 0.01 λ/D for tip-tilt at 638 nm when used in conjunction with a four quadrant phase mask (FQPM) in the laboratory. To further demonstrate our concept, we have installed the reflective Lyot stops on the Subaru Coronagraphic Extreme AO (SCExAO) system at the Subaru Telescope and modified the system to support small IWA phase mask coronagraphs (< 1λ/D) on-sky such as FQPM, eight octant phase mask, vector vortex coronagraph and the phase induced amplitude apodization complex phase mask coronagraph with a goal of obtaining milli arc-second pointing accuracy. Laboratory results have shown the measurement of tip, tilt, focus, oblique and right astigmatism at 1.55 μm for the vector vortex coronagraph. Our initial on-sky result demonstrate the closed loop accuracy of < 7 x 10-3 λ/D at 1.6 μm for tip, tilt and focus aberrations with the vector vortex coronagraph.

  10. SPICA infrared coronagraph for the direct observation of exo-planets

    NASA Astrophysics Data System (ADS)

    Enya, Keigo; Spica Working Group

    2010-04-01

    We present a mid-infrared coronagraph to target the direct observation of extrasolar planets, for Space Infrared telescope for Cosmology and Astrophysics (SPICA). SPICA is a proposed JAXA-ESA mission, which will carry a telescope cooled to 5 K with a 3.5 m diameter aperture, and is planned to be launched in 2018 by an H II family rocket. The SPICA mission gives us a unique opportunity for high-contrast observations because of the large telescope aperture, the simple pupil shape, and the capability for infrared observations from space. We have commenced studies for a coronagraph for SPICA, in which this coronagraph is currently regarded as an option of the focal plane instruments. The primary target of the SPICA coronagraph is the direct observation of Jovian exo-planets. A strategy of the baseline survey and the specifications for the coronagraph instrument for the survey are introduced together. The main wavelengths and the contrast required for the observations are 3.5-27 μm, and 10 -6, respectively. Laboratory experiments were performed with a visible laser to demonstrate the principles of the coronagraphs. In an experiment using binary-shaped pupil coronagraphs, a contrast of 6.7 × 10 -8 was achieved, as derived from the linear average in the dark region and the core of the point spread function (PSF). A coronagraph by a binary-shaped pupil mask is a baseline solution for SPICA because of its feasibility and robustness. On the other hand, a laboratory experiment of the phase induced amplitude apodization/binary-mask hybrid coronagraph has been executed to obtain an option of higher performance (i.e., smaller inner working angle and higher throughput), and a contrast of 6.5 × 10 -7 was achieved with active wavefront control. Potentially important by-product of the instrument, transit monitoring for characterization of exo-planets, is also described. We also present recent progress of technology on a design of a binary-shaped pupil mask for the actual pupil of

  11. FEM analysis of bonding process used for minimization of deformation of optical surface under Metis coronagraph mirrors manufacturing

    NASA Astrophysics Data System (ADS)

    Procháska, F.; Vít, T.; Matoušek, O.; Melich, R.

    2016-11-01

    High demands on the final surfaces micro-roughness as well as great shape accuracy have to be achieved under the manufacturing process of the precise mirrors for Metis orbital coronagraph. It is challenging engineering task with respect to lightweight design of the mirrors and resulting objectionable optical surface shape stability. Manufacturing of such optical elements is usually affected by number of various effects. Most of them are caused by instability of temperature field. It is necessary to explore, comprehend and consequently minimize all thermo - mechanical processes which take place during mirror cementing, grinding and polishing processes to minimize the optical surface deformation. Application of FEM simulation was proved as a useful tool to help to solve this task. FEM simulations were used to develop and virtually compare different mirror holders to minimize the residual stress generated by temperature changes and to suppress the shape deformation of the optical surface below the critical limit of about 100 nm.

  12. Super-Gaussian apodization in ground based telescopes for high contrast coronagraph imaging.

    PubMed

    Cagigas, Miguel A; Valle, Pedro J; Cagigal, Manuel P

    2013-05-20

    We introduce the use of Super-Gaussian apodizing functions in the telescope pupil plane and/or the coronagraph Lyot plane to improve the imaging contrast in ground-based coronagraphs. We describe the properties of the Super-Gaussian function, we estimate its second-order moment in the pupil and Fourier planes and we check it as an apodizing function. We then use Super-Gaussian function to apodize the telescope pupil, the coronagraph Lyot plane or both of them. The result is that a proper apodizing masks combination can reduce the exoplanet detection distance up to a 45% with respect to the classic Lyot coronagraph, for moderately aberrated wavefronts. Compared to the prolate spheroidal function the Super-Gaussian apodizing function allows the planet light up to 3 times brighter. An extra help to increase the extinction rate is to perform a frame selection (Lucky Imaging technique). We show that a selection of the 10% best frames will reduce up to a 20% the detection angular distance when using the classic Lyot coronagraph but that the reduction is only around the 5% when using an apodized coronagraph.

  13. StarFinder: A code for stellar field analysis

    NASA Astrophysics Data System (ADS)

    Diolaiti, Emiliano; Bendinelli, Orazio; Bonaccini, Domenico; Close, Laird M.; Currie, Doug G.; Parmeggiani, Gianluigi

    2000-11-01

    StarFinder is an IDL code for the deep analysis of stellar fields, designed for Adaptive Optics well-sampled images with high and low Strehl ratio. The Point Spread Function is extracted directly from the frame, to take into account the actual structure of the instrumental response and the atmospheric effects. The code is written in IDL language and organized in the form of a self-contained widget-based application, provided with a series of tools for data visualization and analysis. A description of the method and some applications to Adaptive Optics data are presented.

  14. Status of the Terrestrial Planet Finder Interferometer (TPF-I)

    NASA Technical Reports Server (NTRS)

    Beichman, Charles; Lawson, Peter; Lay, Oliver; Ahmed, Asif; Unwin, Steve; Johnston, K.

    2006-01-01

    The interferometric version of the Terrestrial Planet Finder (TPF-I) has the potential to find and characterize earth-sized planets in the habitable zones of over 250 nearby stars and to search for life using biomarkers in the atmospheres of any planets found. The scientific case for such a mission continues to be strengthened by on-going progress in the detection of planets via indirect means. This paper summarizes the status of TPF-I, illustrative scientific requirements for the mission, and its enabling technologies.

  15. Key software architecture decisions for the automated planet finder

    NASA Astrophysics Data System (ADS)

    Lanclos, Kyle; Deich, William T. S.; Holden, Bradford P.; Allen, S. L.

    2016-08-01

    The Automated Planet Finder (APF) at Lick Observatory on Mount Hamilton is a modern 2.4 meter computer controlled telescope. At one Nasmyth focus is the Levy Spectrometer, at present the sole instrument used with the APF. The primary research mission of the APF and the Levy Spectrometer is high-precision Doppler spectroscopy. Observing at the APF is unattended; custom software written by diverse authors in diverse languages manage all aspects of a night's observing. This paper will cover some of the key software architecture decisions made in the development of autonomous observing at the APF. The relevance to future projects of these decisions will be emphasized throughout.

  16. Terrestrial Planet Finder Interferometer Technology Status and Plans

    NASA Technical Reports Server (NTRS)

    Lawson, Perter R.; Ahmed, A.; Gappinger, R. O.; Ksendzov, A.; Lay, O. P.; Martin, S. R.; Peters, R. D.; Scharf, D. P.; Wallace, J. K.; Ware, B.

    2006-01-01

    A viewgraph presentation on the technology status and plans for Terrestrial Planet Finder Interferometer is shown. The topics include: 1) The Navigator Program; 2) TPF-I Project Overview; 3) Project Organization; 4) Technology Plan for TPF-I; 5) TPF-I Testbeds; 6) Nulling Error Budget; 7) Nulling Testbeds; 8) Nulling Requirements; 9) Achromatic Nulling Testbed; 10) Single Mode Spatial Filter Technology; 11) Adaptive Nuller Testbed; 12) TPF-I: Planet Detection Testbed (PDT); 13) Planet Detection Testbed Phase Modulation Experiment; and 14) Formation Control Testbed.

  17. Status of the Terrestrial Planet Finder Interferometer (TPF-I)

    NASA Technical Reports Server (NTRS)

    Beichman, Charles; Lawson, Peter; Lay, Oliver; Ahmed, Asif; Unwin, Steve; Johnston, K.

    2006-01-01

    The interferometric version of the Terrestrial Planet Finder (TPF-I) has the potential to find and characterize earth-sized planets in the habitable zones of over 250 nearby stars and to search for life using biomarkers in the atmospheres of any planets found. The scientific case for such a mission continues to be strengthened by on-going progress in the detection of planets via indirect means. This paper summarizes the status of TPF-I, illustrative scientific requirements for the mission, and its enabling technologies.

  18. Terrestrial Planet Finder Interferometer: Architecture, Mission Design and Technology Development

    NASA Technical Reports Server (NTRS)

    Henry, Curt; Lay, Oliver; Aung, MiMi; Gunter, Steven M.; Dubovitsky, Serge; Blackwood, Gary

    2004-01-01

    This overview paper is a progress report about the system design and technology development of two interferometer concepts studied for the Terrestrial Planet Finder (TPF) project. The two concepts are a structurally-connected interferometer (SCI) intended to fulfill minimum TPF science goals and a formation-flying interferometer (FFI) intended to fulfill full science goals. Described are major trades, analyses, and technology experiments completed. Near term plans are also described. This paper covers progress since August 2003 and serves as an update to a paper presented at that month's SPIE conference, 'Techniques and Instrumentation for Detection of Exoplanets.

  19. Terrestrial Planet Finder Interferometer Technology Status and Plans

    NASA Technical Reports Server (NTRS)

    Lawson, Perter R.; Ahmed, A.; Gappinger, R. O.; Ksendzov, A.; Lay, O. P.; Martin, S. R.; Peters, R. D.; Scharf, D. P.; Wallace, J. K.; Ware, B.

    2006-01-01

    A viewgraph presentation on the technology status and plans for Terrestrial Planet Finder Interferometer is shown. The topics include: 1) The Navigator Program; 2) TPF-I Project Overview; 3) Project Organization; 4) Technology Plan for TPF-I; 5) TPF-I Testbeds; 6) Nulling Error Budget; 7) Nulling Testbeds; 8) Nulling Requirements; 9) Achromatic Nulling Testbed; 10) Single Mode Spatial Filter Technology; 11) Adaptive Nuller Testbed; 12) TPF-I: Planet Detection Testbed (PDT); 13) Planet Detection Testbed Phase Modulation Experiment; and 14) Formation Control Testbed.

  20. Terrestrial Planet Finder Interferometer: Architecture, Mission Design and Technology Development

    NASA Technical Reports Server (NTRS)

    Henry, Curt; Lay, Oliver; Aung, MiMi; Gunter, Steven M.; Dubovitsky, Serge; Blackwood, Gary

    2004-01-01

    This overview paper is a progress report about the system design and technology development of two interferometer concepts studied for the Terrestrial Planet Finder (TPF) project. The two concepts are a structurally-connected interferometer (SCI) intended to fulfill minimum TPF science goals and a formation-flying interferometer (FFI) intended to fulfill full science goals. Described are major trades, analyses, and technology experiments completed. Near term plans are also described. This paper covers progress since August 2003 and serves as an update to a paper presented at that month's SPIE conference, 'Techniques and Instrumentation for Detection of Exoplanets.

  1. Strategies for chemical reaction searching in SciFinder

    PubMed

    Ridley

    2000-09-01

    The bibliographic, chemical structure, and chemical reaction databases produced by Chemical Abstracts Service allow a number of possibilities for chemical reaction searching. While these same databases may be searched through the STN network, many end-users find the intuitive software interface SciFinder simpler, but there still are issues to address. Searching may be performed through keywords, chemical structures, or chemical reactions, and the answers may vary with respect to precision and comprehension. Often combinations of search options may be needed to best solve the problem. Retrosynthetic analyses are easily performed in the chemical reaction database and can give unique insights into synthetic alternatives.

  2. Introduction to Structure Searching with SciFinder Scholar

    NASA Astrophysics Data System (ADS)

    Ridley, Damon D.

    2001-04-01

    CAS Registry Numbers provide a key to searching for chemical substances in CAS databases, and the challenge is to obtain the Registry Numbers for all the substances required. When the substances can be represented by structures, then one option is to find the Registry Numbers through structure searches. With SciFinder Scholar, the process of drawing and searching structures is intuitive; however, there are underlying issues and opportunities that need some explanation in courses on chemical information retrieval.We describe here our introductory course, which addresses the major ones.

  3. Performance of the hybrid externally occulted Lyot solar coronagraph. Application to ASPIICS

    NASA Astrophysics Data System (ADS)

    Rougeot, R.; Flamary, R.; Galano, D.; Aime, C.

    2017-02-01

    Context. High-contrast hybrid coronagraphs, which combine an external occulter and a Lyot-style coronagraph became a reality in recent years, despite the lack of analytic and numerical end-to-end performance studies. The solar coronagraph ASPIICS which will fly on the future ESA Formation Flying mission Proba-3 is a good example of such a hybrid coronograph. Aims: We aim to provide a numerical model to compute theoretical performance of the hybrid externally occulted Lyot-style coronagraph, which we then aim to compare to the performance of the classical Lyot coronagraph and the externally occulted solar coronagraph. We will provide the level and intensity distribution of the stray light, when the Sun is considered as an extended source. We also investigate the effect of different sizes for the internal occulter and Lyot stop. Methods: First, we have built on a recently published approach, to express the diffracted wave front from Fresnel diffraction produced by an external occulter at the entrance aperture of the coronagraph. Second, we computed the coherent propagation of the wave front coming from a given point of the Sun through the instrument. This is performed in three steps: from the aperture to the image of the external occulter, where the internal occulter is set, from this plane to the image of the entrance aperture, where the Lyot stop is set, and from there to the final image plane. Making use of the axis-symmetry, we considered wave fronts originating from one radius of the Sun and we circularly average the intensities. Our numerical computation used the parameters of ASPIICS. Results: The hybrid externally occulted Lyot coronagraph rejects sunlight below 10-8B⊙ from 1.3 R⊙ - in the particular configuration of ASPIICS. The Lyot coronagraph effectively complements the external occultation. We show that reducing the Lyot stop allows a clear gain in rejection, being even better than oversizing the internal occulter, that tends to exclude observations

  4. LinkFinder: An expert system that constructs phylogenic trees

    NASA Technical Reports Server (NTRS)

    Inglehart, James; Nelson, Peter C.

    1991-01-01

    An expert system has been developed using the C Language Integrated Production System (CLIPS) that automates the process of constructing DNA sequence based phylogenies (trees or lineages) that indicate evolutionary relationships. LinkFinder takes as input homologous DNA sequences from distinct individual organisms. It measures variations between the sequences, selects appropriate proportionality constants, and estimates the time that has passed since each pair of organisms diverged from a common ancestor. It then designs and outputs a phylogenic map summarizing these results. LinkFinder can find genetic relationships between different species, and between individuals of the same species, including humans. It was designed to take advantage of the vast amount of sequence data being produced by the Genome Project, and should be of value to evolution theorists who wish to utilize this data, but who have no formal training in molecular genetics. Evolutionary theory holds that distinct organisms carrying a common gene inherited that gene from a common ancestor. Homologous genes vary from individual to individual and species to species, and the amount of variation is now believed to be directly proportional to the time that has passed since divergence from a common ancestor. The proportionality constant must be determined experimentally; it varies considerably with the types of organisms and DNA molecules under study. Given an appropriate constant, and the variation between two DNA sequences, a simple linear equation gives the divergence time.

  5. Knickpoint finder: A software tool that improves neotectonic analysis

    NASA Astrophysics Data System (ADS)

    Queiroz, G. L.; Salamuni, E.; Nascimento, E. R.

    2015-03-01

    This work presents a new software tool for morphometric analysis of drainage networks based on the methods of Hack (1973) and Etchebehere et al. (2004). This tool is applicable to studies of morphotectonics and neotectonics. The software used a digital elevation model (DEM) to identify the relief breakpoints along drainage profiles (knickpoints). The program was coded in Python for use on the ArcGIS platform and is called Knickpoint Finder. A study area was selected to test and evaluate the software's ability to analyze and identify neotectonic morphostructures based on the morphology of the terrain. For an assessment of its validity, we chose an area of the James River basin, which covers most of the Piedmont area of Virginia (USA), which is an area of constant intraplate seismicity and non-orogenic active tectonics and exhibits a relatively homogeneous geodesic surface currently being altered by the seismogenic features of the region. After using the tool in the chosen area, we found that the knickpoint locations are associated with the geologic structures, epicenters of recent earthquakes, and drainages with rectilinear anomalies. The regional analysis demanded the use of a spatial representation of the data after processing using Knickpoint Finder. The results were satisfactory in terms of the correlation of dense areas of knickpoints with active lineaments and the rapidity of the identification of deformed areas. Therefore, this software tool may be considered useful in neotectonic analyses of large areas and may be applied to any area where there is DEM coverage.

  6. Laser Range and Bearing Finder for Autonomous Missions

    NASA Technical Reports Server (NTRS)

    Granade, Stephen R.

    2004-01-01

    NASA has recently re-confirmed their interest in autonomous systems as an enabling technology for future missions. In order for autonomous missions to be possible, highly-capable relative sensor systems are needed to determine an object's distance, direction, and orientation. This is true whether the mission is autonomous in-space assembly, rendezvous and docking, or rover surface navigation. Advanced Optical Systems, Inc. has developed a wide-angle laser range and bearing finder (RBF) for autonomous space missions. The laser RBF has a number of features that make it well-suited for autonomous missions. It has an operating range of 10 m to 5 km, with a 5 deg field of view. Its wide field of view removes the need for scanning systems such as gimbals, eliminating moving parts and making the sensor simpler and space qualification easier. Its range accuracy is 1% or better. It is designed to operate either as a stand-alone sensor or in tandem with a sensor that returns range, bearing, and orientation at close ranges, such as NASA's Advanced Video Guidance Sensor. We have assembled the initial prototype and are currently testing it. We will discuss the laser RBF's design and specifications. Keywords: laser range and bearing finder, autonomous rendezvous and docking, space sensors, on-orbit sensors, advanced video guidance sensor

  7. Post-processing images from the WFIRST-AFTA coronagraph testbed

    NASA Astrophysics Data System (ADS)

    Zimmerman, Neil T.; Ygouf, Marie; Pueyo, Laurent; Soummer, Remi; Perrin, Marshall D.; Mennesson, Bertrand; Cady, Eric; Mejia Prada, Camilo

    2016-01-01

    The concept for the exoplanet imaging instrument on WFIRST-AFTA relies on the development of mission-specific data processing tools to reduce the speckle noise floor. No instruments have yet functioned on the sky in the planet-to-star contrast regime of the proposed coronagraph (1E-8). Therefore, starlight subtraction algorithms must be tested on a combination of simulated and laboratory data sets to give confidence that the scientific goals can be reached. The High Contrast Imaging Testbed (HCIT) at Jet Propulsion Lab has carried out several technology demonstrations for the instrument concept, demonstrating 1E-8 raw (absolute) contrast. Here, we have applied a mock reference differential imaging strategy to HCIT data sets, treating one subset of images as a reference star observation and another subset as a science target observation. We show that algorithms like KLIP (Karhunen-Loève Image Projection), by suppressing residual speckles, enable the recovery of exoplanet signals at contrast of order 2E-9.

  8. Debris Disk Science Enabled by a Probe-scale Space Coronagraph Mission

    NASA Astrophysics Data System (ADS)

    Stapelfeldt, Karl R.; Trauger, J. T.; Krist, J. E.

    2010-01-01

    Debris disks are the signposts of planetary systems: collisions between rocky/icy parent bodies maintain debris dust around main sequence stars against losses to radiation pressure and P-R drag. Debris disk structures show the location of asteroid/Kuiper belts around nearby stars, and reflect dynamical interactions with local extrasolar planets. Only 17 debris disks with high optical depth have been spatially resolved to date in scattered light images made with the Hubble Space Telescope and ground-based adaptive optics. Hundreds more with lower optical depth have been identified among nearby stars through far-IR photometry with the Spitzer Space Telescope, and more should follow in the next few years from Herschel. The most capable means for imaging this larger disk population is a next-generation coronagraphic instrument on a 1.5m class optical space telescope. Utilizing high-contrasat imaging simulations validated by laboratory demonstrations on the JPL High Contrast Imaging Testbed, we show that such a mission will be capable of imaging Kuiper disk structures down to the 10 zodi level, and exozodiacal dust down to the 1 zodi level, around a major sample of nearby stars. This performance goes well beyond what is about to be achieved with upcoming extreme adaptive optics systems or the ALMA array, and thus provides the best path for imaging exploration of planetary systems in the solar neighborhood.

  9. CME dynamics using coronagraph and interplanetary ejecta data

    NASA Astrophysics Data System (ADS)

    Dal Lago, Alisson; Gonzalez, Walter D.; De Lucas, Aline; Braga, Carlos Roberto; Vieira, Lucas Ramos; Stekel, Tardelli Ronan Coelho; Rockenbach, Marlos

    2013-05-01

    In this work, we present a study of the coronal mass ejection (CME) dynamics using LASCO coronagraph observations combined with in-situ ACE plasma and magnetic field data, covering a continuous period of time from January 1997 to April 2001, complemented by few extreme events observed in 2001 and 2003. We show, for the first time, that the CME expansion speed correlates very well with the travel time to 1 AU of the interplanetary ejecta (or ICMEs) associated with the CMEs, as well as with their preceding shocks. The events analyzed in this work are a subset of the events studied in Schwenn et al. (2005), from which only the CMEs associated with interplanetary ejecta (ICMEs) were selected. Three models to predict CME travel time to Earth, two proposed by Gopalswamy et al. (2001) and one by Schwenn et al. (2005), were used to characterize the dynamical behavior of this set of events. Extreme events occurred in 2001 and 2003 were used to test the prediction capability of the models regarding CMEs with very high LASCO C3 speeds.

  10. Telescope polarization and image quality: Lyot coronagraph performance

    NASA Astrophysics Data System (ADS)

    Breckinridge, J. B.; Chipman, R. A.

    2016-07-01

    In this paper we apply a vector representation of physical optics, sometimes called polarization aberration theory to study image formation in astronomical telescopes and instruments. We describe image formation in-terms of interferometry and use the Fresnel polarization equations to show how light, upon propagation through an optical system become partially polarized. We make the observation that orthogonally polarized light does not interfere to form an intensity image. We show how the two polarization aberrations (diattenuation and and retardance) distort the system PSF, decrease transmittance, and increase unwanted background above that predicted using the nonphysical scalar models. We apply the polarization aberration theory (PolAbT) described earlier (Breckinridge, Lam and Chipman, 2015, PASP 127, 445-468) to the fore-optics of the system designed for AFTA-WFIRST- CGI to obtain a performance estimate. Analysis of the open-literature design using PolAbT leads us to estimate that the WFIRST-CGI contrast will be in the 10-5 regime at the occulting mask. Much above the levels predicted by others (Krist, Nemati and Mennesson, 2016, JATIS 2, 011003). Remind the reader: 1. Polarizers are operators, not filters in the same sense as colored filters, 2. Adaptive optics does not correct polarization aberrations, 3. Calculations of both diattenuation and retardance are needed to model real-world telescope/coronagraph systems.

  11. DESIGN OF PHASE INDUCED AMPLITUDE APODIZATION CORONAGRAPHS OVER SQUARE APERTURES

    SciTech Connect

    Pueyo, Laurent; Jeremy Kasdin, N.; Carlotti, Alexis; Vanderbei, Robert

    2011-08-01

    The purpose of this paper is to present the results of a theoretical study pertaining to the feasibility of Phase Induced Amplitude Apodization (PIAA) units using deformable mirrors (DMs). We begin by reviewing the general derivation of the design equations driving PIAA. We then show how to solve these equations for square apertures and show the performance of pure PIAA systems in the ray optics regime. We tie these design equations into the study of edge diffraction effects and provide a general expression for the field after a full propagation through a PIAA coronagraph. Third, we illustrate how a combination of pre- and post-apodizers yields a contrast of 10{sup -10} even in the presence of diffractive effects, for configuration with neither wavefront errors or wavefront control. Finally, we present novel PIAA configurations over square apertures which circumvent the constraints on the manufacturing of PIAA optics by inducing the apodization with two square DMs. Such solutions rely on pupil size smaller than currently envisioned static PIAA solutions and thus require aggressive pre- and post-apodizing screens in order to mitigate for diffractive effect between the two mirrors. As a result they are associated with significant loss in performance, throughput in particular.

  12. Vector vortex coronagraph: first results in the visible

    NASA Astrophysics Data System (ADS)

    Mawet, Dimitri; Trauger, John T.; Serabyn, Eugene; Moody, Dwight C., Jr.; Liewer, Kurt M.; Krist, John E.; Shemo, David M.; O'Brien, Nada A.

    2009-08-01

    We report the status of JPL and JDSU ongoing technological developments and contrast results of the vector vortex coronagraph (VVC) made out of liquid crystal polymers (LCP). The first topological charge 4 VVC was tested on the high contrast imaging testbed (HCIT) around 800 nm, under vacuum and with active wavefront control (32x32 Xinetics deformable mirror). We measured the inner working angle or IWA (50% off-axis transmission) at ~ 1.8λ/d. A one-sided dark hole ranging from 3λ/d to 10λ/d was created in polarized light, showing a mean contrast of ~ 2 × 10-7 over a 10% bandwidth. This contrast was maintained very close in (3 λ/d) in a reduced 2% bandwidth. These tests begin to demonstrate the potential of the LCP technology in the most demanding application of a space-based telescope dedicated to extrasolar planet characterization. The main limitations were identified as coming from incoherent sources such as multiple reflections, and residual chromaticity. A second generation of improved masks tackling these issues is being manufactured and will be tested on the HCIT in the coming months.

  13. Experimental validation of the high-order coronagraphic phase diversity (COFFEE) on the SPHERE system

    NASA Astrophysics Data System (ADS)

    Paul, Baptiste; Sauvage, Jean-François; Mugnier, Laurent M.; Dohlen, Kjetil; Mouillet, David; Fusco, Thierry; Beuzit, Jean-Luc; N'Diaye, Mamadou; Ferrari, Marc

    2013-09-01

    The final performance of current and future instruments dedicated to exoplanet detection and characterization (such as SPHERE on the VLT, GPI on Gemini North or future instruments on the E-ELT) is limited by intensity residuals in the scientific image plane, which originate in uncorrected optical aberrations. After correction of the atmospheric turbulence, the main contribution to these residuals comes from the quasi-static aberrations introduced upstream of the coronagraph. In order to measure and compensate for these aberrations, we propose a dedicated focal-plane sensor called COFFEE (for COronagraphic Focal-plane wave-Front Estimation for Exoplanet detection), which consists in an extension of conventional phase diversity to a coronagraphic system: aberrations both upstream and downstream of the coronagraph are estimated using two coronagraphic focal-plane images, recorded from the scientific camera itself, without any differential aberration. This communication gathers COFFEE's improvements: the phase estimation is performed on a pixel-wise map coupled with a dedicated regularization metric. This allows COFFEE to estimate very high order aberrations, making possible to estimate and compensate for quasi-static aberrations with nanometric precision, leading to an optimization of the contrast on the scientific detector in the whole AO corrected area. Besides, COFFEE has been modified so that it can be used with any coronagraphic focal plane mask. Lastly, we use COFFEE to measure and correct the wavefront on the SPHERE (Spectro-Polarimetric High-contrast Exoplanet Research) instrument during its integration phase: COFFEE's estimation is used to compensate for the quasi-static aberrations upstream of the coronagraph, leading to a contrast improvement on the scientific camera.

  14. Stop-less Lyot coronagraph for exoplanet characterization: first on-sky validation in VLT/SPHERE

    NASA Astrophysics Data System (ADS)

    Vigan, A.; N'Diaye, M.; Dohlen, K.; Beuzit, J.-L.; Costille, A.; Caillat, A.; Baruffolo, A.; Blanchard, P.; Carle, M.; Ferrari, M.; Fusco, T.; Gluck, L.; Hugot, E.; Jaquet, M.; Langlois, M.; Le Mignant, D.; Llored, M.; Madec, F.; Mouillet, D.; Origné, A.; Puget, P.; Salasnich, B.; Sauvage, J.-F.

    2016-07-01

    The VLT/SPHERE instrument includes a unique long-slit spectroscopy (LSS) mode coupled with Lyot coronagraphy dedicated to the spectral characterization of directly imaged giant exoplanets. The performance of this mode is limited by its non-optimal coronagraph, but in a previous work we demonstrated that it could be significantly improved at small inner-working angles using the stop-less Lyot coronagraph (SLLC). A prototype of the SLLC was installed in VLT/SPHERE in 2014 during the reintegration of the instrument in Paranal, and it was extensively tested in 2015 to characterize its performance. The performance is tested in both imaging and spectroscopy using data acquired on the internal source of SPHERE. In imaging, we obtain a raw contrast gain of a factor 10 at 0.3" with the SLLC. We also demonstrate that no Lyot stop is required to reach the full performance, which validates the SLLC concept. Comparison with a realistic simulation model shows that we are currently limited by the internal phase aberrations of SPHERE. In spectroscopy, we obtain a gain of 1 mag in a limited range of angular separations. Simulations show that although the main limitation comes from phase errors, the performance in the non-SLLC case is very close to the ultimate limit of the LSS mode. We present the very first on-sky data with the SLLC, which appear extremely promising for the future scientific exploitation of an apodized LSS mode in SPHERE. Finally, we explore a new possibility for the speckle subtraction in the LSS mode that could significantly improve the data analysis with respect to methods based on spectral differences.

  15. Shaped pupil Lyot coronagraphs: high-contrast solutions for restricted focal planes

    NASA Astrophysics Data System (ADS)

    Zimmerman, Neil T.; Eldorado Riggs, A. J.; Jeremy Kasdin, N.; Carlotti, Alexis; Vanderbei, Robert J.

    2016-01-01

    Coronagraphs of the apodized pupil and shaped pupil varieties use the Fraunhofer diffraction properties of amplitude masks to create regions of high contrast in the vicinity of a target star. Here we present a hybrid coronagraph architecture in which a binary, hard-edged shaped pupil mask replaces the gray, smooth apodizer of the apodized pupil Lyot coronagraph (APLC). For any contrast and bandwidth goal in this configuration, as long as the prescribed region of contrast is restricted to a finite area in the image, a shaped pupil is the apodizer with the highest transmission. We relate the starlight cancellation mechanism to that of the conventional APLC. We introduce a new class of solutions in which the amplitude profile of the Lyot stop, instead of being fixed as a padded replica of the telescope aperture, is jointly optimized with the apodizer. Finally, we describe shaped pupil Lyot coronagraph (SPLC) designs for the baseline architecture of the Wide-Field Infrared Survey Telescope-Astrophysics Focused Telescope Assets (WFIRST-AFTA) coronagraph. These SPLCs help to enable two scientific objectives of the WFIRST-AFTA mission: (1) broadband spectroscopy to characterize exoplanet atmospheres in reflected starlight and (2) debris disk imaging.

  16. The Vector Vortex Coronagraph: Sensitivity to Low-Order Aberrations, Central Obscuration, Chromaticism, and Polarization

    NASA Technical Reports Server (NTRS)

    Mawet, Dimitri; Pueyo, Laurent; Moody, Dwight; Krist, John; Serabyn, Eugene

    2010-01-01

    The Vector Vortex Coronagraph is a phase-based coronagraph, one of the most efficient in terms of inner working angle, throughput, discovery space, contrast, and simplicity. Using liquid-crystal polymer technology, this new coronagraph has recently been the subject of lab demonstrations in the near-infrared, visible and was also used on sky at the Palomar observatory in the H and K bands (1.65 and 2.2 micrometers, respectively) to image the brown dwarf companion to HR 7672, and the three extasolar planets around HR 8799. However, despite these recent successes, the Vector Vortex Coronagraph is, as are most coronagraphs, sensitive to the central obscuration and secondary support structures, low-order aberrations (tip-tilt, focus, etc), bandwidth (chromaticism), and polarization when image-plane wavefront sensing is performed. Here, we consider in detail these sensitivities as a function of the topological charge of the vortex and design properties inherent to the manufacturing technology, and show that in practice all of them can be mitigated to meet specific needs.

  17. Exoplanet Coronagraph Shaped Pupil Masks and Laboratory Scale Star Shade Masks: Design, Fabrication and Characterization

    NASA Technical Reports Server (NTRS)

    Balasubramanian, Kunjithapatha; White, Victor; Yee, Karl; Echternach, Pierre; Muller, Richard; Dickie, Matthew; Cady, Eric; Mejia Prada, Camilo; Ryan, Daniel; Poberezhskiy, Ilya; hide

    2015-01-01

    Star light suppression technologies to find and characterize faint exoplanets include internal coronagraph instruments as well as external star shade occulters. Currently, the NASA WFIRST-AFTA mission study includes an internal coronagraph instrument to find and characterize exoplanets. Various types of masks could be employed to suppress the host star light to about 10 -9 level contrast over a broad spectrum to enable the coronagraph mission objectives. Such masks for high contrast internal coronagraphic imaging require various fabrication technologies to meet a wide range of specifications, including precise shapes, micron scale island features, ultra-low reflectivity regions, uniformity, wave front quality, achromaticity, etc. We present the approaches employed at JPL to produce pupil plane and image plane coronagraph masks by combining electron beam, deep reactive ion etching, and black silicon technologies with illustrative examples of each, highlighting milestone accomplishments from the High Contrast Imaging Testbed (HCIT) at JPL and from the High Contrast Imaging Lab (HCIL) at Princeton University. We also present briefly the technologies applied to fabricate laboratory scale star shade masks.

  18. The Vector Vortex Coronagraph: sensitivity to central obscuration, low-order aberrations, chromaticism, and polarization

    NASA Astrophysics Data System (ADS)

    Mawet, Dimitri; Pueyo, Laurent; Moody, Dwight; Krist, John; Serabyn, Eugene

    2010-07-01

    The Vector Vortex Coronagraph is a phase-based coronagraph, one of the most efficient in terms of inner working angle, throughput, discovery space, contrast, and simplicity. Using liquid-crystal polymer technology, this new coronagraph has recently been the subject of lab demonstrations in the near-infrared, visible and was also used on sky at the Palomar observatory in the H and K bands (1.65 and 2.2 μm, respectively) to image the brown dwarf companion to HR 7672, and the three extra-solar planets around HR 8799. However, despite these recent successes, the Vector Vortex Coronagraph is, as are most coronagraphs, sensitive to the central obscuration and secondary support structures, low-order aberrations (tip-tilt, focus, etc), bandwidth (chromaticism), and polarization when image-plane wavefront sensing is performed. Here, we consider in detail these sensitivities as a function of the topological charge of the vortex and design features inherent to the manufacturing technology, and show that in practice all of them can be mitigated to meet specific needs.

  19. Exoplanet coronagraph shaped pupil masks and laboratory scale star shade masks: design, fabrication and characterization

    NASA Astrophysics Data System (ADS)

    Balasubramanian, Kunjithapatham; White, Victor; Yee, Karl; Echternach, Pierre; Muller, Richard; Dickie, Matthew; Cady, Eric; Mejia Prada, Camilo; Ryan, Daniel; Poberezhskiy, Ilya; Zhou, Hanying; Kern, Brian; Riggs, A. J.; Zimmerman, Neil T.; Sirbu, Dan; Shaklan, Stuart; Kasdin, Jeremy

    2015-09-01

    Star light suppression technologies to find and characterize faint exoplanets include internal coronagraph instruments as well as external star shade occulters. Currently, the NASA WFIRST-AFTA mission study includes an internal coronagraph instrument to find and characterize exoplanets. Various types of masks could be employed to suppress the host star light to about 10-9 level contrast over a broad spectrum to enable the coronagraph mission objectives. Such masks for high contrast internal coronagraphic imaging require various fabrication technologies to meet a wide range of specifications, including precise shapes, micron scale island features, ultra-low reflectivity regions, uniformity, wave front quality, achromaticity, etc. We present the approaches employed at JPL to produce pupil plane and image plane coronagraph masks by combining electron beam, deep reactive ion etching, and black silicon technologies with illustrative examples of each, highlighting milestone accomplishments from the High Contrast Imaging Testbed (HCIT) at JPL and from the High Contrast Imaging Lab (HCIL) at Princeton University. We also present briefly the technologies applied to fabricate laboratory scale star shade masks.

  20. RING-APODIZED VORTEX CORONAGRAPHS FOR OBSCURED TELESCOPES. I. TRANSMISSIVE RING APODIZERS

    SciTech Connect

    Mawet, D.; Pueyo, L.; Carlotti, A.; Mennesson, B.; Serabyn, E.; Wallace, J. K.

    2013-11-01

    The vortex coronagraph (VC) is a new generation small inner working angle (IWA) coronagraph currently offered on various 8 m class ground-based telescopes. On these observing platforms, the current level of performance is not limited by the intrinsic properties of actual vortex devices, but by wavefront control residuals and incoherent background (e.g., thermal emission of the sky), or the light diffracted by the imprint of the secondary mirror and support structures on the telescope pupil. In the particular case of unfriendly apertures (mainly large central obscuration) when very high contrast is needed (e.g., direct imaging of older exoplanets with extremely large telescopes or space-based coronagraphs), a simple VC, like most coronagraphs, cannot deliver its nominal performance because of the contamination due to the diffraction from the obscured part of the pupil. Here, we propose a novel yet simple concept that circumvents this problem. We combine a vortex phase mask in the image plane of a high-contrast instrument with a single pupil-based amplitude ring apodizer, tailor-made to exploit the unique convolution properties of the VC at the Lyot-stop plane. We show that such a ring-apodized vortex coronagraph (RAVC) restores the perfect attenuation property of the VC regardless of the size of the central obscuration, and for any (even) topological charge of the vortex. More importantly, the RAVC maintains the IWA and conserves a fairly high throughput, which are signature properties of the VC.

  1. Technologies Required to Image Earth 2.0 with a Space Coronagraph

    NASA Astrophysics Data System (ADS)

    Siegler, Nicholas

    2017-01-01

    NASA's Exoplanet Exploration Program (ExEP) guides the development of technology that enables the direct imaging and characterization of exo-Earths in the habitable zone of their stars for future space observatories. Here we present the coronagraph portion of the 2017 ExEP Technology Gap List, an annual update to ExEP's list of of technologies, to be advanced in the next 1-5 years. A coronagraph is an internal occulter that allows a space telescope to achieve exo-Earth imaging contrast requirements (more than 10 billion) by blocking on-axis starlight while allowing the reflected light of off-axis exoplanets be detected. Building and operating a space coronagraph capable of imaging an exo-Earth will require new technologies beyond those of WFIRST, the first high-contrast conronagraph in space. We review the current state-of-the-art performance of space coronagraphs and the performance level that must be achieved for a coronagraph..

  2. The Vector Vortex Coronagraph: Sensitivity to Low-Order Aberrations, Central Obscuration, Chromaticism, and Polarization

    NASA Technical Reports Server (NTRS)

    Mawet, Dimitri; Pueyo, Laurent; Moody, Dwight; Krist, John; Serabyn, Eugene

    2010-01-01

    The Vector Vortex Coronagraph is a phase-based coronagraph, one of the most efficient in terms of inner working angle, throughput, discovery space, contrast, and simplicity. Using liquid-crystal polymer technology, this new coronagraph has recently been the subject of lab demonstrations in the near-infrared, visible and was also used on sky at the Palomar observatory in the H and K bands (1.65 and 2.2 micrometers, respectively) to image the brown dwarf companion to HR 7672, and the three extasolar planets around HR 8799. However, despite these recent successes, the Vector Vortex Coronagraph is, as are most coronagraphs, sensitive to the central obscuration and secondary support structures, low-order aberrations (tip-tilt, focus, etc), bandwidth (chromaticism), and polarization when image-plane wavefront sensing is performed. Here, we consider in detail these sensitivities as a function of the topological charge of the vortex and design properties inherent to the manufacturing technology, and show that in practice all of them can be mitigated to meet specific needs.

  3. The ROCKSTAR Phase-space Temporal Halo Finder and the Velocity Offsets of Cluster Cores

    NASA Astrophysics Data System (ADS)

    Behroozi, Peter S.; Wechsler, Risa H.; Wu, Hao-Yi

    2013-01-01

    We present a new algorithm for identifying dark matter halos, substructure, and tidal features. The approach is based on adaptive hierarchical refinement of friends-of-friends groups in six phase-space dimensions and one time dimension, which allows for robust (grid-independent, shape-independent, and noise-resilient) tracking of substructure; as such, it is named ROCKSTAR (Robust Overdensity Calculation using K-Space Topologically Adaptive Refinement). Our method is massively parallel (up to 105 CPUs) and runs on the largest current simulations (>1010 particles) with high efficiency (10 CPU hours and 60 gigabytes of memory required per billion particles analyzed). A previous paper has shown ROCKSTAR to have excellent recovery of halo properties; we expand on these comparisons with more tests and higher-resolution simulations. We show a significant improvement in substructure recovery compared to several other halo finders and discuss the theoretical and practical limits of simulations in this regard. Finally, we present results that demonstrate conclusively that dark matter halo cores are not at rest relative to the halo bulk or substructure average velocities and have coherent velocity offsets across a wide range of halo masses and redshifts. For massive clusters, these offsets can be up to 350 km s-1 at z = 0 and even higher at high redshifts. Our implementation is publicly available at http://code.google.com/p/rockstar.

  4. Terrestrial Planet Finder: Coda to 10 Years of Technology Development

    NASA Technical Reports Server (NTRS)

    Lawson, Peter R.

    2009-01-01

    The Terrestrial Planet Finder (TPF) was proposed as a mission concept to the 2000 Decadal Survey, and received a very high ranking amongst the major initiatives that were then reviewed. As proposed, it was a formation flying array of four 3-m class mid-infrared telescopes, linked together as an interferometer. Its science goal was to survey 150 nearby stars for the presence of Earth-like planets, to detect signs of life or habitability, and to enable revolutionary advances in high angular resolution astrophysics. The Decadal Survey Committee recommended that $200M be invested to advance TPF technology development in the Decade of 2000-2010. This paper presents the results of NASA's investment.

  5. Design for a source-agile automatic direction finder (ADF)

    NASA Astrophysics Data System (ADS)

    Myler, Harley

    2015-05-01

    The design is intended for aircraft although any vehicle or even a man-mobile system could use the concept. An automatically reconfigurable antenna using MEMS RF switches is driven to seek signals consistent with the current location of the system. The antenna feeds a Software Defined Radio (SDR) that scans for signals and when a signal is found, it is identified and then the azimuth to the signal is used, along with a signal strength parameter, to confirm the location of the system. This is an extension of the now obsolete Automatic Direction Finder (ADF) aircraft navigation tool that used AM broadcast non-directional beacons (NDB), many of which are still in service. The current system can access any radio signal within the limits of the reconfigurable antenna and the SDR.

  6. Terrestrial Planet Finder: Coda to 10 Years of Technology Development

    NASA Technical Reports Server (NTRS)

    Lawson, Peter R.

    2009-01-01

    The Terrestrial Planet Finder (TPF) was proposed as a mission concept to the 2000 Decadal Survey, and received a very high ranking amongst the major initiatives that were then reviewed. As proposed, it was a formation flying array of four 3-m class mid-infrared telescopes, linked together as an interferometer. Its science goal was to survey 150 nearby stars for the presence of Earth-like planets, to detect signs of life or habitability, and to enable revolutionary advances in high angular resolution astrophysics. The Decadal Survey Committee recommended that $200M be invested to advance TPF technology development in the Decade of 2000-2010. This paper presents the results of NASA's investment.

  7. Echo tracker/range finder for radars and sonars

    NASA Technical Reports Server (NTRS)

    Constantinides, N. J. (Inventor)

    1982-01-01

    An echo tracker/range finder or altimeter is described. The pulse repetition frequency (PFR) of a predetermined plurality of transmitted pulses is adjusted so that echo pulses received from a reflecting object are positioned between transmitted pulses and divided their interpulse time interval into two time intervals having a predetermined ratio with respect to each other. The invention described provides a means whereby the arrival time of a plurality of echo pulses is defined as the time at which a composite echo pulse formed of a sum of the individual echo pulses has the highest amplitude. The invention is applicable to radar systems, sonar systems, or any other kind of system in which pulses are transmitted and echoes received therefrom.

  8. Electromagnetic formation flight for the Terrestrial Planet Finder

    NASA Astrophysics Data System (ADS)

    Kwon, Daniel W.; Miller, David W.

    2005-08-01

    Current techniques for actuating spacecraft in formation flying systems such as NASA's Terrestrial Planet Finder (TPF) use propellant-based systems. While maintaining relative orientation, propellant can become a critical consumable which can limit the mission lifetime. Additionally, propellant can cause optimal contamination, plume impingement, thermal emission, and vibration excitation. A novel technique called Electromagnetic Formation Flight (EMFF) can be used to eliminate propellant-based systems to control the relative degrees of freedom for TPF. The EMFF system consists of electromagnets in concert with reaction wheels and is used to replace the consumables. Solar energy, a renewable resource provides power for EMFF. This paper investigates the design for TPF using EMFF. The results show that EMFF is a viable option for TPF and compares favorably in terms of mass to propellant-based systems.

  9. Terrestrial Planet Finder Interferometer Science Working Group Report

    NASA Technical Reports Server (NTRS)

    Lawson, Peter R. (Editor); Lay, Oliver P. (Editor); Johnston, Kenneth J. (Editor); Beichman, Charles A. (Editor)

    2007-01-01

    Over the past two years, the focus of the project for the interferometric version of the Terrestrial Planet Finder(TPF-I) has been on the development of the scientific rational for the mission, the assessment of TPF-I architectures, the laboratory demonstration of key technologies, and the development of a detailed technology roadmap. The Science Working Group (SWG), in conjunction with European colleagues working on the European Space Agency's (ESA's) Darwin project, has reaffirmed the goals of TPF-I as part of a broad vision for the detection and characterization of Earth-like planets orbiting nearby stars and for the search for life on those planets. The SWG also helped to assess the performance of different interferometric configurations for TPF-I/Darwin. Building on earlier SWG reports, this document restates the scientific case for TPF-I, assesses suitable target stars and relevant wavelengths for observation, discusses dramatic new capabilities for general astrophysical observations, and summarizes how Spitzer has improved our knowledge of the incidence of zodiacal emission on the search for planets. This document discusses in some detail on laboratory advances in interferometric nulling and formation flying. Laboratory experiments have now achieved stable narrow- and broad-band nulling the levels of 10-6 and 2.0x10-5, respectively. A testbed has demonstrated formation flying using two realistic spacecraft mockups. With a suitably funded program of technology development, as summarized herein and described in more detail in the Technology Plan for the Terrestrial Planet Finder Interferometer (2005), the National Aeronautics and Space Administration (NASA) and ESA would be able to start within the coming decade a full-scale TPF-I/Darwin mission capable of finding Earths orbiting more than 150 nearby stars, or a scaled back interferometer capable of studying more than 30 stars. Finding evidence for life on just one of those planets would revolutionize our

  10. Laser Range and Bearing Finder with No Moving Parts

    NASA Technical Reports Server (NTRS)

    Bryan, Thomas C.; Howard, Richard T.; Book, Michael L.

    2007-01-01

    A proposed laser-based instrument would quickly measure the approximate distance and approximate direction to the closest target within its field of view. The instrument would not contain any moving parts and its mode of operation would not entail scanning over of its field of view. Typically, the instrument would be used to locate a target at a distance on the order of meters to kilometers. The instrument would be best suited for use in an uncluttered setting in which the target is the only or, at worst, the closest object in the vicinity; for example, it could be used aboard an aircraft to detect and track another aircraft flying nearby. The proposed instrument would include a conventional time-of-flight or echo-phase-shift laser range finder, but unlike most other range finders, this one would not generate a narrow cylindrical laser beam; instead, it would generate a conical laser beam spanning the field of view. The instrument would also include a quadrant detector, optics to focus the light returning from the target onto the quadrant detector, and circuitry to synchronize the acquisition of the quadrant-detector output with the arrival of laser light returning from the nearest target. A quadrant detector constantly gathers information from the entire field of view, without scanning; its output is a direct measure of the position of the target-return light spot on the focal plane and is thus a measure of the direction to the target. The instrument should be able to operate at a repetition rate high enough to enable it to track a rapidly moving target. Of course, a target that is not sufficiently reflective could not be located by this instrument. Preferably, retroreflectors should be attached to the target to make it sufficiently reflective.

  11. Terrestrial Planet Finder Interferometer Science Working Group Report

    NASA Technical Reports Server (NTRS)

    Lawson, Peter R. (Editor); Lay, Oliver P. (Editor); Johnston, Kenneth J. (Editor); Beichman, Charles A. (Editor)

    2007-01-01

    Over the past two years, the focus of the project for the interferometric version of the Terrestrial Planet Finder(TPF-I) has been on the development of the scientific rational for the mission, the assessment of TPF-I architectures, the laboratory demonstration of key technologies, and the development of a detailed technology roadmap. The Science Working Group (SWG), in conjunction with European colleagues working on the European Space Agency's (ESA's) Darwin project, has reaffirmed the goals of TPF-I as part of a broad vision for the detection and characterization of Earth-like planets orbiting nearby stars and for the search for life on those planets. The SWG also helped to assess the performance of different interferometric configurations for TPF-I/Darwin. Building on earlier SWG reports, this document restates the scientific case for TPF-I, assesses suitable target stars and relevant wavelengths for observation, discusses dramatic new capabilities for general astrophysical observations, and summarizes how Spitzer has improved our knowledge of the incidence of zodiacal emission on the search for planets. This document discusses in some detail on laboratory advances in interferometric nulling and formation flying. Laboratory experiments have now achieved stable narrow- and broad-band nulling the levels of 10-6 and 2.0x10-5, respectively. A testbed has demonstrated formation flying using two realistic spacecraft mockups. With a suitably funded program of technology development, as summarized herein and described in more detail in the Technology Plan for the Terrestrial Planet Finder Interferometer (2005), the National Aeronautics and Space Administration (NASA) and ESA would be able to start within the coming decade a full-scale TPF-I/Darwin mission capable of finding Earths orbiting more than 150 nearby stars, or a scaled back interferometer capable of studying more than 30 stars. Finding evidence for life on just one of those planets would revolutionize our

  12. THERMAL STRUCTURE OF CORONAL LOOPS AS SEEN WITH NORIKURA CORONAGRAPH

    SciTech Connect

    Prasad, S. Krishna; Singh, Jagdev; Ichimoto, K.

    2013-03-10

    The thermal structure of a coronal loop, both along and across the loop, is vital in determining the exact plasma heating mechanism. High-resolution spectroscopic observations of the off-limb corona were made using the 25 cm Norikura coronagraph, located at Norikura, Japan. Observations on a number of days were made simultaneously in four forbidden iron emission lines, namely, the [Fe XI] 7892 A line, the [Fe XIII] 10747 A and 10798 A lines, and the [Fe XIV] 5303 A line and on some days made only in the [Fe XI] 7892 A and [Fe X] 6374 A lines. Using temperature sensitive emission line ratios [Fe XIV] 5303 A/[Fe XIII] 10747 A and [Fe XI] 7892 A/[Fe X] 6374 A, we compute the electron temperatures along 18 different loop structures observed on different days. We find a significant negative temperature gradient in all of the structures observed in Fe XIV and Fe XIII and a positive temperature gradient in the structures observed in Fe XI and Fe X. Combining these results with the previous investigations by Singh and his collaborators, we infer that the loop tops, in general, appear hotter when observed in colder lines and colder when observed in relatively hotter lines as compared to their coronal foot points. We suggest that this contrasting trend observed in the temperature variation along the loop structures can be explained by a gradual interaction of different temperature plasma. The exact mechanism responsible for this interaction must be investigated further and has the potential to constrain loop heating models.

  13. An Overview of the Formation and Attitude Control System for the Terrestrial Planet Finder Formation Flying Interferometer

    NASA Technical Reports Server (NTRS)

    Scharf, Daniel P.; Hadaegh, Fred Y.; Rahman, Zahidul H.; Shields, Joel F.; Singh, Gurkipal; Wette, Matthew R.

    2004-01-01

    The Terrestrial Planet Finder formation flying Interferometer (TPF-I) will be a five-spacecraft, precision formation operating near the second Sun-Earth Lagrange point. As part of technology development for TPF-I, a formation and attitude control system (FACS) is being developed that achieves the precision and functionality needed for the TPF-I formation and that will be demonstrated in a distributed, real-time simulation environment. In this paper we present an overview of FACS and discuss in detail its formation estimation, guidance and control architectures and algorithms. Since FACS is currently being integrated into a high-fidelity simulation environment, component simulations demonstrating algorithm performance are presented.

  14. An Overview of the Formation and Attitude Control System for the Terrestrial Planet Finder Formation Flying Interferometer

    NASA Technical Reports Server (NTRS)

    Scharf, Daniel P.; Hadaegh, Fred Y.; Rahman, Zahidul H.; Shields, Joel F.; Singh, Gurkipal

    2004-01-01

    The Terrestrial Planet Finder formation flying Interferometer (TPF-I) will be a five-spacecraft, precision formation operating near a Sun-Earth Lagrange point. As part of technology development for TPF-I, a formation and attitude control system (FACS) is being developed that achieves the precision and functionality associated with the TPF-I formation. This FACS will be demonstrated in a distributed, real-time simulation environment. In this paper we present an overview of the FACS and discuss in detail its constituent formation estimation, guidance and control architectures and algorithms. Since the FACS is currently being integrated into a high-fidelity simulation environment, component simulations demonstrating algorithm performance are presented.

  15. An Overview of the Formation and Attitude Control System for the Terrestrial Planet Finder Formation Flying Interferometer

    NASA Technical Reports Server (NTRS)

    Scharf, Daniel P.; Hadaegh, Fred Y.; Rahman, Zahidul H.; Shields, Joel F.; Singh, Gurkipal

    2004-01-01

    The Terrestrial Planet Finder formation flying Interferometer (TPF-I) will be a five-spacecraft, precision formation operating near a Sun-Earth Lagrange point. As part of technology development for TPF-I, a formation and attitude control system (FACS) is being developed that achieves the precision and functionality associated with the TPF-I formation. This FACS will be demonstrated in a distributed, real-time simulation environment. In this paper we present an overview of the FACS and discuss in detail its constituent formation estimation, guidance and control architectures and algorithms. Since the FACS is currently being integrated into a high-fidelity simulation environment, component simulations demonstrating algorithm performance are presented.

  16. Science yield estimate with the Wide-Field Infrared Survey Telescope coronagraph

    NASA Astrophysics Data System (ADS)

    Traub, Wesley A.; Breckinridge, James; Greene, Thomas P.; Guyon, Olivier; Jeremy Kasdin, N.; Macintosh, Bruce

    2016-01-01

    The coronagraph instrument (CGI) on the Wide-Field Infrared Survey Telescope will directly image and spectrally characterize planets and circumstellar disks around nearby stars. Here we estimate the expected science yield of the CGI for known radial-velocity (RV) planets and potential circumstellar disks. The science return is estimated for three types of coronagraphs: the hybrid Lyot and shaped pupil are the currently planned designs, and the phase-induced amplitude apodizing complex mask coronagraph is the backup design. We compare the potential performance of each type for imaging as well as spectroscopy. We find that the RV targets can be imaged in sufficient numbers to produce substantial advances in the science of nearby exoplanets. To illustrate the potential for circumstellar disk detections, we estimate the brightness of zodiacal-type disks, which could be detected simultaneously during RV planet observations.

  17. Method for reducing sidelobe impact of low order aberration in a coronagraph

    NASA Technical Reports Server (NTRS)

    Ftaclas, Christ (Inventor); Crout, Robert R. (Inventor)

    1995-01-01

    The invention relates to a method for reducing a sidelobe impact of low order aberrations using a coronagraph (2) having an apodized occulting mask (10), comprising the steps of: (a) providing in the coronagraph (2) the apodized occulting disk (10) having a transmission profile which graduates from opaque to transparent along its radius and the negative of whose amplitude transmission is a Gaussian profile; (b) determining a predicted sidelobe impact of the aberrations from a particular mix of low order aberration measured in a system as described by the Zernike polynomials; (c) applying the coronagraph to a system point spread function using a given rms width for the Gaussian profile describing the apodized occulting mask (10) and determining an attenuation level of the aberration sidelobes; (d) scaling the Gaussian occulting mask (10) profile to a wider rms width if the sidelobe attenuation level is too low; and (e) repeating the steps (b) through (d) until the attenuation level is acceptable.

  18. Assessing the Performance Limits of Internal Coronagraphs Through End-to-End Modeling

    NASA Technical Reports Server (NTRS)

    Krist, John E.; Belikov, Ruslan; Pueyo, Laurent; Mawet, Dimitri P.; Moody, Dwight; Trauger, John T.; Shaklan, Stuart B.

    2013-01-01

    As part of the NASA ROSES Technology Demonstrations for Exoplanet Missions (TDEM) program, we conducted a numerical modeling study of three internal coronagraphs (PIAA, vector vortex, hybrid bandlimited) to understand their behaviors in realistically-aberrated systems with wavefront control (deformable mirrors). This investigation consisted of two milestones: (1) develop wavefront propagation codes appropriate for each coronagraph that are accurate to 1% or better (compared to a reference algorithm) but are also time and memory efficient, and (2) use these codes to determine the wavefront control limits of each architecture. We discuss here how the milestones were met and identify some of the behaviors particular to each coronagraph. The codes developed in this study are being made available for community use. We discuss here results for the HBLC and VVC systems, with PIAA having been discussed in a previous proceeding.

  19. Assessing the Performance Limits of Internal Coronagraphs Through End-to-End Modeling

    NASA Technical Reports Server (NTRS)

    Krist, John E.; Belikov, Ruslan; Pueyo, Laurent; Mawet, Dimitri P.; Moody, Dwight; Trauger, John T.; Shaklan, Stuart B.

    2013-01-01

    As part of the NASA ROSES Technology Demonstrations for Exoplanet Missions (TDEM) program, we conducted a numerical modeling study of three internal coronagraphs (PIAA, vector vortex, hybrid bandlimited) to understand their behaviors in realistically-aberrated systems with wavefront control (deformable mirrors). This investigation consisted of two milestones: (1) develop wavefront propagation codes appropriate for each coronagraph that are accurate to 1% or better (compared to a reference algorithm) but are also time and memory efficient, and (2) use these codes to determine the wavefront control limits of each architecture. We discuss here how the milestones were met and identify some of the behaviors particular to each coronagraph. The codes developed in this study are being made available for community use. We discuss here results for the HBLC and VVC systems, with PIAA having been discussed in a previous proceeding.

  20. On the 3-D reconstruction of Coronal Mass Ejections using coronagraph data

    NASA Astrophysics Data System (ADS)

    Mierla, M.; Inhester, B.; Antunes, A.; Boursier, Y.; Byrne, J. P.; Colaninno, R.; Davila, J.; de Koning, C. A.; Gallagher, P. T.; Gissot, S.; Howard, R. A.; Howard, T. A.; Kramar, M.; Lamy, P.; Liewer, P. C.; Maloney, S.; Marqué, C.; McAteer, R. T. J.; Moran, T.; Rodriguez, L.; Srivastava, N.; St. Cyr, O. C.; Stenborg, G.; Temmer, M.; Thernisien, A.; Vourlidas, A.; West, M. J.; Wood, B. E.; Zhukov, A. N.

    2010-01-01

    Coronal Mass ejections (CMEs) are enormous eruptions of magnetized plasma expelled from the Sun into the interplanetary space, over the course of hours to days. They can create major disturbances in the interplanetary medium and trigger severe magnetic storms when they collide with the Earth's magnetosphere. It is important to know their real speed, propagation direction and 3-D configuration in order to accurately predict their arrival time at the Earth. Using data from the SECCHI coronagraphs onboard the STEREO mission, which was launched in October 2006, we can infer the propagation direction and the 3-D structure of such events. In this review, we first describe different techniques that were used to model the 3-D configuration of CMEs in the coronagraph field of view (up to 15 R⊙). Then, we apply these techniques to different CMEs observed by various coronagraphs. A comparison of results obtained from the application of different reconstruction algorithms is presented and discussed.

  1. Coronagraphic search for exo-planets with a hypertelescope. I. In the thermal IR

    NASA Astrophysics Data System (ADS)

    Riaud, P.; Boccaletti, A.; Gillet, S.; Schneider, J.; Labeyrie, A.; Arnold, L.; Baudrand, J.; Lardiè, O.; Dejonghe, J.; Borkowski, V.

    2002-12-01

    Following the idea developed in Boccaletti et al. (2000), a snapshot imaging interferometer is proposed as an alternative to the nulling interferometer for the NASA Origin project, ``Terrestrial Planet Finder". This concept is based on hypertelescope, i.e. densified-pupil, imaging (Labeyrie \\cite{l96}) and phase-mask coronagraphy (Rouan et al. \\cite{ro00}) to combine a very high angular resolution and a deep attenuation of starlight (10-8) as required to image extra-terrestrial planets. This article aims at presenting thorough estimations of the signal to noise ratio for different classes of stars (from F0V to M5V) and includes several sources of background noise (zodiacal and exozodiacal lights for instance). In addition, numerical simulations have been carried out and are compared to the analytical results. We find that the image of Earth-like planets can be formed with a large hypertelescope ( ~ 80 m) in the thermal infra-red for about 73% of the stars within 25pc. The Appendix is only available in electonic form at http://www.edpsciences.org

  2. Design of vein finder with multi tuning wavelength using RGB LED

    NASA Astrophysics Data System (ADS)

    Chandra, Franky; Wahyudianto, Aries; Yasin, M.

    2017-05-01

    Detection of intra vena is very important technique in the medical clinic applications. For intravenous detection, some nurses usually have a mistake which can cause a pain or injured to the patient. When the nurses are headed with this problem, it becomes dangerous for the patient. To solve the problem, in this paper, vein finder with multi-tuning wavelength for intra vena detection is proposed and investigated. Vein finder is tested to various skin colour and body mass. The results show that vein finder was successfully designed with controllable wavelength in the range of 600-696 nm using RGB LED.

  3. Optimizing the subwavelength grating of L-band annular groove phase masks for high coronagraphic performance

    NASA Astrophysics Data System (ADS)

    Vargas Catalán, E.; Huby, E.; Forsberg, P.; Jolivet, A.; Baudoz, P.; Carlomagno, B.; Delacroix, C.; Habraken, S.; Mawet, D.; Surdej, J.; Absil, O.; Karlsson, M.

    2016-11-01

    Context. The annular groove phase mask (AGPM) is one possible implementation of the vector vortex coronagraph, where the helical phase ramp is produced by a concentric subwavelength grating. For several years, we have been manufacturing AGPMs by etching gratings into synthetic diamond substrates using inductively coupled plasma etching. Aims: We aim to design, fabricate, optimize, and evaluate new L-band AGPMs that reach the highest possible coronagraphic performance, for applications in current and forthcoming infrared high-contrast imagers. Methods: Rigorous coupled wave analysis (RCWA) is used for designing the subwavelength grating of the phase mask. Coronagraphic performance evaluation is performed on a dedicated optical test bench. The experimental results of the performance evaluation are then used to accurately determine the actual profile of the fabricated gratings, based on RCWA modeling. Results: The AGPM coronagraphic performance is very sensitive to small errors in etch depth and grating profile. Most of the fabricated components therefore show moderate performance in terms of starlight rejection (a few 100:1 in the best cases). Here we present new processes for re-etching the fabricated components in order to optimize the parameters of the grating and hence significantly increase their coronagraphic performance. Starlight rejection up to 1000:1 is demonstrated in a broadband L filter on the coronagraphic test bench, which corresponds to a raw contrast of about 10-5 at two resolution elements from the star for a perfect input wave front on a circular, unobstructed aperture. Conclusions: Thanks to their exquisite performance, our latest L-band AGPMs are good candidates for installation in state of the art and future high-contrast thermal infrared imagers, such as METIS for the E-ELT.

  4. Photographic coronagraph, Skylab particulate experiment T025. [earth atmospheric pollution and Kohoutek Comet monitoring

    NASA Technical Reports Server (NTRS)

    Giovane, F.; Schuerman, D. W.; Greenberg, J. M.

    1977-01-01

    A photographic coronagraph, built to monitor Skylab's extravehicular contamination, is described. This versatile instrument was used to observe the earth's vertical aerosol distribution and Comet Kohoutek (1973f) near perihelion. Although originally designed for deployment from the solar airlock, the instrument was modified for EVA operation when the airlock was rendered unusable. The results of the observations made in four EVA's were almost completely ruined by the failure of a Skylab operational camera used with the coronagraph. Nevertheless, an aerosol layer at 48 km was discovered in the southern hemisphere from the few useful photographs.

  5. Utilizing Astrometric Orbits to Obtain Coronagraphic Images of Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Davidson, John M.

    2011-08-01

    this target pool with a probability of unity and that the maximum number of visits required (i.e., the worst case) is 36 visits. The probable number of visits is considerably smaller, about 18. This is a dramatic improvement in efficiency over previous methods proposed for utilizing astrometric orbits. We examine how the implementation of this approach is complicated and limited by operational constraints and how it is impacted by formal errors. We find that it can be fully implemented for internal coronagraph and visual nuller missions, with a success rate approaching 100%. External occulter missions will also benefit, but to a lesser degree.

  6. Progress in four-beam nulling: results from the Terrestrial Planet Finder Planet Detection Testbed

    NASA Technical Reports Server (NTRS)

    Martin, Stefan

    2006-01-01

    The Terrestrial Planet Finder Interferometer (TPF-I) is a large space telescope consisting of four 4 meter diameter telescopes flying in formation in space together with a fifth beam combiner spacecraft.

  7. Progress in four-beam nulling: results from the Terrestrial Planet Finder planet detection testbed

    NASA Technical Reports Server (NTRS)

    Martin, Stefan

    2006-01-01

    The Terrestrial Planet Finder Interferometer (TPF-I) is a large space telescope consisting of four 4 meter diameter telescopes flying in formation in space together with a fifth beam combiner spacecraft.

  8. Recognition of three dimensional obstacles by an edge detection scheme. [for Mars roving vehicle using laser range finder

    NASA Technical Reports Server (NTRS)

    Reed, M. A.

    1974-01-01

    The need for an obstacle detection system on the Mars roving vehicle was assumed, and a practical scheme was investigated and simulated. The principal sensing device on this vehicle was taken to be a laser range finder. Both existing and original algorithms, ending with thresholding operations, were used to obtain the outlines of obstacles from the raw data of this laser scan. A theoretical analysis was carried out to show how proper value of threshold may be chosen. Computer simulations considered various mid-range boulders, for which the scheme was quite successful. The extension to other types of obstacles, such as craters, was considered. The special problems of bottom edge detection and scanning procedure are discussed.

  9. Experimental study of a low-order wavefront sensor for high-contrast coronagraphic imagers: results in air and in vacuum

    NASA Astrophysics Data System (ADS)

    Lozi, Julien; Belikov, Ruslan; Thomas, Sandrine J.; Pluzhnik, Eugene; Bendek, Eduardo; Guyon, Olivier; Schneider, Glenn

    2014-08-01

    For the technology development of the mission EXCEDE (EXoplanetary Circumstellar Environments and Disk Explorer)—a 0.7 m telescope equipped with a Phase-Induced Amplitude Apodization Coronagraph (PIAA- C) and a 2000-element MEMS deformable mirror, capable of raw contrasts of 10-6 at 1.2 λ/D and 10-7 above 2 λ /D — we developed two test benches simulating its key components, one in air, the other in vacuum. To achieve this level of contrast, one of the main goals is to remove low-order aberrations, using a Low-Order WaveFront Sensor (LOWFS). We tested this key component, together with the coronagraph and the wavefront control, in air at NASA Ames Research Center and in vacuum at Lockheed Martin. The LOWFS, controlling tip/tilt modes in real time at 1 kHz, allowed us to reduce the disturbances in air to 10-3 λ/D rms, letting us achieve a contrast of 2.8×10-7 between 1.2 and 2 λ/D. Tests are currently being performed to achieve the same or a better level of correction in vacuum. With those results, and by comparing them to simulations, we are able to deduce its performances on different coronagraphs— different sizes of telescopes, inner working angles, contrasts, etc. — and therefore study its contribution beyond EXCEDE.

  10. Path Length Control in a Nulling Coronagraph with a MEMS Deformable Mirror and a Calibration Interferometer

    NASA Technical Reports Server (NTRS)

    Rao, Shanti R.; Wallacea, J. Kent; Samuele, Rocco; Chakrabarti, Supriya; Cook, Timothy; Hicks, Brian; Jung, Paul; Lane, Benjamin; Levine, B. Martin; Mendillo, Chris; hide

    2008-01-01

    We report progress on a nulling coronagraph intended for direct imaging of extrasolar planets. White light is suppressed in an interferometer, and phase errors are measured by a second interferometer. A 1020-pixel MEMS deformable mirror in the first interferometer adjusts the path length across the pupil. A feedback control system reduces deflections of the deformable mirror to order of 1 nm rms.

  11. Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (PISCES) for WFIRST/AFTA

    NASA Technical Reports Server (NTRS)

    Gong, Qian; Mcelwain, Michael; Greeley, Bradford; Grammer, Bryan; Marx, Catherine; Memarsadeghi, Nargess; Stapelfeldt, Karl; Hilton, George; Sayson, Jorge Llop; Perrin, Marshall; hide

    2015-01-01

    Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (PISCES) is a lenslet array based integral field spectrometer (IFS) designed for high contrast imaging of extrasolar planets. PISCES will be used to advance the technology readiness of the high contrast IFS baselined on the Wide-Field InfraRed Survey Telescope/Astrophysics Focused Telescope Assets (WFIRST/AFTA) coronagraph instrument. PISCES will be integrated into the high contrast imaging testbed (HCIT) at the Jet Propulsion Laboratory and will work with both the Hybrid Lyot Coronagraph (HLC) and the Shaped Pupil Coronagraph (SPC) cofigurations. We discuss why the lenslet array based IFS is selected for PISCES. We present the PISCES optical design, including the similarities and differences of lenslet based IFSs to normal spectrometers, the trade-off between a refractive design and reflective design, as well as the specific function of our pinhole mask on the back surface of the lenslet array to further suppress star light introduced speckles. The optical analysis, alignment plan, and mechanical design of the instrument will be discussed.

  12. Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (PISCES) for WFIRST-AFTA

    NASA Technical Reports Server (NTRS)

    Gong, Qian; Mcelwain, Michael; Greeley, Bradford; Grammer, Bryan; Marx, Catherine; Memarsadeghi, Nargess; Stapelfeldt, Karl; Hilton, George; Sayson, Jorge Llop; Perrin, Marshall; hide

    2015-01-01

    Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (PISCES) is a lenslet array based integral field spectrometer (IFS) designed for high contrast imaging of extrasolar planets. PISCES will be used to advance the technology readiness of the high contrast IFS baselined on the Wide-Field InfraRed Survey Telescope/Astrophysics Focused Telescope Assets (WFIRST-AFTA) coronagraph instrument. PISCES will be integrated into the high contrast imaging testbed (HCIT) at the Jet Propulsion Laboratory (JPL) and will work with both the Hybrid Lyot Coronagraph (HLC) and the Shaped Pupil Coronagraph (SPC) configurations. We discuss why the lenslet array based IFS was selected for PISCES. We present the PISCES optical design, including the similarities and differences of lenslet based IFSs to normal spectrometers, the trade-off between a refractive design and reflective design, as well as the specific function of our pinhole mask on the back surface of the lenslet array to reduce the diffraction from the edge of the lenslets. The optical analysis, alignment plan, and mechanical design of the instrument will be discussed.

  13. Lessons from Coronagraphic Imaging with HST that may apply to JWST

    NASA Astrophysics Data System (ADS)

    Grady, C. A.; Hines, Dean C.; Schneider, Glenn; McElwain, Michael W.

    2017-06-01

    One of the major capabilities offered by JWST is coronagraphic imaging from space, covering the near through mid-IR and optimized for study of planet formation and the evolution of planetary systems. Planning for JWST has resulted in expectations for instrument performance, observation strategies and data reduction approaches. HST with 20 years of coronagraphic imaging offers some experience which may be useful to those planning for JWST. 1) Real astronomical sources do not necessarily conform to expectations. Debris disks may be accompanied by more distant material, and some systems may be conspicuous in scattered light when offering only modest IR excesses. Proto-planetary disks are not constantly illuminated, and thus a single epoch observation of the source may not be sufficient to reveal everything about it. 2) The early expectation with NICMOS was that shallow, 2-roll observations would reveal a wealth of debris disks imaged in scattered light, and that only a limited set of PSF observations would be required. Instead, building up a library of spatially resolved disks in scattered light has proven to require alternate observing strategies, is still on-going, and has taken far longer than expected. 3) A wealth of coronagraphic options with an instrument may not be scientifically informative, unless there is a similar time investment in acquisition of calibration data in support of the science observations. 4) Finally, no one anticipated what can be gleaned from coronagraphic imaging. We should expect similar, unexpected, and ultimately revolutionary discoveries with JWST.

  14. Design and Fabrication of the All-Reflecting H-Lyman alpha Coronagraph/Polarimeter

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.; Johnson, R. Barry; Fineschi, Silvano; Walker, Arthur B. C., Jr.; Baker, Phillip C.; Zukic , Muamer; Kim, Jongmin

    1993-01-01

    We have designed, analyzed, and are now fabricating an All-Reflecting H-Lyman alpha Coronagraph/Polarimeter for solar research. This new instrument operates in a narrow bandpass centered at lambda 1215.7 A-the neutral hydrogen Lyman alpha (Ly-alpha) line. It is shorter and faster than the telescope which produced solar Ly-alpha images as a part of the MSSTA payload that was launched on May 13, 1991. The Ly-alpha line is produced and linearly polarized in the solar corona by resonance scattering, and the presence of a magnetic field modifies this polarization according to the Hanle effect. The Lyman alpha Coronagraph/Polarimeter instrument has been designed to measure coronal magnetic fields by interpreting, via the Hanle effect, the measured linear polarization of the coronal Ly-alpha line. Ultrasmooth mirrors, polarizers, and filters are being flow-polished for this instrument from CVD silicon carbide substrates. These optical components will be coated using advanced induced transmission and absorption thin film multilayer coatings, to optimize the reflectivity and polarization properties at 1215.7 A. We describe some of the solar imaging results obtained with the MSSTA Lyman alpha coronagraph. We also discuss the optical design parameters and fabrication plans for the All-Reflecting H-Lyman alpha Coronagraph/Polarimeter.

  15. Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (PISCES) for WFIRST-AFTA

    NASA Technical Reports Server (NTRS)

    Gong, Qian; Mcelwain, Michael; Greeley, Bradford; Grammer, Bryan; Marx, Catherine; Memarsadeghi, Nargess; Stapelfeldt, Karl; Hilton, George; Sayson, Jorge Llop; Perrin, Marshall; Demers, Richard; Tang, Hong; Kern, Brian; Ferdosi, Janan

    2015-01-01

    Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (PISCES) is a lenslet array based integral field spectrometer (IFS) designed for high contrast imaging of extrasolar planets. PISCES will be used to advance the technology readiness of the high contrast IFS baselined on the Wide-Field InfraRed Survey Telescope/Astrophysics Focused Telescope Assets (WFIRST-AFTA) coronagraph instrument. PISCES will be integrated into the high contrast imaging testbed (HCIT) at the Jet Propulsion Laboratory (JPL) and will work with both the Hybrid Lyot Coronagraph (HLC) and the Shaped Pupil Coronagraph (SPC) configurations. We discuss why the lenslet array based IFS was selected for PISCES. We present the PISCES optical design, including the similarities and differences of lenslet based IFSs to normal spectrometers, the trade-off between a refractive design and reflective design, as well as the specific function of our pinhole mask on the back surface of the lenslet array to reduce the diffraction from the edge of the lenslets. The optical analysis, alignment plan, and mechanical design of the instrument will be discussed.

  16. A coronagraph based on two spatial light modulators for active amplitude apodizing and phase corrections

    NASA Astrophysics Data System (ADS)

    Dou, Jiangpei; Ren, Deqing; Zhang, Xi; Zhu, Yongtian; Zhao, Gang; Wu, Zhen; Chen, Rui; Liu, Chengchao; Yang, Feng; Yang, Chao

    2014-08-01

    Almost all high-contrast imaging coronagraphs proposed until now are based on passive coronagraph optical components. Recently, Ren and Zhu proposed for the first time a coronagraph that integrates a liquid crystal array (LCA) for the active pupil apodizing and a deformable mirror (DM) for the phase corrections. Here, for demonstration purpose, we present the initial test result of a coronagraphic system that is based on two liquid crystal spatial light modulators (SLM). In the system, one SLM is served as active pupil apodizing and amplitude correction to suppress the diffraction light; another SLM is used to correct the speckle noise that is caused by the wave-front distortions. In this way, both amplitude and phase error can be actively and efficiently compensated. In the test, we use the stochastic parallel gradient descent (SPGD) algorithm to control two SLMs, which is based on the point spread function (PSF) sensing and evaluation and optimized for a maximum contrast in the discovery area. Finally, it has demonstrated a contrast of 10-6 at an inner working angular distance of ~6.2 λ/D, which is a promising technique to be used for the direct imaging of young exoplanets on ground-based telescopes.

  17. Lyot-plane phase masks for improved high-contrast imaging with a vortex coronagraph

    NASA Astrophysics Data System (ADS)

    Ruane, G. J.; Huby, E.; Absil, O.; Mawet, D.; Delacroix, C.; Carlomagno, B.; Swartzlander, G. A.

    2015-11-01

    Context. The vortex coronagraph is an optical instrument that precisely removes on-axis starlight allowing for high contrast imaging at small angular separation from the star, a crucial capability for direct detection and characterization of exoplanets and circumstellar disks. Telescopes with aperture obstructions, such as secondary mirrors and spider support structures, require advanced coronagraph designs to provide adequate starlight suppression. Aims: We introduce a phase-only Lyot-plane optic to the vortex coronagraph, which offers improved contrast performance on telescopes with complicated apertures. Potential solutions for the European Extremely Large Telescope (E-ELT) are described. Methods: Adding a Lyot-plane phase mask relocates residual starlight away from a region of the image plane, thereby reducing stellar noise and improving sensitivity to off-axis companions. The phase mask is calculated using an iterative phase retrieval algorithm. Results: Numerically, we achieve a contrast on the order of 10-6 for a companion with angular displacement as small as 4λ/D with an E-ELT type aperture. Even in the presence of aberrations, improved performance is expected compared to either a conventional vortex coronagraph or an optimized pupil plane phase element alone.

  18. Low-order wavefront sensing and control for WFIRST-AFTA coronagraph

    NASA Astrophysics Data System (ADS)

    Shi, Fang; Balasubramanian, Kunjithapatham; Hein, Randall; Lam, Raymond; Moore, Douglas; Moore, James; Patterson, Keith; Poberezhskiy, Ilya; Shields, Joel; Sidick, Erkin; Tang, Hong; Truong, Tuan; Wallace, J. Kent; Wang, Xu; Wilson, Daniel

    2016-01-01

    To maintain the required Wide-Field Infrared Survey Telescope (WFIRST) coronagraph performance in a realistic space environment, a low-order wavefront sensing and control (LOWFS/C) subsystem is necessary. The LOWFS/C uses the rejected stellar light from the coronagraph to sense and suppress the telescope pointing errors as well as low-order wavefront errors (WFEs) due to changes in thermal loading of the telescope and the rest of the observatory. We will present a conceptual design of a LOWFS/C subsystem for the WFIRST-AFTA coronagraph. This LOWFS/C uses a Zernike phase contrast wavefront sensor (ZWFS) with a phase shifting disk combined with the stellar light rejecting occulting masks, a key concept to minimize the noncommon path error. We will present our analysis of the sensor performance and evaluate the performance of the line-of-sight jitter suppression loop, as well as the low-order WFE correction loop with a deformable mirror on the coronagraph. We will also report the LOWFS/C testbed design and the preliminary in-air test results, which show a very promising performance of the ZWFS.

  19. Low order wavefront sensing and control for WFIRST-AFTA coronagraph

    NASA Astrophysics Data System (ADS)

    Shi, Fang; Balasubramanian, Kunjithapatham; Bartos, Randall; Hein, Randall; Kern, Brian; Krist, John; Lam, Raymond; Moore, Douglas; Moore, James; Patterson, Keith; Poberezhskiy, Ilya; Shields, Joel; Sidick, Erkin; Tang, Hong; Truong, Tuan; Wallace, Kent; Wang, Xu; Wilson, Dan

    2015-09-01

    To maintain the required WFIRST Coronagraph starlight suppression performance in a realistic space environment, a low order wavefront sensing and control (LOWFS/C) subsystem is necessary. The LOWFS/C uses the rejected stellar light from coronagraph to sense and suppress the telescope pointing drift and jitter as well as the low order wavefront errors due to changes in thermal loading on the telescope and the rest of the observatory. In this paper we will present an overview of the low order wavefront sensing and control subsystem for the WFIRST Coronagraph. We will describe LOWFS/C's Zernike wavefront sensor concept and control design, and present an overview of sensing performance analysis and modeling, predicted line-of-sight jitter suppression loop performance, as well as the low order wavefront error correction with the coronagraph's deformable mirror. We will also report the LOWFS/C testbed design and the preliminary in-air test results, which show promising performance of the Zernike wavefront sensor and FSM feedback loop.

  20. Double stage Lyot coronagraph with the apodized reticulated stop for the Extremely Large Telescope

    NASA Astrophysics Data System (ADS)

    Yaitskova, Natalia

    2005-08-01

    One of the science drivers for the Extremely Large Telescope (ELT) is imaging and spectroscopy of exo-solar planets located as close as 20mas to their parent star [1]. The application requires a well thought-out design of the high contrast imaging instrumentation. Several working coronagraphic concepts have already been developed for the monolithic telescope with the diameter up to 8 meter. Nevertheless the conclusions made about the performance of these systems cannot be applied directly to the telescope of the diameter 30-100m. The existing schemes are needed to be reconsidered taking into account the specific characteristics of a segmented surface. We start this work with the classical system - Lyot coronagraph. We show that while the increase in telescope diameter is an advantage for the high contrast range science, the segmentation sets a limit on the performance of the coronagraph. Diffraction from intersegment gaps sets a floor to the achievable extinction of the starlight. Masking out the bright segment gaps in the Lyot plane although helps increasing the contrast, does not solve completely the problem: the high spatial frequency component of the diffractive light remains. We suggest using the Lyot stop which acts on the light within gaps in order to produce the uniform illumination in the Lyot plane. We show that for the diffraction limit regime and a perfect phasing this type of coronagraph achieves a sufficient star light extinction.

  1. Scaled-model guidelines for formation-flying solar coronagraph missions.

    PubMed

    Landini, Federico; Romoli, Marco; Baccani, Cristian; Focardi, Mauro; Pancrazzi, Maurizio; Galano, Damien; Kirschner, Volker

    2016-02-15

    Stray light suppression is the main concern in designing a solar coronagraph. The main contribution to the stray light for an externally occulted space-borne solar coronagraph is the light diffracted by the occulter and scattered by the optics. It is mandatory to carefully evaluate the diffraction generated by an external occulter and the impact that it has on the stray light signal on the focal plane. The scientific need for observations to cover a large portion of the heliosphere with an inner field of view as close as possible to the photospheric limb supports the ambition of launching formation-flying giant solar coronagraphs. Their dimension prevents the possibility of replicating the flight geometry in a clean laboratory environment, and the strong need for a scaled model is thus envisaged. The problem of scaling a coronagraph has already been faced for exoplanets, for a single point source on axis at infinity. We face the problem here by adopting an original approach and by introducing the scaling of the solar disk as an extended source.

  2. A 4-meter wide field coronagraph space telescope for general astrophysics and exoplanet observations

    NASA Astrophysics Data System (ADS)

    Tenerelli, Domenick; Angel, Roger; Burge, Jim; Guyon, Olivier; Zabludoff, Ann; Belikov, Ruslan; Pluzhnik, Eugene; Egerman, Robert

    2010-07-01

    The Wide Field Coronagraph Telescope (WFCT) is a 4-meter space telescope for general astrophysics and exoplanet observations that meets the 2000 Decadal Committee requirements. This paper presents a design for a 4-m diameter, off-axis space telescope that offers high performance in both wide field and coronagraphic imaging modes. A 3.8 x 3.3-m unobstructed elliptical pupil is provided for direct coronagraphic imaging of exoplanets and a 4-m diameter pupil for wide-field imaging from far-ultraviolet (UV) to near-infrared (IR). The off-axis wide-field optics are all reflective and designed to deliver an average of 12 nm wavefront aberrations over a 6 x 24 arcminute field of view (FOV), therefore providing diffraction-limited images down to 300 nm wavelength and 15 mas images down to a wavelength limit set only by the mirror coatings. The coronagraph with phase-induced amplitude apodization (PIAA) provides diffraction suppression around a 360-degree field with high Strehl and sensitivity at the 1e-10 level to an inner working angle of 2 λ/D (or 50 mas at 500 nm wavelength). This paper focuses on the optical design that allows the above imaging features to be combined in single telescope, and gives a preliminary spacecraft design and costing, assuming a distant trailing orbit.

  3. Reconstructing the open-field magnetic geometry of solar corona using coronagraph images

    NASA Astrophysics Data System (ADS)

    Uritsky, Vadim M.; Davila, Joseph M.; Jones, Shaela; Burkepile, Joan

    2015-04-01

    The upcoming Solar Probe Plus and Solar Orbiter missions will provide an new insight into the inner heliosphere magnetically connected with the topologically complex and eruptive solar corona. Physical interpretation of these observations will be dependent on the accurate reconstruction of the large-scale coronal magnetic field. We argue that such reconstruction can be performed using photospheric extrapolation codes constrained by white-light coronagraph images. The field extrapolation component of this project is featured in a related presentation by S. Jones et al. Here, we focus on our image-processing algorithms conducting an automated segmentation of coronal loop structures. In contrast to the previously proposed segmentation codes designed for detecting small-scale closed loops in the vicinity of active regions, our technique focuses on the large-scale geometry of the open-field coronal features observed at significant radial distances from the solar surface. Coronagraph images are transformed into a polar coordinate system and undergo radial detrending and initial noise reduction followed by an adaptive angular differentiation. An adjustable threshold is applied to identify candidate coronagraph features associated with the large-scale coronal field. A blob detection algorithm is used to identify valid features against a noisy background. The extracted coronal features are used to derive empirical directional constraints for magnetic field extrapolation procedures based on photospheric magnetograms. Two versions of the method optimized for processing ground-based (Mauna Loa Solar Observatory) and satellite-based (STEREO Cor1 and Cor2) coronagraph images are being developed.

  4. 4D Cellular Automaton Track Finder in the CBM Experiment

    NASA Astrophysics Data System (ADS)

    Akishina, Valentina; Kisel, Ivan

    2016-11-01

    The CBM experiment (FAIR/GSI, Darmstadt, Germany) will focus on the measurement of rare probes at interaction rates up to 10MHz with data flow of up to 1 TB/s. It requires a novel read-out and data-acquisition concept with self-triggered electronics and free-streaming data. In this case resolving different collisions is a non-trivial task and event building must be performed in software online. That requires full online event reconstruction and selection not only in space, but also in time, so-called 4D event building and selection. This is a task of the First-Level Event Selection (FLES). The FLES reconstruction and selection package consists of several modules: track finding, track fitting, short-lived particles finding, event building and event selection. The Cellular Automaton (CA) track finder algorithm was adapted towards time-based reconstruction. In this article, we describe in detail the modification done to the algorithm, as well as the performance of the developed time-based CA approach.

  5. APF—The Lick Observatory Automated Planet Finder

    NASA Astrophysics Data System (ADS)

    Vogt, Steven S.; Radovan, Matthew; Kibrick, Robert; Butler, R. Paul; Alcott, Barry; Allen, Steve; Arriagada, Pamela; Bolte, Mike; Burt, Jennifer; Cabak, Jerry; Chloros, Kostas; Cowley, David; Deich, William; Dupraw, Brian; Earthman, Wayne; Epps, Harland; Faber, Sandra; Fischer, Debra; Gates, Elinor; Hilyard, David; Holden, Brad; Johnston, Ken; Keiser, Sandy; Kanto, Dick; Katsuki, Myra; Laiterman, Lee; Lanclos, Kyle; Laughlin, Greg; Lewis, Jeff; Lockwood, Chris; Lynam, Paul; Marcy, Geoffrey; McLean, Maureen; Miller, Joe; Misch, Tony; Peck, Michael; Pfister, Terry; Phillips, Andrew; Rivera, Eugenio; Sandford, Dale; Saylor, Mike; Stover, Richard; Thompson, Matthew; Walp, Bernie; Ward, James; Wareham, John; Wei, Mingzhi; Wright, Chris

    2014-04-01

    The Automated Planet Finder (APF) is a facility purpose-built for the discovery and characterization of extrasolar planets through high-cadence Doppler velocimetry of the reflex barycentric accelerations of their host stars. Located atop Mt. Hamilton, the APF facility consists of a 2.4-m telescope and its Levy spectrometer, an optical echelle spectrometer optimized for precision Doppler velocimetry. APF features a fixed format spectral range from 374 nm - 970 nm, and delivers a "Throughput" (resolution * slit width product) of 114,000 arc-seconds, with spectral resolutions up to 150,000. Overall system efficiency (fraction of photons incident on the primary mirror that are detected by the science CCD) on blaze at 560 nm in planet-hunting mode is 15%. First-light tests on the RV standard stars HD 185144 and HD 9407 demonstrate sub-meter per second precision (RMS per observation) held over a 3-month period. This paper reviews the basic features of the telescope, dome, and spectrometer, and gives a brief summary of first-light performance.

  6. On-sky Performance Analysis of the Vector Apodizing Phase Plate Coronagraph on MagAO/Clio2

    NASA Astrophysics Data System (ADS)

    Otten, Gilles P. P. L.; Snik, Frans; Kenworthy, Matthew A.; Keller, Christoph U.; Males, Jared R.; Morzinski, Katie M.; Close, Laird M.; Codona, Johanan L.; Hinz, Philip M.; Hornburg, Kathryn J.; Brickson, Leandra L.; Escuti, Michael J.

    2017-01-01

    We report on the performance of a vector apodizing phase plate coronagraph that operates over a wavelength range of 2–5 μm and is installed in MagAO/Clio2 at the 6.5 m Magellan Clay telescope at Las Campanas Observatory, Chile. The coronagraph manipulates the phase in the pupil to produce three beams yielding two coronagraphic point-spread functions (PSFs) and one faint leakage PSF. The phase pattern is imposed through the inherently achromatic geometric phase, enabled by liquid crystal technology and polarization techniques. The coronagraphic optic is manufactured using a direct-write technique for precise control of the liquid crystal pattern and multitwist retarders for achromatization. By integrating a linear phase ramp to the coronagraphic phase pattern, two separated coronagraphic PSFs are created with a single pupil-plane optic, which makes it robust and easy to install in existing telescopes. The two coronagraphic PSFs contain a 180° dark hole on each side of a star, and these complementary copies of the star are used to correct the seeing halo close to the star. To characterize the coronagraph, we collected a data set of a bright (mL = 0–1) nearby star with ∼1.5 hr of observing time. By rotating and optimally scaling one PSF and subtracting it from the other PSF, we see a contrast improvement by 1.46 magnitudes at 3.5 λ /D. With regular angular differential imaging at 3.9 μm, the MagAO vector apodizing phase plate coronagraph delivers a 5σ {{Δ }}{mag} contrast of 8.3 (={10}-3.3) at 2 λ /D and 12.2 (={10}-4.8) at 3.5 λ /D.

  7. Can a More User-Friendly Medicare Plan Finder Improve Consumers' Selection of Medicare Plans?

    PubMed

    Martino, Steven C; Kanouse, David E; Miranda, David J; Elliott, Marc N

    2017-10-01

    To evaluate the efficacy for consumers of two potential enhancements to the Medicare Plan Finder (MPF)-a simplified data display and a "quick links" home page designed to match the specific tasks that users seek to accomplish on the MPF. Participants (N = 641) were seniors and adult caregivers of seniors who were recruited from a national online panel. Participants browsed a simulated version of the MPF, made a hypothetical plan choice, and reported on their experience. Participants were randomly assigned to one of eight conditions in a fully factorial design: 2 home pages (quick links, current MPF home page) × 2 data displays (simplified, current MPF display) × 2 plan types (stand-alone prescription drug plan [PDP], Medicare Advantage plan with prescription drug coverage [MA-PD]). The quick links page resulted in more favorable perceptions of the MPF, improved users' understanding of the information, and increased the probability of choosing the objectively best plan. The simplified data display resulted in a more favorable evaluation of the website, better comprehension of the displayed information, and, among those choosing a PDP only, an increased probability of choosing the best plan. Design enhancements could markedly improve average website users' understanding, ability to use, and experience of using the MPF. © Health Research and Educational Trust.

  8. Lightning Radio Source Retrieval Using Advanced Lightning Direction Finder (ALDF) Networks

    NASA Technical Reports Server (NTRS)

    Koshak, William J.; Blakeslee, Richard J.; Bailey, J. C.

    1998-01-01

    A linear algebraic solution is provided for the problem of retrieving the location and time of occurrence of lightning ground strikes from an Advanced Lightning Direction Finder (ALDF) network. The ALDF network measures field strength, magnetic bearing and arrival time of lightning radio emissions. Solutions for the plane (i.e., no Earth curvature) are provided that implement all of tile measurements mentioned above. Tests of the retrieval method are provided using computer-simulated data sets. We also introduce a quadratic planar solution that is useful when only three arrival time measurements are available. The algebra of the quadratic root results are examined in detail to clarify what portions of the analysis region lead to fundamental ambiguities in source location. Complex root results are shown to be associated with the presence of measurement errors when the lightning source lies near an outer sensor baseline of the ALDF network. In the absence of measurement errors, quadratic root degeneracy (no source location ambiguity) is shown to exist exactly on the outer sensor baselines for arbitrary non-collinear network geometries. The accuracy of the quadratic planar method is tested with computer generated data sets. The results are generally better than those obtained from the three station linear planar method when bearing errors are about 2 deg. We also note some of the advantages and disadvantages of these methods over the nonlinear method of chi(sup 2) minimization employed by the National Lightning Detection Network (NLDN) and discussed in Cummins et al.(1993, 1995, 1998).

  9. Design status of ASPIICS, an externally occulted coronagraph for PROBA-3

    NASA Astrophysics Data System (ADS)

    Renotte, Etienne; Alia, Andres; Bemporad, Alessandro; Bernier, Joseph; Bramanti, Cristina; Buckley, Steve; Capobianco, Gerardo; Cernica, Ileana; Dániel, Vladimir; Darakchiev, Radoslav; Darmetko, Marcin; Debaize, Arnaud; Denis, François; Desselle, Richard; de Vos, Lieve; Dinescu, Adrian; Fineschi, Silvano; Fleury-Frenette, Karl; Focardi, Mauro; Fumel, Aurélie; Galano, Damien; Galy, Camille; Gillis, Jean-Marie; Górski, Tomasz; Graas, Estelle; Graczyk, Rafał; Grochowski, Konrad; Halain, Jean-Philippe A.; Hermans, Aline; Howard, Russ; Jackson, Carl; Janssen, Emmanuel; Kasprzyk, Hubert; Kosiec, Jacek; Koutchmy, Serge; Kovačičinová, Jana; Kranitis, Nektarios; Kurowski, Michał; Ładno, Michał; Lamy, Philippe; Landini, Federico; Lapáček, Radek; Lédl, Vít.; Liebecq, Sylvie; Loreggia, Davide; McGarvey, Brian; Massone, Giuseppe; Melich, Radek; Mestreau-Garreau, Agnes; Mollet, Dominique; Mosdorf, Łukasz; Mosdorf, Michał; Mroczkowski, Mateusz; Muller, Raluca; Nicolini, Gianalfredo; Nicula, Bogdan; O'Neill, Kevin; Orleański, Piotr; Palau, Marie-Catherine; Pancrazzi, Maurizio; Paschalis, Antonios; Patočka, Karel; Peresty, Radek; Popescu, Irina; Psota, Pavel; Rataj, Miroslaw; Rautakoski, Jan; Romoli, Marco; Rybecký, Roman; Salvador, Lucas; Servaye, Jean-Sébastien; Solomon, Cornel; Stockman, Yvan; Swat, Arkadiusz; Thizy, Cédric; Thomé, Michel; Tsinganos, Kanaris; Van der Meulen, Jim; Van Vooren, Nico; Vit, Tomáš; Walczak, Tomasz; Zarzycka, Alicja; Zender, Joe; Zhukov, Andrei

    2015-09-01

    The "sonic region" of the Sun corona remains extremely difficult to observe with spatial resolution and sensitivity sufficient to understand the fine scale phenomena that govern the quiescent solar corona, as well as phenomena that lead to coronal mass ejections (CMEs), which influence space weather. Improvement on this front requires eclipse-like conditions over long observation times. The space-borne coronagraphs flown so far provided a continuous coverage of the external parts of the corona but their over-occulting system did not permit to analyse the part of the white-light corona where the main coronal mass is concentrated. The proposed PROBA-3 Coronagraph System, also known as ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun), with its novel design, will be the first space coronagraph to cover the range of radial distances between ~1.08 and 3 solar radii where the magnetic field plays a crucial role in the coronal dynamics, thus providing continuous observational conditions very close to those during a total solar eclipse. PROBA-3 is first a mission devoted to the in-orbit demonstration of precise formation flying techniques and technologies for future European missions, which will fly ASPIICS as primary payload. The instrument is distributed over two satellites flying in formation (approx. 150m apart) to form a giant coronagraph capable of producing a nearly perfect eclipse allowing observing the sun corona closer to the rim than ever before. The coronagraph instrument is developed by a large European consortium including about 20 partners from 7 countries under the auspices of the European Space Agency. This paper is reviewing the recent improvements and design updates of the ASPIICS instrument as it is stepping into the detailed design phase.

  10. The Automated Planet Finder's automation & first two years of science

    NASA Astrophysics Data System (ADS)

    Burt, Jennifer; Laughlin, Greg; Vogt, Steven S.; Holden, Bradford

    2016-01-01

    The Automated Planet Finder (APF) is the newest facility at Lick Observatory, comprised of a 2.4m telescope coupled with the high-resolution Levy echelle spectrograph. Purpose built for exoplanet detection and characterization, 80% of the telescope's observing time is dedicated to these science goals. The APF has demonstrated 1 m/s radial velocity precision on bright, RV standard stars and performs with the same speed-on-sky as Keck/HIRES when observing M-dwarfs.The telesope is fully automated for RV operations, using a dynamic scheduler that makes informed decisions on which targets to observe based on scientific interest, desired cadence, required precision levels and current observing conditions, all on a minute-to-minute basis. This ensures that time is not wasted chasing non-optimal targets on nights with poor conditions and enables rapid changes to the overall science observing strategy.The APF has contributed to the detection of four planetary systems in its first two years of scientific operations. Our most recent detection is that of a 6-planet system around the bright (V=5.5), nearby (d=6.5pc), K3V star HD 219134. The planets in this system have masses ranging from 3.5 to108 MEarth, with orbital periods from 3 to 2247 days. An independent detection of the inner 4 planets in this system by the HARPS-N team has shown that the 3d planet transits the star, making this system ideal for follow-up observations.I will discuss the design and implementation of the APF's dynamic scheduler, the telescope's planet detections to date, overall performance results of the telescope and our future observing strategy.

  11. Enceladus Life Finder: Search for Life in a Habitable Moon.

    NASA Astrophysics Data System (ADS)

    Lunine, J. I.; Waite, J. H., Jr.; Spilker, L. J.; Postberg, F.; Cable, M. L.; Srama, R.; Clark, K.; Lee, S. W.

    2015-12-01

    A thousand times smaller in mass than Ganymede, Enceladus was known from Voyager data to be extremely bright and a dearth of craters on some parts of its surface suggested geologic activity. Cassini discovered the presence and composition of a plume erupting from the south polar terrain of Enceladus, approximately 100 narrow, distinct "geysers" or "jets" that feed it, and anomalous thermal signatures along fractures from which the geysers erupt. Cassini discovered organic and nitrogen-bearing molecules in the plume vapor, and detected salts in the plume icy grains, arguing strongly for ocean water being in contact with a rocky core. As much as Cassini has done, it cannot tell us whether the ocean of Enceladus hosts an active biota today. Enceladus Life Finder (ELF) is a Discovery-class solar-powered Saturn orbiter designed to fly multiple times through the plume of Enceladus. It carries two state-of-the-art mass spectrometers designed to analyze the gas and grains in the plume. The goals of the mission are derived directly from the most recent decadal survey: first, to determine primordial sources of organics and sites of organic synthesis today, second, to determine if there are modern habitats in the solar system beyond Earth where the conditions for life exist today and third, if life exists there now. ELF conducts three tests for life. The first test looks for a non-abiotic distribution of amino acids, the second determines whether the carbon number distribution in fatty acids or isoprenoids is biased toward a particular rule, and the third measures carbon and hydrogen isotopic ratios, together with the abundance of methane relative to other alkanes, to assess whether the values fall in the range for biological processes. The ELF mission spacecraft conducts ten science plume fly-throughs; the baseline science is completed in the first five plume passages.

  12. The Integrated Cluster Finder for the ARCHES project

    NASA Astrophysics Data System (ADS)

    Mints, Alexey; Schwope, Axel; Rosen, Simon; Pineau, François-Xavier; Carrera, Francisco

    2017-01-01

    Context. Clusters of galaxies are important for cosmology and astrophysics. They may be discovered through either the summed optical/IR radiation originating from their member galaxies or via X-ray emission originating from the hot intracluster medium. X-ray samples are not affected by projection effects but a redshift determination typically needs optical and infrared follow-up to then infer X-ray temperatures and luminosities. Aims: We want to confirm serendipitously discovered X-ray emitting cluster candidates and measure their cosmological redshift through the analysis and exploration of multi-wavelength photometric catalogues. Methods: We developed a tool, the Integrated Cluster Finder (ICF), to search for clusters by determining overdensities of potential member galaxies in optical and infrared catalogues. Based on a spectroscopic meta-catalogue we calibrated colour-redshift relations that combine optical (SDSS) and IR data (UKIDSS, WISE). The tool is used to quantify the overdensity of galaxies against the background via a modified redMaPPer technique and to quantify the confidence of a cluster detection. Results: Cluster finding results are compared to reference catalogues found in the literature. The results agree to within 95-98%. The tool is used to confirm 488 out of 830 cluster candidates drawn from 3XMMe in the footprint of the SDSS and CFHT catalogues. Conclusions: The ICF is a flexible and highly efficient tool to search for galaxy clusters in multiple catalogues and is freely available to the community. It may be used to identify the cluster content in future X-ray catalogues from XMM-Newton and eventually from eROSITA.

  13. Eye safe short range standoff aerosol cloud finder.

    SciTech Connect

    Bambha, Ray P.; Schroder, Kevin L.; Reichardt, Thomas A.

    2005-02-01

    Because many solid objects, both stationary and mobile, will be present in an indoor environment, the design of an indoor aerosol cloud finding lidar (light detection and ranging) instrument presents a number of challenges. The cloud finder must be able to discriminate between these solid objects and aerosol clouds as small as 1-meter in depth in order to probe suspect clouds. While a near IR ({approx}1.5-{micro}m) laser is desirable for eye-safety, aerosol scattering cross sections are significantly lower in the near-IR than at visible or W wavelengths. The receiver must deal with a large dynamic range since the backscatter from solid object will be orders of magnitude larger than for aerosol clouds. Fast electronics with significant noise contributions will be required to obtain the necessary temporal resolution. We have developed a laboratory instrument to detect aerosol clouds in the presence of solid objects. In parallel, we have developed a lidar performance model for performing trade studies. Careful attention was paid to component details so that results obtained in this study could be applied towards the development of a practical instrument. The amplitude and temporal shape of the signal return are analyzed for discrimination of aerosol clouds in an indoor environment. We have assessed the feasibility and performance of candidate approaches for a fieldable instrument. With the near-IR PMT and a 1.5-{micro}m laser source providing 20-{micro}J pulses, we estimate a bio-aerosol detection limit of 3000 particles/l.

  14. IC-Finder: inferring robustly the hierarchical organization of chromatin folding.

    PubMed

    Haddad, Noelle; Vaillant, Cédric; Jost, Daniel

    2017-01-26

    The spatial organization of the genome plays a crucial role in the regulation of gene expression. Recent experimental techniques like Hi-C have emphasized the segmentation of genomes into interaction compartments that constitute conserved functional domains participating in the maintenance of a proper cell identity. Here, we propose a novel method, IC-Finder, to identify interaction compartments (IC) from experimental Hi-C maps. IC-Finder is based on a hierarchical clustering approach that we adapted to account for the polymeric nature of chromatin. Based on a benchmark of realistic in silico Hi-C maps, we show that IC-Finder is one of the best methods in terms of reliability and is the most efficient numerically. IC-Finder proposes two original options: a probabilistic description of the inferred compartments and the possibility to explore the various hierarchies of chromatin organization. Applying the method to experimental data in fly and human, we show how the predicted segmentation may depend on the normalization scheme and how 3D compartmentalization is tightly associated with epigenomic information. IC-Finder provides a robust and generic 'all-in-one' tool to uncover the general principles of 3D chromatin folding and their influence on gene regulation. The software is available at http://membres-timc.imag.fr/Daniel.Jost/DJ-TIMC/Software.html.

  15. Stochastic parallel gradient descent based adaptive optics used for a high contrast imaging coronagraph

    NASA Astrophysics Data System (ADS)

    Dong, Bing; Ren, De-Qing; Zhang, Xi

    2011-08-01

    An adaptive optics (AO) system based on a stochastic parallel gradient descent (SPGD) algorithm is proposed to reduce the speckle noises in the optical system of a stellar coronagraph in order to further improve the contrast. The principle of the SPGD algorithm is described briefly and a metric suitable for point source imaging optimization is given. The feasibility and good performance of the SPGD algorithm is demonstrated by an experimental system featured with a 140-actuator deformable mirror and a Hartmann-Shark wavefront sensor. Then the SPGD based AO is applied to a liquid crystal array (LCA) based coronagraph to improve the contrast. The LCA can modulate the incoming light to generate a pupil apodization mask of any pattern. A circular stepped pattern is used in our preliminary experiment and the image contrast shows improvement from 10-3 to 10-4.5 at an angular distance of 2λ/D after being corrected by SPGD based AO.

  16. Direct imaging of nonsolar planets with infrared telescopes using apodized coronagraphs

    NASA Technical Reports Server (NTRS)

    Mills, James P.; Gaiser, Steven L.; Diner, David J.; Watson, Steven M.

    1991-01-01

    This research examines the use of modified Lyot coronagraphs with monolithic and segmented infrared telescopic systems for imaging nonsolar planets. These systems are investigated with the aim of reducing the effects of stellar diffracted energy on the planet image in the final image plane. A square telescope objective is best for this purpose. The associated coronagraph is composed of a cross-shaped apodizer in the first focal plane and either a square Lyot stop or circular corner Lyot stops in the corners of the pupil plane. The consequences of segmenting the aperture and the effects of various segment spacings and random piston and tilt errors of the individual segments are examined. A system to correct for the misalignments is proposed.

  17. Planet detection and spectroscopy in visible light with a single aperture telescope and a nulling coronagraph

    NASA Technical Reports Server (NTRS)

    Shao, Michael; Serabyn, Eugene; Levine, Bruce Martin; Beichman, Charles; Liu, Duncan; Martin, Stefan; Orton, Glen; Mennesson, Bertrand; Morgan, Rhonda; Velusamy, Thangasamy; Wallace, J. Kent; Unwin, Stephen

    2003-01-01

    This talk describes a new concept for visible direct detection of Earth like extra solar planets using a nulling coronagraph instrument behind a 4m telescope in space. In the baseline design, a 4 beam nulling interferometer is synthesized from the telescope pupil, producing a very deep theta^4null which is then filtered by a coherent array of single mode fibers to suppress the residual scattered light. With perfect optics, the stellar leakage is less than 1e-11 of the starlight at the location of the planet. With diffraction limited telescope optics (lambda/20), suppression of the starlight to 1e-10 is possible. The concept is described along with the key advantages over more traditional approaches such as apodized aperture telescopes and Lyot type coronagraphs.

  18. High Contrast Internal and External Coronagraph Masks Produced by Various Techniques

    NASA Technical Reports Server (NTRS)

    Balasubramanian, Kunjithapatha; Wilson, Daniel; White, Victor; Muller, Richard; Dickie, Matthew; Yee, Karl; Ruiz, Ronald; Shaklan, Stuart; Cady, Eric; Kern, Brian; Belikov, Ruslan; Guyon, Olivier; Kasdin, N. Jeremy

    2013-01-01

    Masks for high contrast internal and external coronagraphic imaging require a variety of masks depending on different architectures to suppress star light. Various fabrication technologies are required to address a wide range of needs including gradient amplitude transmission, tunable phase profiles, ultra-low reflectivity, precise small scale features, and low-chromaticity. We present the approaches employed at JPL to produce pupil plane and image plane coronagraph masks, and lab-scale external occulter type masks by various techniques including electron beam, ion beam, deep reactive ion etching, and black silicon technologies with illustrative examples of each. Further development is in progress to produce circular masks of various kinds for obscured aperture telescopes.

  19. Optimized focal and pupil plane masks for vortex coronagraphs on telescopes with obstructed apertures

    NASA Astrophysics Data System (ADS)

    Ruane, Garreth J.; Absil, Olivier; Huby, Elsa; Mawet, Dimitri; Delacroix, Christian; Carlomagno, Brunella; Piron, Pierre; Swartzlander, Grover A.

    2015-09-01

    We present methods for optimizing pupil and focal plane optical elements that improve the performance of vortex coronagraphs on telescopes with obstructed or segmented apertures. Phase-only and complex masks are designed for the entrance pupil, focal plane, and the plane of the Lyot stop. Optimal masks are obtained using both analytical and numerical methods. The latter makes use of an iterative error reduction algorithm to calculate "correcting" optics that mitigate unwanted diffraction from aperture obstructions. We analyze the achieved performance in terms of starlight suppression, contrast, off-axis image quality, and chromatic dependence. Manufacturing considerations and sensitivity to aberrations are also discussed. This work provides a path to joint optimization of multiple coronagraph planes to maximize sensitivity to exoplanets and other faint companions.

  20. CT-Finder: A Web Service for CRISPR Optimal Target Prediction and Visualization.

    PubMed

    Zhu, Houxiang; Misel, Lauren; Graham, Mitchell; Robinson, Michael L; Liang, Chun

    2016-05-23

    The CRISPR system holds much promise for successful genome engineering, but therapeutic, industrial, and research applications will place high demand on improving the specificity and efficiency of this tool. CT-Finder (http://bioinfolab.miamioh.edu/ct-finder) is a web service to help users design guide RNAs (gRNAs) optimized for specificity. CT-Finder accommodates the original single-gRNA Cas9 system and two specificity-enhancing paired-gRNA systems: Cas9 D10A nickases (Cas9n) and dimeric RNA-guided FokI nucleases (RFNs). Optimal target candidates can be chosen based on the minimization of predicted off-target effects. Graphical visualization of on-target and off-target sites in the genome is provided for target validation. Major model organisms are covered by this web service.

  1. Exhaustive Search for Over-represented DNA Sequence Motifs with CisFinder

    PubMed Central

    Sharov, Alexei A.; Ko, Minoru S.H.

    2009-01-01

    We present CisFinder software, which generates a comprehensive list of motifs enriched in a set of DNA sequences and describes them with position frequency matrices (PFMs). A new algorithm was designed to estimate PFMs directly from counts of n-mer words with and without gaps; then PFMs are extended over gaps and flanking regions and clustered to generate non-redundant sets of motifs. The algorithm successfully identified binding motifs for 12 transcription factors (TFs) in embryonic stem cells based on published chromatin immunoprecipitation sequencing data. Furthermore, CisFinder successfully identified alternative binding motifs of TFs (e.g. POU5F1, ESRRB, and CTCF) and motifs for known and unknown co-factors of genes associated with the pluripotent state of ES cells. CisFinder also showed robust performance in the identification of motifs that were only slightly enriched in a set of DNA sequences. PMID:19740934

  2. MutationFinder: a high-performance system for extracting point mutation mentions from text.

    PubMed

    Caporaso, J Gregory; Baumgartner, William A; Randolph, David A; Cohen, K Bretonnel; Hunter, Lawrence

    2007-07-15

    Discussion of point mutations is ubiquitous in biomedical literature, and manually compiling databases or literature on mutations in specific genes or proteins is tedious. We present an open-source, rule-based system, MutationFinder, for extracting point mutation mentions from text. On blind test data, it achieves nearly perfect precision and a markedly improved recall over a baseline. MutationFinder, along with a high-quality gold standard data set, and a scoring script for mutation extraction systems have been made publicly available. Implementations, source code and unit tests are available in Python, Perl and Java. MutationFinder can be used as a stand-alone script, or imported by other applications. http://bionlp.sourceforge.net.

  3. LISA and LISA PathFinder, the endeavour to detect low frequency GWs

    NASA Astrophysics Data System (ADS)

    Araújo, H.; Boatella, C.; Chmeissani, M.; Conchillo, A.; García-Berro, E.; Grimani, C.; Hajdas, W.; Lobo, A.; Martínez, Ll; Nofrarias, M.; Ortega, J. A.; Puigdengoles, C.; Ramos-Castro, J.; Sanjuán, J.; Wass, P.; Xirgu, X.

    2007-05-01

    This is a review about LISA and its technology demonstrator, LISAPathFinder. We first describe the conceptual problems which need to be overcome in order to set up a working interferometric detector of low frequency Gravitational Waves (GW), then summarise the solutions to them as currently conceived by the LISA mission team. This will show that some of these solutions require new technological abilities which are still under development, and which need proper test before being fully implemented. LISAPathFinder (LPF) is the the testbed for such technologies. The final part of the paper will address the ideas and concepts behind the PathFinder as well as their impact on LISA.

  4. CT-Finder: A Web Service for CRISPR Optimal Target Prediction and Visualization

    PubMed Central

    Zhu, Houxiang; Misel, Lauren; Graham, Mitchell; Robinson, Michael L.; Liang, Chun

    2016-01-01

    The CRISPR system holds much promise for successful genome engineering, but therapeutic, industrial, and research applications will place high demand on improving the specificity and efficiency of this tool. CT-Finder (http://bioinfolab.miamioh.edu/ct-finder) is a web service to help users design guide RNAs (gRNAs) optimized for specificity. CT-Finder accommodates the original single-gRNA Cas9 system and two specificity-enhancing paired-gRNA systems: Cas9 D10A nickases (Cas9n) and dimeric RNA-guided FokI nucleases (RFNs). Optimal target candidates can be chosen based on the minimization of predicted off-target effects. Graphical visualization of on-target and off-target sites in the genome is provided for target validation. Major model organisms are covered by this web service. PMID:27210050

  5. Measurement of stray radiance in the High Altitude Observatory's Skylab coronagraph.

    PubMed

    Csoeke-Poeckh, A; Macqueen, R M; Poland, A I

    1977-04-01

    The stray radiance present in the field of view of the High Altitude Observatory's Skylab coronagraph has been measured from results obtained in orbit with two techniques. First, employing images of the lunar disk made near the time of solar eclipse, a comparison of the apparent contrasts recorded by the coronagraph of maria and highlands with those of previous studies, allows the determination of the magnitude of the stray radiance and its variation along a radius. Next, the azimuthal (position angle) variation was found through measurement of the change in the net radiance of a point in the coronal image, as the image (coronagraph) was rotated. From these measurements the stray radiance was found to be a maximum near the inner limit of the instrument field of view, variable in azimuth from 1.4 to 5.6 10(-9)B(O), where B(O) is the mean solar disk radiance. Further, the stray radiance was found to be a steep, decreasing function of distance along a radius, falling to a nearly uniform, azimuthally independent va ue of ~3.5 x 10(-10)B(O) in the outer field. In this latter region, the coronagraph stray radiance is well below a typical midtotality eclipse sky radiance of ~1.8 x 10(-9)B(O). Finally, the radiance of lunar maria and highlands (in units of 10(-10)B(O)) was determined to be 2.2 and 4.5, respectively, for the 30 June 1973 eclipse and 1.4 and 3.0, respectively, for the 24 December 1973 eclipse, in agreement with other observers.

  6. Exploration of the environments of nearby stars with the NICMOS coronagraph: instrumental performance considerations

    NASA Astrophysics Data System (ADS)

    Schneider, Glenn; Thompson, Rodger I.; Smith, Bradford A.; Terrile, Richard J.

    1998-08-01

    The Near IR Camera and Multi-Object Spectrometer (NICMOS), installed into the Hubble Space Telescope (HST) in February 1997, incorporates a coronagraphic imaging capability. The coronagraph is comprised of two optical elements. The camera 2 field divider mirror, upon which the HST f/24 input beam is imaged, includes a 170 micrometers diameter hole which contains approximately 93 percent of the encircled energy from a stellar Point Spread Function (PSF) at a wavelength of 1.6 micrometers . The coronagraphic hole lowers both the diffracted energy in the surrounding region by reducing the high spatial frequency components of the occulted core of the PSF< and down stream scattering. The geometrical radius of this occulting spot, when re-imaged through the camera 2 f/45 optics, is approximately 4 pixels at the detector focal plane. An oversized cold pupil-plane mask, with radial structures co-aligned with the HST secondary mirror spider, acts over the whole 19.1 inch by 19.2 field to further reduce the diffracted energy in the direction of the spider vanes. The absolute performance levels of the coronagraph were ascertained during the servicing mission observatory verification program. Using a differential imaging strategy we expect to achieve statistically significant detectors of sub-stellar companions at 1.6 micrometers with a (Delta) H of approximately 10 and separations as close as 0.5 inch. The NICMOS environments of nearby stars programs is exploiting this capability in systematic surveys of nearby, and young stars searching for brown dwarfs and giant planets, and protoplanetary disks around main-sequence stars.

  7. Calibrating IR optical densities for the Gemini Planet Imager extreme adaptive optics coronagraph apodizers

    NASA Astrophysics Data System (ADS)

    Sivaramakrishnan, Anand; Soummer, Rémi; Carr, G. Lawrence; Dorrer, Christophe; Bolognesi, Allen; Zimmerman, Neil; Oppenheimer, Ben R.; Roberts, Robin; Greenbaum, Alexandra

    2009-08-01

    High contrast imaging sometimes uses apodized masks in coronagraphs to suppress diffracted starlight from a bright source in order to observe its environs. Continuously graded opacity material and metallic half-tone dots are two possible apodizers fabrication techniques. In the latter approach if dot sizes are comparable to the wavelength of the light, surface plasmon effects can complicate the optical density (OD) vs. superficial dot density relation. OD can also be a complicated function of wavelength. We measured half-tone microdot screens' and continuous materials' transmissions. Our set-up replicated the f/ 64 optical configuration of the Gemini Planet Imager's Apodized Pupil Lyot Coronagraph pupil plane, where we plan to place our pupil plane masks. Our half-tone samples were fabricated with 2, 5, and 10 micron dot sizes, our continuous greyscale was High Energy Electron Beam Sensitive (HEBS) glass (Canyon Materials Inc.). We present optical density (OD) vs. wavelength curves for our half-tone and continuous greyscale samples 1.1 - 2.5 μm wavelength range. Direct measurements of the beam intensity in the far field using a Fourier Transform Infrared Spectrograph on Beamline U4IR at Brookhaven National Laboratory's National Synchrotron Light Source (NSLS) provided transmission spectra of test patches and apodizers. We report the on-axis IR transmission spectra through screens composed of metallic dots that are comparable in size with the wavelength of the light used, over a range of optical densities. We also measured departures from simple theory describing the array of satellite spots created by thin periodic grids in the pupil of the system. Such spots are used for photometry and astrometry in coronagraphic situations. Our results pertain to both ground and space based coronagraphs that use spatially variable attenuation, typically in focal plane or pupil plane masks.

  8. Ultraviolet Coronagraph Spectrometer for the Solar and Heliospheric Observatory: optical testings

    NASA Astrophysics Data System (ADS)

    Fineschi, Silvano; Romoli, Marco; Gardner, Larry D.; Kohl, J. L.; Noci, G.; Tondello, Giuseppe

    1994-11-01

    The Ultraviolet Coronagraph Spectrometer (UVCS) of the Solar and Heliospheric (SOHO) mission has been developed for spectroscopic and polarimetric determinations of temperatures, densities and flow velocities in the extended solar corona. The instrument consists of two ultraviolet (UV) spectrometers and a visible light (VL) polarimeter. The grating of the UV channel optimized for the HI Lyman (alpha) (Ly-(alpha) ) line ((lambda) 1236 angstrom) and that for the OVI doublet ((lambda) (lambda) 1032/1037 angstrom) have been characterized.

  9. Development and characterization of Four-Quadrant Phase Mask coronagraph (FQPM)

    NASA Astrophysics Data System (ADS)

    Bonafous, M.; Galicher, R.; Baudoz, P.; Firminy, J.; Boussaha, F.

    2016-07-01

    The goal of a coronagraph is to reduce the flux of a bright object (e.g. a star) in order to distinguish its faint neighborhood (e.g. exoplanets and disks). In this context, we proposed one coronagraph that uses a four quadrant phase mask (FQPM). Since 2000, we fabricated several monochromatic FQPM working in visible and near-infrared light at the Paris Observatory. We have developed systematic procedures for fabrication and characterization of the phase masks. Visual inspections with an optical microscope are performed for every component and a coronagraphic performance measurement based on inclination of the component is done on a dedicated bench that is set up in a clean room. This procedure gives a quick feedback on the quality and performance of the component. Depending on the results, images of the central transition can be recorded with an electron microscope to understand the limitations of the fabrication process. This procedure allowed us to understand the influence of various parameters such as the width of the transitions between the quadrants, the alignment of the transitions or the step depth. Based on these results, we modified the mask design and the fabrication process to improve our success rate to nearly 100% when building a FQPM for any given optimal wavelength in visible or near-infrared. Moreover, we improved the performance of the components, reaching attenuations of more than 20,000 on the central peak in raw images for most coronagraphs. The best of these components are now used on the THD bench, an optical/NIR bench developed for the study of high contrast imaging techniques, reaching 10-8 contrast level routinely.

  10. Design of a mirror pointing and occulting mechanism for the Ultraviolet Coronagraph Spectrometer (UVCS)

    NASA Technical Reports Server (NTRS)

    Highman, Clifton O.; Woolaway, Scott M.; Belmont, Kenneth L.

    1992-01-01

    The Mirror and Occulter Mechanism (MOM), a lightweight stable optical assembly which is a critical component to the Ultraviolet Coronagraph Spectrometer to be flown on the European SOHO spacecraft, is discussed. The MOM combines the functions of precision mirror pointing and occultation of stray light into a single package. The mirror mechanism and occulter mechanism designs are described and development testing and life testing activities are discussed.

  11. Laboratory demonstration of a mid-infrared AGPM vector vortex coronagraph

    NASA Astrophysics Data System (ADS)

    Delacroix, C.; Absil, O.; Forsberg, P.; Mawet, D.; Christiaens, V.; Karlsson, M.; Boccaletti, A.; Baudoz, P.; Kuittinen, M.; Vartiainen, I.; Surdej, J.; Habraken, S.

    2013-05-01

    Context. Coronagraphy is a powerful technique to achieve high contrast imaging, hence to image faint companions around bright targets. Various concepts have been used in the visible and near-infrared regimes, while coronagraphic applications in the mid-infrared nowadays remain largely unexplored. Vector vortex phase masks based on concentric subwavelength gratings show great promise for such applications. Aims: We aim at producing and validating the first high-performance broadband focal plane phase mask coronagraphs for applications in the mid-infrared regime, and in particular the L band with a fractional bandwidth of ~16% (3.5-4.1 μm). Methods: Based on rigorous coupled wave analysis, we designed an annular groove phase mask (AGPM) producing a vortex effect in the L band, and etched it onto a series of diamond substrates. The grating parameters were measured by means of scanning electron microscopy. The resulting components were then tested on a mid-infrared coronagraphic test bench. Results: A broadband raw null depth of 2 × 10-3 was obtained for our best L-band AGPM after only a few iterations between design and manufacturing. This corresponds to a raw contrast of about 6 × 10-5 (10.5 mag) at 2λ/D. This result is fully in line with our projections based on rigorous coupled wave analysis modelling, using the measured grating parameters. The sensitivity to tilt and focus has also been evaluated. Conclusions: After years of technological developments, mid-infrared vector vortex coronagraphs have finally become a reality and live up to our expectations. Based on their measured performance, our L-band AGPMs are now ready to open a new parameter space in exoplanet imaging at major ground-based observatories.

  12. Recent achievements on ASPIICS, an externally occulted coronagraph for PROBA-3

    NASA Astrophysics Data System (ADS)

    Renotte, Etienne; Buckley, Steve; Cernica, Ileana; Denis, François; Desselle, Richard; De Vos, Lieve; Fineschi, Silvano; Fleury-Frenette, Karl; Galano, Damien; Galy, Camille; Gillis, Jean-Marie; Graas, Estelle; Graczyk, Rafal; Horodyska, Petra; Kranitis, Nektarios; Kurowski, Michal; Ladno, Michal; Liebecq, Sylvie; Loreggia, Davide; Mechmech, Idriss; Melich, Radek; Mollet, Dominique; Mosdorf, Michał; Mroczkowski, Mateusz; O'Neill, Kevin; Patočka, Karel; Paschalis, Antonis; Peresty, Radek; Radzik, Bartlomiej; Rataj, Miroslaw; Salvador, Lucas; Servaye, Jean-Sébastien; Stockman, Yvan; Thizy, Cédric; Walczak, Tomasz; Zarzycka, Alicja; Zhukov, Andrei

    2016-07-01

    This paper presents the current status of ASPIICS, a solar coronagraph that is the primary payload of ESA's formation flying in-orbit demonstration mission PROBA-3. The "sonic region" of the Sun corona remains extremely difficult to observe with spatial resolution and sensitivity sufficient to understand the fine scale phenomena that govern the quiescent solar corona, as well as phenomena that lead to coronal mass ejections (CMEs), which influence space weather. Improvement on this front requires eclipse-like conditions over long observation times. The space-borne coronagraphs flown so far provided a continuous coverage of the external parts of the corona but their over-occulting system did not permit to analyse the part of the white-light corona where the main coronal mass is concentrated. The PROBA-3 Coronagraph System, also known as ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun) is designed as a classical externally occulted Lyot coronagraph but it takes advantage of the opportunity to place the external occulter on a companion spacecraft, about 150m apart, to perform high resolution imaging of the inner corona of the Sun as close as ~1.1 solar radii. The images will be tiled and compressed on board in an FPGA before being down-linked to ground for scientific analyses. ASPIICS is built by a large European consortium including about 20 partners from 7 countries under the auspices of the European Space Agency. This paper is reviewing the recent development status of the ASPIICS instrument as it is approaching CDR.

  13. PIAA Coronagraph Development at NASA Ames: High Contrast Laboratory Demonstration at 2 l/D

    NASA Astrophysics Data System (ADS)

    Belikov, Ruslan; Pluzhnik, E.; Witteborn, F. C.; Lynch, D. H.; Greene, T. P.; Zell, P. T.; Balasubramanian, K.; Guyon, O.

    2011-01-01

    Coronagraph technology is advancing and promises to directly image and spectrally characterize extrasolar Earth-like planets in the foreseeable future (such as the 2020 decade) with a telescope as small as 1.5m. A small Explorer-sized telescope can also be launched in the 2010 decade capable of seeing debris disks as small as 10s of zodis and potentially a few large planets. The Phase Induced Amplitude Apodization (PIAA) coronagraph makes such aggressive performance possible. We report on the latest results from a testbed at NASA Ames that is focused on developing and testing the PIAA coronagraph. This laboratory facility was built in 2008 and is designed to be flexible, operated in an actively thermally stabilized air environment, and to complement collaborative efforts at NASA JPL's High Contrast Imaging Testbed. For our wavefront control we are using small Micro-Electro-Mechanical-System deformable mirrors (MEMS DMs), which promise to reduce the size of the beam and overall instrument, a consideration that becomes very important for small telescopes. We describe our lab efforts and results, which include: the operation of our new active thermal control system; the demonstration of 5.4x10-8 (at time of this writing) average raw contrast in a dark zone from 2.0 - 5.2 λ/D in monochromatic light with a refractive PIAA system; preliminary results with an innovative low-cost set of reflective PIAA from JPL; preliminary results with a set of next-generation reflective PIAA built by Tinsley and designed to have the best theoretical broadband performance so far; and finally, an innovative design for a chromatically compensated focal plane occulter that promises to enhance broadband performance by matching the wavelength-dependent inner working angle of coronagraphs such as PIAA.

  14. Flight System Implementation of the Pupil-Mapping Exoplanet Coronagraphic Observer (PECO)

    NASA Astrophysics Data System (ADS)

    Tenerelli, Domenick; PECO Team

    2009-01-01

    The 3-year Pupil Mapping Exoplanet Coronagraphic Observer (PECO) mission concept is a 1.4-m coronagraphic telescope aimed at directly imaging the habitable zones of nearby stars at optical wavelengths. PECO detects and characterizes planets down to Earth size and maps dust clouds to a fraction of our zodiacal cloud dust brightness. It uses a low CTE substrate 1.4 m diameter off-axis narrow field telescope in an Earth drift-away achieving its goals using a Phase-Induced Amplitude Apodization (PIAA) coronagraph combining high contrast, high throughput, low inner working angle and full angular resolution. Telescope heritage is TDM and NextView. It incorporates quality optics and coatings and operates in the visible (400-900 mm) region. The secondary mirror has a linear focus actuator. The structure is thermally and vibrationally stable. PIAA's highly aspheric optics apodize the telescope's beam without losing light. PECO also includes a high accuracy wavefront control system. Pointing is controlled at the sub-milliarcsecond level using starlight in the coronagraph. Each of the spectral channels is designed to be very compact and stable, with a small beam size to maintain high wavefront quality. The PIAA design is fine-tuned in each channel ensuring minimal inner working angle. The SC structure is a modular design built of dimensionally stable composite material with 6 bays. We are considering the Disturbance Free Payload (DFP) which eliminates vibration coupling between the SC reaction wheels and the optical system payload. The SC pointing control system (PCS) provides 1 mas at the focal plane with a 1 Hz pointing correction bandwidth and payload provided accurate control signal from a bright star image. Propulsion employs a Spitzer-heritage redundant cold gas system using nitrogen propellant sized for 5 years. SC I&T uses the existing LM LOTIS facility to demonstrate required light contrast under Thermal Vacuum conditions.

  15. Coronagraphic methods for detecting faint astronomical objects near bright ones: Application to the 2.5-m telescope of Sternberg Astronomical Institute

    NASA Astrophysics Data System (ADS)

    Cherepashchuk, A. M.; Bugaenko, O. I.; Kim, I. S.; Popov, V. V.

    2017-03-01

    Possible methods for reducing the instrumental background of astronomical telescopes are discussed: the classical Lyot coronagraphic method, the multi-cascade coronagraphic method, the use of special masks in the plane of the entrance aperture, and the use of super-smooth and medium-smooth primary optics. For the first time, analytical expressions describing the intensity distribution at the exit pupil are presented for the case when a mask is placed in the primary focal plane in order to block the light from a bright object. An algorithm for computing the point-spread function (PSF) of a coronagraphic telescope employing super-smooth primary optics and the coronagraphic method is proposed. Computed PSFs for the 2.5-m telescope of the Caucasian Mountain Observatory of Sternberg Astronomical Institute are presented, without allowance for diffusive and turbulent scattering in the Earth's atmosphere, and for operation both without coronagraphic elements and in the coronagraphic mode of the telescope.

  16. Recent Improvements to the Finite-Fault Rupture Detector Algorithm: FinDer II

    NASA Astrophysics Data System (ADS)

    Smith, D.; Boese, M.; Heaton, T. H.

    2015-12-01

    Constraining the finite-fault rupture extent and azimuth is crucial for accurately estimating ground-motion in large earthquakes. Detecting and modeling finite-fault ruptures in real-time is thus essential to both earthquake early warning (EEW) and rapid emergency response. Following extensive real-time and offline testing, the finite-fault rupture detector algorithm, FinDer (Böse et al., 2012 & 2015), was successfully integrated into the California-wide ShakeAlert EEW demonstration system. Since April 2015, FinDer has been scanning real-time waveform data from approximately 420 strong-motion stations in California for peak ground acceleration (PGA) patterns indicative of earthquakes. FinDer analyzes strong-motion data by comparing spatial images of observed PGA with theoretical templates modeled from empirical ground-motion prediction equations (GMPEs). If the correlation between the observed and theoretical PGA is sufficiently high, a report is sent to ShakeAlert including the estimated centroid position, length, and strike, and their uncertainties, of an ongoing fault rupture. Rupture estimates are continuously updated as new data arrives. As part of a joint effort between USGS Menlo Park, ETH Zurich, and Caltech, we have rewritten FinDer in C++ to obtain a faster and more flexible implementation. One new feature of FinDer II is that multiple contour lines of high-frequency PGA are computed and correlated with templates, allowing the detection of both large earthquakes and much smaller (~ M3.5) events shortly after their nucleation. Unlike previous EEW algorithms, FinDer II thus provides a modeling approach for both small-magnitude point-source and larger-magnitude finite-fault ruptures with consistent error estimates for the entire event magnitude range.

  17. Development and implementation of a 'Mental Health Finder' software tool within an electronic medical record system.

    PubMed

    Swan, D; Hannigan, A; Higgins, S; McDonnell, R; Meagher, D; Cullen, W

    2017-02-01

    In Ireland, as in many other healthcare systems, mental health service provision is being reconfigured with a move toward more care in the community, and particularly primary care. Recording and surveillance systems for mental health information and activities in primary care are needed for service planning and quality improvement. We describe the development and initial implementation of a software tool ('mental health finder') within a widely used primary care electronic medical record system (EMR) in Ireland to enable large-scale data collection on the epidemiology and management of mental health and substance use problems among patients attending general practice. In collaboration with the Irish Primary Care Research Network (IPCRN), we developed the 'Mental Health Finder' as a software plug-in to a commonly used primary care EMR system to facilitate data collection on mental health diagnoses and pharmacological treatments among patients. The finder searches for and identifies patients based on diagnostic coding and/or prescribed medicines. It was initially implemented among a convenience sample of six GP practices. Prevalence of mental health and substance use problems across the six practices, as identified by the finder, was 9.4% (range 6.9-12.7%). 61.9% of identified patients were female; 25.8% were private patients. One-third (33.4%) of identified patients were prescribed more than one class of psychotropic medication. Of the patients identified by the finder, 89.9% were identifiable via prescribing data, 23.7% via diagnostic coding. The finder is a feasible and promising methodology for large-scale data collection on mental health problems in primary care.

  18. The effect of radiation-induced traps on the WFIRST coronagraph detectors

    NASA Astrophysics Data System (ADS)

    Nemati, Bijan; Effinger, Robert; Demers, Richard; Harding, Leon; Morrissey, Patrick; Bush, Nathan; Hall, David; Skottfelt, Jesper

    2016-08-01

    The WFIRST Coronagraph will be the most sensitive instrument ever built for direct imaging and characterization of extra-solar planets. With a design contrast expected to be better than 1e-9 after post processing, this instrument will directly image gas giants as far in as Jupiter's orbit. Direct imaging places high demand on optical detectors, not only in noise performance, but also in the need to be resistant to traps. Since the typical scene flux is measured in millielectrons per second, the signal collected in each practicable frame will be at most a few electrons. At such extremely small signal levels, traps and their effects on the image become extremely important. To investigate their impact on the WFIRST coronagraph mission science yield, we have constructed a detailed model of the coronagraph sensor performance in the presence of traps. Built in Matlab, this model incorporates the expected and measured trap capture and emission times and cross-sections, as well as occurrence densities after exposure to irradiation in the WFIRST space environment. The model also includes the detector architecture and operation as applicable to trapping phenomena. We describe the model, the results, and implications on sensing performance.

  19. Subaru Near-Infrared Coronagraphic Images of LkHalpha 234

    SciTech Connect

    Kato, Eri; Fukagawa, Misato; Shibai, Hiroshi; Ito, Yusuke; Ootsubo, Takafumi

    2009-08-05

    We present high-resolution (0''.2) near-infrared images of the Herbig Ae/Be star LkHalpha 234 taken with the stellar coronagraphic camera CIAO (Coronagraphic Imager with Adaptive Optics) on the Subaru Telescope. We have observed LkHalpha 234, located in the NGC 7129 star formation region at 1.25 kpc, using the adaptive optics and the coronagraph. Near-infrared (J, H, K, L' and M' bands) images obtained reveal detailed circumstellar structures around LkHalpha 234. Six young stellar object (YSO) candidates are detected at 2''-10'' from LkHalpha 234, and four out of six candidates are identified for the first time. Our high-resolution imaging reveals the complex morphology of the reflection nebula which is located at approximately 3'' from LkHalpha 234 and extended more than 10'' toward the west. The newly found object in H and K bands may be the source of the reflection nebula.

  20. Coronagraphic wavefront sensing with COFFEE: high spatial-frequency diversity and other news

    NASA Astrophysics Data System (ADS)

    Mugnier, L. M.; Sauvage, J.-F.; Herscovici-Schiller, O.; Baudoz, P.; Galicher, R.; Le Duigou, J.-M.

    2016-07-01

    The final performance of current and future instruments dedicated to exoplanet detection and characterization is limited by intensity residuals in the scientific image plane, which originate in uncorrected optical aberrations. In order to reach very high contrasts, these aberrations needs to be compensated for. We have proposed a focalplane wave-font sensor called COFFEE (for COronagraphic Focal-plane wave-Front Estimation for Exoplanet detection), which consists in an extension of conventional phase diversity to a coronagraphic system. In this communication, we study the extension of COFFEE to the joint estimation of the phase and the amplitude in the context of space-based coronagraphic instruments: we optimize the diversity phase in order to minimize the reconstruction error; we also propose and optimize a novel low-amplitude high-frequency diversity that should allow the phase-diverse images to still be used for science. Lastly, we perform a first experimental validation of COFFEE in the very high, space-like contrast conditions of the THD bench and show that COFFEE is able to distinguish between phase and amplitude aberrations.

  1. Color Differential Astrometry: a proposed observing mode for the SPICA Coronagraph

    NASA Astrophysics Data System (ADS)

    Abe, Lyu; Vannier, Martin; Petrov, Romain; Enya, Keigo; Kataza, Hirokazu

    The SPICA coronagraph will be dedicated to detecting and observing extra-solar planets. How-ever, the limited angular resolution of SPICA in the Near/Mid Infrared (0.2 arcsec at 3.5 mi-cron) will prevent the study of very close-in planets, closer than a few A.U. from their parent star. We propose to implement Color Differential Astrometry (originally proposed by Petrov), a complementary observing mode for the coronagraph. It is a spectro-astrometric method which would push the detection range to very close-in planets and up to a few AUs, thus nicely com-plementing the imaging coronagraph. We describe the CDA method and show that it could directly recover the planet orbital elements and low resolution spectrum. The analysis of the fundamental contributions to the SNR (source and background noise, detector noise) give a substantial range of application to the technique provided that certain characteristics of instru-ment stability or calibration methods are met. These instrumental requirements for CDA are then discussed in detail, and we lastly present the current status of a laboratory demonstration of the CDA method.

  2. Optical Vectorial Vortex Coronagraphs using Liquid Crystal Polymers: theory, manufacturing and laboratory demonstration.

    PubMed

    Mawet, D; Serabyn, E; Liewer, K; Hanot, Ch; McEldowney, S; Shemo, D; O'Brien, N

    2009-02-02

    In this paper, after briefly reviewing the theory of vectorial vortices, we describe our technological approach to generating the necessary phase helix, and report results obtained with the first optical vectorial vortex coronagraph (OVVC) in the laboratory. To implement the geometrical phase ramp, we make use of Liquid Crystal Polymers (LCP), which we believe to be the most efficient technological path to quickly synthesize optical vectorial vortices of virtually any topological charge. With the first prototype device of topological charge 2, a maximum peak-to-peak attenuation of 1.4x10(-2) and a residual light level of 3x10(-5) at an angular separation of 3.5 lambda/d (at which point our current noise floor is reached) have been obtained at a wavelength of 1.55 microm. These results demonstrate the validity of using space-variant birefringence distributions to generate a new family of coronagraphs usable in natural unpolarized light, opening a path to high performance coronagraphs that are achromatic and have low-sensitivity to low-order wavefront aberrations.

  3. Automatic Detection and Tracking of Coronal Mass Ejections. II. Multiscale Filtering of Coronagraph Images

    NASA Astrophysics Data System (ADS)

    Byrne, Jason P.; Morgan, Huw; Habbal, Shadia R.; Gallagher, Peter T.

    2012-06-01

    Studying coronal mass ejections (CMEs) in coronagraph data can be challenging due to their diffuse structure and transient nature, and user-specific biases may be introduced through visual inspection of the images. The large amount of data available from the Solar and Heliospheric Observatory (SOHO), Solar TErrestrial RElations Observatory (STEREO), and future coronagraph missions also makes manual cataloging of CMEs tedious, and so a robust method of detection and analysis is required. This has led to the development of automated CME detection and cataloging packages such as CACTus, SEEDS, and ARTEMIS. Here, we present the development of a new CORIMP (coronal image processing) CME detection and tracking technique that overcomes many of the drawbacks of current catalogs. It works by first employing the dynamic CME separation technique outlined in a companion paper, and then characterizing CME structure via a multiscale edge-detection algorithm. The detections are chained through time to determine the CME kinematics and morphological changes as it propagates across the plane of sky. The effectiveness of the method is demonstrated by its application to a selection of SOHO/LASCO and STEREO/SECCHI images, as well as to synthetic coronagraph images created from a model corona with a variety of CMEs. The algorithms described in this article are being applied to the whole LASCO and SECCHI data sets, and a catalog of results will soon be available to the public.

  4. AUTOMATIC DETECTION AND TRACKING OF CORONAL MASS EJECTIONS. II. MULTISCALE FILTERING OF CORONAGRAPH IMAGES

    SciTech Connect

    Byrne, Jason P.; Morgan, Huw; Habbal, Shadia R.; Gallagher, Peter T.

    2012-06-20

    Studying coronal mass ejections (CMEs) in coronagraph data can be challenging due to their diffuse structure and transient nature, and user-specific biases may be introduced through visual inspection of the images. The large amount of data available from the Solar and Heliospheric Observatory (SOHO), Solar TErrestrial RElations Observatory (STEREO), and future coronagraph missions also makes manual cataloging of CMEs tedious, and so a robust method of detection and analysis is required. This has led to the development of automated CME detection and cataloging packages such as CACTus, SEEDS, and ARTEMIS. Here, we present the development of a new CORIMP (coronal image processing) CME detection and tracking technique that overcomes many of the drawbacks of current catalogs. It works by first employing the dynamic CME separation technique outlined in a companion paper, and then characterizing CME structure via a multiscale edge-detection algorithm. The detections are chained through time to determine the CME kinematics and morphological changes as it propagates across the plane of sky. The effectiveness of the method is demonstrated by its application to a selection of SOHO/LASCO and STEREO/SECCHI images, as well as to synthetic coronagraph images created from a model corona with a variety of CMEs. The algorithms described in this article are being applied to the whole LASCO and SECCHI data sets, and a catalog of results will soon be available to the public.

  5. GLS-Finder: An Automated Data-Mining System for Fast Profiling Glucosinolates and its Application in Brassica Vegetables

    USDA-ARS?s Scientific Manuscript database

    A rapid computer-aided program for profiling glucosinolates, “GLS-Finder", was developed. GLS-Finder is a Matlab script based expert system that is capable for qualitative and semi-quantitative analysis of glucosinolates in samples using data generated by ultra-high performance liquid chromatograph...

  6. SysFinder: A customized platform for search, comparison and assisted design of appropriate animal models based on systematic similarity.

    PubMed

    Yang, Shuang; Zhang, Guoqing; Liu, Wan; Wang, Zhen; Zhang, Jifeng; Yang, Dongshan; Chen, Y Eugene; Sun, Hong; Li, Yixue

    2017-05-20

    Animal models are increasingly gaining values by cross-comparisons of response or resistance to clinical agents used for patients. However, many disease mechanisms and drug effects generated from animal models are not transferable to human. To address these issues, we developed SysFinder (http://lifecenter.sgst.cn/SysFinder), a platform for scientists to find appropriate animal models for translational research. SysFinder offers a "topic-centered" approach for systematic comparisons of human genes, whose functions are involved in a specific scientific topic, to the corresponding homologous genes of animal models. Scientific topic can be a certain disease, drug, gene function or biological pathway. SysFinder calculates multi-level similarity indexes to evaluate the similarities between human and animal models in specified scientific topics. Meanwhile, SysFinder offers species-specific information to investigate the differences in molecular mechanisms between humans and animal models. Furthermore, SysFinder provides a user-friendly platform for determination of short guide RNAs (sgRNAs) and homology arms to design a new animal model. Case studies illustrate the ability of SysFinder in helping experimental scientists. SysFinder is a useful platform for experimental scientists to carry out their research in the human molecular mechanisms. Copyright © 2017 Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, and Genetics Society of China. Published by Elsevier Ltd. All rights reserved.

  7. Applications of the Integrated High-Performance CMOS Image Sensor to Range Finders - from Optical Triangulation to the Automotive Field.

    PubMed

    Wu, Jih-Huah; Pen, Cheng-Chung; Jiang, Joe-Air

    2008-03-13

    With their significant features, the applications of complementary metal-oxidesemiconductor (CMOS) image sensors covers a very extensive range, from industrialautomation to traffic applications such as aiming systems, blind guidance, active/passiverange finders, etc. In this paper CMOS image sensor-based active and passive rangefinders are presented. The measurement scheme of the proposed active/passive rangefinders is based on a simple triangulation method. The designed range finders chieflyconsist of a CMOS image sensor and some light sources such as lasers or LEDs. Theimplementation cost of our range finders is quite low. Image processing software to adjustthe exposure time (ET) of the CMOS image sensor to enhance the performance oftriangulation-based range finders was also developed. An extensive series of experimentswere conducted to evaluate the performance of the designed range finders. From theexperimental results, the distance measurement resolutions achieved by the active rangefinder and the passive range finder can be better than 0.6% and 0.25% within themeasurement ranges of 1 to 8 m and 5 to 45 m, respectively. Feasibility tests onapplications of the developed CMOS image sensor-based range finders to the automotivefield were also conducted. The experimental results demonstrated that our range finders arewell-suited for distance measurements in this field.

  8. Unique criterion to estimate the performances of some laser diode range finders

    NASA Astrophysics Data System (ADS)

    Journet, Bernard A.; Bazin, Gaelle; Durieu, Cecile

    2001-09-01

    The purpose of this paper is to present a general method to estimate the intrinsic performances of some laser range finders based on flight time measurement. Classically this flight time can be measured directly, or after a conversion into a phase shift, or into a beat frequency. We prose here a criterion based on signal processing notions, as matched filtering to get the best detection, and ambiguity function to estimate the quality of the detection. The concept of characteristic length is introduced and applied to the different kind of laser range finders, which suggest a new possibility for flight time measurement.

  9. IsoMIF Finder: online detection of binding site molecular interaction field similarities.

    PubMed

    Chartier, Matthieu; Adriansen, Etienne; Najmanovich, Rafael

    2016-02-15

    IsoMIF Finder is an online server for the identification of molecular interaction field (MIF) similarities. User defined binding site MIFs can be compared to datasets of pre-calculated MIFs or against a user-defined list of PDB entries. The interface can be used for the prediction of function, identification of potential cross-reactivity or polypharmacological targets and drug repurposing. Detected similarities can be viewed in a browser or within a PyMOL session. IsoMIF Finder uses JSMOL (no java plugin required), is cross-browser and freely available at bcb.med.usherbrooke.ca/imfi. © The Author 2015. Published by Oxford University Press.

  10. DUCHAMP: a 3D source finder for spectral-line data

    NASA Astrophysics Data System (ADS)

    Whiting, Matthew T.

    2012-04-01

    This paper describes the DUCHAMP source finder, a piece of software designed to find and describe sources in three-dimensional, spectral-line data cubes. DUCHAMP has been developed with H I (neutral hydrogen) observations in mind, but is widely applicable to many types of astronomical images. It features efficient source detection and handling methods, noise suppression via smoothing or multi-resolution wavelet reconstruction, and a range of graphical and text-based outputs to allow the user to understand the detections. This paper details some of the key algorithms used and illustrates the effectiveness of the finder on different data sets.

  11. Positive cloud-to-ground lightning detection by a direction-finder network

    NASA Technical Reports Server (NTRS)

    Macgorman, Donald R.; Taylor, William L.

    1989-01-01

    Consideration is given to the ability of an automatic direction-finder network to identify cloud-to-ground flashes that effectively lower positive charge to the ground (+CG flashes). Records from an extremely low frequency system are examined to determine whether or not 340 +CG flashes detected by the network have coincident waveforms characteristic of +CG flashes. It is found that false detection in the system is negligible for +CG flashes with range-normalized amplitudes of at least 50 direction-finder units. Also, it is shown that no more than about 15 percent of the +CG flashes detected by the system at smaller amplitudes are false detections.

  12. High-order myopic coronagraphic phase diversity (COFFEE) for wave-front control in high-contrast imaging systems

    NASA Astrophysics Data System (ADS)

    Paul, B.; Mugnier, L. M.; Sauvage, J.-F.; Ferrari, M.; Dohlen, K.

    2013-12-01

    The estimation and compensation of quasi-static aberrations is mandatory to reach the ultimate performance of high-contrast imaging systems. COFFEE is a focal plane wave-front sensing method that consists in the extension of phase diversity to high-contrast imaging systems. Based on a Bayesian approach, it estimates the quasi-static aberrations from two focal plane images recorded from the scientific camera itself. In this paper, we present COFFEE's extension which allows an estimation of low and high order aberrations with nanometric precision for any coronagraphic device. The performance is evaluated by realistic simulations, performed in the SPHERE instrument framework. We develop a myopic estimation that allows us to take into account an imperfect knowledge on the used diversity phase. Lastly, we evaluate COFFEE's performance in a compensation process, to optimize the contrast on the detector, and show it allows one to reach the 10^-6 contrast required by SPHERE at a few resolution elements from the star. Notably, we present a non-linear energy minimization method which can be used to reach very high contrast levels (better than 10^-7 in a SPHERE-like context)

  13. High-order myopic coronagraphic phase diversity (COFFEE) for wave-front control in high-contrast imaging systems.

    PubMed

    Paul, B; Mugnier, L M; Sauvage, J-F; Dohlen, K; Ferrari, M

    2013-12-30

    The estimation and compensation of quasi-static aberrations is mandatory to reach the ultimate performance of high-contrast imaging systems. COFFEE is a focal plane wave-front sensing method that consists in the extension of phase diversity to high-contrast imaging systems. Based on a Bayesian approach, it estimates the quasi-static aberrations from two focal plane images recorded from the scientific camera itself. In this paper, we present COFFEE's extension which allows an estimation of low and high order aberrations with nanometric precision for any coronagraphic device. The performance is evaluated by realistic simulations, performed in the SPHERE instrument framework. We develop a myopic estimation that allows us to take into account an imperfect knowledge on the used diversity phase. Lastly, we evaluate COFFEE's performance in a compensation process, to optimize the contrast on the detector, and show it allows one to reach the 10(-6) contrast required by SPHERE at a few resolution elements from the star. Notably, we present a non-linear energy minimization method which can be used to reach very high contrast levels (better than 10(7) in a SPHERE-like context).

  14. Experimental study of the low-order wavefront sensor for the high-contrast coronagraphic imager EXCEDE

    NASA Astrophysics Data System (ADS)

    Lozi, Julien; Belikov, Ruslan; Schneider, Glenn; Guyon, Olivier; Pluzhnik, Eugene; Thomas, Sandrine J.; Martinache, Frantz

    2013-09-01

    The mission EXCEDE (EXoplanetary Circumstellar Environments and Disk Explorer), selected by NASA for technology development, is designed to study the formation, evolution and architectures of exoplanetary systems and characterize circumstellar environments into stellar habitable zones. It is composed of a 0.7 m telescope equipped with a Phase-Induced Amplitude Apodization Coronagraph (PIAA-C) and a 2000-element MEMS deformable mirror, capable of raw contrasts of 10-6 at 1.2 λ/D and 10-7 above 2 λ/D. One of the key challenges to achieve those contrasts is to remove low-order aberrations, using a Low-Order WaveFront Sensor (LOWFS). An experiment simulating the starlight suppression system is currently developed at NASA Ames Research Center, and includes a LOWFS controlling tip/tilt modes in real time at 500 Hz. The LOWFS allowed us to reduce the tip/tilt disturbances to 10-3 λ/D rms, enhancing the previous contrast by a decade, to 8×10-7 between 1.2 and 2 λ/D. A Linear Quadratic Gaussian (LQG) controller is currently implemented to improve even more that result by reducing residual vibrations. This testbed shows that a good knowledge of the low-order disturbances is a key asset for high contrast imaging, whether for real-time control or for post processing.

  15. Threshold raw retrieved contrast in coronagraphs is limited by internal polarization

    NASA Astrophysics Data System (ADS)

    Breckinridge, James

    The objective of this work is to provide the exoplanet program with an accurate model of the coronagraph complex point spread function, methods to correct chromatic aberration in the presence of polarization aberrations, device requirements to minimize and compensate for these aberrations at levels needed for exoplanet coronagraphy, and exoplanet retrieval algorithms in the presence of polarizaiton aberrations. Currently, space based coronagraphs are designed and performance analyzed using scalar wave aberration theory. Breckinridge, Lam & Chipman (2015) PASP 127: 445-468 and Breckinridge & Oppenheimer (2004) ApJ 600: 1091-1098 showed that astronomical telescopes designed for exoplanet and precision astrometric science require polarization or vector-wave analysis. Internal instrument polarization limits both threshold raw contrast and measurements of the vector wave properties of the electromagnetic radiation from stars, exoplanets, gas and dust. The threshold raw contrast obtained using only scalar wave theory is much more optimistic than that obtained using the more hardware-realistic vector wave theory. Internal polarization reduces system contrast, increases scattered light, alters radiometric measurements, distorts diffraction-limited star images and reduces signal-to-noise ratio. For example, a vector-wave analysis shows that the WFIRST-CGI instrument will have a threshold raw contrast of 10-7 not the 10-8 forecasted using the scalar wave analysis given in the WFIRST-CGI 2015 report. The physical nature of the complex point spread function determines the exoplanet scientific yield of coronagraphs. We propose to use the Polaris-M polarization aberration ray-tracing software developed at the College of Optical Science of the University of Arizona to ray trace both a "typical" exoplanet coronagraph system as well as the WFIRST-CGI system. Threshold raw contrast and the field across the complex PSF will be calculated as a function of optical device vector E

  16. Optimal Jet Finder (v1.0 C++)

    NASA Astrophysics Data System (ADS)

    Chumakov, S.; Jankowski, E.; Tkachov, F. V.

    2006-10-01

    We describe a C++ implementation of the Optimal Jet Definition for identification of jets in hadronic final states of particle collisions. We explain interface subroutines and provide a usage example. The source code is available from http://www.inr.ac.ru/~ftkachov/projects/jets/. Program summaryTitle of program: Optimal Jet Finder (v1.0 C++) Catalogue identifier: ADSB_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADSB_v2_0 Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Computer: any computer with a standard C++ compiler Tested with:GNU gcc 3.4.2, Linux Fedora Core 3, Intel i686; Forte Developer 7 C++ 5.4, SunOS 5.9, UltraSPARC III+; Microsoft Visual C++ Toolkit 2003 (compiler 13.10.3077, linker 7.10.30777, option /EHsc), Windows XP, Intel i686. Programming language used: C++ Memory required:˜1 MB (or more, depending on the settings) No. of lines in distributed program, including test data, etc.: 3047 No. of bytes in distributed program, including test data, etc.: 17 884 Distribution format: tar.gz Nature of physical problem: Analysis of hadronic final states in high energy particle collision experiments often involves identification of hadronic jets. A large number of hadrons detected in the calorimeter is reduced to a few jets by means of a jet finding algorithm. The jets are used in further analysis which would be difficult or impossible when applied directly to the hadrons. Grigoriev et al. [D.Yu. Grigoriev, E. Jankowski, F.V. Tkachov, Phys. Rev. Lett. 91 (2003) 061801] provide brief introduction to the subject of jet finding algorithms and a general review of the physics of jets can be found in [R. Barlow, Rep. Prog. Phys. 36 (1993) 1067]. Method of solution: The software we provide is an implementation of the so-called Optimal Jet Definition (OJD). The theory of OJD was developed in [F.V. Tkachov, Phys. Rev. Lett. 73 (1994) 2405; Erratum, Phys. Rev. Lett. 74 (1995) 2618; F.V. Tkachov, Int. J. Modern Phys

  17. General Astrophysics and Comparative Planetology with the Terrestrial Planet Finder Missions

    NASA Technical Reports Server (NTRS)

    Kuchner, Marc J. (Editor)

    2005-01-01

    This document discusses the potential of the Terrestrial Planet Finder (TPF) for general astrophysics beyond its base mission, focusing on science obtainable with no or minimal modifications to the mission design, but also exploring possible modifications of TPF with high scientific merit and no impact on the basic search for extrasolar Earth analogs.

  18. The Relationship between Kolb's Learning Styles and StrengthsFinder's Talent Themes

    ERIC Educational Resources Information Center

    Caldwell, Adonna B.

    2009-01-01

    The purpose of this study was to investigate if there were relationships between college students' talent themes as defined by the Clifton StrengthsFinder(TM) Instrument and their learning style as defined by Kolb Learning Styles Inventory. Logistical regression methodology was utilized to assess the relationship between learning styles and talent…

  19. Test of the principle of operation of a wideband magnetic direction finder for lightning return strokes

    NASA Technical Reports Server (NTRS)

    Herrman, B. D.; Uman, M. A.; Brantley, R. D.; Krider, E. P.

    1976-01-01

    The principle of operation of a wideband crossed-loop magnetic-field direction finder is studied by comparing the bearing determined from the NS and EW magnetic fields at various times up to 155 microsec after return stroke initiation with the TV-determined lightning channel base direction. For 40 lightning strokes in the 3 to 12 km range, the difference between the bearings found from magnetic fields sampled at times between 1 and 10 microsec and the TV channel-base data has a standard deviation of 3-4 deg. Included in this standard deviation is a 2-3 deg measurement error. For fields sampled at progressively later times, both the mean and the standard deviation of the difference between the direction-finder bearing and the TV bearing increase. Near 150 microsec, means are about 35 deg and standard deviations about 60 deg. The physical reasons for the late-time inaccuracies in the wideband direction finder and the occurrence of these effects in narrow-band VLF direction finders are considered.

  20. Subtle.Nets.Finder: finely tuned interaction networks in DNA/RNA/protein complexes.

    PubMed

    Kantardjiev, Alexander A

    2017-03-01

    Graphical Abstract Subtle.Nets.Finder is a workflow of algorithms for identification of subtly interacting groups in DNA/RNA/protein complexes. It is founded on detailed and sophisticated evaluation of the self-consistency in the cooperative network of residue interactions via a combination of advanced calculations (fast multipole method and statistical mechanics) supplemented with graph-theoretical procedures.

  1. Precise pulsed time-of-flight laser range finder for industrial distance measurements

    NASA Astrophysics Data System (ADS)

    Kilpelä, Ari; Pennala, Riku; Kostamovaara, Juha

    2001-04-01

    A pulsed time-of-flight laser range finder with a 1 GHz avalanche photo diode (APD) receiver and a laser pulser with ˜35 ps pulse width has been developed and tested. The receiver channel is constructed using a silicon ASIC chip and a commercially available silicon APD placed on a hybrid ceramic susbstrate. The laser pulser utilizes a single heterostructure laser operating in Q-switching mode. It is shown that the single-shot precision of the complete laser range finder is ˜2.1 mm (σ value) at best. The nonaccuracy in the distance range of 0.5-34.5 m was ˜±2 mm excluding errors caused by the statistical variations and long-term instability. The single-shot precision is clearly better than the single-shot precision of the earlier laser range finders with ˜100-200 MHz bandwidths. Also, two types of optics, coaxial and paraxial, were tested. The linearity of the coaxial optics was better, especially with a long (4 m) receiver fiber. Some possible applications of the laser range finder utilizing ps level pulses are, for example, fast three-dimensional vision in industrial environments and structure analysis of materials.

  2. A Novel MEMS Gyro North Finder Design Based on the Rotation Modulation Technique

    PubMed Central

    Zhang, Yongjian; Zhou, Bin; Song, Mingliang; Hou, Bo; Xing, Haifeng; Zhang, Rong

    2017-01-01

    Gyro north finders have been widely used in maneuvering weapon orientation, oil drilling and other areas. This paper proposes a novel Micro-Electro-Mechanical System (MEMS) gyroscope north finder based on the rotation modulation (RM) technique. Two rotation modulation modes (static and dynamic modulation) are applied. Compared to the traditional gyro north finders, only one single MEMS gyroscope and one MEMS accelerometer are needed, reducing the total cost since high-precision gyroscopes and accelerometers are the most expensive components in gyro north finders. To reduce the volume and enhance the reliability, wireless power and wireless data transmission technique are introduced into the rotation modulation system for the first time. To enhance the system robustness, the robust least square method (RLSM) and robust Kalman filter (RKF) are applied in the static and dynamic north finding methods, respectively. Experimental characterization resulted in a static accuracy of 0.66° and a dynamic repeatability accuracy of 1°, respectively, confirming the excellent potential of the novel north finding system. The proposed single gyro and single accelerometer north finding scheme is universal, and can be an important reference to both scientific research and industrial applications. PMID:28452936

  3. A Novel MEMS Gyro North Finder Design Based on the Rotation Modulation Technique.

    PubMed

    Zhang, Yongjian; Zhou, Bin; Song, Mingliang; Hou, Bo; Xing, Haifeng; Zhang, Rong

    2017-04-28

    Gyro north finders have been widely used in maneuvering weapon orientation, oil drilling and other areas. This paper proposes a novel Micro-Electro-Mechanical System (MEMS) gyroscope north finder based on the rotation modulation (RM) technique. Two rotation modulation modes (static and dynamic modulation) are applied. Compared to the traditional gyro north finders, only one single MEMS gyroscope and one MEMS accelerometer are needed, reducing the total cost since high-precision gyroscopes and accelerometers are the most expensive components in gyro north finders. To reduce the volume and enhance the reliability, wireless power and wireless data transmission technique are introduced into the rotation modulation system for the first time. To enhance the system robustness, the robust least square method (RLSM) and robust Kalman filter (RKF) are applied in the static and dynamic north finding methods, respectively. Experimental characterization resulted in a static accuracy of 0.66° and a dynamic repeatability accuracy of 1°, respectively, confirming the excellent potential of the novel north finding system. The proposed single gyro and single accelerometer north finding scheme is universal, and can be an important reference to both scientific research and industrial applications.

  4. Flood Finder: Mobile-based automated water level estimation and mapping during floods

    NASA Astrophysics Data System (ADS)

    Pongsiriyaporn, B.; Jariyavajee, C.; Laoharawee, N.; Narkthong, N.; Pitichat, T.; Goldin, S. E.

    2014-02-01

    Every year, Southeast Asia faces numerous flooding disasters, resulting in very high human and economic loss. Responding to a sudden flood is difficult due to the lack of accurate and up-to- date information about the incoming water status. We have developed a mobile application called Flood Finder to solve this problem. Flood Finder allows smartphone users to measure, share and search for water level information at specified locations. The application uses image processing to compute the water level from a photo taken by users. The photo must be of a known reference object with a standard size. These water levels are more reliable and consistent than human estimates since they are derived from an algorithmic measuring function. Flood Finder uploads water level readings to the server, where they can be searched and mapped by other users via the mobile phone app or standard browsers. Given the widespread availability of smartphones in Asia, Flood Finder can provide more accurate and up-to-date information for better preparation for a flood disaster as well as life safety and property protection.

  5. Problem-based learning using the online Medicare Part D Plan Finder tool.

    PubMed

    Cutler, Timothy W; Stebbins, Marilyn R; Lai, Eric; Smith, Amanda R; Lipton, Helene Levens

    2008-06-15

    To implement didactic and problem-based learning curricular innovations aimed at increasing students' knowledge of Medicare Part D, improving their ability to apply the online Medicare Prescription Drug Plan Finder tool to a patient case, and improving their attitudes toward patient advocacy for Medicare beneficiaries. A survey instrument and a case-based online Medicare Prescription Drug Plan Finder tool exercise were administered to a single group (n = 120) of second-year pharmacy graduate students prior to and following completion of a course on health policy. Three domains (knowledge, skill mastery and attitudes) were measured before and after two 90-minute lectures on Medicare Part D. The online Medicare Prescription Drug Plan Finder exercise and Medicare Part D didactic lectures had positive effects on students' knowledge of Part D, attitudes toward patient advocacy, and ability to accurately use the Medicare Prescription Drug Plan Finder tool. The success of these didactic and problem-based curricular innovations in improving pharmacy students' knowledge, skills, and attitudes regarding Part D warrants further evaluation to determine their portability to clinical settings and other pharmacy schools.

  6. Microlithography and resist technology information at your fingertips via SciFinder

    NASA Astrophysics Data System (ADS)

    Konuk, Rengin; Macko, John R.; Staggenborg, Lisa

    1997-07-01

    Finding and retrieving the information you need about microlithography and resist technology in a timely fashion can make or break your competitive edge in today's business environment. Chemical Abstracts Service (CAS) provides the most complete and comprehensive database of the chemical literature in the CAplus, REGISTRY, and CASREACT files including 13 million document references, 15 million substance records and over 1.2 million reactions. This includes comprehensive coverage of positive and negative resist formulations and processing, photoacid generation, silylation, single and multilayer resist systems, photomasks, dry and wet etching, photolithography, electron-beam, ion-beam and x-ray lithography technologies and process control, optical tools, exposure systems, radiation sources and steppers. Journal articles, conference proceedings and patents related to microlithography and resist technology are analyzed and indexed by scientific information analysts with strong technical background in these areas. The full CAS database, which is updated weekly with new information, is now available at your desktop, via a convenient, user-friendly tool called 'SciFinder.' Author, subject and chemical substance searching is simplified by SciFinder's smart search features. Chemical substances can be searched by chemical structure, chemical name, CAS registry number or molecular formula. Drawing chemical structures in SciFinder is easy and does not require compliance with CA conventions. Built-in intelligence of SciFinder enables users to retrieve substances with multiple components, tautomeric forms and salts.

  7. Teenage Pregnancy: An Intensive and Critical Problem in Search of a Solution. Student Fact Finder Leaflet.

    ERIC Educational Resources Information Center

    Glover-Smith, Alma

    This document presents materials from a course designed to teach adolescents about teenage pregnancy and parenting. The materials are organized into nine modules, each of which contains instructions on how to use the module; a pre- and post-test on the information presented in the module; a fact finder leaflet of information; and relevant…

  8. Experimental study of a low-order wavefront sensor for a high-contrast coronagraphic imager at 1.2 lambda/D

    NASA Astrophysics Data System (ADS)

    Lozi, Julien; Belikov, Ruslan; Schneider, Glenn; Guyon, Olivier; Pluzhnik, Eugene; Thomas, Sandrine; Martinache, Frantz

    2013-12-01

    High-contrast imaging will be a challenge for future ELTs, because their vibrations create low-order aberrations - mostly tip/tilt - that reduce coronagraphic performances at 1.2 lambda/D and above. A Low-Order WaveFront Sensor (LOWFS) is essential to measure and control those aberrations. An experiment simulating a starlight suppression system is currently developed at NASA Ames Research Center, and includes a LOWFS controlling tip/tilt modes in real time at 500 Hz. The LOWFS allowed us to reduce the tip/tilt disturbances to 1e-3 lambda/D rms, enhancing the previous contrast by a decade, to 8e-7 between 1.2 and 2 lambda/D. A Linear Quadratic Gaussian (LQG) controller is currently implemented to improve even more that result by reducing residual vibrations. This testbed is developed for the mission EXCEDE (EXoplanetary Circumstellar Environments and Disk Explorer), selected by NASA for technology development, and designed to study the formation, evolution and architectures of exoplanetary systems and characterize circumstellar environments into stellar habitable zones. It is composed of a 0.7 m telescope equipped with a Phase-Induced Amplitude Apodization Coronagraph (PIAA-C) and a 2000-element MEMS deformable mirror, capable of raw contrasts of 1e-6 at 1.2 lambda/D and 1e-7 above 2 lambda/D. Although the testbed simulates space conditions, its LOWFS has the same design than on the SCExAO instrument at Subaru telescope, with whom it shares the same kind of problematic. Experimental results show that a good knowledge of the low-order disturbances is a key asset for high contrast imaging, whether for real-time control or for post processing, both in space and on ground telescopes.

  9. Solar wind research with the Large Angle Spectroscopic Coronagraph (LASCO) experiment onboard the Solar and Heliospheric Observatory (SOHO) satellite

    NASA Technical Reports Server (NTRS)

    Brueckner, G. E.

    1995-01-01

    The ESA-NASA satellite, to be launched in October 1995, carries three nested coronagraphs, which will image the solar corona from 1.1 R(solar mass) to 30 R(solar mass). Super polished mirrors have been developed for the design of a mirror Lyot coronagraph which has a straylight level comparable with the coronal intensity from 1.1 R, to 30 R(solar mass) Coronal details can be imaged with a spatial resolution of 6 arc seconds. A Fabry Perot interferometer with a spectral resolution of 0.7 A at the wavelength of the green coronal emission line will allow the simultaneous construction of spectra over the entire field of view of 10(exp 6) pixels. The middle coronagraph (1.5 R(solar mass) - 6 R(solar mass)) and the outer coronagraph (3 R(solar mass) - 30 R(solar mass)) are externally occulted lens Lyot coronagraphs. Their straylight level 10(exp -11) B(solar mass) and 10(exp -12) B(solar mass) respectively is an order of magnitude smaller than the intensity of the corona. The sensitivity of LASCO to distinguish between different solar wind acceleration mechanisms will be discussed as well as its ability to discern different CME models.

  10. Lead Finder docking and virtual screening evaluation with Astex and DUD test sets

    NASA Astrophysics Data System (ADS)

    Novikov, Fedor N.; Stroylov, Viktor S.; Zeifman, Alexey A.; Stroganov, Oleg V.; Kulkov, Val; Chilov, Ghermes G.

    2012-06-01

    Lead Finder is a molecular docking software. Sampling uses an original implementation of the genetic algorithm that involves a number of additional optimization procedures. Lead Finder's scoring functions employ a set of semi-empiric molecular mechanics functionals that have been parameterized independently for docking, binding energy predictions and rank-ordering for virtual screening. Sampling and scoring both utilize a staged approach, moving from fast but less accurate algorithm versions to computationally more intensive but more accurate versions. Lead Finder includes tools for the preparation of full atom protein and ligand models. In this exercise, Lead Finder achieved 72.9% docking success rate on the Astex test set when the original author-prepared full atom models were used, and 74.1% success rate when the structures were prepared by Lead Finder. The major cause of docking failures were scoring errors resulting from the use of imperfect solvation models. In many cases, docking errors could be corrected by the proper protonation and the use of correct cyclic conformations of ligands. In virtual screening experiments on the DUD test set the early enrichment factor of several tens was achieved on average. However, the area under the ROC curve ("AUC ROC") ranged from 0.70 to 0.74 depending on the screening protocol used, and the separation from the null model was not perfect—0.12-0.15 units of AUC ROC. We assume that effective virtual screening in the whole range of enrichment curve and not just at the early enrichment stages requires more accurate solvation modeling and accounting for the protein backbone flexibility.

  11. Applications of the Integrated High-Performance CMOS Image Sensor to Range Finders — from Optical Triangulation to the Automotive Field

    PubMed Central

    Wu, Jih-Huah; Pen, Cheng-Chung; Jiang, Joe-Air

    2008-01-01

    With their significant features, the applications of complementary metal-oxide semiconductor (CMOS) image sensors covers a very extensive range, from industrial automation to traffic applications such as aiming systems, blind guidance, active/passive range finders, etc. In this paper CMOS image sensor-based active and passive range finders are presented. The measurement scheme of the proposed active/passive range finders is based on a simple triangulation method. The designed range finders chiefly consist of a CMOS image sensor and some light sources such as lasers or LEDs. The implementation cost of our range finders is quite low. Image processing software to adjust the exposure time (ET) of the CMOS image sensor to enhance the performance of triangulation-based range finders was also developed. An extensive series of experiments were conducted to evaluate the performance of the designed range finders. From the experimental results, the distance measurement resolutions achieved by the active range finder and the passive range finder can be better than 0.6% and 0.25% within the measurement ranges of 1 to 8 m and 5 to 45 m, respectively. Feasibility tests on applications of the developed CMOS image sensor-based range finders to the automotive field were also conducted. The experimental results demonstrated that our range finders are well-suited for distance measurements in this field. PMID:27879789

  12. Stop-less Lyot coronagraph for exoplanet characterization: design, manufacturing, and tests of the apodizer

    NASA Astrophysics Data System (ADS)

    Vigan, A.; N'Diaye, M.; Dohlen, K.

    2014-07-01

    Upcoming high-contrast imagers will all provide spectroscopic capabilities for the characterization of directly detected giant planets in wide orbits. While integral field spectroscopy (IFS) can provide both spatial and spectral information, it is usually limited in terms of field of view and resolution. The alternative is to use long slit spectroscopy coupled with coronagraphy (LSC), which can easily provide higher resolution and larger field of view. The SPHERE instrument for the VLT provides a LSC mode in its near-infrared imager and spectrograph, IRDIS. However, the fact that the occulting coronagraphic mask is merged in the focal plane with the slit reduces significantly its capacity to attenuate the diffraction, limiting the high-contrast capabilities of the instrument at close angular separations (0.3"-0.4"). To improve the diffraction suppression of the LSC in IRDIS, we recently proposed to use the stop-less Lyot coronagraph (SLLC) to build an apodized long slit coronagraph (ALSC), and we demonstrated that it improves notably the performance at small angular separation, allowing the spectral analysis of colder planets. The design of the SLLC apodizer has been optimized for an implementation in SPHERE/IRDIS, and it has recently been manufactured before being inserted into the instrument during reintegration of SPHERE in Paranal. In the current work, we present the final design of the SLLC apodizer, its specifications for the manufacturing step, and the first results obtained on SPHERE. We compare the results between the simple LSC and the new ALSC, and we draw the conclusions on the advantages and drawbacks of our design.

  13. High-Contrast Imaging and Wavefront Control with a PIAA Coronagraph: Laboratory System Validation

    NASA Astrophysics Data System (ADS)

    Guyon, Olivier; Pluzhnik, Eugene; Martinache, Frantz; Totems, Julien; Tanaka, Shinichiro; Matsuo, Taro; Blain, Celia; Belikov, Ruslan

    2010-01-01

    The Phase-Induced Amplitude Apodization (PIAA) coronagraph is a high-performance coronagraph concept able to work at small angular separation with little loss in throughput. We present results obtained with a laboratory PIAA system including active wavefront control. The system has a 94.3% throughput (excluding coating losses) and operates in air with monochromatic light. Our testbed achieved a 2.27 × 10-7 raw contrast between 1.65λ/D (inner working angle of the coronagraph configuration tested) and 4.4λ/D (outer working angle). Through careful calibration, we were able to separate this residual light into a dynamic coherent component (turbulence, vibrations) at 4.5 × 10-8 contrast and a static incoherent component (ghosts and/or polarization mismatch) at 1.6 × 10-7 contrast. Pointing errors are controlled at the 10-3λ/D level using a dedicated low-order wavefront sensor. While not sufficient for direct imaging of Earthlike planets from space, the 2.27 × 10-7 raw contrast achieved already exceeds requirements for a ground-based extreme adaptive optics system aimed at direct detection of more massive exoplanets. We show that over a 4 hr period, averaged wavefront errors have been controlled to the 3.5 × 10-9 contrast level. This result is particularly encouraging for ground-based extreme-AO systems relying on long-term stability and absence of static wavefront errors to recover planets much fainter than the fast boiling speckle halo.

  14. An Off-Axis Four-Quadrant Phase Mask (FQPM) Coronagraph for Palomar: High-Contrast Near Bright Stars Imager

    NASA Technical Reports Server (NTRS)

    Haguenauer, Pierre; Serabyn, Eugene; Bloemhof, Eric E.; Troy, Mitchell; Wallace, James K.; Koresko, Chris D.; Mennesson, Bertrand

    2005-01-01

    Direct detection of planets around nearby stars requires the development of high-contrast imaging techniques because of the high difference between their respective fluxes. This led us to test a new coronagraphic approach based on the use of phase mask instead of dark occulting ones. Combined with high-level wavefront correction on an unobscured off-axis section of a large telescope, this method allows imaging very close to the star. Calculations indicate that for a given ground-based on-axis telescope, use of such an off-axis coronagraph provides a near-neighbor detection capability superior to that of a traditional coronagraph utilizing the full telescope aperture. Setting up a laboratory experiment working in near infrared allowed us to demonstrate the principle of the method, and a rejection of 2000:1 has already been achieved.

  15. In-orbit determination of the straylight in the SOHO/LASCO-C2 coronagraph and its temporal evolution

    NASA Astrophysics Data System (ADS)

    Llebaria, A.; Loirat, J.; Lamy, P.

    2012-09-01

    The LASCO-C2 coronagraph aboard SOHO (the SOlar and Heliospheric Observatory) is continuously observing the solar corona since early 1996. The instrument as well as the experimental context underwent during this period many changes and observational constraints. The consequences for the in-orbit calibration procedures are illustrated with the systematic measure of the coronagraph straylight. Disentangle the coronal signal and the straylight is the crucial point. The separation and monitoring of the straylight component rely on the daily sets of polarized observations of the corona and a minimal set of assumptions about the symmetry of the F-corona (the dust component of the solar corona). Four main changes have been detected since 1996. Specific recommendations for the in-orbit calibration of future spatial coronagraphs will be presented.

  16. Phase-induced amplitude apodization complex mask coronagraph mask fabrication, characterization, and modeling for WFIRST-AFTA

    NASA Astrophysics Data System (ADS)

    Kern, Brian; Guyon, Olivier; Belikov, Ruslan; Wilson, Daniel; Muller, Richard; Sidick, Erkin; Balasubramanian, Bala; Krist, John; Poberezhskiy, Ilya; Tang, Hong

    2016-01-01

    This work describes the fabrication, characterization, and modeling of a second-generation occulting mask for a phase-induced amplitude apodization complex mask coronagraph, designed for use on the WFIRST-AFTA mission. The mask has many small features (˜micron lateral scales) and was fabricated at the Jet Propulsion Laboratory Microdevices Laboratory, then characterized using a scanning electron microscope, atomic force microscope, and optical interferometric microscope. The measured fabrication errors were then fed to a wavefront control model which predicts the contrast performance of a full coronagraph. The expected coronagraphic performance using this mask is consistent with observing ˜15 planetary targets with WFIRST-AFTA in a reasonable time (<1 day/target).

  17. Moisture effects and control for the UVCS composite structure. [Ultraviolet Coronagraph Spectrograph

    NASA Technical Reports Server (NTRS)

    Austin, James D.

    1992-01-01

    The Ultraviolet Coronagraph Spectrograph (UVCS) is an optical instrument to be flown on the European spacecraft Solar Heliospheric Observatory (SOHO) to the sun-earth L1 point. The stability requirements of the instrument require the moisture content of the pseudoisotropic composite material not to exceed 0.06 percent during alignment and calibration. This paper describes the steps necessary to meet this requirement. These steps include a dynamic moisture content analysis, selection of bake out conditions and moisture controls, verification sampling, and use of witness specimens to monitor the moisture content during the prelaunch life of the structure.

  18. Coronagraphic technique to infer the nature of the Skylab particulate environment

    NASA Technical Reports Server (NTRS)

    Schuerman, D. W.; Beeson, D. E.; Giovane, F.

    1977-01-01

    Photographs taken with the High Altitude Observatory's White Light Coronagraph (Skylab experiment S052) are shown to contain information on the sizes and velocities of contaminant particulates around Skylab. Sizes as small as 5 micron (radius) are derived for particles as far away as 200 m from the spacecraft. The random error in the size derivation is about 30%, and no particle larger than 120 micron was observed. Transverse velocities are determined to within 0.08 m/sec and radial velocities to within 9 m/sec. The S052 data bank contains about 3500 contaminated frames from which the nature of the Skylab environment can be inferred.

  19. Fabrication and Characteristics of Free Standing Shaped Pupil Masks for TPF-Coronagraph

    NASA Technical Reports Server (NTRS)

    Balasubramanian, Kunjithapatham; Echternach, Pierre M.; Dickie, Matthew R.; Muller, Richard E.; White, Victor E.; Hoppe, Daniel J.; Shaklan, Stuart B.; Belikov, Ruslan; Kasdin, N. Jeremy; Vanderbei, Robert J.; Ceperley, Daniel; Neureuther, Andrew R.

    2006-01-01

    Direct imaging and characterization of exo-solar terrestrial planets require coronagraphic instruments capable of suppressing star light to 10-10. Pupil shaping masks have been proposed and designed1 at Princeton University to accomplish such a goal. Based on Princeton designs, free standing (without a substrate) silicon masks have been fabricated with lithographic and deep etching techniques. In this paper, we discuss the fabrication of such masks and present their physical and optical characteristics in relevance to their performance over the visible to near IR bandwidth.

  20. Coronagraphic technique to infer the nature of the Skylab particulate environment

    NASA Technical Reports Server (NTRS)

    Schuerman, D. W.; Beeson, D. E.; Giovane, F.

    1977-01-01

    Photographs taken with the High Altitude Observatory's White Light Coronagraph (Skylab experiment S052) are shown to contain information on the sizes and velocities of contaminant particulates around Skylab. Sizes as small as 5 micron (radius) are derived for particles as far away as 200 m from the spacecraft. The random error in the size derivation is about 30%, and no particle larger than 120 micron was observed. Transverse velocities are determined to within 0.08 m/sec and radial velocities to within 9 m/sec. The S052 data bank contains about 3500 contaminated frames from which the nature of the Skylab environment can be inferred.

  1. DESIGN AND MEASUREMENT OF THE STOKES POLARIMETER FOR THE COSMO K-CORONAGRAPH

    SciTech Connect

    Hou Junfeng; De Wijn, Alfred G.; Tomczyk, Steven E-mail: dwijn@ucar.edu

    2013-09-01

    We present the Stokes polarimeter for the new Coronal Solar Magnetism Observatory K-coronagraph. The polarimeter can be used in two modes. In observation mode, it is sensitive to linear polarization only and operates as a ''Stokes definition'' polarimeter. In the ideal case, such a modulator isolates a particular Stokes parameter in each modulation state. For calibrations, the polarimeter can diagnose the full Stokes vector. We present here the design process of the polarimeter, analyze its tolerances with a Monte Carlo method, develop a way to align the individual elements, and measure and evaluate its performance in both modes.

  2. Hubble Space Telescope ACS Multiband Coronagraphic Imaging of the Debris Disk around β Pictoris

    NASA Astrophysics Data System (ADS)

    Golimowski, D. A.; Ardila, D. R.; Krist, J. E.; Clampin, M.; Ford, H. C.; Illingworth, G. D.; Bartko, F.; Benítez, N.; Blakeslee, J. P.; Bouwens, R. J.; Bradley, L. D.; Broadhurst, T. J.; Brown, R. A.; Burrows, C. J.; Cheng, E. S.; Cross, N. J. G.; Demarco, R.; Feldman, P. D.; Franx, M.; Goto, T.; Gronwall, C.; Hartig, G. F.; Holden, B. P.; Homeier, N. L.; Infante, L.; Jee, M. J.; Kimble, R. A.; Lesser, M. P.; Martel, A. R.; Mei, S.; Menanteau, F.; Meurer, G. R.; Miley, G. K.; Motta, V.; Postman, M.; Rosati, P.; Sirianni, M.; Sparks, W. B.; Tran, H. D.; Tsvetanov, Z. I.; White, R. L.; Zheng, W.; Zirm, A. W.

    2006-06-01

    We present F435W (B), F606W (broad V), and F814W (broad I) coronagraphic images of the debris disk around β Pictoris obtained with the Hubble Space Telescope's Advanced Camera for Surveys. These images provide the most photometrically accurate and morphologically detailed views of the disk between 30 and 300 AU from the star ever recorded in scattered light. We confirm that the previously reported warp in the inner disk is a distinct secondary disk inclined by ~5° from the main disk. The projected spine of the secondary disk coincides with the isophotal inflections, or ``butterfly asymmetry,'' previously seen at large distances from the star. We also confirm that the opposing extensions of the main disk have different position angles, but we find that this ``wing-tilt asymmetry'' is centered on the star rather than offset from it, as previously reported. The main disk's northeast extension is linear from 80 to 250 AU, but the southwest extension is distinctly bowed with an amplitude of ~1 AU over the same region. Both extensions of the secondary disk appear linear, but not collinear, from 80 to 150 AU. Within ~120 AU of the star, the main disk is ~50% thinner than previously reported. The surface brightness profiles along the spine of the main disk are fitted with four distinct radial power laws between 40 and 250 AU, while those of the secondary disk between 80 and 150 AU are fitted with single power laws. These discrepancies suggest that the two disks have different grain compositions or size distributions. The F606W/F435W and F814W/F435W flux ratios of the composite disk are nonuniform and asymmetric about both projected axes of the disk. The disk's northwest region appears 20%-30% redder than its southeast region, which is inconsistent with the notion that forward scattering from the nearer northwest side of the disk should diminish with increasing wavelength. Within ~120 AU, the mF435W-mF606W and mF435W-mF814W colors along the spine of the main disk are ~10

  3. Constraining the pass-band of future space-based coronagraphs for observations of solar eruptions in the FeXIV 530.3 nm "green line"

    NASA Astrophysics Data System (ADS)

    Bemporad, Alessandro; Pagano, Paolo; Giordano, Silvio; Fineschi, Silvano

    2017-06-01

    Observations of the solar corona in the FeXIV 530.3 nm "green line" have been very important in the past, and are planned for future coronagraphs on-board forthcoming space missions such as PROBA-3 and Aditya. For these instruments, a very important parameter to be optimized is the spectral width of the band-pass filter to be centred over the "green line". Focusing on solar eruptions, motions occurring along the line of sight will Doppler shift the line profiles producing an emission that will partially fall out of the narrower pass-band, while broader pass-band will provide observations with reduced spectral purity. To address these issues, we performed numerical (MHD) simulation of CME emission in the "green line" and produced synthetic images assuming 4 different widths of the pass-band (Δλ = 20 Å, 10 Å, 5 Å, and 2 Å). It turns out that, as expected, during solar eruptions a significant fraction of "green line" emission will be lost using narrower filters; on the other hand these images will have a higher spectral purity and will contain emission coming from parcels of plasma expanding only along the plane of the sky. This will provide a better definition of single filamentary features and will help isolating single slices of plasma through the eruption, thus reducing the problem of superposition of different features along the line of sight and helping physical interpretation of limb events. For these reasons, we suggest to use narrower band passes (Δλ ≤ 2 Å) for the observations of solar eruptions with future coronagraphs.

  4. Constraining the pass-band of future space-based coronagraphs for observations of solar eruptions in the FeXIV 530.3 nm "green line"

    NASA Astrophysics Data System (ADS)

    Bemporad, Alessandro; Pagano, Paolo; Giordano, Silvio; Fineschi, Silvano

    2017-10-01

    Observations of the solar corona in the FeXIV 530.3 nm "green line" have been very important in the past, and are planned for future coronagraphs on-board forthcoming space missions such as PROBA-3 and Aditya. For these instruments, a very important parameter to be optimized is the spectral width of the band-pass filter to be centred over the "green line". Focusing on solar eruptions, motions occurring along the line of sight will Doppler shift the line profiles producing an emission that will partially fall out of the narrower pass-band, while broader pass-band will provide observations with reduced spectral purity. To address these issues, we performed numerical (MHD) simulation of CME emission in the "green line" and produced synthetic images assuming 4 different widths of the pass-band (Δλ = 20 Å, 10 Å, 5 Å, and 2 Å). It turns out that, as expected, during solar eruptions a significant fraction of "green line" emission will be lost using narrower filters; on the other hand these images will have a higher spectral purity and will contain emission coming from parcels of plasma expanding only along the plane of the sky. This will provide a better definition of single filamentary features and will help isolating single slices of plasma through the eruption, thus reducing the problem of superposition of different features along the line of sight and helping physical interpretation of limb events. For these reasons, we suggest to use narrower band passes (Δλ ≤ 2 Å) for the observations of solar eruptions with future coronagraphs.

  5. Achromatic interfero-coronagraph with variable rotational shear: reducing of star leakage effect, white light nulling with lab prototype

    NASA Astrophysics Data System (ADS)

    Frolov, Pavel; Shashkova, Inna; Bezymyannikova, Yuliya; Kiselev, Alexander; Tavrov, Alexander

    2016-01-01

    Stellar coronagraphs with a small inner working angle have limited possibilities to detect exoplanets due to the star leakage effect caused by incomplete suppression of the star of finite angular size. We consider an improved instrument for direct imaging of exoplanets: common-path achromatic interfero-coronagraph with variable rotational shear (CP-ARC). CP-ARC reduces the star leakage effect by several orders of magnitude (with small angles of rotational shear relative to a fixed angle of 180 deg) with telescope size more than 1 m. Operation capacity of CP-ARC was experimentally verified by laser light nulling and white light nulling with lab prototype treated.

  6. End-to-end simulation of high-contrast imaging systems: methods and results for the PICTURE mission family

    NASA Astrophysics Data System (ADS)

    Douglas, Ewan S.; Hewasawam, Kuravi; Mendillo, Christopher B.; Cahoy, Kerri L.; Cook, Timothy A.; Finn, Susanna C.; Howe, Glenn A.; Kuchner, Marc J.; Lewis, Nikole K.; Marinan, Anne D.; Mawet, Dimitri; Chakrabarti, Supriya

    2015-09-01

    We describe a set of numerical approaches to modeling the performance of space flight high-contrast imaging payloads. Mission design for high-contrast imaging requires numerical wavefront error propagation to ensure accurate component specifications. For constructed instruments, wavelength and angle-dependent throughput and contrast models allow detailed simulations of science observations, allowing mission planners to select the most productive science targets. The PICTURE family of missions seek to quantify the optical brightness of scattered light from extrasolar debris disks via several high-contrast imaging techniques: sounding rocket (the Planet Imaging Concept Testbed Using a Rocket Experiment) and balloon flights of a visible nulling coronagraph, as well as a balloon flight of a vector vortex coronagraph (the Planetary Imaging Concept Testbed Using a Recoverable Experiment - Coronagraph, PICTURE-C). The rocket mission employs an on-axis 0.5m Gregorian telescope, while the balloon flights will share an unobstructed off-axis 0.6m Gregorian. This work details the flexible approach to polychromatic, end-to-end physical optics simulations used for both the balloon vector vortex coronagraph and rocket visible nulling coronagraph missions. We show the preliminary PICTURE-C telescope and vector vortex coronagraph design will achieve 10-8 contrast without post-processing as limited by realistic optics, but not considering polarization or low-order errors. Simulated science observations of the predicted warm ring around Epsilon Eridani illustrate the performance of both missions.

  7. OSCA, an Optimized Stellar Coronagraph for Adaptive optics: Description and first light

    NASA Astrophysics Data System (ADS)

    Thompson, Samantha; Doel, Andrew P.; Bingham, Richard G.; Charalambous, Andrew; Bissonauth, Nirmal; Clark, Paul; Myers, Richard M.; Talbot, Gordon

    2003-02-01

    We describe a coronagraph facility built for use with the 4.2 metre William Herschel Telescope (WHT) and its adaptive optics system (NAOMI). The use of the NAOMI adaptive optics system gives an improved image resolution of ~0.15 arcsec at a wavelength of 2.2 microns. This enables our Optimised Stellar Coronagraph for Adaptive optics (OSCA) to null stellar light with smaller occulting masks and thus allows regions closer to bright astronomical objects to be imaged. OSCA is a fully deployable instrument and when in use leaves the focus of the NAOMI beam unchanged. This enables OSCA to be used in conjunction with a number of instruments already commissioned at the WHT. The main imaging camera to be used with OSCA will be INGRID; a 1024×1024 HgCdTe cooled SWIR detector at the NAOMI focus. OSCA can also be used in conjunction with an integral field spectrograph for imaging at visible wavelengths. OSCA provides a selection of 10 different occulting mask sizes from 0.25 - 2.0 arcsec and some with a novel gaussian profile. There is also a choice of 2 different Lyot stops (pupil plane masks). A dichroic placed before the AO system can give us improved nulling when occulting masks larger than the seeing disk are used. We also present results from initial testing and commissioning at the William Herschel Telescope.

  8. On Advanced Estimation Techniques for Exoplanet Detection and Characterization Using Ground-based Coronagraphs.

    PubMed

    Lawson, Peter R; Poyneer, Lisa; Barrett, Harrison; Frazin, Richard; Caucci, Luca; Devaney, Nicholas; Furenlid, Lars; Gładysz, Szymon; Guyon, Olivier; Krist, John; Maire, Jérôme; Marois, Christian; Mawet, Dimitri; Mouillet, David; Mugnier, Laurent; Pearson, Iain; Perrin, Marshall; Pueyo, Laurent; Savransky, Dmitry

    2012-07-01

    The direct imaging of planets around nearby stars is exceedingly difficult. Only about 14 exoplanets have been imaged to date that have masses less than 13 times that of Jupiter. The next generation of planet-finding coronagraphs, including VLT-SPHERE, the Gemini Planet Imager, Palomar P1640, and Subaru HiCIAO have predicted contrast performance of roughly a thousand times less than would be needed to detect Earth-like planets. In this paper we review the state of the art in exoplanet imaging, most notably the method of Locally Optimized Combination of Images (LOCI), and we investigate the potential of improving the detectability of faint exoplanets through the use of advanced statistical methods based on the concepts of the ideal observer and the Hotelling observer. We propose a formal comparison of techniques using a blind data challenge with an evaluation of performance using the Receiver Operating Characteristic (ROC) and Localization ROC (LROC) curves. We place particular emphasis on the understanding and modeling of realistic sources of measurement noise in ground-based AO-corrected coronagraphs. The work reported in this paper is the result of interactions between the co-authors during a week-long workshop on exoplanet imaging that was held in Squaw Valley, California, in March of 2012.

  9. On Advanced Estimation Techniques for Exoplanet Detection and Characterization Using Ground-based Coronagraphs

    PubMed Central

    Lawson, Peter R.; Poyneer, Lisa; Barrett, Harrison; Frazin, Richard; Caucci, Luca; Devaney, Nicholas; Furenlid, Lars; Gładysz, Szymon; Guyon, Olivier; Krist, John; Maire, Jérôme; Marois, Christian; Mawet, Dimitri; Mouillet, David; Mugnier, Laurent; Pearson, Iain; Perrin, Marshall; Pueyo, Laurent; Savransky, Dmitry

    2015-01-01

    The direct imaging of planets around nearby stars is exceedingly difficult. Only about 14 exoplanets have been imaged to date that have masses less than 13 times that of Jupiter. The next generation of planet-finding coronagraphs, including VLT-SPHERE, the Gemini Planet Imager, Palomar P1640, and Subaru HiCIAO have predicted contrast performance of roughly a thousand times less than would be needed to detect Earth-like planets. In this paper we review the state of the art in exoplanet imaging, most notably the method of Locally Optimized Combination of Images (LOCI), and we investigate the potential of improving the detectability of faint exoplanets through the use of advanced statistical methods based on the concepts of the ideal observer and the Hotelling observer. We propose a formal comparison of techniques using a blind data challenge with an evaluation of performance using the Receiver Operating Characteristic (ROC) and Localization ROC (LROC) curves. We place particular emphasis on the understanding and modeling of realistic sources of measurement noise in ground-based AO-corrected coronagraphs. The work reported in this paper is the result of interactions between the co-authors during a week-long workshop on exoplanet imaging that was held in Squaw Valley, California, in March of 2012. PMID:26347393

  10. The Debris Disk Explorer: A Balloon-Borne Coronagraph for Observing Debris Disks

    NASA Technical Reports Server (NTRS)

    Roberts, Lewis C. Jr; Bryden, Geoffrey; Traub, Wesley; Unwin, Stephen; Trauger, John; Krist, John; Aldrich, Jack; Brugarolas, Paul; Stapelfeldt, Karl; Wyatt, Mark; Stuchlik, David; Lanzi, James

    2013-01-01

    The Debris Disk Explorer (DDX) is a proposed balloon-borne investigation of debris disks around nearby stars. Debris disks are analogs of the Asteroid Belt (mainly rocky) and Kuiper Belt (mainly icy) in our Solar System. DDX will measure the size, shape, brightness, and color of tens of disks. These measurements will enable us to place the Solar System in context. By imaging debris disks around nearby stars, DDX will reveal the presence of perturbing planets via their influence on disk structure, and explore the physics and history of debris disks by characterizing the size and composition of disk dust. The DDX instrument is a 0.75-m diameter off-axis telescope and a coronagraph carried by a stratospheric balloon. DDX will take high-resolution, multi-wavelength images of the debris disks around tens of nearby stars. Two flights are planned; an overnight test flight within the United States followed by a month-long science flight launched from New Zealand. The long flight will fully explore the set of known debris disks accessible only to DDX. It will achieve a raw contrast of 10(exp -7), with a processed contrast of 10(exp -8). A technology benefit of DDX is that operation in the near-space environment will raise the Technology Readiness Level of internal coronagraphs, deformable mirrors, and wavefront sensing and control, all potentially needed for a future space-based telescope for high-contrast exoplanet imaging.

  11. A General Tool for Evaluating High-Contrast Coronagraphic Telescope Performance Error Budgets

    NASA Technical Reports Server (NTRS)

    Marchen, Luis F.; Shaklan, Stuart B.

    2009-01-01

    This paper describes a general purpose Coronagraph Performance Error Budget (CPEB) tool that we have developed under the NASA Exoplanet Exploration Program. The CPEB automates many of the key steps required to evaluate the scattered starlight contrast in the dark hole of a space-based coronagraph. It operates in 3 steps: first, a CodeV or Zemax prescription is converted into a MACOS optical prescription. Second, a Matlab program calls ray-trace code that generates linear beam-walk and aberration sensitivity matrices for motions of the optical elements and line-of-sight pointing, with and without controlled coarse and fine-steering mirrors. Third, the sensitivity matrices are imported by macros into Excel 2007 where the error budget is created. Once created, the user specifies the quality of each optic from a predefined set of PSDs. The spreadsheet creates a nominal set of thermal and jitter motions and combines them with the sensitivity matrices to generate an error budget for the system. The user can easily modify the motion allocations to perform trade studies.

  12. Diagnosing the Structure of the HD 163296 Protoplanetary Disk Via Coronagraphic Imaging Polarimetry

    NASA Technical Reports Server (NTRS)

    Kowalski, Adam F.; Wisniewski, John P.; Clampin, M.; Grady, C. A.; Sitko, M. L.; Bjorkman, K. S.; Fukagawa, M.; Hines, D. C.; Katoh, E.; Whitney, B. A.

    2008-01-01

    Coronagraphic imaging polarimetry is a high contrast imaging technique which can diagnose both the spatial distribution and size distribution of dust grains which comprise primordial protoplanetary disks. It can therefore be a useful tool to test our understanding of how the structure of young disks evolves through the era of gas giant planet formation. We report our initial analysis of the H-band polarized and total intensity of the nearby Herbig Ae star HD 163296, and characterize the morphology of the scattered light disk in the context of previous optical HST coronagraphic imagery. Our observations were obtained as part of a multi-epoch campaign designed to diagnose and correlate the behavior of the inner and outer regions of select protoplanetary disks. This campaign will help test recent suggestions (Sitko et al. 2008; Wisniewski et al. 2008) that that HD 163296 dis experiences the novel phenomenon of time-variable self-shadowing, whereby occasional changes in the scale height of the inner disk wall induces changes in the illumination of the outer disk.

  13. On advanced estimation techniques for exoplanet detection and characterization using ground-based coronagraphs

    NASA Astrophysics Data System (ADS)

    Lawson, Peter R.; Poyneer, Lisa; Barrett, Harrison; Frazin, Richard; Caucci, Luca; Devaney, Nicholas; Furenlid, Lars; Gładysz, Szymon; Guyon, Olivier; Krist, John; Maire, Jérôme; Marois, Christian; Mawet, Dimitri; Mouillet, David; Mugnier, Laurent; Pearson, Iain; Perrin, Marshall; Pueyo, Laurent; Savransky, Dmitry

    2012-07-01

    The direct imaging of planets around nearby stars is exceedingly difficult. Only about 14 exoplanets have been imaged to date that have masses less than 13 times that of Jupiter. The next generation of planet-finding coronagraphs, including VLT-SPHERE, the Gemini Planet Imager, Palomar P1640, and Subaru HiCIAO have predicted contrast performance of roughly a thousand times less than would be needed to detect Earth-like planets. In this paper we review the state of the art in exoplanet imaging, most notably the method of Locally Optimized Combination of Images (LOCI), and we investigate the potential of improving the detectability of faint exoplanets through the use of advanced statistical methods based on the concepts of the ideal observer and the Hotelling observer. We propose a formal comparison of techniques using a blind data challenge with an evaluation of performance using the Receiver Operating Characteristic (ROC) and Localization ROC (LROC) curves. We place particular emphasis on the understanding and modeling of realistic sources of measurement noise in ground-based AO-corrected coronagraphs. The work reported in this paper is the result of interactions between the co-authors during a week-long workshop on exoplanet imaging that was held in Squaw Valley, California, in March of 2012.

  14. The Ultraviolet Spectro-Coronagraph Pathfinder Mission for the Detection of Coronal Suprathermal Seed Particles

    NASA Astrophysics Data System (ADS)

    Strachan, Leonard; Laming, J. Martin; Ko, Yuan-Kuen; Korendyke, Clarence M.; Tun Beltran, Samuel; Socker, Dennis G.; Brown, Charles; Provornikova, Elena

    2016-05-01

    The Ultraviolet Spectro-Coronagraph (UVSC) Pathfinder is a Naval Research Laboratory experiment designed to make the first detection of suprathermal seed particles close to the Sun. It uses an innovative “stacked” occulting system to significantly increase the effective light gathering power of a traditional, 1-meter length, externally occulted coronagraph. The external occultation in combination with a low scatter variable line spaced grating provide the stray light suppression needed to measure non-Maxwellian departures in the wings of the H Lyman alpha emission line profile. After the removal of other factors, these departures may be interpreted as the signature of suprathermal tails of the proton velocity distribution in the corona. UVSC Pathfinder will provide information on the origins and spatial/temporal variability of proton seed particle populations. We will discuss the accuracy needed to make such measurements and describe how the results can be used to develop a capability for predicting the onset of Solar Energetic Particle (SEP) storms. The experiment is scheduled for a launch by the DoD Space Test Program in late 2018/early 2019 and should have excellent overlap with the Solar Orbiter and Solar Probe Plus missions.UVSC Pathfinder is supported by funds from the Chief of Naval Research (via the NRL basic research program) and from NASA (via NDPR NNG13WF951 and NNH16AC29I).

  15. Testing and Calibration of the NASA COR1 Coronagraph for the Solar Terrestrial Relations Observatory (STEREO)

    NASA Technical Reports Server (NTRS)

    Burkepile, J. T.

    2001-01-01

    This proposal is for a no cost extension on the period of performance of the existing grant. The period of performance shall be extended to the end of FY 2003. This extension is required due to schedule changes in the COR1 program. Funding for Phase II and Phase III of this grant has been obtained. This unsolicited proposal was for scientific and engineering collaboration between NASA s Goddard Space Flight Center (GSFC) and HAO. Performance testing of the COR1 engineering test unit has been partially completed. The COR1 coronagraph engineering test unit requires further testing at NASA s GSFC and the National Center for Atmospheric Research (NCAR) Mauna Loa Solar Observatory (MLSO), operated by the High Altitude Observatory (HAO). HAO personnel have recently supported efforts to test component and breadboard versions of the COR1 using the NCAR Vacuum Tunnel Facility (NVTF). HAO personnel will continue to work closely with scientists and engineers at NASA/GSFC in the development, design, assembly, testing, and operation of this key element of NASA's Solar Terrestrial Relations Observatory (STEREO) mission. The element is an internally-occulted coronagraphic telescope, and the design and development effort is already underway at GSFC.

  16. On Advanced Estimation Techniques for Exoplanet Detection and Characterization using Ground-Based Coronagraphs

    NASA Technical Reports Server (NTRS)

    Lawson, Peter R.; Frazin, Richard; Barrett, Harrison; Caucci, Luca; Devaney, Nicholas; Furenlid, Lars; Gladysz, Szymon; Guyon, Olivier; Krist, John; Maire, Jerome; Marois, Christian; Mawet, Dimitri; Mouillet, David; Mugnier, Laurent; Perrin, Marshall; Poyneer, Lisa; Pueyo, Laurent; Savransky, Dmitry; Soummer, Remi

    2012-01-01

    The direct imaging of planets around nearby stars is exceedingly difficult. Only about 14 exoplanets have been imaged to date that have masses less than 13 times that of Jupiter. The next generation of planet-finding coronagraphs, including VLT-SPHERE, the Gemini Planet Imager, Palomar P1640, and Subaru HiCIAO have predicted contrast performance of roughly a thousand times less than would be needed to detect Earth-like planets. In this paper we review the state of the art in exoplanet imaging, most notably the method of Locally Optimized Combination of Images (LOCI), and we investigate the potential of improving the detectability of faint exoplanets through the use of advanced statistical methods based on the concepts of the ideal observer and the Hotelling observer. We provide a formal comparison of techniques through a blind data challenge and evaluate performance using the Receiver Operating Characteristic (ROC) and Localization ROC (LROC) curves. We place particular emphasis on the understanding and modeling of realistic sources of measurement noise in ground-based AO-corrected coronagraphs. The work reported in this paper is the result of interactions between the co-authors during a week-long workshop on exoplanet imaging that was held in Squaw Valley, California, in March of 2012.

  17. On Advanced Estimation Techniques for Exoplanet Detection and Characterization using Ground-based Coronagraphs

    NASA Technical Reports Server (NTRS)

    Lawson, Peter; Frazin, Richard

    2012-01-01

    The direct imaging of planets around nearby stars is exceedingly difficult. Only about 14 exoplanets have been imaged to date that have masses less than 13 times that of Jupiter. The next generation of planet-finding coronagraphs, including VLT-SPHERE, the Gemini Planet Imager, Palomar P1640, and Subaru HiCIAO have predicted contrast performance of roughly a thousand times less than would be needed to detect Earth-like planets. In this paper we review the state of the art in exoplanet imaging, most notably the method of Locally Optimized Combination of Images (LOCI), and we investigate the potential of improving the detectability of faint exoplanets through the use of advanced statistical methods based on the concepts of the ideal observer and the Hotelling observer. We propose a formal comparison of techniques using a blind data challenge with an evaluation of performance using the Receiver Operating Characteristic (ROC) and Localization ROC (LROC) curves. We place particular emphasis on the understanding and modeling of realistic sources of measurement noise in ground-based AO-corrected coronagraphs. The work reported in this paper is the result of interactions between the co-authors during a week-long workshop on exoplanet imaging that was held in Squaw Valley, California, in March of 2012

  18. The CORIMP CME Catalogue: Automatically Detecting and Tracking CMEs in Coronagraph Data

    NASA Astrophysics Data System (ADS)

    Byrne, Jason; Morgan, H.; Habbal, S. R.

    2012-05-01

    Studying CMEs in coronagraph data can be challenging due to their diffuse structure and transient nature, and user-specific biases may be introduced through visual inspection of the images. The large amount of data available from the SOHO and STEREO missions also makes manual cataloguing of CMEs tedious, and so a robust method of detection and analysis is required. This has led to the development of automated CME detection and cataloguing packages such as CACTus, SEEDS and ARTEMIS. Here we present the development of the CORIMP (coronal image processing) Catalogue: a new, automated, multiscale, CME detection and tracking catalogue, that overcomes many of the drawbacks of current catalogues. It works by first employing a dynamic CME separation technique to remove the static background, and then characterizing CME structure via a multiscale edge-detection algorithm. The detections are chained through time to determine the CME kinematics and morphological changes as it propagates across the plane-of-sky. The effectiveness of the method is demonstrated by its application to a selection of SOHO/LASCO and STEREO/SECCHI images, as well as to synthetic coronagraph images created from a model corona with a variety of CMEs. These algorithms are being applied to the whole LASCO and SECCHI datasets, and a CORIMP catalogue of results will soon be available to the community.

  19. Electron multiplication CCD detector technology advancement for the WFIRST-AFTA coronagraph

    NASA Astrophysics Data System (ADS)

    Harding, Leon K.; Demers, Richard T.; Hoenk, Michael; Peddada, Pavani; Nemati, Bijan; Cherng, Michael; Michaels, Darren; Loc, Anthony; Bush, Nathan; Hall, David; Murray, Neil; Gow, Jason; Burgon, Ross; Holland, Andrew; Reinheimer, Alice; Jorden, Paul R.; Jordan, Douglas

    2015-11-01

    The WFIRST-AFTA (Wide Field InfraRed Survey Telescope-Astrophysics Focused Telescope Asset) is a NASA space observatory. It will host two major astronomical instruments: a wide-field imager (WFI) to search for dark energy and carry out wide field near infrared (NIR) surveys, and a coronagraph instrument (CGI) to image and spectrally characterize extrasolar planets. In this paper, we discuss the work that has been carried out at JPL in advancing Electron Multiplying CCD (EMCCD) technology to higher flight maturity, with the goal of reaching a NASA technology readiness level of 6 (TRL-6) by early-to-mid 2016. The EMCCD has been baselined for both the coronagraph's imager and integral field spectrograph (IFS) based on its sub-electron noise performance at extremely low flux levels - the regime where the AFTA CGI will operate. We present results from a study that fully characterizes the beginning of life performance of the EMCCD. We also discuss, and present initial results from, a recent radiation test campaign that was designed and carried out to mimic the conditions of the WFIRST-AFTA space environment in an L2 orbit, where we sought to assess the sensor's end of life performance, particularly degradation of its charge transfer efficiency, in addition to other parameters such as dark current, electron multiplication gain, clock induced charge and read noise.

  20. Conceptual Design of the Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS) for the Subaru Telescope

    NASA Technical Reports Server (NTRS)

    Peters, Mary Anne; Groff, Tyler; Kasdin, N. Jeremy; McElwain, Michael W.; Galvin, Michael; Carr, Michael A.; Lupton, Robert; Gunn, James E.; Knapp, Gillian; Gong, Qian; Carlotti, Alexis; Brandt, Timothy; Janson, Markus; Guyon, Olivier; Martinache, Frantz; Hayashi, Masahiko; Takato, Naruhisa

    2012-01-01

    Recent developments in high-contrast imaging techniques now make possible both imaging and spectroscopy of planets around nearby stars. We present the conceptual design of the Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS), a lenslet-based, cryogenic integral field spectrograph (IFS) for imaging exoplanets on the Subaru telescope. The IFS will provide spectral information for 140 x 140 spatial elements over a 1.75 arcsecs x 1.75 arcsecs field of view (FOV). CHARIS will operate in the near infrared (lambda = 0.9 - 2.5 micron) and provide a spectral resolution of R = 14, 33, and 65 in three separate observing modes. Taking advantage of the adaptive optics systems and advanced coronagraphs (AO188 and SCExAO) on the Subaru telescope, CHARIS will provide sufficient contrast to obtain spectra of young self-luminous Jupiter-mass exoplanets. CHARIS is in the early design phases and is projected to have first light by the end of 2015. We report here on the current conceptual design of CHARIS and the design challenges.