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Sample records for aavso photoelectric photometry

  1. The AAVSO Photoelectric Photometry Program in Its Scientific and Socio-Historic Context

    NASA Astrophysics Data System (ADS)

    Percy, J. R.

    2012-06-01

    In this paper, I review the work of the AAVSO in the area of photoelectric photometry (PEP). This work was influenced by several trends: in science, in technology, and in the sociology of amateur astronomy. Through the 1980s, the AAVSO photoelectric photometry program competed with other such programs and, in recent years, has been overshadowed by CCD photometry programs. Nevertheless, the AAVSO PEP program has, through careful organization, motivation, and feedback, produced extensive scientific results, and can continue to do so. In the case of my own research, AAVSO PEP observations have also contributed significantly to the education of my students.

  2. The AAVSO Photoelectric Photometry Program in its Scientific and Socio-Historic Context

    NASA Astrophysics Data System (ADS)

    Percy, John R.

    2011-05-01

    Photoelectric photometry began in the 1900s through the work of Guthnick, Stebbins, and others who constructed and used photometers based on the recently-discovered photoelectric effect. The mid 20th century saw a confluence of several areas of amateur interest: astronomy, telescope making, radio and electronics, and general interest in space. This is the time when AAVSO photoelectric photometry (PEP) began, with observers using mostly hand-built photometers on hand-built telescopes. The 1980s brought a revolution: affordable off-the-shelf solid-state photometers, and infrastructure such as the International Amateur-Professional Photoelectric Photometry (IAPPP) conferences, books, and journal. The AAVSO developed a formal PEP program in the early 1980s. Its emphasis was on long-term monitoring of pulsating red giants. It was competing, not always successfully, with programs such as active sun-like binaries (RS CVn stars) which offered "instant gratification" in the form of publicity and quick publications. Nevertheless, the AAVSO PEP program has, through careful organization, motivation, and feedback to observers, produced extensive scientific results. In this presentation, I shall describe, as examples, my own work, its scientific significance, its educational benefit to dozens of my students, and its satisfaction to the observers. To some extent, the AAVSO PEP program has been superceded by its CCD program, but there is still a useful place for ongoing PEP observations of thousands of variable stars. Reference: http://www.aavso.org/sites/default/files/newsletter/PEP/lastpepnl.pdf Acknowledgements: I thank NSERC Canada for research support, my students, and AAVSO staff and observers, especially Howard Landis.

  3. Photoelectric photometry of 14 asteroids

    NASA Astrophysics Data System (ADS)

    di Martino, M.; Cacciatori, S.

    1984-10-01

    Results of observations of 14 asteroids are reported; all of them, except 181 Eucharis, have been previously observed at least once. V photoelectric lightcurves were obtained from September 1982 to June 1983 at the Astronomical Observatory of Torino and at the Astrophysical Observatory of Catania. Part of this program aims to obtain complete lightcurves and, when possible, phasecurve information and to determine amplitudes and V magnitudes at different longitudes for a selected group of asteroids, in order to enlarge the set of known rotational axis directions.

  4. Photoelectric Photometry of Asteroid 6 Hebe

    NASA Astrophysics Data System (ADS)

    Hutton, R. G.; Blain, A.

    1988-03-01

    Photoelectric observations of the asteroid 6 Hebe were made from Observatorio Municipal de Mercedes during the period June 18 - June 27, 1987. The reported synodic rotational period is consistent with previously determined rotation periods.

  5. Photoelectric UBV-photometry of triple-star components

    NASA Astrophysics Data System (ADS)

    Anosova, Zh. P.; Sudakov, S. V.

    Photoelectric UBV photometry has been obtained for components of 30 bright and nearby (V ⪉ 10m, r ⪉ 100 pc) triple stars for purposes of finding physically linked triple systems, their distances and the subsequent investigation of their dynamical evolution. For every component colour excesses EB-V and EU-B are determined and photometric parallaxes πph are calculated.

  6. RASNZ Photometry Section, Incorporating the Auckland Photoelectric Observers' Group

    NASA Astrophysics Data System (ADS)

    Walker, S.

    2012-06-01

    (Abstract only) This review traces the development of amateur photoelectric and CCD photometry in New Zealand from its beginnings in the late 1960s at Christchurch and Auckland, through the Auckland Photoelectric Observers' Group and the RASNZ Photometry Section to its present place in Variable Stars South. For this period of over forty years the participants have been heavily involved with southern hemisphere variable star astronomy and observatories such as Carter, Mt. John, and Auckland, together with which were sponsored the highly successful photoelectric conferences, PEP 1-5. Samples of various projects are shown and described. The full text can be seen at http://www.variablestarssouth.org/index.php/community/member-publications/posters

  7. Photoelectric photometry of comet Kohoutek (1973f)

    NASA Technical Reports Server (NTRS)

    Kohoutek, L.

    1976-01-01

    Comet Kohoutek was observed with the 50 cm (f/15) reflecting telescope of the European Southern Observatory, La Silla, Chile, on fourteen nights between January 16 and 30, when the heliocentric and geocentric distances of the comet were r=0.66 - 1.00 A.U. and delta=0.81 - 0.96 A.U., respectively. The 40 inch and 80 inch diaphragms were used for the photometry of the cometary head in the UBV system and with six interference filters. The atmospheric conditions were good but the accuracy of observations was low due to large extinction and twilight. The mean error of one measurement of log F in all but Na 5893 A filters can be estimated at plus or minus 0.02, whereas the accuracy through the Na filter was substantially lower.

  8. Photoelectric photometry era at the Astronomical Institute of the Slovak Academy of Sciences III. Fast photometry

    NASA Astrophysics Data System (ADS)

    Vaňko, M.; Kollár, V.; Komžík, R.; Koza, J.; Pribulla, T.

    2015-12-01

    We present a continuation of the article series describing the photoelectric photometry era at the Astronomical Institute of the Slovak Academy of Sciences. The paper aims to provide a comprehensive technical description of implementation of the fast photometry at the Stará Lesná Observatory and estimates its photometric precision. Using integration times of 0.1 s and 0.01 s, an estimated photometric precision of the fast photometry is about 0.02 mag and 0.06 mag, respectively. Here, we also show the observation principles of the fast photometry and its use in positive observation of stellar occultation lasting 18.44 s by the asteroid (85) Io.

  9. Detecting Problematic Observer Offsets in Sparse Photometry

    NASA Astrophysics Data System (ADS)

    Calderwood, T.

    2014-06-01

    A heuristic method, based upon histogram analysis, is presented for detecting offsets pervasive enough to be symptoms of problematic observing technique or calibration. This method is illustrated by a study of scatter in AAVSO photoelectric photometry (PEP) for five well-observed variable stars.

  10. Detecting Problematic Observer Offsets in Sparse Photometry

    NASA Astrophysics Data System (ADS)

    Calderwood, Tom

    2014-05-01

    A heuristic method, based upon histogram analysis, is presented for detecting offsets pervasive enough to be symptoms of problematic observing technique or calibration. This method is illustrated by a study of scatter in AAVSO photoelectric photometry (PEP) for five well-observed variable stars.

  11. Physical studies of asteroids. XXV - Photoelectric photometry of asteroids obtained at ESO and Hoher List Observatory

    NASA Astrophysics Data System (ADS)

    Lagerkvist, C.-I.; Magnusson, P.; Debehogne, H.; Hoffmann, M.; Erikson, A.; de Campos, A.; Cutispoto, G.

    1992-11-01

    Photoelectric photometry of 14 asteroids, carried out at ESO and the Hoher List Observatory during 1990 and 1991, are presented. Composite lightcurves were derived for the asteroids 140 Siwa, 238 Hypatia, 347 Pariana, 389 Industria and 1593 Fagnes. UBV colors are also given for ten of the asteroids.

  12. Photoelectric Photometry of the Eclipsing Binary V505-MONOCEROTIS

    NASA Astrophysics Data System (ADS)

    Chochol, D.; Bakos, G. A.; Bartolini, C.; Guarnieri, A.; Dapergolas, A.; Szabados, L.

    Photoelectric U, B, V observations of the eclipsing binary V 505 Mon, performed at the observatories in Skalnate Pleso, Budapest, Bologna and Waterloo in the years 1972-1984 are presented. The following ephemeris has been derived, using all these data: prim.min. Indications of ongoing mass transfer in a semidetached binary configuration are presented. The possible causes of the observed short-term changes of brightness are discussed.

  13. Photoelectric photometry of J V. [Jupiter satellite Amalthea

    NASA Technical Reports Server (NTRS)

    Millis, R. L.

    1978-01-01

    UBV photometry of J V (Amalthea) near greatest western elongation shows this satellite to be about one magnitude fainter than previously believed. It is observed to be very red, having a B-V color index near + 1.5 mag. Unlike the Galilean satellites, J V appears to be a low-albedo object.

  14. Five-color photoelectric photometry of asteroid 433 Eros

    NASA Technical Reports Server (NTRS)

    Miner, E.; Young, J.

    1976-01-01

    Five-color (UVBGR) photoelectric light curves of Eros are presented which were obtained on nine nights during the asteroid's 1974/75 close apparition. Indications that three reversals occurred in the relative depths of the two minima between late December 1974 and late January 1975 are noted along with definite evidence of phase reddening. The maximum amplitude observed was 1.44 magnitudes, and the absolute visual magnitude at primary maximum (corrected to zero phase and to 1 AU from the earth and the sun) was about 10.8 magnitudes. Since the observations indicate that Eros has no significant rotational color variations, it is suggested that the light-curve amplitudes are due primarily to the asteroid's shape and to shadowing effects. Based on its colors relative to the sun, it is concluded that Eros appears to be an S-type asteroid.

  15. Photoelectric Photometry of the Bright Cepheid U Aql

    NASA Astrophysics Data System (ADS)

    Genet, C. L.

    2002-05-01

    In the fall of 2001 I participated in a unique astronomy course at the Superstition Mountain Campus of Central Arizona College. The course objectives were to help students learn about science and astronomy by participation in actual research. Observations were made with the Phoenix-10 automatic photoelectric telescope at the Fairborn Observatory. It was fascinating to take the data on U Aql, nothing but a lists of numbers, and turn these numbers into a light curve that told me something tangible about this particular cepheid. Our instructor, Russell Genet, arranged helpful conference calls to Michael Seeds, who manages the Phoenix-10, and Louis Boyd, who is the director of the Fairborn Observatory. We also spoke with Kenneth Kissell of Kissell Associates, who helped us pick the best observational possibilities, and Douglas Hall at Vanderbilt University, who helped us select suitable comparison and check stars. The data consisted of eighteen nightly UBV photoelectric measurements and contained heliocentric corrections, magnitudes given in thousandths, and comparison and check values that established the constancy of the comparison star. I calculated the phase for U Aql using the epoch and period suggested by Szabados at Konkoly Observatory. I then plotted a V light curve, as well as U-B and B-V color curves. My light and color curves were, unexpectedly, quite different from those of other students as my data clumped with two or three observations occurring nearly on top of each other. At first baffled by this, I soon realized that the period was so close to 24 hours that the available nighttime observations represented only half of the variation. It was an interesting, though frustrating result. I am continuing observations on this star and plan to contact Konkoly Observatory to see if any further observations are available elsewhere during what would be our daytime hours.

  16. Analysis of Mount St. Helens ash from optical photoelectric photometry

    NASA Technical Reports Server (NTRS)

    Cardelli, J. A.; Ackerman, T. P.

    1983-01-01

    The optical properties of suspended dust particles from the eruption of Mt. St. Helens on July 23, 1980 are investigated using photoelectric observations of standard stars obtained on the 0.76-m telescope at the University of Washington 48 hours after the eruption. Measurements were made with five broad-band filters centered at 3910, 5085, 5480, 6330, and 8050 A on stars of varying color and over a wide range of air masses. Anomalous extinction effects due to the volcanic ash were detected, and a significant change in the wavelength-dependent extinction parameter during the course of the observations was established by statistical analysis. Mean particle size (a) and column density (N) are estimated using the Mie theory, assuming a log-normal particle-size distribution: a = 0.18 micron throughout; N = 1.02 x 10 to the 9th/sq cm before 7:00 UT and 2.33 x 10 to the 9th/sq cm after 8:30 UT on July 25, 1980. The extinction is attributed to low-level, slowly migrating ash, possibly combined with products of gas-to-particle conversion and coagulation.

  17. Photoelectric photometry of Comet P/Halley from Mauna Kea Observatory

    NASA Technical Reports Server (NTRS)

    Piscitelli, J. R.; Tholen, D. J.; Hammel, H. B.; Lark, N.

    1986-01-01

    A program of photoelectric photometry of comet Halley yielded 60 nights of usable photometry. The uncertainty in the photometry in all filters except OH is better than 2%. Throughout the apparition, the comet is brightest in the filters that isolated the neutral gas emission features of OH, CN, C2, and C3. The fluxes in the filters that isolated the ionic emission features of CO(+) and H2O(+) are comparable to the continuum when centered upon the optocenter, thereby making the ionic emission weak to undetectable above the continuum. The continuum colors do not appear to be a function of phase angle; therefore, the colors are probably indicative of dust grain composition and are not dominated by scattering geometry effects.

  18. The Secret Lives of Cepheids: Searching for Evolutionary Changes Using Photoelectric Photometry

    NASA Astrophysics Data System (ADS)

    Toce, Michael; Guinan, Edward F.; Engle, Scott G.; Wasatonic, Richard P.

    2016-01-01

    Classical Cepheids are pulsating, yellow supergiants and one of the most important classes of variable stars. They have a direct linear relationship between their period and luminosity and thus serve as crucial "standard candles" for determining the cosmic distance scale and measuring the Hubble Constant. Also, Cepheids play a fundamental role in the calibration of Type Ia supernovae, indicating that the expansion of the Universe is accelerating, and also infer the existence of dark energy. Studies of changes in their pulsation periods and amplitudes reveal evolutionary changes too subtle to detect directly, and understanding these various characteristics of Cepheids is critical to their use as high-precision standard candles. To this end, the Villanova Secret Lives of Cepheids (SLiC) program was created as a comprehensive study of Cepheid behavior, evolution, pulsations, atmospheres, heating dynamics, shocks and winds. As part of the SLiC program, ground-based photometry is being carried out of small sample of bright Cepheids. The observations are being made using the 14-inch reflector telescope at Villanova Campus Observatory. Mounted on the telescope is a SBIG photoelectric photometer equipped with standard Johnson UBVRI filters. Photometry is being carried out of the following stars along with their spectral type, period, and visual mag: X Cyg (F7Ib, ~16.39d, 6.47mag), DT Cyg (F7.5Ib, ~2.5d, 5.82mag), S Sge (G5Ibv, ~8.38d, 5.36mag), FF Aql (F6Ib, ~4.47d, 5.38mag), Eta Aql (F6Iab, ~7.18d,3.80mag), and Delta Cep (F5Iab, ~5.37d, 3.75mag). The primary scientific objectives are to obtain light curves to investigate possible evolutionary changes from small variations in luminosity, light amplitude and pulsation period. Special emphasis was placed on the classical Cepheid X Cyg due to recent changes in pulsation period, shown by Szabados via a phase jump in X Cyg's O-C (observed - calculated). X Cyg holds priority in our observations as we attempt to affirm or deny

  19. Photoelectric photometry era at the Astronomical Institute of the Slovak Academy of Sciences II. Software and reduction techniques

    NASA Astrophysics Data System (ADS)

    Vaňko, M.; Komžík, R.; Kollár, V.; Sekeráš, M.

    2014-10-01

    We present a continuation of Paper9 I describing the photoelectric photometry at the Astronomical Institute of the Slovak Academy of Sciences at Tatranská Lomnica. In this article we show the observation principles and the basic ideas and philosophy of the photometer control software — the code UNIV, written by R. Komžík and V. Kollár, and used for the data resulting from observations.

  20. Photoelectric photometry of the peculiar emission-line star GG Carinae

    NASA Astrophysics Data System (ADS)

    Gosset, E.; Surdej, J.; Swings, J. P.

    1984-03-01

    The first extensive sets of photoelectric observations of the peculiar emission-line star GG Carinae were obtained from 1977 to 1981, in both the standard UBV and Strömgren systems. A Fourier analysis of 767 independent measurements leads to the determination of a period P = 31d.020 for the light variations. Different physical arguments based on the analysis of the present photoelectric - as well as previous photographic - data clearly indicate, however, that the true period is P = 62d.039. The resulting composite lightcurve displays two distinct maxima and minima with a total light amplitude Δm ≡ 0.5 mag. Additional interesting features are noticed in the mean lightcurve. Although it is not possible to classify GG Carinae among any known type of variable stars, the light variations of this object are similar to those observed for β Lyrae-type systems.

  1. AAVSO in the Big Data Era

    NASA Astrophysics Data System (ADS)

    Kafka, Stella; Templeton, Matthew

    2015-08-01

    The AAVSO was formed in 1911 as a group of US-based amateur observers obtaining data in support of professional astronomer’s projects. Now, it has now evolved into an international organization with members and observers in all continents, contributing photometry to a public database of more than 150,000 variable objects. This database, being the core of the AAVSO’s portfolio, is also used to communicate science with the public while providing opportunities to citizens working alongside professional astronomers on science projects. We discuss the various means the AAVSO is using to engage the public in science and communicate scientific results, and the Association's role in the Big Data Era.

  2. Photoelectric photometry of the mutual events of the Galilean satellites in 1985

    SciTech Connect

    Westfall, J.E.

    1989-01-01

    This report analyzes 30 amateur photoelectric observations of 25 separate mutual events, both eclipses and occultations, involving the Galilean satellites of Jupiter in 1985. Parabolic least-squares regression fits to the observed light curves were used to determine the amount and time of maximum light loss. The maximum light losses were in reasonable agreement with the Aksnes and Franklin (1984) predictions. Small but statistically significant differences between the observed times and the times predicted by Aksnes and Franklin and Gregorio (1983) were found for most events. As compared with Io, Europa tended to be about 29 + or - 2 seconds, and Ganymede about 26 + or - 6 seconds, ahead in its orbital motion. 8 references.

  3. Photoelectric photometry of the RS CVn binary EI Eridani = HD 26337

    NASA Technical Reports Server (NTRS)

    Hooten, J. T.; Strassmeier, K. G.; Hall, D. S.; Barksdale, W. S., Jr.; Bertoglio, A.

    1989-01-01

    Differential UBV(RI)sub KC and UBVRI photometry of the RS CVn binary EI Eridani obtained during December 1987 and January 1988 at fourteen different observatories is presented. A combined visual bandpass light curve, corrected for systematic errors of different observatories, utilizes the photometric period of 1,945 days to produce useful results. The analysis shows the visual light curve to have twin maxima, separated by about 0.4 phase, and a full amplitude of approximately 0.06 mag for the period of observation, a smaller amplitude than reported in the past. The decrease in amplitude may be due to a decrease or homogenization of spot coverage. To fit the asymmetrical light curve, a starspot model would have to employ at least two spotted regions separated in longitude.

  4. The AAVSO as a Resource for Variable Star Research

    NASA Astrophysics Data System (ADS)

    Kafka, Stella

    2016-07-01

    The AAVSO was formed in 1911 as a group of US-based amateur observers obtaining data in support of professional astronomy projects. Now, it has evolved into an International Organization with members and observers from both the professional and non-professional astronomical community, contributing photometry to a public photometric database of about 22,000 variable objects, and using it for research projects. As such, the AAVSO's main claim to fame is that it successfully engages backyard Astronomers, educators, students and professional astronomers in astronomical research. I will present the main aspects of the association and how it has evolved with time to become a premium resource for variable star researchers. I will also discuss the various means that the AAVSO is using to support cutting-edge variable star science, and how it engages its members in projects building a stronger international astronomical community.

  5. Testing of a photoelectric photometer. 2: Observational testing

    NASA Technical Reports Server (NTRS)

    Dawson, D. W.; Tedesco, E. F.

    1976-01-01

    The versatility is demonstrated of the 41 cm. Tortugas reflector's photoelectric system through observations of V566 Oph and R CrB with four associated AAVSO comparison stars. These observations were made between May and October, 1974.

  6. AAVSO Solar Observers Worldwide

    NASA Astrophysics Data System (ADS)

    Howe, R.

    2013-06-01

    (Abstract only) For visual solar observers there has been no biological change in the "detector" (human eye) - at century scales (eye + visual cortex) does not change much over time. Our capacity to "integrate" seeing distortions is not just simple averaging! The visual cortex plays an essential role, and until recently only the SDO-HMI (Solar Dynamics Observatory, Helioseismic and Magnetic Imager) has had the capacity to detect the smallest sunspots, called pores. Prior to this the eye was superior to photography and CCD. Imaged data are not directly comparable or substitutable to counts by eye, as the effects of sensor/optical resolution and seeing will have a different influence on the resulting sunspot counts for images when compared to the human eye. Also contributing to the complex task of counting sunspots is differentiating between a sunspot (which is usually defined as having a darker center (umbra) and lighter outer ring (penumbra)) and a pore, made even more complex by the conflicting definitions of the word "pore" in the solar context: "pore" can mean a small spot without penumbra or "pore" can mean a random intergranular blemish that is not a true sunspot. The overall agreement is that the smallest spot size is near 2,000 km or ~3 arc sec, (Loughhead, R. E. and Bray, R. J. 1961, Australian J. Phys., 14, 347). Sunspot size is dictated by granulation dynamics rather than spot size (cancellation of convective motion), and by the lifetime of the pore, which averages from 10 to 30 minutes. There is no specific aperture required for AAVSO observers contributing sunspot observations. However, the detection of the smallest spots is influenced by the resolution of the telescope. Two factors to consider are the theoretical optical resolution (unobstructed aperture), Rayleigh criterion: theta = 138 / D(mm), and Dawes criterion: theta = 116 / D(mm) (http://www.telescope-optics.net/telescope_resolution.htm). However, seeing is variable with time; daytime range will

  7. Professional Astronomers in Service to the AAVSO

    NASA Astrophysics Data System (ADS)

    Saladyga, Michael; Waagen, E. O.

    2011-05-01

    Throughout its 100-year history, the American Association of Variable Star Observers (AAVSO) has welcomed professional astronomers to its membership ranks, and has encouraged their participation as organization leaders. The AAVSO has been fortunate to have many distinguished professionals serve as officers (Directors, Presidents, Council), and as participants in its various scientific and organizational committees.

  8. Professional Astronomers in Service to the AAVSO

    NASA Astrophysics Data System (ADS)

    Saladyga, M.; Waagen, E. O.

    2012-06-01

    (Abstract only) Throughout its 100-year history, the American Association of Variable Star Observers (AAVSO) has welcomed professional astronomers to its membership ranks, and has encouraged their participation as organization leaders. The AAVSO has been fortunate to have over 60 distinguished professionals serve as officers (Directors, Presidents, Council), and as participants in its various scientific and organizational committees.

  9. AAVSO Long-Period Variable Section Update

    NASA Astrophysics Data System (ADS)

    Hutton, Kate; Simonsen, Mike

    2009-05-01

    The first of the new AAVSO "sections" is the LPV section. This section has decided to "own" SR, L & RV stars, as well as Miras. There is an LPV Section Wiki, and there has been much discussion on the AAVSO discussion e-mail list regarding the type and number of stars that should be included in the AAVSO LPV Programs. One of our first major tasks is to produce a list of stars to recommend to observers, stars for which the observers can feel that their work will be of value in the present & future age of automated surveys. The core of the list is the AAVSO "legacy stars". The legacy stars will include those stars that have a long & rich history with the AAVSO (more than 15,000 AAVSO observations in 50+ years) and those that have been the subject of many scientific publications. The remaining LPV program stars will include those with at least 5,000 observations in the AAVSO International database, those too bright for most surveys, those that are in fields too crowded for the surveys, plus any that are specifically requested by researchers. The AAVSO Binocular Program will include stars with minima brighter than about 10th magnitude, visible in binoculars for the majority of their cycles.

  10. The GTN-AAVSO Blazar Program

    NASA Astrophysics Data System (ADS)

    Spear, G. G.; Mattei, J. A.; Price, A.; Graves, T.; Borders, T.; Slater, G.; Cominsky, L. R.

    2002-12-01

    The GLAST Telescope Network (GTN) is a collaboration among observers and small observatories who will obtain observations of base-line activity levels and follow-up observations for bright blazars. These AGNs have their jets pointed directly toward us, and are one of the key science objectives for NASA's Gamma-ray Large Area Space Telescope (GLAST) mission. Funded by the GLAST Education and Public Outreach Program, the GTN consists of students, teachers, amateur astronomers, small college observatories, and professional astronomers. The American Association of Variable Star Observers (AAVSO) is a non-profit international scientific and educational organization of thousands of advanced amateur and professional astronomers interested in stars or star-like objects that change in brightness. With millions of variable star observations dating back more than 90 years, the AAVSO has unique experience with handling, processing, and displaying large amounts of data and with coordinating observers from every corner of the globe. The GTN-AAVSO blazar program will recommend observing programs, and provide advice and mentoring for observing techniques and data reduction. The program will archive magnitude estimates and measurements of blazars, as well as CCD images of blazar fields. The GTN-AAVSO program will employ the AAVSO database system and lightcurve generator (http://www.aavso.org/adata/curvegenerator.shtml) to archive magnitude estimates. The magnitudes will either be visual estimates or CCD measurements. Magnitudes are submitted online, and will be immediately available to the public for use in planning observing programs and estimating current activity levels. The GTN-AAVSO program will also employ the online image archiving system developed by the GTN. Images of blazar fields will be available for subsequent analysis by contributors to the program, and by the GLAST science team for mission planning and follow-up studies. We will present examples of the AAVSO

  11. The GTN-AAVSO Blazar Program

    NASA Astrophysics Data System (ADS)

    Cominsky, L. R.; Spear, G. G.; Graves, T.; Slater, G.; Price, A.

    2004-08-01

    The GLAST Telescope Network (GTN) is a collaboration among students, teachers, amateur astronomers, small college observatories, and professional astronomers who will obtain observations of base-line activity levels and follow-up observations for bright blazars, one of the key science objectives for NASA's Gamma-ray Large Area Space Telescope (GLAST) mission. A key partner in the GTN is the American Association of Variable Star Observers (AAVSO, a non-profit international scientific and educational organization that has considerable experience with handling, processing, and displaying large amounts of data and with coordinating observers from every corner of the globe. The GTN-AAVSO blazar program will recommend observing sequences, and provide advice and mentoring for observing techniques and data reduction. The program will archive magnitude estimates using the AAVSO database system and lightcurve generator, as well as CCD images of blazar fields. The program will also employ the online image archiving system developed by the GTN. Images of blazar fields will be available for subsequent analysis by contributors to the program, and by the GLAST science team for mission planning and follow-up studies. We will present examples of the AAVSO lightcurve generator, examples of the GTN image archive system, plus examples of the data we are currently accumulating. The GTN-AAVSO collaboration is partially funded by the NASA's GLAST Education and Public Outreach Program.

  12. The AAVSO 2011 Demographic and Background Survey

    NASA Astrophysics Data System (ADS)

    Price, A.

    2012-04-01

    In 2011, the AAVSO conducted a survey of 615 people who are or were recently active in the organization. The survey included questions about their demographic background and variable star interests. Data are descriptively analyzed and compared with prior surveys. Results show an organization of very highly educated, largely male amateur and professional astronomers distributed across 108 countries. Participants tend to be loyal, with the average time of involvement in the AAVSO reported as 14 years. Most major demographic factors have not changed much over time. However, the average age of new members is increasing. Also, a significant portion of the respondents report being strictly active in a non-observing capacity, reflecting the growing mission of the organization. Motivations of participants are more aligned with scientific contribution than with that reported by other citizen science projects. This may help explain why a third of all respondents are an author or co-author of a paper in an astronomical journal. Finally, there is some evidence that participation in the AAVSO has a greater impact on the respondents' view of their role in astronomy compared to that expected through increasing amateur astronomy experience alone.

  13. The American Association of Variable Star Observers (AAVSO)

    NASA Astrophysics Data System (ADS)

    Searle, Travis; Templeton, M.; Price, A.; Henden, A.

    2006-12-01

    Founded in 1911 and headquartered in Cambridge, Massachusetts, the American Association of Variable Star Observers (AAVSO) is a non-profit worldwide scientific and educational organization of professional and amateur astronomers dedicated to the observing and research of variable stars. The AAVSO International Database has over 13 million observations contributed by over 2,500 observers from around the world. The AAVSO receives thousands of data requests per year from the astronomical community. AAVSO observers also contribute to active research programs and community support activities like target-of-opportunity monitoring and coordinated observing campaigns, as well as providing early notification of rare events like novae and supernovae. In 2006, the AAVSO received over 700,000 new observations. Approximately 2/3rds were photometric (UBVRIJH) and about 3/5ths of AAVSO active observers reside outside the United States. The AAVSO is also active in training amateurs in observing techniques, data mining, and data analysis and also runs an active education and public outreach (E/PO) program including the NSF-funded Hands-On Astrophysics Curriculum. AAVSO data is available for download in near real-time at www.aavso.org.

  14. Photoelectric UVBY beta photometry of 230 stars brighter than m(pg) = 13.0 in the two B = +75 deg fields SA 80 and SA 81

    NASA Astrophysics Data System (ADS)

    Knude, J.

    1993-04-01

    The study presents uvby and beta photometry for 123 and 107 stars in SA 80 and SA 81 brighter than m(pg) = 13 and earlier than G1. Most stars seem to be of type A or F with sample limits V is not greater than 12.6 and beta is not less than 2.60. SA 80 and SA 81 have 34 and 27 BD stars in common with a general b is not less than 70 deg program, respectively. uvby photometry for 19 and 12 stars fainter than m(pg) = 13 is also presented. If situated on the standard line, the sample of absolutely less luminous F9-G0 stars are complete in the volume confined to the distance range from 80 to 300-400 pc. Several lines of sight have E(b-y) exceeding 0.050 m. In both areas the remote A stars seem to be virtually unreddened or are perhaps bluer than typical for population I stars. SA 80 covers part of the Virgo cluster, and the data may be used to estimate the galactic reddening in this direction.

  15. THE SHAPE OF LONG OUTBURSTS IN U GEM TYPE DWARF NOVAE FROM AAVSO DATA

    SciTech Connect

    Cannizzo, John K.

    2012-10-01

    We search the American Association of Variable Star Observers (AAVSO) archives of the two best-studied dwarf novae in an attempt to find light curves for long outbursts that are extremely well characterized. The systems are U Gem and SS Cyg. Our goal is to search for embedded precursors such as those that have been found recently in the high-fidelity Kepler data for superoutbursts (SOs) of some members of the SU UMa subclass of dwarf novae. For the vast majority of AAVSO data, the combination of low data cadence and large errors associated with individual measurements precludes one from making any strong statement about the shape of the long outbursts. However, for a small number of outbursts, extensive long-term monitoring with digital photometry yields high-fidelity light curves. We report the discovery of embedded precursors in two of three candidate long outbursts. This is the first time that such embedded precursors have been found in dwarf novae above the period gap in other than kepler data, and reinforces van Paradijs' finding that long outbursts in dwarf novae above the period gap and SOs in systems below the period gap constitute a unified class. The thermal-tidal instability to account for SOs in the SU UMa stars predicts embedded precursors only for short orbital period dwarf novae, therefore the presence of embedded precursors in long orbital period systems-U Gem and SS Cyg-argues for a more general mechanism to explain long outbursts.

  16. Variable Star Photometry at West Challow Observatory

    NASA Astrophysics Data System (ADS)

    Boyd, D.

    2007-05-01

    This paper describes the facilities and observing programme of a small personal observatory set up in the UK for CCD photometry of variable stars. Its development has been driven by the belief that committed amateurs can make a valuable scientific contribution to the study of variable stars. Observing projects carried out at WCO are described including examples of Pro-Am collaboration and contributions to the observing programmes of the BAAVSS, AAVSO and CBA.

  17. The AAVSO Widow—Or Should We Say Spouse?

    NASA Astrophysics Data System (ADS)

    Williams, T. R.

    2012-06-01

    In past discussions of AAVSO observers over our first century of progress, the familial consequences of membership received little attention. However, non-astronomer friends commonly ask AAVSO observers, “But how does your wife feel about your spending so much time at the telescope and not in bed with her?” Although our Directors have not all been “observers,” they too are forced to keep unusual office hours, answer telephones in the middle of the night, and so on. This paper attempts to portray the many surprising ways in which the AAVSO spouse (not all observers are male nor directors female!) responds to their partner’s pre-occupation with variable stars.

  18. Astronomical Photoelectric Photometry for Undergraduate Research

    ERIC Educational Resources Information Center

    Grauer, Albert D.

    1974-01-01

    Discusses instrumentation and describes such research areas as the albedos of the brighter planets, rotation rates and atmospheres of the larger and brighter satellites, brightness changes of outer planets, asteroid rotation rates, and variable stars. (GS)

  19. Transformed photometry of young stars in Cha requested

    NASA Astrophysics Data System (ADS)

    Waagen, Elizabeth O.

    2013-01-01

    Dr. Peter Abraham (Konkoly Observatory, Budapest, Hungary) requested the assistance of AAVSO observers in monitoring eight young stars in Chamaeleon in support of photometry he and his colleagues will be obtaining with the VLT/ISAAC (infrared) and Herschel Space Observatory (far-infrared) during January-February 2013. The targets are CR Cha, CT Cha, HP Cha (Glass I), VW Cha, VZ Cha, WW CHa, WX Cha, XX Cha. Calibrated, transformed VRI photometry is requested to precisely monitor changes in the optical brightness and colors of these objects. Calibration and transformation of the photometry is crucial - if all of the data are not on the same system and particularly if the colors are not transformed, it will be extremely difficult to correlate the data usefully. Previous observations indicate that the stars are highly variable. Brightness changes can be expected from a few tenths of a magnitude to up to 1-2 magnitudes on a timescale of a few days to a few weeks. Observers are asked to try to obtain one to two sets of VRI images per night. Finder charts with sequences may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

  20. Early-Time Flux Measurements of SN 2014J Obtained with Small Robotic Telescopes: Extending the AAVSO Light Curve

    NASA Astrophysics Data System (ADS)

    Poppe, B.; Plaggenborg, T.; Zheng, W.; Shivvers, I.; Itagaki, K.; Filippenko, A. V.; Kunz, J.

    2015-06-01

    In this work, early-time photometry of supernova (SN) 2014J is presented, extending the AAVSO CCD database to prediscovery dates. The applicability of NASA's small robotic MicroObservatory Network telescopes for photometric measurements is evaluated. Prediscovery and postdiscovery photometry of SN 2014J is measured from images taken by two different telescopes of the network, and is compared to measurements from the Katzman Automatic Imaging Telescope and the Itagaki Observatory. In the early light-curve phase (which exhibits stable spectral behavior with constant color indices), these data agree with reasonably high accuracy (better than 0.05 mag around maximum brightness, and 0.15 mag at earlier times). Owing to the changing spectral energy distribution of the SN and the different spectral characteristics of the systems used, differences increase after maximum light. We augment light curves of SN 2014J downloaded from the American Association of Variable Star Observers (AAVSO) online database with these data, and consider the complete brightness evolution of this important Type Ia SN. Furthermore, the first detection presented here (Jan. 15.427, 2014) appears to be one of the earliest observations of SN 2014J yet published, taken less than a day after the SN exploded.

  1. From Archives to Analysis: Computers Redefine the AAVSO Mission

    NASA Astrophysics Data System (ADS)

    Foster, Grant

    1992-10-01

    Recent advances in computer technology and program development promise great progress for the AAVSO in the near future. Not only have we improved our methods of archiving and evaluating variable star observations, but we will also soon be ready to enter the field of substantial in-house data analysis.

  2. Spectroscopy and photometry campaign on three bright Wolf Rayet stars

    NASA Astrophysics Data System (ADS)

    Waagen, Elizabeth O.

    2013-06-01

    Dr. Noel Richardson (Universite de Montreal) and colleagues have invited AAVSO observers to participate in an international professional-amateur spectroscopy and photometry campaign on the Wof Rayet stars WR 134, WR 135, and WR 137 (HD 191765, HD 192103, and HD 192641). The campaign has begun and runs through September 17, 2013. The purpose of the campaign is to study clumping aspects of the strong winds and changes present in large structures in the stellar winds in these WR stars. Spectroscopy and UBVRI time-series observations are requested. Supplemental targets to be observed if time permits are V905 Sco (HD 160529) and V4375 Sgr (HD 316285). Finder charts with sequences may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp). Photometry should be submitted to the AAVSO International Database. Details of the campaign are given at: http://www.stsci.de/wr134/index.htm. Instructions for sending spectroscopy data to Dr. Richardson are given at http! ://www.stsci.de/wr134/pdf/data_transfer.pdf.

  3. Multicolor photometry of triple system b Per requested

    NASA Astrophysics Data System (ADS)

    Waagen, Elizabeth O.

    2013-01-01

    Dr. Bob Zavala (U.S. Naval Observatory, Flagstaff) has requested AAVSO assistance in obtaining multicolor photometry of the bright triple system b Per in order to prepare for and detect a possible eclipse of the AB components by the C component predicted for 2013 January 23. Multi-color photometric observations of 4.5V b Per are requested 2013 January 23 through February 04. Based on a revised period of 702.45 ± 0.05 days, the next time of minimum light is predicted for HJD = 2456321.35 ± 0.05 (UT 2013 January 28 20:24UT ± 1.5 hours). The eclipse may last for up to four days, so the coverage requested will provide both a baseline out-of-eclipse light curve and a multi-color eclipse light curve for analysis. Photometry is needed at the level of 0.02-0.03 magnitude or better, as the eclipse may be as deep as 0.1 magnitude. For PEP observers, V coverage, and B if possible, is requested. DSLR observers should use whatever band(s) are available to them. Finder charts may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details and links.

  4. Astronomical League Observing Programs Supported by the AAVSO (Abstract)

    NASA Astrophysics Data System (ADS)

    Simonsen, M.

    2016-06-01

    (Abstract only) The Astronomical League provides many different observing programs designed to provide direction and goals for League members. The programs have certificates and pins to recognize the observers' accomplishments and for demonstrating their observing skills with a variety of instruments and objects. The AAVSO supports a Variable Star Observing award and the Astronomical League has recently agreed to adopt a new Binocular Variable Star Program.

  5. The Shape of Long Outbursts in U Gem Type Dwarf Novae from AAVSO Data

    NASA Technical Reports Server (NTRS)

    Cannizzo, John K.

    2012-01-01

    We search the American Association of Variable Star Observers (AAVSO) archives of the two best studied dwarf novae in an attempt to find light curves for long out bursts that are extremely well-characterized. The systems are U Gem and S8 Cyg. Our goal is to search for embedded precursors such as those that have been found recently in the high fidelity Kepler data for superoutbursts of some members of the 8U UMa subclass of dwarf novae. For the vast majority of AAV80 data, the combination of low data cadence and large errors associated with individual measurements precludes one from making any strong statement about the shape of the long outbursts. However, for a small number of outbursts, extensive long term monitoring with digital photometry yields high fidelity light curves. We report the finding of embedded precursors in two of three candidate long outbursts. This reinforces van Paradijs' finding that long outbursts in dwarf novae above the period gap and superoutbursts in systems below the period gap constitute a unified class. The thermal-tidal instability to account for superoutbursts in the SU UMa stars predicts embedded precursors only for short orbital period dwarf novae, therefore the presence of embedded precursors in long orbital period systems - U Gem and SS Cyg - argues for a more general mechanism to explain long outbursts.

  6. Reconsidering the History of the AAVSO-Part I

    NASA Astrophysics Data System (ADS)

    Williams, Thomas R.

    2001-06-01

    A review of the history of the American Association of Variable Star Observers (AAVSO) reveals that its development in the first half of the twentieth century requires reconsideration in two important respects. This first part of a two-part paper eals with one historical issue, the founding of the association and it operation during its first six years, including the role played by Edward Charles Pickering, and Harvard College Observatory, and recognizes that William Tyler Olcott played a more prominent role than has previously been acknowledged.

  7. An Overview of the Evolution of the AAVSO's Information Technology Infrastructure Between 1965-1997

    NASA Astrophysics Data System (ADS)

    Kinne, Richard C. S.; Saladyga, M.; Waagen, E. O.

    2011-05-01

    We trace the history and usage of computers and data processing equipment at the AAVSO HQ between its beginings in the 1960s to 1997. We focus on equipment, people, and the purpose such computational power was put to use. We examine how the AAVSO evolved its use of computing and data processing resources as the technology evolved in order to further its mission.

  8. The Birch Street Irregulars: mysteries found and resolved in the AAVSO data archives

    NASA Astrophysics Data System (ADS)

    Beck, Sara J.; Saladyga, Michael; Mattei, Janet A.

    As they evaluate AAVSO data, AAVSO technical staff members run across several kinds of errors. This paper takes a humorous and Sherlock Holmes-style look at some of the most common kinds of errors detected, from observers recording the wrong Julian Date, misidentifying stars, transposing entries on the observer form, to garden-variety data entry errors.

  9. AAVSO and the International Year of Light (Poster abstract)

    NASA Astrophysics Data System (ADS)

    Larsen, K.

    2015-06-01

    (Abstract only) The United Nations General Assembly has officially designated 2015 to be the International Year of Light (IYL). Modeled in part on the earlier International Year of Astronomy (IYA), this cross-disciplinary, international educational and outreach project will celebrate the importance of light in science, technology, cultural heritage, and the arts. It ties in with several important anniversaries, such as the 1000th anniversary of the publication of Ibn Al Haythem's “Book of Optics,” the 150th anniversary of Maxwell's equations of electromagnetism, the centenary of Einstein's General Theory of Relativity, and the 50th anniversary of the discovery of the Cosmic Microwave Background Radiation. Because variable stars are defined as such due to the variability of the light we observe from them, all of the AAVSO programs, regardless of type of variable or instrumentation (eye, DSLR, PEP, or CCD) have natural tie-ins to the study of light. This poster will highlight a number of specific ways that AAVSO members and the organization as a whole can become intimately involved with this unique outreach opportunity.

  10. Photoelectric sensor with PSD

    NASA Astrophysics Data System (ADS)

    Zhao, Yuan; Dai, Yong-Jiang; Cai, Xi-Ping; Li, Chun-Fei

    1991-12-01

    The photoelectric sensor with the Position Sensitive Detector (PSD) for Rendezvous and Docking (RVD) is described. The principle of measuring relative position and attitude of the target spacecraft by the sensor is given. Measuring the target by the principle, the experiment result is presented. The result indicates that it is practical using PSD as photoelectric sensor for RVD in close range.

  11. AAVSO Visual Sunspot Observations vs. SDO HMI Sunspot Catalog

    NASA Astrophysics Data System (ADS)

    Howe, R.

    2014-06-01

    (Abstract only) The most important issue with regard to using the SDO HMI data from the National Solar Observatory (NSO, http://www.nso.edu/staff/fwatson/STARA) is that their current model for creating sunspot counts does not split in groups and consequently does not provide a corresponding group count and Wolf number. As it is a different quantity, it cannot be mixed with the data from our sunspot networks. For the AAVSO with about seventy stations contributing each day, adding HMI sunspot data would anyway hardly change the resulting index. Perhaps, the best use of HMI data is for an external validation, by exploiting the fact that HMI provides a series that is rather close to the sunspot number and is acquired completely independently. So, it is unlikely to suffer from the same problems (jumps, biases) at the same time. This validation only works for rather short durations, as the lifetime of space instruments is limited and aging effects are often affecting the data over the mission. In addition, successive instruments have different properties: for example, the NSO model has not managed yet to reconcile the series from MDI and HMI. There is a ~10-15% jump. The first challenge that should be addressed by AAVSO using HMI data is the splitting in groups and deriving group properties. Then, together with the sunspot counts and areas per group, a lot more analyses and diagnostics can be derived (like the selective disappearance of the smallest sunspots?), that can help interpreting trends in the ratio SSN/other solar indices and many other solar effects.

  12. New Release of the BSM Epoch Photometry Database

    NASA Astrophysics Data System (ADS)

    Henden, A.

    2016-06-01

    (Abstract only) The Bright Star Monitor (BSM) Epoch Photometry Database (EPD) is a searchable catalog of all observations made by one of the AAVSO's five BSM systems. The newest release of this database contains some 100 million datasets, from both northern and southern hemispheres, taken over the last six years. These have been calibrated by both nightly visits to Landolt standard fields as well as through the use of the Tycho2 photometric catalog. The paper will describe how the observations were made, how to access the catalog, and the limitations to the photometric accuracy. Some examples of well-studied fields will be shown.

  13. EUVE photometry of SS Cygni: Dwarf nova outbursts and oscillations

    SciTech Connect

    Mauche, C.W.

    1995-05-15

    The authors present EUVE Deep Survey photometry and AAVSO optical measurements of the 1993 August and 1994 June/July outbursts of the dwarf nova SS Cygni. The EUV and optical light curves are used to illustrate the different response of the accretion disk to outbursts which begin at the inner edge and propagate outward, and those which begin at the outer edge and propagate inward. Furthermore, the authors describe the properties of the quasi-coherent 7--9 s sinusoidal oscillations in the EUV flux detected during the rise and plateau stages of these outbursts.

  14. Photoelectric Observations and Analysis of Variability of the Beta-Cephei Type Star Kp-Persei

    NASA Astrophysics Data System (ADS)

    Jarzebowski, T.; Jerzykiewics, M.; Rios-Herrera, M.; Rios-Berumen, M.

    1981-06-01

    Photoelectric observations of the p Cephei-type variable, KP Persei, made in 1977 and 1978 in Zacatecas and San Pedro Ma stir are presented. The photometry was performed mainly in the B system and some nights also in the UB or UBK A frequency naly photometry was carried out. Three sine-wave components with periods P1 = 0. 201779,P2=0. 198085, and P3 = 0d227099 were found.

  15. 20 Million Observations: The AAVSO International Database and Its First Century

    NASA Astrophysics Data System (ADS)

    Waagen, E. O.

    2012-06-01

    (Abstract only) The American Association of Variable Star Observers (AAVSO) turns 100 in 2011 - a century of service to the astronomical community! Another milestone was reached in 2011: the AAVSO International Database (AID) received its 20 millionth variable star observation! The AID contains observations of over 14,750 objects contributed by over 7,500 amateur and professional astronomers worldwide. Data on hundreds of objects extend from the AAVSO's founding in 1911 or earlier (mid-1800s) to present. Some objects' data are of shorter duration but of intense, high-precision coverage. Historical datasets come from published/unpublished professional/amateur observations, astronomical plate collections, and contributed archives of other variable star observing organizations. Hundreds of observations are added to the AID daily as observers upload their data in near real-time. Approximately 69% (~13.9M) of AID observations are visual, 30.4% (~6.2M) CCD (BVRI, unfiltered, Sloan colors, others), 0.5% (~75K) PEP (BVJH), and 0.1% (~17K) photographic/photovisual. Many objects have exclusively visual data, some PEP or CCD data only, and many a combination of types and bands. Objects range from young stellar objects through highly evolved stars. Included are intrinsic variables - pulsating (SX Phe stars through Miras and semiregulars) and eruptive (cataclysmic variables of all types) - and extrinsic variables - eclipsing binaries, rotating (RS CVns) - and exoplanets and suspected variables. Blazars, polars, quasars, HMXBs - today's AID is a thriving, exciting resource! The AID is maintained in a dynamic MySQL database, easily accessible to contributors and users alike through the AAVSO website (http://www.aavso.org). The Light Curve Generator, Quick Look page (recent observations), and Data Download form offer different ways to view/investigate your targets. Quality control performed from submission through validation ensures reliable data for your research. Visit the AAVSO

  16. The photoelectric displacement converter

    NASA Astrophysics Data System (ADS)

    Dragoner, Valeriu V.

    2005-02-01

    In the article are examined questions of constructing photoelectric displacement converter satisfying demands that are stated above. Converter has channels of approximate and precise readings. The approximate reading may be accomplished either by the method of reading from a code mask or by the method of the consecutive calculation of optical scale gaps number. Phase interpolator of mouar strips" gaps is determined as a precise measuring. It is shown mathematical model of converter that allow evaluating errors and operating speed of conversion.

  17. Orion Project: A Photometry and Spectroscopy Project for Small Observatories

    NASA Astrophysics Data System (ADS)

    Hopkins, Jeffrey L.

    2014-05-01

    Orion, the hunter, is one of the most famous constellations. Its declination is such that it is visible from most of the civilized world. In addition, most of the stars of Orion are very bright and interesting. Originally this Project was called the Betelgeuse Campaign, but four more stars were added so the name was changed to the Orion Project. The Project now includes Betelgeuse, Rigel and the three stars of Orion's belt, Mintaka, Alnilam and Alnitak. Both photometry and spectroscopy provide data for the Project. The Project has several goals. First is to help beginners with photometry and spectroscopy. The second goal is the actual observations and data. Because these stars are very bright, they are seldom observed in detail. Their brightness also posses a problem for most professional observatories. It is hoped that by having observations over a long time, interesting changes can be seen that will warrant closer investigation. The AAVSO has an excellent archive of photometric data, but is still lacking a means of handling spectroscopic data. As a third goal it is hoped that the procedures refined in this Project for spectroscopic data may help promote a similar system for the AAVSO.

  18. Photoelectric photometry of asteroids 33 Polyhymnia and 386 Siegena

    NASA Technical Reports Server (NTRS)

    Zappala, V.; Scaltriti, F.; Lagerkvist, C.-I.; Rickman, H.; Harris, A. W.

    1982-01-01

    The photometric parameters of 33 Polyhymnia and 386 Siegena were determined in the course of an international campaign performed during August 15-September 14, 1980 at Table Mountain Observatory, European Southern Observatory, and Catania Astrophysical Observatory. The rotational periods and amplitudes were determined, and the multiple-scattering factor was found to be 0.15 plus or minus 0.06 for 386 and 0.26 plus or minus 0.33 for 33, implying higher albedos in each case than expected according to their taxonomic classes, C and S, respectively. The color indices B-V and U-B were measured and found to differ significantly from those given by Bowell et al. (1979).

  19. The History of AAVSO Charts, Part III: The Henden Era (Abstract)

    NASA Astrophysics Data System (ADS)

    Simonsen, M.

    2015-06-01

    (Abstract only) In this paper we pick up where “The History of AAVSO Charts, Part II: The 1960s Through 2006” left off and discuss the evolution of the automated chart plotter, the comp star database, the new tools available to the chart and sequences team and Director Arne Henden's influence and legacy.

  20. Utilizing the AAVSO's Variable Star Index (VSX) In Undergraduate Research Projects

    NASA Astrophysics Data System (ADS)

    Larsen, Kristine

    2016-01-01

    Among the many important services that the American Association of Variable Star Observers (AAVSO) provides to the astronomical community is the Variable Star Index (VSX - https://www.aavso.org/vsx/). This online catalog of variable stars is the repository of data on over 334,000 variable stars, including information on spectral type, range of magnitude, period, and type of variable, among other properties. A number of these stars were identified as being variable through automated telescope surveys, such as ASAS (All Sky Automated Survey). The computer code of this survey classified newly discovered variables as best it could, but a significant number of false classifications have been noted. The reclassification of ASAS variables in the VSX data, as well as a closer look at variables identified as miscellaneous type in VSX, are two of many projects that can be undertaken by interested undergraduates. In doing so, students learn about the physical properties of various types of variable stars as well as statistical analysis and computer software, especially the VStar variable star data visualization and analysis tool that is available to the astronomical community free of charge on the AAVSO website (https://www.aavso.org/vstar-overview). Two such projects are described in this presentation, the first to identify BY Draconis variables erroneously classified as Cepheids in ASAS data, and the second to identify SRD semiregular variables misidentified as "miscellaneous" in VSX.

  1. VizieR Online Data Catalog: 1889-2015 photometry of Stingray nebula (Schaefer+, 2015)

    NASA Astrophysics Data System (ADS)

    Schaefer, B. E.; Edwards, Z. I.

    2016-02-01

    To get broad-band magnitudes for the Stingray, we have pulled from a wide variety of sources --the Harvard photographic plate collection from 1889 to 1989, the visual magnitude estimates of Albert Jones as archived by the American Association of Variable Star Observers (AAVSO) from 1994 to 2007, the All Sky Automated Survey (ASAS) from 2001 to 2009, the AAVSO telescopes going into the AAVSO Photometric All-sky Survey (APASS) from 2011 to 2015, plus our own photometry from CCD images with DECam on the Cerro Tololo 4-m Blanco telescope from 2014. We have added 15 mag from the literature or derived by us from the literature, all on six nights from 1969 to 1996. At our request, A. Henden has put the Stingray in the queue for time series photometry on the 0.61-m Optical Craftsmen Telescope at the Mount John Observatory in New Zealand. The 1-minute CCD integrations were through a Johnson V filter on the nights of 2015 March 23, 26, and 27. (1 data file).

  2. Photoelectric solar cell array

    SciTech Connect

    Lidorenko, N.S.; Afian, V.V.; Martirosian, R.G.; Ryabikov, S.V.; Strebkov, D.S.; Vartanian, A.V.

    1983-11-29

    A photoelectric solar cell device comprises a dispersing element exposed to the sun's radiation and followed in the optical path by photocells having different spectral sensitivities. Each photocell has its working surface so oriented that the light beam with the wavelength corresponding to the maximum spectral sensitivity of that photocell impinges on its working surface. The dispersing element is a hologram representing light sources with different wavelengths. The photocells are positioned in the image planes of the light sources producing the light beams of the corresponding wavelengths.

  3. Photoelectric angle converter

    NASA Astrophysics Data System (ADS)

    Podzharenko, Volodymyr A.; Kulakov, Pavlo I.

    2001-06-01

    The photo-electric angle transmitter of rotation is offered, at which the output voltage is linear function of entering magnitude. In a transmitter the linear phototransducer is used on the basis of pair photo diode -- operating amplifier, which output voltage is linear function of the area of an illuminated photosensitive stratum, and modulator of a light stream of the special shape, which ensures a linear dependence of this area from an angle of rotation. The transmitter has good frequent properties and can be used for dynamic measurements of an angular velocity and angle of rotation, in systems of exact drives and systems of autocontrol.

  4. Teaching the Photoelectric Effect Inductively

    ERIC Educational Resources Information Center

    Sokolowski, Andrzej

    2013-01-01

    Research has shown that students have difficulty understanding the underlying process of the photoelectric effect. Thus, this study sought to utilize an inductively situated lesson for teaching the photoelectric effect, hypothesizing that this type of enquiry would help learners delve deeper into the principles of the phenomenon and provide a…

  5. Exoplanetary Photometry

    NASA Astrophysics Data System (ADS)

    Harrington, Joseph

    2008-09-01

    The Spitzer Space Telescope measured the first photons from exoplanets (Charbonneau et al. 2005, Deming et al. 2005). These secondary eclipses (planet passing behind star) revealed the planet's emitted infrared flux, and under a blackbody assumption provide a brightness temperature in each measured bandpass. Since the initial direct detections, Spitzer has made numerous measurements in the four Infrared Array Camera bandpasses at 3.6, 4.5, 5.7, and 8.0 microns; the Infrared Spectrograph's Blue Peakup Array at 16 microns; and the Multiband Imaging Photometer for Spitzer's 24-micron array. Initial measurements of orbital variation and further photometric study (Harrington et al. 2006, 2007) revealed the extreme day-night variability of some exoplanets, but full orbital phase curves of different planets (Knutson et al. 2007, 2008) demonstrated that not all planets are so variable. This talk will review progress and prospects in exoplanetary photometry.

  6. Photoelectric inclination sensor

    NASA Astrophysics Data System (ADS)

    Kato, Hisao; Kojima, Masahiko; Hayashi, Morihiko; Sasaki, Shunji

    1986-06-01

    A new photoelectric inclination sensor consisting of a light emitting diode (LED) spirit level mounted on a photodiode array is introduced. Light from the LED projects a bubble in the level and throws a shadow onto the surface of the array composed of four equivalent square-shaped diodes, isolated from each other by a cross on a wafer. When the transducer is kept horizontal, the area of the shadow in each diode is exactly equivalent. By taking the difference output positioned obliquely in the array, the water level in the two-dimensional plane is detected. This transducer detects the two-dimensional water level accurately, can be compact, and the response is fast.

  7. VizieR Online Data Catalog: AAVSO International Variable Star Index VSX (Watson+, 2006-2014)

    NASA Astrophysics Data System (ADS)

    Watson, C.; Henden, A. A.; Price, A.

    2016-08-01

    This file contains Galactic stars known or suspected to be variable. It lists all stars that have an entry in the AAVSO International Variable Star Index (VSX; http://www.aavso.org/vsx). The database consisted initially of the General Catalogue of Variable Stars (GCVS) and the New Catalogue of Suspected Variables (NSV) and was then supplemented with a large number of variable star catalogues, as well as individual variable star discoveries or variables found in the literature. Effort has also been invested to update the entries with the latest information regarding position, type and period and to remove duplicates. The VSX database is being continually updated and maintained. For historical reasons some objects outside of the Galaxy have been included. (3 data files).

  8. UBV photometry of OB and field stars at l = 250

    SciTech Connect

    Reed, B.C. )

    1990-09-01

    Photoelectric UBV photometry is presented for 70 stars in the SLS Catalog and 35 field stars in the vicinity of l = 250. Reddenings vary from a minimum of 0.25 up to 0.9. Except for six stars, possibly possessing a common distance and reddening, the distance modulus-color excess diagram of the SLS stars reveals no obvious clusters or associations. SLS stars 989 and 999 may be variable. 23 refs.

  9. Photoelectric detection system. [manufacturing automation

    NASA Technical Reports Server (NTRS)

    Currie, J. R.; Schansman, R. R. (Inventor)

    1982-01-01

    A photoelectric beam system for the detection of the arrival of an object at a discrete station wherein artificial light, natural light, or no light may be present is described. A signal generator turns on and off a signal light at a selected frequency. When the object in question arrives on station, ambient light is blocked by the object, and the light from the signal light is reflected onto a photoelectric sensor which has a delayed electrical output but is of the frequency of the signal light. Outputs from both the signal source and the photoelectric sensor are fed to inputs of an exclusively OR detector which provides as an output the difference between them. The difference signal is a small width pulse occurring at the frequency of the signal source. By filter means, this signal is distinguished from those responsive to sunlight, darkness, or 120 Hz artificial light. In this fashion, the presence of an object is positively established.

  10. Photometry Transforms Generation with PTGP (Abstract)

    NASA Astrophysics Data System (ADS)

    Myers, G.; Menzies, K.; Silvis, G.; Harris, B.

    2015-06-01

    (Abstract only) Historically the development of photometry transformation coefficients required extensive manual effort and the use of large spreadsheets. A new release—version 5.0—of the Photometry Transformations Generation Program (PTGP) achieves the goal of generating transformation coefficients without the use of spreadsheets—saving considerable time and ensuring data accuracy. PTGP version 5.0 works directly with VSP to retrieve the most recent standard star reference magnitudes (currently for M67 and NGC7790). It then processes instrument magnitude file(s) downloaded from vphot or exported from AIP4WIN or MAXIM. Either AUID or “Boulder” star identifications can be used for AIP4WIN and MAXIM. When using VPHOT data or “Boulder” star identifications, PTGP determines the AUID names for each of the reference standard stars. All standard transforms are calculated. Plots of each transform's data can be reviewed, and individual star observations added/deleted. Transform sets can be saved for further use. Transform sets can be compared and selected sets averaged. The averaged sets can be exported in a file format compatible with the AAVSO TA tool. The presentation will provide a brief overview and demonstration of the tool. It will also discuss the implications of using PYTHON for the development—both benefits and potential problems. The program runs on both PCs and Macs. A subsequent presentation will discuss the use of VPHOT and PTGP to generate transforms and the testing of the impacts of varying key VPHOT and PTGP parameters.

  11. Photoelectric Effect: Back to Basics.

    ERIC Educational Resources Information Center

    Powell, R. A.

    1978-01-01

    Presents a simplified theoretical analysis of the variation of quantum yield with photon energy in the photoelectric experiment. Describes a way to amplify the experiment and make it more instructive to advanced students through the measurement of quantum yield of a photo cell. (GA)

  12. Aperture Fever and the Quality of AAVSO Visual Estimates: mu Cephei as an Example

    NASA Astrophysics Data System (ADS)

    Turner, D. G.

    2014-06-01

    (Abstract only) At the limits of human vision the eye can reach precisions of 10% or better in brightness estimates for stars. So why did the quality of AAVSO visual estimates suddenly drop to 50% or worse for many stars following World War II? Possibly it is a consequence of viewing variable stars through ever-larger aperture instruments than was the case previously, a time when many variables were observed without optical aid. An example is provided by the bright red supergiant variable mu Cephei, a star that has the potential to be a calibrating object for the extragalactic distance scale if its low-amplitude brightness variations are better defined. It appears to be a member of the open cluster Trumpler 37, so its distance and luminosity can be established provided one can pinpoint the amount of interstellar extinction between us and it. mu Cep appears to be a double-mode pulsator, as suggested previously in the literature, but with periods of roughly 700 and 1,000 days it is unexciting to observe and its red color presents a variety of calibration problems. Improving quality control for such variable stars is an issue important not only to the AAVSO, but also to science in general.

  13. RR Lyrae Star Metallicities From Caby Photometry

    NASA Astrophysics Data System (ADS)

    Baird, Scott R.

    1996-11-01

    Ten RR Lyr stars have been observed at different pulsational phases with Caby photoelectric photometry to calibrate the response of this system to RR Lyr metallicity. As has been done for nonvariable stars, the data are displayed in a color-color diagram of hk vs b-y, where hk=(Ca-b)-(b-y). It is found that the system is much more sensitive to metal abundance than the Stromgren m1 index, and that the system retains good sensitivity even at the hottest phases of pulsation. The data produce lines of constant metallicity on the hk/b-y diagram which are single valued with respect to both b-y and hk. Therefore Caby photometry gives a metallicity which is independent of pulsational phase, a distinct advantage over ΔS and other techniques used to find RR Lyr abundances. This phase independence probably arises from the fact that Caby photometry is concerned largely with total absorption from the Ca K and H lines and the b - y continuum, and not the specific shapes of the hydrogen lines, which can be affected by changes in surface gravity as a function of phase in the pulsation and by emission near maximum light. The metallicity of the RRc star V7S3 Cen is determined to be -0.69±0.2 dex using the Caby technique.

  14. Photoelectric converters with quantum coherence.

    PubMed

    Su, Shan-He; Sun, Chang-Pu; Li, Sheng-Wen; Chen, Jin-Can

    2016-05-01

    Photon impingement is capable of liberating electrons in electronic devices and driving the electron flux from the lower chemical potential to higher chemical potential. Previous studies hinted that the thermodynamic efficiency of a nanosized photoelectric converter at maximum power is bounded by the Curzon-Ahlborn efficiency η_{CA}. In this study, we apply quantum effects to design a photoelectric converter based on a three-level quantum dot (QD) interacting with fermionic baths and photons. We show that, by adopting a pair of suitable degenerate states, quantum coherences induced by the couplings of QDs to sunlight and fermion baths can coexist steadily in nanoelectronic systems. Our analysis indicates that the efficiency at maximum power is no longer limited to η_{CA} through manipulation of carefully controlled quantum coherences. PMID:27300826

  15. Photoelectric converters with quantum coherence

    NASA Astrophysics Data System (ADS)

    Su, Shan-He; Sun, Chang-Pu; Li, Sheng-Wen; Chen, Jin-Can

    2016-05-01

    Photon impingement is capable of liberating electrons in electronic devices and driving the electron flux from the lower chemical potential to higher chemical potential. Previous studies hinted that the thermodynamic efficiency of a nanosized photoelectric converter at maximum power is bounded by the Curzon-Ahlborn efficiency ηCA. In this study, we apply quantum effects to design a photoelectric converter based on a three-level quantum dot (QD) interacting with fermionic baths and photons. We show that, by adopting a pair of suitable degenerate states, quantum coherences induced by the couplings of QDs to sunlight and fermion baths can coexist steadily in nanoelectronic systems. Our analysis indicates that the efficiency at maximum power is no longer limited to ηCA through manipulation of carefully controlled quantum coherences.

  16. Photoelectric Charging of Dust Particles

    NASA Technical Reports Server (NTRS)

    Sickafoose, A.; Colwell, J.; Horanyi, M.; Robertson, S.; Walch, B.

    1999-01-01

    Laboratory experiments have been performed on the photoelectric charging of dust particles which are either isolated or adjacent to a surface that is also a photoemitter. We find that zinc dust charges to a positive potential of a few volts when isolated in vacuum and that it charges to a negative potential of a few volts when passed by a photoemitting surface. The illumination is an arc lamp emitting wavelengths longer than 200 nm and the emitting surface is a zirconium foil.

  17. Using a Web Cam CCD to do V Band Photometry

    NASA Astrophysics Data System (ADS)

    Temple, Paul

    2009-05-01

    With the plethora of cheap web cam based CCD cameras in the market today, it seemed expedient to find out if they can be used to do photometry. An experiment was planned to determine if it was possible to do this kind of exacting measurement. Arne Henden (AAVSO) believed it would be possible to do V band photometry to 0.05 mag accuracy with a web cam CCD. Using a 6" refractor, the heart of M42 was repeatedly imaged. Theta 2 and SAO 132322 were the comparison stars and V361 Orion was the target variable. Since the 1/4 HAD CCD chip only allows for a field of 10x7 arc minutes using the 6" refractor, the number targets was limited. The RGB on the chip itself provides the filters needed for photometry. The G band pass on the chip ranges from 425-650 nm with a peak band pass at 540, V band pass is 475-645 with a peak at 525. The results indicate that a web cam CCD can be used for V band photometry. With a 10 second calibrated exposure without the Peltier cooling being engaged, the results for the 2 target stars were ± 0.18 mag. The star Theta 2 was 0.18 brighter in V than the actual measurement from the Tycho catalog. SAO 132322 was -0.012 mag dimmer than the listed Tycho measurement. Then using SAO 132322 and Theta 2 as comparison stars, V361 Orion was estimated at 7.786 magnitudes. This is inline with visual estimates received before and after this date. With more estimates of known magnitude comparison stars, a correction factor should be estimated and applied to the variable work that will make it more accurate. This correction factor should bring it close to Arne Henden's estimate of 0.05 mag accuracy.

  18. Citizen Sky, An Update on the AAVSO's New Citizen Science Project

    NASA Astrophysics Data System (ADS)

    Turner, Rebecca; Price, A.; Henden, A.; Stencel, R.; Kloppenborg, B.

    2011-01-01

    Citizen Sky is a multi-year, NSF-funded, citizen science project focusing on the bright variable star, epsilon Aurigae. Citizen Sky goes beyond simple observing to include a major data analysis component. The goal is to introduce the participant to the full scientific process from background research to paper writing for a peer-reviewed journal. The first year of the project, 2009-10, was dedicated to developing project infrastructure, educating participants about epsilon Aurigae, and training these participants to observe the star and report their data. Looking forward, years two and three of the project will focus on assembling teams of participants to work on their own analysis and research. Results will be published in a special issue of the peer-reviewed Journal of the AAVSO. This project has been made possible by the National Science Foundation.

  19. Techniques for Automated Single-Star Photometry

    NASA Technical Reports Server (NTRS)

    Henry, Gregory W.

    2001-01-01

    Tennessee State University operates several automatic photoelectric telescopes (APTs) located at Fairborn Observatory in the Patagonia Mountains of southern Arizona. The APTs are dedicated to photometric monitoring programs that would be expensive and difficult to accomplish without the advantages of automation. I review the operation of two of the telescopes (a 0.75- and 0.80-meter (m) APT) and the quality-control techniques that result in the routine acquisition of single-star differential photometry with a precision of 0.001 mag for single observations and 0.0001 - 0.0002 mag for seasonal means. I also illustrate the capabilities of the APTS with sample results from a program to measure luminosity cycles in sun-like stars and a related program to search for the signatures of extrasolar planets around these stars.

  20. Photoelectric devices with quantum coherence

    NASA Astrophysics Data System (ADS)

    Shanhe, Su

    A phtotoelectric device consisting of a three-level system contacted with two fermionic baths and a photon bath is built. Making the Born-Markov approximation, the equation of motion for the density operator in a Lindblad-like form is derived. We obtain the coherence and the efficiency of the system under the steady-state condition. Results show that quantum coherence can enhance the photoelectric conversion efficiency. The efficiency at maximum power can be larger than the CA efficiency bound with the existence of coherence.

  1. A photoelectric lightcurve survey of small main belt asteroids

    NASA Technical Reports Server (NTRS)

    Binzel, R. P.; Mulholland, J. D.

    1983-01-01

    A survey to obtain photoelectric lightcurves of small main-belt asteroids was conducted from November 1981 to April 1982 using the 0.91- and 2.1-m telescopes at the University of Texas McDonald Observatory. A total of 18 main-belt asteroids having estimated dimaters under 30 km were observed with over half of these being smaller than 15 km. Rotational periods were determined or estimated from multiple nights of observation for nearly all of these yielding a sample of 17 small main-belt asteroids which is believed to be free of observational selection effects. All but two of these objects were investigated for very short periods in the range of 1 min to 2 hr using power spectrum analysis of a continuous set of integrations. No evidence for such short periods was seen in this sample. Rotationally averaged B(1,0) magnitudes were determined for most of the surveyed asteroids, allowing diameter estimates to be made. Imposing the suspected selection effects of photogaphic photometry on the results of this survey gives excellent agreement with the results from that technique. This shows that the inability of photographic photometry to obtain results for many asteroids is indeed due to the rotational parameter of those asteroids.

  2. VizieR Online Data Catalog: AAVSO Photometric All Sky Survey (APASS) DR9 (Henden+, 2016)

    NASA Astrophysics Data System (ADS)

    Henden, A. A.; Templeton, M.; Terrell, D.; Smith, T. C.; Levine, S.; Welch, D.

    2016-01-01

    The AAVSO Photometric All Sky Survey (APASS) project is designed to bridge the gap between the shallow Tycho2 two-bandpass photometric catalog that is complete to V=11 and the deeper, but less spatially-complete catalogs like SDSS or PanSTARRS. It can be used for calibration of a specific field; for obtaining spectral information about single sources, determining reddening in a small area of the sky; or even obtaining current-epoch astrometry for rapidly moving objects. The survey is being performed at two locations: near Weed, New Mexico in the Northern Hemisphere; and at CTIO in the Southern Hemisphere. Each site consists of dual bore-sighted 20cm telescopes on a single mount, designed to obtain two bandpasses of information simultaneously. Each telescope covers 9 square degrees of sky with 2.5arcsec pixels, with the main survey taken with B,V,g',r',i' filters and covering the magnitude range 10

  3. A photoelectric investigation of Ap-stars in open clusters. II - NGC 6475

    NASA Astrophysics Data System (ADS)

    Maitzen, H. M.; Floquet, M.

    1981-07-01

    Results are presented of photoelectric study of Ap stars in the old galactic cluster NGC 6475. Photometry was obtained in the y, g1 and g2 filters at the 50-cm ESO telescope on La Silla. Observations confirm the presence of the three silicon stars found by Abt (1975) (K 88, 55 and 59) and reveal the Ap nature of two additional stars, K 23 and K 14. A b-y reddening value of 0.050 is obtained which is somewhat lower than that found by Snowden (1976), due to evolutionary effects and the calibration used. In addition, virtually no variable reddening in the cluster is observed.

  4. QDPHOT: Quick & Dirty PHOTometry

    NASA Astrophysics Data System (ADS)

    Mighell, Kenneth

    2016-01-01

    QDPHOT is a fast CCD stellar photometry task which quickly produces CCD stellar photometry from two CCD images of a star field. It was designed to be a data mining tool for finding high-quality stellar observations in the data archives of the National Virtual Observatory. QDPHOT typically takes just a few seconds to analyze two Hubble Space Telescope WFPC2 observations of Local Group star clusters. It is also suitable for real-time data-quality analysis of CCD observations; on-the-fly instrumental color-magnitude diagrams can be produced at the telescope console during the few seconds between CCD readouts.

  5. No Time Lag in the Photoelectric Effect

    NASA Astrophysics Data System (ADS)

    Gluck, Paul; Saering, Bernd

    2010-05-01

    The photoelectric effect was discovered in the 19th century by Heinrich Hertz. It is interesting to note that the same scientist showed experimentally the wave nature of light, and thereby vindicated Maxwell's wave theory, and discovered the effect in which light shows corpuscular behavior. This paper describes a simple demonstration, enabling one to show the absence of a time lag in the photoelectric effect to an accuracy of a microsecond.

  6. Stromvil CCD Photometry in Globular Cluster M 3

    NASA Astrophysics Data System (ADS)

    Boyle, Richard P.; Janusz, R.; Philip, A. G. D.; Straizys, V.; Vrba, F.

    2007-12-01

    We observed the globular cluster M 3 in the 7-band Stromvil system plus Vilnius X-band at the 1.8-m Vatican Advanced Technology Telescope with a 2K CCD giving a 6-arcmin field. We observed the open cluster M 67 in the same run. Here from the residuals of many stars fit to quality CCD Vilnius photometry (Laugalys et al., 2004, Baltic Astronomy, 13, 1) we reshape and thus correct the initial flatfields. M 67 with a wide color base gives the color transformations of the run by calibrating from about 12 photoelectric standards in the Stromvil and similar Vilnius systems. In M 3 six photoelectric standards of moderate quality, all red stars of 13th magnitude in the Vilnius system calibrate the zero-point magnitude scale. Point-spread-function fitting to the stars in the crowded M 3 field resolves blends. With relatively short exposures of minutes a limiting magnitude V=15 is obtained with a signal/noise ratio about 100. So from this new photometry we subsequently can classify all types of stars and treat questions of reddening, distances, membership and metallicity at least at the horizontal branch of the cluster.

  7. Introductory remarks: Photometry section

    NASA Technical Reports Server (NTRS)

    Ahearn, M. F.

    1981-01-01

    The principal goals of photometry and polarimetry are summarized. These goals include studies of the emission features of gaseous species of comets, the wavelength depenence of albedo, the phase function of scatter distribution, and time variation of rotation. Recent advances in photometric techniques were reviewed and include: use of proper filters, extension to the shortest and longest wavelengths, higher spectral resolving power, and polarizaton techniques.

  8. ARCHANGEL: Galaxy Photometry System

    NASA Astrophysics Data System (ADS)

    Schombert, James

    2011-07-01

    ARCHANGEL is a Unix-based package for the surface photometry of galaxies. While oriented for large angular size systems (i.e. many pixels), its tools can be applied to any imaging data of any size. The package core contains routines to perform the following critical galaxy photometry functions: sky determinationframe cleaningellipse fittingprofile fittingtotal and isophotal magnitudes The goal of the package is to provide an automated, assembly-line type of reduction system for galaxy photometry of space-based or ground-based imaging data. The procedures outlined in the documentation are flux independent, thus, these routines can be used for non-optical data as well as typical imaging datasets. ARCHANGEL has been tested on several current OS's (RedHat Linux, Ubuntu Linux, Solaris, Mac OS X). A tarball for installation is available at the download page. The main routines are Python and FORTRAN based, therefore, a current installation of Python and a FORTRAN compiler are required. The ARCHANGEL package also contains Python hooks to the PGPLOT package, an XML processor and network tools which automatically link to data archives (i.e. NED, HST, 2MASS, etc) to download images in a non-interactive manner.

  9. Third Workshop on Photometry

    NASA Technical Reports Server (NTRS)

    Borucki, William J. (Editor); Lasher, Lawrence E. (Editor)

    2001-01-01

    The discoveries of extrasolar planets by Wolszczan, Mayor and Queloz, Butler et al., and others have stimulated a widespread effort to obtain a body of data sufficient to understand their occurrence and characteristics. Doppler velocity techniques have found dozens of extrasolar planets with masses similar to that of Jupiter. Approximately ten percent of the stars that show planets with orbital periods of a few days to a week are expected to show transits. With the mass obtained from Doppler velocity measurements and the size from transit photometry, the densities of the planets can be determined. Theoretical models of the structure of "hot Jupiters" (i.e., those planets within a tenth of an astronomical unit (AU) of the parent star) indicate that these planets should be substantially larger in size and lower in density than Jupiter. Thus the combination of transit and Doppler velocity measurements provide a critical test of the theories of planetary structure. Furthermore, because photometry can be done with small-aperture telescopes rather than requiring the use of much larger telescopes, transit photometry should also reduce the cost of discovering extrasolar planets.

  10. Photographic photometry of variable stars

    NASA Technical Reports Server (NTRS)

    Kholopov, P. N.

    1973-01-01

    Photographic methods of determining stellar magnitude and measuring brightness of variable stars on negatives include the photoelectric method and the contascope. Calibration curves are usually plotted by the UBV method. Magnitudes of comparison stars can be determined from photographs.

  11. Multifunctional laser facility with photoelectric recording for plasma diagnostics

    SciTech Connect

    Pyatnitsky, L.N.; Yakushev, G.G.; Oberman, F.M. )

    1989-01-01

    A laser facility with photoelectric recording is described. It can be used in performing plasma diagnostics by four different measuring techniques. The application of photoelectric recording considerably simplifies the automation of measurements.

  12. VizieR Online Data Catalog: uvby photometry of 4 CP stars (Adelman, 1997)

    NASA Astrophysics Data System (ADS)

    Adelman, S. J.

    1996-11-01

    Differential Stroemgren uvby photometric observations from the Four College Automated Photoelectric Telescope are presented for four magnetic chemically peculiar stars. Comparison with uvby photometry of Pedersen & Thomsen for HD 37776 yields an improved period of 1.538675 days. New periods of 15.0305 days and 18.065 days are found for the sharp-lined stars HR 2258 and HR 6958, respectively, rather than one of their aliases. For HR 6958 each color shows a slightly different time of maximum. Comparison of the four color photometry of 108 Aqr taken during the fall of 1995 which well covers the period shows the presence of a secondary minimum near primary maximum in u, v, and b. Comparison with published photometry indicates indicates that subtle changes in the shapes of the light curves have occurred suggesting that this star might be precessing. (5 data files).

  13. 21 CFR 870.2780 - Hydraulic, pneumatic, or photoelectric plethysmographs.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Hydraulic, pneumatic, or photoelectric... § 870.2780 Hydraulic, pneumatic, or photoelectric plethysmographs. (a) Identification. A hydraulic... using hydraulic, pneumatic, or photoelectric measurement techniques. (b) Classification. Class...

  14. 21 CFR 870.2780 - Hydraulic, pneumatic, or photoelectric plethysmographs.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Hydraulic, pneumatic, or photoelectric... § 870.2780 Hydraulic, pneumatic, or photoelectric plethysmographs. (a) Identification. A hydraulic... using hydraulic, pneumatic, or photoelectric measurement techniques. (b) Classification. Class...

  15. 21 CFR 870.2780 - Hydraulic, pneumatic, or photoelectric plethysmographs.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Hydraulic, pneumatic, or photoelectric... § 870.2780 Hydraulic, pneumatic, or photoelectric plethysmographs. (a) Identification. A hydraulic... using hydraulic, pneumatic, or photoelectric measurement techniques. (b) Classification. Class...

  16. 21 CFR 870.2780 - Hydraulic, pneumatic, or photoelectric plethysmographs.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Hydraulic, pneumatic, or photoelectric... § 870.2780 Hydraulic, pneumatic, or photoelectric plethysmographs. (a) Identification. A hydraulic... using hydraulic, pneumatic, or photoelectric measurement techniques. (b) Classification. Class...

  17. 16 CFR 1211.11 - Requirements for photoelectric sensors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Requirements for photoelectric sensors. 1211... Requirements for photoelectric sensors. (a) Normal operation test. (1) When installed as described in § 1211.10(a) (1)-(4), a photoelectric sensor shall sense an obstruction as described in paragraph (a)(2)...

  18. 16 CFR 1211.11 - Requirements for photoelectric sensors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Requirements for photoelectric sensors. 1211... Requirements for photoelectric sensors. (a) Normal operation test. (1) When installed as described in § 1211.10(a) (1)-(4), a photoelectric sensor shall sense an obstruction as described in paragraph (a)(2)...

  19. 16 CFR 1211.11 - Requirements for photoelectric sensors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Requirements for photoelectric sensors. 1211... Requirements for photoelectric sensors. (a) Normal operation test. (1) When installed as described in § 1211.10(a) (1)-(4), a photoelectric sensor shall sense an obstruction as described in paragraph (a)(2)...

  20. 16 CFR 1211.11 - Requirements for photoelectric sensors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Requirements for photoelectric sensors. 1211... Requirements for photoelectric sensors. (a) Normal operation test. (1) When installed as described in § 1211.10(a) (1)-(4), a photoelectric sensor shall sense an obstruction as described in paragraph (a)(2)...

  1. 21 CFR 870.2780 - Hydraulic, pneumatic, or photoelectric plethysmographs.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Hydraulic, pneumatic, or photoelectric... § 870.2780 Hydraulic, pneumatic, or photoelectric plethysmographs. (a) Identification. A hydraulic... using hydraulic, pneumatic, or photoelectric measurement techniques. (b) Classification. Class...

  2. Photoelectric spectrophotometry of Wolf-Rayet stars

    NASA Technical Reports Server (NTRS)

    Bahng, J. D. R.

    1974-01-01

    Photoelectric spectrum scans of five southern Wolf-Rayet stars in the spectral range lambda lambda 4600-4720 were analyzed to study the variability of brightness and of emission line strengths. No variations of any kind in short time scale were found. However, in WC stars night-to-night variations of three to four percent were detected in the emission line strengths.

  3. Photoelectric absorption cross sections with variable abundances

    NASA Technical Reports Server (NTRS)

    Balucinska-Church, Monika; Mccammon, Dan

    1992-01-01

    Polynomial fit coefficients have been obtained for the energy dependences of the photoelectric absorption cross sections of 17 astrophysically important elements. These results allow the calculation of X-ray absorption in the energy range 0.03-10 keV in material with noncosmic abundances.

  4. No Time Lag in the Photoelectric Effect

    ERIC Educational Resources Information Center

    Gluck, Paul; Saering, Bernd

    2010-01-01

    The photoelectric effect was discovered in the 19th century by Heinrich Hertz. It is interesting to note that the same scientist showed experimentally the wave nature of light, and thereby vindicated Maxwell's wave theory, and discovered the effect in which light shows corpuscular behavior. This paper describes a simple demonstration, enabling one…

  5. Photoelectric system continuously monitors liquid level

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Immersion probe presents a depth-sensitive optical transmission path between a light source and a photoelectric cell to continuously monitor the level of a transparent liquid in a tank. This system operates automatically, without moving parts, and provides output signals to a remote recorder.

  6. APASS Landolt-Sloan BVgri Photometry of RAVE Stars. I. Data, Effective Temperatures, and Reddenings

    NASA Astrophysics Data System (ADS)

    Munari, U.; Henden, A.; Frigo, A.; Zwitter, T.; Bienaymé, O.; Bland-Hawthorn, J.; Boeche, C.; Freeman, K. C.; Gibson, B. K.; Gilmore, G.; Grebel, E. K.; Helmi, A.; Kordopatis, G.; Levine, S. E.; Navarro, J. F.; Parker, Q. A.; Reid, W.; Seabroke, G. M.; Siebert, A.; Siviero, A.; Smith, T. C.; Steinmetz, M.; Templeton, M.; Terrell, D.; Welch, D. L.; Williams, M.; Wyse, R. F. G.

    2014-11-01

    We provide AAVSO Photometric All-Sky Survey (APASS) photometry in the Landolt BV and Sloan g'r'i' bands for all 425,743 stars included in the fourth RAVE Data Release. The internal accuracy of the APASS photometry of RAVE stars, expressed as the error of the mean of data obtained and separately calibrated over a median of four distinct observing epochs and distributed between 2009 and 2013, is 0.013, 0.012, 0.012, 0.014, and 0.021 mag for the B, V, g', r', and i' bands, respectively. The equally high external accuracy of APASS photometry has been verified on secondary Landolt and Sloan photometric standard stars not involved in the APASS calibration process and on a large body of literature data on field and cluster stars, confirming the absence of offsets and trends. Compared with the Carlsberg Meridian Catalog (CMC-15), APASS astrometry of RAVE stars is accurate to a median value of 0.098 arcsec. Brightness distribution functions for the RAVE stars have been derived in all bands. APASS photometry of RAVE stars, augmented by 2MASS JHK infrared data, has been χ2 fitted to a densely populated synthetic photometric library designed to widely explore temperature, surface gravity, metallicity, and reddening. Resulting T eff and E B - V , computed over a range of options, are provided and discussed, and will be kept updated in response to future APASS and RAVE data releases. In the process, we find that the reddening caused by a homogeneous slab of dust, extending for 140 pc on either side of the Galactic plane and responsible for EpolesB-V = 0.036 ± 0.002 at the Galactic poles, is a suitable approximation of the actual reddening encountered at Galactic latitudes |b| >= 25°.

  7. APASS Landolt-Sloan BVgri photometry of Rave stars. I. Data, effective temperatures, and reddenings

    SciTech Connect

    Munari, U.; Siviero, A.; Henden, A.; Frigo, A.; Bienaymé, O.; Siebert, A.; Bland-Hawthorn, J.; Boeche, C.; Grebel, E. K.; Freeman, K. C.; Gibson, B. K.; Gilmore, G.; Kordopatis, G.; Helmi, A.; Levine, S. E.; Navarro, J. F.; Parker, Q. A.; Reid, W.; Seabroke, G. M.; and others

    2014-11-01

    We provide AAVSO Photometric All-Sky Survey (APASS) photometry in the Landolt BV and Sloan g'r'i' bands for all 425,743 stars included in the fourth RAVE Data Release. The internal accuracy of the APASS photometry of RAVE stars, expressed as the error of the mean of data obtained and separately calibrated over a median of four distinct observing epochs and distributed between 2009 and 2013, is 0.013, 0.012, 0.012, 0.014, and 0.021 mag for the B, V, g', r', and i' bands, respectively. The equally high external accuracy of APASS photometry has been verified on secondary Landolt and Sloan photometric standard stars not involved in the APASS calibration process and on a large body of literature data on field and cluster stars, confirming the absence of offsets and trends. Compared with the Carlsberg Meridian Catalog (CMC-15), APASS astrometry of RAVE stars is accurate to a median value of 0.098 arcsec. Brightness distribution functions for the RAVE stars have been derived in all bands. APASS photometry of RAVE stars, augmented by 2MASS JHK infrared data, has been χ{sup 2} fitted to a densely populated synthetic photometric library designed to widely explore temperature, surface gravity, metallicity, and reddening. Resulting T {sub eff} and E {sub B–V}, computed over a range of options, are provided and discussed, and will be kept updated in response to future APASS and RAVE data releases. In the process, we find that the reddening caused by a homogeneous slab of dust, extending for 140 pc on either side of the Galactic plane and responsible for E{sub B−V}{sup poles} = 0.036 ± 0.002 at the Galactic poles, is a suitable approximation of the actual reddening encountered at Galactic latitudes |b| ≥ 25°.

  8. Steps toward a physical calibration of UBV photometry

    NASA Astrophysics Data System (ADS)

    Buser, R.; Kurucz, R. L.

    The large data base of photoelectric measurements on the Johnson UBV system has been a primary source of information in many fields of astrophysical interest. The availability of UBV data for virtually all types of stars known to make up the stellar populations in galaxies requires a continued effort toward establishing a fully physical calibration of these data in order to propagate effectively the improving knowledge on stellar evolution and stellar atmospheres (i.e., the HR diagram) through the observations relevant to the structure and evolution of the galaxies. One of the major links in this long chain of scientific progress is provided by the synthesis of stellar photometric properties from theoretical model atmospheres. This paper will briefly address some of the basic problems involved in the synthetic color calculations and discuss the theoretical calibration of UBV photometry as obtained from various grids of model atmospheres covering a large range of stellar types.

  9. Orion Project: A Photometry and Spectroscopy Project for Small Observatories (Abstract)

    NASA Astrophysics Data System (ADS)

    Hopkins, J. L.

    2014-12-01

    (Abstract only) Orion, the hunter, is one of the most famous constellations. Its declination is such that it is visible from most of the civilized world. In addition, most of the stars of Orion are very bright and interesting. Originally this project was called the Betelgeuse Campaign, but four more stars were added so the name was changed to the Orion Project. The project now includes Betelgeuse, Rigel, and the three stars of Orion’s belt, Mintaka, Alnilam, and Alnitak. Both photometry and spectroscopy provide data for the project. The project has several goals, the first of which is to help beginners with photometry and spectroscopy. The second goal is to obtain the actual observations and data. Because these stars are very bright, they are seldom observed in detail. Their brightness also poses a problem for most professional observatories. It is hoped that by having observations over a long time, interesting changes can be seen that will warrant closer investigation. As a third goal it is hoped that the procedures refined in the project for spectroscopic data may help promote a similar system for the AAVSO, which has an excellent archive of photometric data, but is still lacking a means of handling spectroscopic data.

  10. A search for continuous fluorescence in reflection nebulae. [using photoelectric photometry and spectrophotometric observations

    NASA Technical Reports Server (NTRS)

    Rush, W. F.; Witt, A. N.

    1973-01-01

    Photometric and spectrophotometric observations were made of the reflection nebulae NGC1435, NGC2068, NGC7023, and IC1287 in an attempt to detect continuous fluorescence by dust grains. Several effects of importance for observations of such faint objects are discussed, including instrumental light scattering, a photographic effect, and a time delay effect which can occur if the illuminating star is a spectrum variable. It is found that continuous fluorescence by interstellar grains is not likely to exist and that it cannot account for more than 10 percent of the total surface brightness of these reflection nebulae. No evidence of diffuse interstellar features is found in the spectra of these nebulae.

  11. Qualitative model of a plasma photoelectric converter

    NASA Astrophysics Data System (ADS)

    Gorbunov, N. A.; Flamant, G.

    2009-01-01

    A converter of focused optical radiation into electric current is considered on the basis of the photovoltaic effect in plasmas. The converter model is based on analysis of asymmetric spatial distributions of charge particle number density and ambipolar potential in the photoplasma produced by external optical radiation focused in a heat pipe filled with a mixture of alkali vapor and a heavy inert gas. Energy balance in the plasma photoelectric converter is analyzed. The conditions in which the external radiation energy is effectively absorbed in the converter are indicated. The plasma parameters for which the energy of absorbed optical radiation is mainly spent on sustaining the ambipolar field in the plasma are determined. It is shown that the plasma photoelectric converter makes it possible to attain a high conversion efficiency for focused solar radiation.

  12. Photoelectric detection electric arc in energetic arrangements

    NASA Astrophysics Data System (ADS)

    Leks, Jan

    2001-08-01

    The evolution of photoelectric converter, fiber optics and integrated circuits, in particular optic detectors, increases area of applying of the industrial measuring and control systems that used IR detectors. One of the more important is optic detection of electric arc in industrial energetic arrangements. That kind of detection is sure, easy to apply in existing industrial apparatus a d it is cheaper than another way of detection. Additionally optic detection of electric arc is safety for attendance persons and may work on computer system. The article presents an example of circuit with semiconductor IR photoelectric detector to detection of electric arc and points at the most important questions which should be taken into consideration in designing instruments like described one.

  13. A photoelectric guide for sunspot images

    NASA Astrophysics Data System (ADS)

    Druzhinin, S. A.; Maslov, I. L.; Pevtsov, A. A.

    A photoelectric guide designed to directly handle sunspot images is described. A quadrant photodiode (serving as the photodetector) is placed in the beam reflected from the Dove prism face. The actuators are two plane-parallel plates attached to low-inertia electromagnetic drives, ensuring a high frequency (up to 3 Hz) of control action in response to image motion. The guide is placed in front of the spectrograph entrance slit and can be used with any standard AZU-5 telescope.

  14. k2photometry: Read, reduce and detrend K2 photometry

    NASA Astrophysics Data System (ADS)

    Van Eylen, Vincent; Nowak, Grzegorz; Albrecht, Simon; Palle, Enric; Ribas, Ignasi; Bruntt, Hans; Perger, Manuel; Gandolfi, Davide; Hirano, Teriyuki; Sanchis-Ojeda, Roberto; Kiilerich, Amanda; Arranz, Jorge P.; Badenas, Mariona; Dai, Fei; Deeg, Hans J.; Guenther, Eike W.; Montanes-Rodriguez, Pilar; Narita, Norio; Rogers, Leslie A.; Bejar, Victor J. S.; Shrotriya, Tushar S.; Winn, Joshua N.; Sebastian, Daniel

    2016-02-01

    k2photometry reads, reduces and detrends K2 photometry and searches for transiting planets. MAST database pixel files are used as input; the output includes raw lightcurves, detrended lightcurves and a transit search can be performed as well. Stellar variability is not typically well-preserved but parameters can be tweaked to change that. The BLS algorithm used to detect periodic events is a Python implementation by Ruth Angus and Dan Foreman-Mackey (https://github.com/dfm/python-bls).

  15. Photometry and the Virtual Observatory

    NASA Astrophysics Data System (ADS)

    Rodrigo, C.; Solano, E.

    2013-05-01

    Building Spectral Energy Distributions combining data from different sources is becoming more important as astronomy takes an increasingly multi-wavelength approach. In order to do this, photometry data must be described in sufficient detail to allow for the conversion to compatible flux density units (including the description of magnitude systems and zero points). Furthermore, comparing observed photometry with the synthetic one for theoretical models allows to infer physical properties from the observed objects. But in order to do that, an even more detailed description of the observed photometric points is needed, including the transmission curves of the filters corresponding to the observed data. In the Virtual Observatory an important effort has been done towards this standardization with the Photometry Data Model. And in the SVO we have developed several services to help in this direction, providing detailed information about filters, synthetic photometry for theoretical models and tools to use all this to analyze observed data and estimate object physical properties.

  16. Asteroid Lightcurve Photometry

    NASA Astrophysics Data System (ADS)

    Harris, A. W.

    2004-05-01

    With the advent of modestly priced CCD cameras and computer controller and reduction software, amateurs can now do photometry on fainter targets than was possible even from large observatories only a decade or so ago. This has led to an explosion of lightcurve data that in turn has yielded rich results. We now have rotation periods for more than 1500 asteroids, extending down to objects only tens of meters in diameter, and well determined shapes and pole orientations of more than 100 objects. Among smaller asteroids, the dispersion in rotation rates ranges from minutes to months, with the slower ones mostly "tumbling," or in states of non-principal axis rotation. The fastest ones must be monolithic, as centrifugal force exceeds their gravity. But among those larger than a few hundred meters diameter, there is a "rotation barrier" at the rate where gravity and centrifugal force match, suggesting that most asteroids this large or larger are "rubble piles." The broad dispersion in spin rates, almost a bimodal distribution, has long been a mystery, but now appears likely to be due to thermal radiation torques from the randomly asymmetric shapes of small asteroids. This is a major paradigm shift from the past, where mutual collisions were considered to be the dominant (or only) evolutionary process affecting spins. Amateur observations have already contributed a great deal leading to this new view, and much remains to be done, providing abundant opportunities for amateur-professional collaborations.

  17. Photometry from space

    NASA Technical Reports Server (NTRS)

    Nelson, M. J.; Bless, R. C.; Percival, J. W.; White, R. L.

    1992-01-01

    A brief description of the High Speed Photometer (HSP) of the Hubble Space Telescope is given, in particular the HSP light path, detectors, entrance apertures, and filters. The status of HSP testing to date is reported, and problems encountered with the bright earth and the telescope pointing system are described. The calibration effort for the HSP is well under way. Results of internal (instrument coordinate) aperture locations good to 0.05 arcsec and external (telescope coordinate) locations good to 0.02 arcsec are shown. The effects of spacecraft pointing and jitter on HSP photometry are detailed, and a preliminary measurement of spacecraft jitter with HSP is shown. The aperture calibration effort is verified by accurate pointing of a star to different HSP 1.0 arcsec entrance apertures, and photometric performance of the instrument is shown to be accurate to the 2 percent photon noise of the observations. Future science verification and guaranteed observing time programs are listed. Suggestions are made for future space-based photometers.

  18. VizieR Online Data Catalog: Photometry of nova LMC 2012 (Schwarz+, 2015)

    NASA Astrophysics Data System (ADS)

    Schwarz, G. J.; Shore, S. N.; Page, K. L.; Osborne, J. P.; Beardmore, A. P.; Walter, F. M.; Bode, M. F.; Drake, J. J.; Ness, J.-U.; Starrfield, S.; van Rossum, D. R.; Woodward, C. E.

    2015-03-01

    Nova LMC 2012 was discovered on March 26.397 UT (MJD56012.897) at a visual magnitude of 10.7 (Seach et al., 2012CBET.3071....1S). After discovery, LMC 2012 was observed by a number of different facilities at a variety of wavelengths. The discovery date is taken as day zero and the shorthand "Dn," where "n" is the number of days after day zero, is used here. Swift is a revolutionary facility for studying novae (see Schwarz et al. 2011, cat. J/ApJS/197/31, for details). Its three instruments cover the γ-ray (BAT), X-ray (XRT), plus UV and optical (UVOT) bandpasses. Swift obtained 74 uvm2 band (λeff=2246Å, FWHM=498Å) observations of LMC 2012 with the UVOT instrument from D1.2 until D671. There were also 12 uvw2 band (λeff=1928Å, FWHM=657Å) and nine uvw1 band (λeff=2600Å, FWHM=693Å) observations which were only obtained early on D1.2 and later during the observations after D300. The UVOT photometry is provided in Table2. LMC 2012 was extensively observed photometrically between D0.6 and D635 with the Small & Moderate Aperture Research Telescope System (SMARTS) at Cerro Tololo (see Walter et al., 2012PASP..124.1057W, for details). We obtained 250 photometric observations in BVRI/JHK from SMARTS. The optical photometry is supplemented with 54 early time CCD BVRI observations from the American Association of Variable Star Observers (AAVSO). The optical and near-infrared photometry is also given in Table2. (2 data files).

  19. Photoelectric Charging of Dust in Space

    NASA Astrophysics Data System (ADS)

    Sickafoose, A. A.; Robertson, S.; Colwell, J. E.; Horanyi, M.

    1999-09-01

    Illumination of surfaces in space by solar ultraviolet light produces photoelectrons which form a plasma sheath near the surface. Dust particles on the surface can acquire a charge and be transported horizontally and vertically by electric fields within the sheath. On the moon, suspended dust grains have been observed on multiple occasions, and there is evidence for horizontal lunar dust transport. Photoelectron production and dust particle charging are also expected to be significant near the surface of Mars. Understanding the photoelectric charging properties of dust can help explain the observed dynamics of lunar dust and help predict the behavior of dust on surfaces of planetary satellites, asteroids, planetary ring particles, and planetesimals. In addition, any human or spacecraft activity on planetary bodies is affected by dust dynamics near the surface. We have examined the photoelectric charging of dust dropped through UV illumination and dust dropped past a UV illuminated surface having a photoelectron sheath. Experiments are performed in vacuum with illumination from a 1 kW Hg-Xe arc lamp. The lamp produces a spectrum down to ~ 200 nm ( ~ 6.2 eV), and the photoemitter is a 12 cm diameter zirconium plate. Dust dropped through UV illumination loses electrons due to photoemission, while dust dropped past an illuminated surface gains electrons from the photoelectron sheath. Initial results are consistent with expected charge calculated from the work function of the materials, the energy of incoming photons, and the capacitance of the grains. Photoelectric charging experiments have been done for several different kinds of dust 90-106 mu m in diameter. We will present the results of these experiments and compare the charging properties of zinc, copper, graphite, Martian regolith simulant (JSC Mars-1), lunar regolith simulant (JSC-1), and lunar soil from an Apollo 17 sample. This research is supported by NASA.

  20. High resolution obtained by photoelectric scanning techniques.

    NASA Technical Reports Server (NTRS)

    Hall, J. S.

    1972-01-01

    Several applications of linear scanning of different types of objects are described; examples include double stars, satellites, the Red Spot of Jupiter and a landing site on the moon. This technique allows one to achieve a gain of about an order of magnitude in resolution over conventional photoelectric techniques; it is also effective in providing sufficient data for removing background effects and for the application of deconvolution procedures. Brief consideration is given to two-dimensional scanning, either at the telescope or of electronographic images in the laboratory. It is suggested that some of the techniques described should be given serious consideration for space applications.

  1. Lunar Dust Charging by Photoelectric Emissions

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Tankosic, D.; Craven, P. D.; Spann, J. F.; LeClair, A.; West, E. A.

    2007-01-01

    The lunar surface is covered with a thick layer of sub-micron/micron size dust grains formed by meteoritic impact over billions of years. The fine dust grains are levitated and transported on the lunar surface, as indicated by the transient dust clouds observed over the lunar horizon during the Apollo 17 mission. Theoretical models suggest that the dust grains on the lunar surface are charged by the solar UV radiation as well as the solar wind. Even without any physical activity, the dust grains are levitated by electrostatic fields and transported away from the surface in the near vacuum environment of the Moon. The current dust charging and levitation models, however, do not fully explain the observed phenomena. Since the abundance of dust on the Moon s surface with its observed adhesive characteristics has the potential of severe impact on human habitat and operations and lifetime of a variety of equipment, it is necessary to investigate the charging properties and the lunar dust phenomena in order to develop appropriate mitigating strategies. Photoelectric emission induced by the solar UV radiation with photon energies higher than the work function of the grain materials is recognized to be the dominant process for charging of the lunar dust, and requires measurements of the photoelectric yields to determine the charging and equilibrium potentials of individual dust grains. In this paper, we present the first laboratory measurements of the photoelectric efficiencies and yields of individual sub-micron/micron size dust grains selected from sample returns of Apollo 17, and Luna 24 missions, as well as similar size dust grains from the JSC-1 simulants. The measurements were made on a laboratory facility based on an electrodynamic balance that permits a variety of experiments to be conducted on individual sub-micron/micron size dust grains in simulated space environments. The photoelectric emission measurements indicate grain size dependence with the yield

  2. Study of Compton vs. Photoelectric Interactions

    SciTech Connect

    Gronberg, J B; Johnson, S C; Lange, D J; Wright, D M; Beiersdorfer, P

    2004-07-09

    We have studied how often incoming photons interact via a Compton interaction and/or a photoelectric interaction as a function of energy and detector material Results are using a 1m{sup 3} detector, and discrete energy photons from 0.1 MeV up to 10 MeV. Essentially all of the lower energy photons interact at least once in a detector of this size. This is not the case at higher energies. Each detector, photon energy combination was simulated with 2000 photons.

  3. Photoelectric Effect for Twist-deformed Space-time

    NASA Astrophysics Data System (ADS)

    Daszkiewicz, M.

    In this article, we investigate the impact of twisted space-time on the photoelectric effect, i.e., we derive the $\\theta$-deformed threshold frequency. In such a way we indicate that the space-time noncommutativity strongly enhances the photoelectric process.

  4. Photoelectric Effects in Lipid Bilayer Membranes. A Pedagogical Review.

    ERIC Educational Resources Information Center

    Huebner, Jay S.; And Others

    1988-01-01

    Provides information appropriate for introductory lectures on photoelectric effects in membranes. Describes the apparatus and supplies required for laboratory exercises. Outlines typical laboratory exercises. Identifies the chromophores known to induce photoelectric effects. Concludes that this topic can provide useful subjects for undergraduate…

  5. Detection by Transit Photometry

    NASA Technical Reports Server (NTRS)

    Borucki, William J.; Koch, David G.; Jenkins, Jon M.; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    A periodic sequence of planetary transits provides a valid detection of an orbiting planet and provides the relative size of the planet and its orbital period. Ancillary measurements of the stellar spectrum and the variations of the star's radial velocity or position combined with stellar models allow the absolute size of the planet and its mass to be obtained. The results of this approach have already shown that the planet orbiting HD209458 has only 70% of the mass of Jupiter, but is nearly 50% larger in radius. Based on models of planetary structure, these results imply that the planet must have spent most of its lifetime so close to the star that it has not been able to cool and contract as have the giant planets in our Solar System. Thus its density is much less than Jupiter and Saturn and is actually less than that of water; i.e., about 0.4 gr/cu cm. If more sensitive measurements of the light curve of stars with closely orbiting planets can be made that provide the varying amplitude of the light reflected by the planet at various phases in its orbit, then characteristics of the planetary atmosphere can be obtained. Potentially, these data can identify major molecular species present in the atmosphere and tell us if clouds are present and yield the phase function of the aerosols. Although such detail cannot be obtained for Earth-size planets because their signal amplitudes are too small, it is possible to get data critical to the determination of the structure of extrasolar planetary systems. In particular, the size distributions and their orbital distributions can be measured by the transit photometry missions now in development. The COROT mission should be able to find large terrestrial planets in short-period orbits while the more ambitious Kepler and Eddington missions should be able to detect planets even smaller than the Earth and at orbital distances that place them in the habitable zone of their stars.

  6. Anomalous photoelectric emission from Ag on zinc-phthalocyanine film

    NASA Astrophysics Data System (ADS)

    Tanaka, Senku; Otani, Tomohiro; Fukuzawa, Ken; Ogawa, Koji; Azuma, Junpei; Yamamoto, Isamu; Takahashi, Kazutoshi; Kamada, Masao; Hiromitsu, Ichiro

    2014-05-01

    Photoelectric emission from organic and metal thin films is generally observed with irradiation of photon energy larger than 4 eV. In this paper, however, we report photoelectric emission from Ag on a zinc-phthalocyanine (ZnPc) layer at a photon energy of 3.4 eV. The threshold energy for this photoelectric emission is much smaller than the work function of Ag estimated by conventional photoelectron spectroscopy. The photoelectric emission by low-energy photons is significant for Ag thicknesses of less than 1 nm. Photoelectron spectroscopy and morphological study of the Ag/ZnPc suggest that the anomalous photoelectric emission from the Ag surface is caused by a vacuum level shift at the Ag/ZnPc interface and by surface plasmons of the Ag nanoparticles.

  7. Anomalous photoelectric emission from Ag on zinc-phthalocyanine film

    SciTech Connect

    Tanaka, Senku; Otani, Tomohiro; Fukuzawa, Ken; Hiromitsu, Ichiro; Ogawa, Koji; Azuma, Junpei; Yamamoto, Isamu; Takahashi, Kazutoshi; Kamada, Masao

    2014-05-12

    Photoelectric emission from organic and metal thin films is generally observed with irradiation of photon energy larger than 4 eV. In this paper, however, we report photoelectric emission from Ag on a zinc-phthalocyanine (ZnPc) layer at a photon energy of 3.4 eV. The threshold energy for this photoelectric emission is much smaller than the work function of Ag estimated by conventional photoelectron spectroscopy. The photoelectric emission by low-energy photons is significant for Ag thicknesses of less than 1 nm. Photoelectron spectroscopy and morphological study of the Ag/ZnPc suggest that the anomalous photoelectric emission from the Ag surface is caused by a vacuum level shift at the Ag/ZnPc interface and by surface plasmons of the Ag nanoparticles.

  8. Second Workshop on Improvements to Photometry

    NASA Technical Reports Server (NTRS)

    Borucki, William J. (Editor)

    1988-01-01

    The papers in these proceedings show that a major effort is under way to improve all aspects of photometry. Astronomical multichannel photometry, photodiodes, analog-to-digital converters, data reduction techniques, interference filters and optical fibers are discussed.

  9. A photoelectric study of Messier 81.

    NASA Technical Reports Server (NTRS)

    Brandt, J. C.; Kalinowski, J. K.; Roosen, R. G.

    1972-01-01

    Results of photoelectric observations in B and V made at over 1200 locations in Messier 81, covering an area of approximately 169 square minutes of arc and including the galaxy's nucleus. Isophote maps in V and B based on these observations have been drawn. Two independent fits on the resulting V and B luminosity distributions yield average integrated magnitudes of V equals 6.94 and B equals 7.89. B - V and (integrated B) - (integrated V) are given as functions of distance from the center of the galaxy along the semimajor axis. A mass model is derived using a rotation curve based on the velocities measured by Muench (1959). The total mass of M81 is found to be 1.62 x 10 to the 11th solar masses. The final apparent mass-to-luminosity ratios in V and B are 11.2 and 15.1, respectively.

  10. A photoelectric amplifier as a dye detector

    USGS Publications Warehouse

    Ebel, Wesley J.

    1962-01-01

    A dye detector, based on a modified photoelectric amplifier, has been planned, built, and tested. It was designed to record automatically the time of arrival of fluorescein dye at predetermined points in a stream system. Laboratory tests and stream trials proved the instrument to be efficient. Small changes in color can be detected in turbid or clear water. The unit has been used successfully for timing intervals of more than 17 hours; significant savings of time and manpower have resulted. Replacement of the clock, included in the original device, with a recording milliammeter increases the efficiency of the unit by contin,!ously recording changes in turbidity. The addition of this component would increase the cost from $75 to approximately $105.

  11. Evidence of vectorial photoelectric effect on copper

    SciTech Connect

    Pedersoli, E.; Banfi, F.; Ressel, B.; Pagliara, S.; Giannetti,C.; Galimberti, G.; Lidia, S.; Corlett, J.; Ferrini, G.; Parmigiani, F.

    2005-05-27

    Quantum Efficiency (QE) measurements of single photon photoemission from a Cu(111) single crystal and a Cu polycrystal photocathodes, irradiated by 150 fs-6.28 eV laser pulses, are reported over a broad range of incidence angle, both in s and p polarizations. The maximum QE (approx. = 4x10-4) for polycrystalline Cu is obtained in p polarization at an angle of incidence theta = 65 deg. We observe a QE enhancement in p polarization which can not be explained in terms of optical absorption, a phenomenon known as vectorial photoelectric effect. Issues concerning surface roughness and symmetry considerations are addressed. An explanation in terms of non local conductivity tensor is proposed.

  12. Photographic surface photometry of the Milky Way. III - Photometry of the central area of the Galaxy in the ultraviolet

    NASA Astrophysics Data System (ADS)

    Proell, H. J.; Schmidt-Kaler, T.; Schlosser, W.

    1983-01-01

    influence, there is generally very good agreement with the results of Seidensticker, Schinidt-Kaler and Schlosser (= paper II), their values being smaller by a statistically insignificant additive difference of -14(± 15) S10U. The comparison (Fig 6) with the photoelectric surface photometry of Pfleiderer and Mayer (1971) shows a negligible additive difference of -8 (± 12) S10U, but a large scale difference of 24(± 9)%, the Bochum values being larger. The comparison with the measurements of Leinert and Richter (1981), obtained by the satellite Helios, shows very good agreement in the run of the intensities (Fig. 7). Computation of a point by point correlation reveals their values being smaller by an additive difference of -5 (± 2) S10U and a scale difference of 17(± 2)%. As obvious from figure 7 the main difference in the two photometry results from the finer structures in our data, due to different resolution and different completeness in eliminating background stars. Thus we constructed a lower envelope to our data. This reveals an additive difference of 0 (± 0.3) S10U and a scale difference of 2.4 (± 9)% in the same sense as above. In the last paragraph we discuss the structure of the Milky Way central region in U, in particular those spiral filaments which appear inclined to the galactic equator (shingles, corrugations). The three shingles discovered by Schmidt-Kaler and Schlosser (1973) in the next-inner spiral arm-I and an additional feature appear if the data-field of the UV photometry is spatially differentiated (Fig. 8).

  13. Design and analysis of APD photoelectric detecting circuit

    NASA Astrophysics Data System (ADS)

    Fang, R.; Wang, C.

    2015-11-01

    In LADAR system, photoelectric detecting circuit is the key part in photoelectric conversion, which determines speed of respond, sensitivity and fidelity of the system. This paper presents the design of a matched APD Photoelectric detecting circuit. The circuit accomplishes low-noise readout and high-gain amplification of the weak photoelectric signal. The main performances, especially noise and transient response of the circuit are analyzed. In order to obtain large bandwidth, decompensated operational amplifiers are applied. Circuit simulations allow the architecture validation and the global performances to be predicted. The simulation results show that the gain of the detecting circuit is 630kΩ while the bandwidth is 100MHz, and 28dB dynamic range is achieved. Furthermore, the variation of the output pulse width is less than 0.9ns.

  14. On the photoelectric quantum yield of small dust particles

    NASA Astrophysics Data System (ADS)

    Kimura, Hiroshi

    2016-07-01

    Photoelectron emission is crucial to electric charging of dust particles around main-sequence stars and gas heating in various dusty environments. An estimate of the photoelectric processes contains an ill-defined parameter called the photoelectric quantum yield, which is the total number of electrons ejected from a dust particle per absorbed photon. Here we revisit the so-called small particle effect of photoelectron emission and provide an analytical model to estimate photoelectric quantum yields of small dust particles in sizes down to nanometers. We show that the small particle effect elevates the photoelectric quantum yields of nanoparticles up to by a factor of 103 for carbon, water ice, and organics, and a factor of 102 for silicate, silicon carbide, and iron. We conclude the surface curvature of the particles is a quantity of great importance to the small particle effect, unless the particles are submicrometers in radius or larger.

  15. Photoelectric scanner makes detailed work function maps of metal surface

    NASA Technical Reports Server (NTRS)

    Rasor, N. S.

    1966-01-01

    Photoelectric scanning device maps the work function of a metal surface by scanning it with a light spot and measuring the resulting photocurrent. The device is capable of use over a range of surface temperatures.

  16. The eclipsing binary CW Eridani. [three-color photoelectric observation

    NASA Technical Reports Server (NTRS)

    Chen, K.-Y.

    1975-01-01

    Results of three-color photoelectric observations of CW Eridani are presented which were made with a 30-inch telescope over the three-year period from 1970 to 1973. The times of minima are computed, solutions of the light curves are obtained, and theoretical light curves are computed from the solutions. The period is determined to be 2.72837 days, and the orbital and photoelectric elements are derived from solutions based on the idealized Russell model.

  17. A new arrangement method for photoelectric cells and its application

    NASA Astrophysics Data System (ADS)

    Chen, Yurong; Yang, Xudong; Wang, Xuanze; Xie, Tiebang

    2006-11-01

    Traditional photoelectric detection methods consider the interference fringes are evenly intensity distributed without random noise and the photoelectric signal satisfies the requirement of counter and subdivision in theory. However, in order to improve the Signal-to-Noise Ratio of detection, not only the requirement of counter and subdivision, but also the space arrangement of photoelectric cells must be taken into account. This paper presents a new arrangement method of photoelectric cells. The four adjacent photoelectric cells of the new method are arrayed in a square photoelectric cell array that inclines from the direction of the interference fringes with a certain offset angle. The new method and the traditional method are analyzed by integral equations and three models of random noise, AC amplitude and DC adrift are founded in this paper. According to the theoretical and experimental analysis, the detection Signal-to-Noise Ratio of the new method is improved remarkably compared with the traditional methods. This new method, which can dramatically restrain DC adrift of light intensity even if the fringes' signal is faint, can be applied in a laser-interference sensor for three-dimensional surface topography measurement.

  18. Far-Ultraviolet Stellar Photometry

    NASA Astrophysics Data System (ADS)

    Schmidt, E. G.; Carruthers, G. R.

    1993-12-01

    During a shuttle flight in May, 1991, wide field images were obtained for 12 star fields with the NRL far-ultraviolet cameras. These cameras provide sensitivity bands with effective wavelengths of lambda eff = 1367 Angstroms and lambda eff = 1702 Angstroms. The properties of the resulting magnitude system will be described and compared with previous photometry from the OAO2, ANS and TD1 satellites. Results from several fields in the vicinity of the galactic center will be discussed.

  19. Characterisation of the Gaia photometry

    NASA Astrophysics Data System (ADS)

    Carrasco, J. M.; Jordi, C.; Fabricius, C.; Voss, H.; Weiler, M.

    2014-07-01

    Our team at the University of Barcelona has contributed since the early phases of the mission to the definition, evaluation and calibration modelling of the Gaia photometry. To maximise the Gaia scientific exploitation, we have frequently shared many different tools and data with the astronomical community. Among this information we have defined several relationships among colours involving Gaia magnitudes and colours from other commonly used photometric systems (Johnson-Cousins, SDSS, Hipparcos, Tycho and 2MASS) for several types of stars (including white dwarfs). These relationships can be used for planning scientific exploitation of Gaia data, performing simulations of the Gaia-like sky, planning ground-based complementary observations and for building catalogues with auxiliary validation data. During the commissioning phase our team (as part of the Payload Experts group) has been intensively checking the first photometric data to analyse the health and properties of the real instrument. These preliminary analyses allowed us to monitor the throughput variations with time, assess the spectral resolution and re-evaluate the performances of the end-of-mission photometry. The Payload Experts group activities continue beyond the commissioning phase aiming to optimize the operations onboard for maximizing the scientific return. Some example of first spectra and photometry are shown.

  20. Photoelectric effects in magnesium aluminum spinel

    NASA Astrophysics Data System (ADS)

    Woosley, J. D.; Wood, C.; Sonder, E.; Weeks, R. A.

    1980-07-01

    The electronic and transport properties of magnesium aluminum spinel have been investigated photoelectrically. Photoemission of holes and electrons into spinel from metal contacts (Pt, Au, Ta, Mo, and Cu) has been used to determine barrier heights. From this information, as well as vacuum-uv photoconductivity data, we have obtained the following energy-band parameters: The Fermi level lies ~3 eV below the bottom of the conduction band, which in turn is located ~ 2 eV below the vacuum level, and the band gap is ~ 9 eV. Photoemission was not observed from graphite electrodes which form Ohmic contacts. Electron, neutron, or gamma irradiation produced three photoconductivity bands of half-width ~0.5 eV, with peaks at 4.5, 5.0, and 5.5 eV. The three bands, equally spaced in energy, may be associated with the same center. The optical absorption band of the F center is in the same region of the spectrum; however, its shape did not correspond to the observed photoconductivity spectrum. A lower limit of 10-6 cm2/V has been calculated for the μτ product of the photogenerated charge carriers.

  1. New 1982-1990 photometry of Lambda Andromedae and its 11-year cycle

    NASA Technical Reports Server (NTRS)

    Hall, Douglas S.; Henry, Gregory W.; Boehme, Dietmar; Brooks, Peter A.; Chang, Sandy; Dolzan, Ales; Fortier, George L.; Fried, Robert E.; Genet, Russell M.; Grim, Bruce S.

    1991-01-01

    The paper presents photoelectric photometry of Lambda And never before published, obtained between February 1982 and December 1990 at 29 different observatories. Then it is combined with all other photometry available (previously published, contained in the I.A.U. Commission 27 Archives, and obtained with the Vanderbilt 16-inch automatic telescope but not yet published), to yield a 14.8-year data base. Analysis reveals a long-term cycle in mean brightness, with a full range of 0.15 m and a period of 11.4 +/- 0.4 years. Because most of the new photometry was concentrated in the 1983-1984 observing season, this one well-defined light curve is analyzed with a two-spot model. Spot A keeps a 0.04 m amplitude throughout four rotation cycles whereas the amplitude of spot B diminishes from 0.09 m down almost to 0.03 m. The spot rotation periods were 55.9 d +/- 0.6 d and 52.8 d +/- 1.0 d, respectively.

  2. UBV photometry of ER Vulpeculae

    NASA Astrophysics Data System (ADS)

    Srivastava, R. K.; Padalia, T. D.; Srivastava, J. B.

    1991-08-01

    UBV photometry of the RS CVn-type eclipsing binary system ER Vulpeculae has been presented. The period comes out to be 0.698093d. The average depths of primary and secondary minima are, respectively, 0.21 and 0.12m. The colors at various phases have been given. A dip is seen around phase 0.73P as was seen in the observations of Arevalo et al. (1988). Large scatter is present in the observations as noticed earlier, and may be due to activity of the components.

  3. Photometric calibration of NGS/POSS and ESO/SRC plates using the NOAO PDS measuring engine. I - Stellar photometry

    NASA Technical Reports Server (NTRS)

    Cutri, Roc M.; Low, Frank J.; Marvel, Kevin B.

    1992-01-01

    The PDS/Monet measuring engine at the National Optical Astronomy Observatory was used to obtain photometry of nearly 10,000 stars on the NGS/POSS and 2000 stars on the ESO/SRC Survey glass plates. These measurements have been used to show that global transformation functions exist that allow calibration of stellar photometry from any blue or red plate to equivalent Johnson B and Cousins R photoelectric magnitudes. The four transformation functions appropriate for the POSS O and E and ESO/SRC J and R plates were characterized, and it was found that, within the measurement uncertainties, they vary from plate to plate only by photometric zero-point offsets. A method is described to correct for the zero-point shifts and to obtain calibrated B and R photometry of stellar sources to an average accuracy of 0.3-0.4 mag within the range R between values of 8 and 19.5 for red plates in both surveys, B between values of 9 and 20.5 on POSS blue plates, and B between values of 10 and 20.5 on ESO/SRC blue plates. This calibration procedure makes it possible to obtain rapid photometry of very large numbers of stellar sources.

  4. SU-E-I-43: Photoelectric Cross Section Revisited

    SciTech Connect

    Haga, A; Nakagawa, K; Kotoku, J; Horikawa, Y

    2015-06-15

    Purpose: The importance of the precision in photoelectric cross-section value increases for recent developed technology such as dual energy computed tomography, in which some reconstruction algorithms require the energy dependence of the photo-absorption in each material composition of human being. In this study, we revisited the photoelectric cross-section calculation by self-consistent relativistic Hartree-Fock (HF) atomic model and compared with that widely distributed as “XCOM database” in National Institute of Standards and Technology, which was evaluated with localdensity approximation for electron-exchange (Fock)z potential. Methods: The photoelectric cross section can be calculated with the electron wave functions in initial atomic state (bound electron) and final continuum state (photoelectron). These electron states were constructed based on the selfconsistent HF calculation, where the repulsive Coulomb potential from the electron charge distribution (Hartree term) and the electron exchange potential with full electromagnetic interaction (Fock term) were included for the electron-electron interaction. The photoelectric cross sections were evaluated for He (Z=2), Be (Z=4), C (Z=6), O (Z=8), and Ne (Z=10) in energy range of 10keV to 1MeV. The Result was compared with XCOM database. Results: The difference of the photoelectric cross section between the present calculation and XCOM database was 8% at a maximum (in 10keV for Be). The agreement tends to be better as the atomic number increases. The contribution from each atomic shell has a considerable discrepancy with XCOM database except for K-shell. However, because the photoelectric cross section arising from K-shell is dominant, the net photoelectric cross section was almost insensitive to the different handling in Fock potential. Conclusion: The photoelectric cross-section program has been developed based on the fully self-consistent relativistic HF atomic model. Due to small effect on the Fock

  5. VizieR Online Data Catalog: ubvy Photometry of magnetic CP stars (Adelman+ 1994)

    NASA Astrophysics Data System (ADS)

    Adelman, S. J.; Knox, J. R., Jr.

    1993-10-01

    Differential Stroemgren uvby photometric observations from the Four College Automated Photoelectric Telescope of four magnetic Chemically Peculiar stars are presented. We refined the period of 63 And to 4.1890 days. The period of the sharp-lined Si star HD 192913 is 16.840 days, a value close to, but slightly different from published values. HR 8240, a sharp-lined Si star, is found not to be a photometric variable. Comparison of four color photometry of 108 Aqr by Morrison and Wolff and from the Four College APT indicates that subtle changes in the shapes of the light curves, especially that for u, have occurred suggesting that this star may be precessing. (4 data files).

  6. VizieR Online Data Catalog: uvby photometry of 4 CP stars (Adelman 1999)

    NASA Astrophysics Data System (ADS)

    Adelman, S. J.

    1998-07-01

    Differential Stroemgren uvby photometry obtained with the Four College Automated Photoelectric Telescope shows that the hot HgMn star 33 Gem is photometrically constant. The Si star HD 15980 is found to be a variable whose period is significantly greater than 2 years. The unusual magnetic chemically peculiar Co star HR 1094 is discovered to be a low amplitude photometric variable with the magnetic field period of Hill & Blake (1996MNRAS.278..183H), 2.9761 days. The ephemeris for the magnetic chemically peculiar star HD 115708 of Wade et al. (1996A&A...307..500W) is confirmed with the error in its period of 5.07622 days being greatly reduced. The u, v, b, and y light curves for both HR 1094 and HD 115708 exhibit differences which indicate complex elemental photospheric abundance distributions. (7 data files).

  7. Uvby-beta photometry of visual double stars - Absolute magnitudes of intrinsically bright stars

    NASA Astrophysics Data System (ADS)

    Olsen, E. H.

    1982-05-01

    Individual absolute visual magnitudes M(v) are derived for intrinsically bright stars and evolved stars. The results are collected for 106 objects believed to be members of binary systems. uvby-beta photometry was empirically calibrated in terms of M(v) for main sequence stars and photoelectrically determined apparent magnitudes. The derived M(v) values are not significantly different from those stated in the Wilson catalogue (1976). Binary systems with main sequence primaries and secondary components off the main sequence were also investigated. Several systems in which at least one component may be in the pre-main sequence contraction stage are pointed out. A wide variety of comments and derived data are given individually for 136 double stars, including metallicities, distance moduli, and masses.

  8. Radiative transfer in the surfaces of atmosphereless bodies. III - Interpretation of lunar photometry

    NASA Technical Reports Server (NTRS)

    Lumme, K.; Irvine, W. M.

    1982-01-01

    Narrowband and UBV photoelectric phase curves of the entire lunar disk and surface photometry of some craters have been interpreted using a newly developed generalized radiative transfer theory for planetary regoliths. The data are well fitted by the theory, yielding information on both macroscopic and microscopic lunar properties. Derived values for the integrated disk geometric albedo are considerably higher than quoted previously, because of the present inclusion of an accurately determined opposition effect. The mean surface roughness, defined as the ratio of the height to the radius of a typical irregularity, is found to be 0.9 + or - 0.1, or somewhat less than the mean value of 1.2 obtained for the asteroids. From the phase curves, wavelength-dependent values of the single scattering albedo and the Henyey-Greenstein asymmetry factor for the average surface particle are derived.

  9. Principle Assumption of Space Object Detection Using Shipborne Great Aperture Photoelectrical Theodolite

    NASA Astrophysics Data System (ADS)

    Ouyang, Jia; Zhang, Tong-shuang; Wang, Qian-xue

    2016-02-01

    In this paper the use of space object detection is introduced. By analyzing the research actuality of space object detection using photoelectrical equipment, a shipborne great aperture photoelectrical theodolite is designed. The principle assumption of space object detection using shipborne great aperture photoelectrical theodolite is put forward.

  10. Photometry of late type stars

    NASA Technical Reports Server (NTRS)

    Doherty, L. R.

    1972-01-01

    Broad band filter photometry for 57 bright stars of spectral type A2 discussed with peak instrument responses at 3320, 2980, 2460 and 1910 A. The data include nearly all usable filter observations of G, K and M types. Sampling is nearly complete for A and F giants and supergiants, with the exception of Cepheid variables. The basic results presented are relative digital counting rates obtained with a field-stop aperture of 10 minutes of arc. Characteristics of the four filter-photometer combinations and errors are discussed. Some observations require substantial correction if they are to represent the visually brightest star in the field. These corrections and the effects of interstellar reddening are discussed. The adjusted counts are then used to construct color-color diagrams and are compared to the recent SAO grid of model atmospheres.

  11. The 2060 Chiron: CCD photometry

    NASA Technical Reports Server (NTRS)

    Bus, Schelte J.; Bowell, Edward; Harris, Alan W.

    1987-01-01

    R-band CCD photometry of 2060 was carried out on nine nights in Nov. and Dec. 1986. The rotation period is 5.9181 + or - 0.0003 hr and the peak to peak lightcurve amplitude is 0.088 + or - 0.0003 mag. Photometric parameters are H sub R = 6.24 + or - 0.02 mag and G sub R = + or - 0.15, though formal errors may not be realistic. The lightcurve has two pairs of extrema, but its asymmetry, as evidenced by the presence of significant odd Fourier harmonics, suggests macroscopic surface irregularities and/or the presence of some large scale albedo variegation. The observational rms residual is + or - 0.015 mag. On time scales from minutes to days there is no evidence for nonperiodic (cometary) brightness changes at the level of a few millimagnitudes.

  12. BV photometry of UX ARIETIS

    NASA Astrophysics Data System (ADS)

    Mohin, S.; Raveendran, A. V.

    1989-03-01

    Differential BV photometry of UX Ari obtained on 58 nights during 1984-1985, 1985-1986, 1986-1987, and 1987-1988 observing season is presented. It is found that (B-V) is phase dependent, with the system being reddest at the light maximum. This is interpreted as being due to the variable fractional contribution by the G5 V component to the total light at shorter wavelengths. An analysis of the available data indicates that, at larger amplitudes of the photometric wave, the brightness at maximum increases and that at minimum decreases, and both converge to DeltaV of about 1.0 mag at very low amplitudes. It implies that the low wave amplitudes are essentially due to more homogeneity in the surface distribution of spots rather than to low levels of spot activity. The variation in wave amplitude is found to be near-sinusoidal with a period around 13-14 years.

  13. TT Arietis: Spectroscopy and Photometry

    NASA Astrophysics Data System (ADS)

    Wu, Xiaoan; Li, Zongyun; Ding, Yuerong; Zhang, Zhousheng; Li, Zili

    2002-04-01

    We report the photometry and spectroscopy of TT Arietis around the turn of the millennium, when the nova-like variable is in high state. A positive superhump since 1997 still exists. A more precise orbital period than before, 0.13755040+/-1.7×10-7 days, is established. The intensity of the Balmer emission core is found to modulate at the superhump period rather than the orbital period and 180° out of phase with continuum. The intensity of Balmer absorption wings is approximately proportional to the continuum flux. The correlation between Balmer lines and continuum provides a new clue to the study of sources of continuum and emission lines. The mass ratio of the binary is found to be in the range of 0.19+/-0.04, which lends strong support to the proposition that superhumps arise from the inner Lindblad 3:1 resonance in TT Ari, as in superoutbursts of SU UMa stars.

  14. Testing of a photoelectric photometer. 1: Determination of operational parameters

    NASA Technical Reports Server (NTRS)

    Dawson, D. W.; Tedesco, E. F.

    1976-01-01

    Observations over four months are used to evaluate magnitude and color transformations, extinction coefficients, and a gain table for the photoelectric photometer of the 41 cm. reflector at the Tortugas Mountain site. Ways of increasing the efficiency and accuracy of this system are discussed.

  15. The Skylab ten color photoelectric polarimeter. [sky brightness

    NASA Technical Reports Server (NTRS)

    Weinberg, J. L.; Hahn, R. C.; Sparrow, J. G.

    1975-01-01

    A 10-color photoelectric polarimeter was used during Skylab missions SL-2 and SL-3 to measure sky brightness and polarization associated with zodiacal light, background starlight, and the spacecraft corona. A description is given of the instrument and observing routines together with initial results on the spacecraft corona and polarization of the zodiacal light.

  16. 16 CFR 1211.11 - Requirements for photoelectric sensors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... (864 mm) from the end. The axis point is to be fixed at a point centered directly above the beam of the... photoelectric sensor's beam from a position 45 degrees from the plane of the door when in the closed position...) when subjected to ambient light impinging at an angle of 15 to 20 degrees from the axis of the...

  17. Spectrophotometry and UBVRI photometry of Eros

    NASA Technical Reports Server (NTRS)

    Wisniewski, W. Z.

    1976-01-01

    Spectrophotometric and broad-band photoelectric observations of Eros are reported. No existing meteorite spectrum matches the asteroid data directly. Assemblages of iron or stony-iron with ordinary-chondrite material generate the best match for the reflectivity curve of Eros. Variability was found in the 0.6 micron band and V-R and V-I colors.

  18. The Founders of the XXth Century Stellar Photometry in Russia

    NASA Astrophysics Data System (ADS)

    Pustylnik, I.; Mironov, A.

    Our contribution is dedicated to two ``godfathers'' of astrophotometry in Russia - Vitold Karlovich Ceraski (1849-1925) and Vladimir Borisovich Nikonov (1905-1987). We discuss their scientific legacy and its impact upon the formation of the school of stellar photometry in Russia and the USSR. The graduate of Moscow University in 1871 V. Ceraski started his scientific career in the University astronomical observatory. Already at the dawn of XXth century he was universally regarded as an indisputable authority in Russian astrophotometry. Ceraski introduced essential improvements into the K.-F. Zöllner's visual polarimetric photometer. With its aid he measured in 1903-1905 the stellar magnitude of the Sun with an accuracy close to its modern value (within a 5 % margin) by carefully comparing the brightness of Venus with that of the speck of the solar light reflected from the convex glass surface (during the day) and by comparing the brightness of Venus with that of the brightest stars (in the night). V. Nikonov, the graduate of Leningrad University, in 1925 embarked upon scientific investigations in the local Astronomical Institute. During these years the 13 inch reflector has been installed by Leningrad astronomers at the mountain Kanobili (Abastumani observatory, Georgia). In 1937 Nikonov constructed the first in the USSR photoelectric photometer. Experiments with it indicated that the attainable precision for 4.5m stars amounted to 0.003m. It was obvious for Nikonov that with such a precision one should exercise extreme care in reduction of stellar magnitudes beyond the earth's upper atmosphere. In 1944 he elaborated a method to account for atmospheric extinction which is now universally known as Nikonov's method. Its underlying idea lies in the observations of all non-variable stars available in the program for different air masses.

  19. WFPC2 Stellar Photometry with HSTphot

    NASA Technical Reports Server (NTRS)

    Dolphin, Andrew E.

    2000-01-01

    HSTphot, a photometry package designed to handle the undersampled PSFs found in WFPC2 images, is introduced and described, as well as some of the considerations that have to be made in order to obtain accurate PSF-fitting stellar photometry with WFPC2 data. Tests of HSTphot's internal reliability are made using multiple observations of the same field, and tests of external reliability are made by comparing with DoPHOT reductions of the same data. Subject headz'ngs: techniques: photometric

  20. Classification of stars with WBVR photometry

    NASA Astrophysics Data System (ADS)

    Sichevskiy, S. G.; Mironov, A. V.; Malkov, O. Yu.

    2013-10-01

    We present a method of obtaining the most reliable stellar spectral type based on multi-color photometry. The method also allows us to estimate color excess EB-V and distance to the star. Approbation of the method using bright stars with known spectral classification and W BV R photometry permits to estimate its reliability. Stellar spectra models from Pickles (1998) library and Fluks et al. (1994) interstellar extinction law were used in the application of the method.

  1. Meteor44 Video Meteor Photometry

    NASA Technical Reports Server (NTRS)

    Swift, Wesley R.; Suggs, Robert M.; Cooke, William J.

    2004-01-01

    Meteor44 is a software system developed at MSFC for the calibration and analysis of video meteor data. The dynamic range of the (8bit) video data is extended by approximately 4 magnitudes for both meteors and stellar images using saturation compensation. Camera and lens specific saturation compensation coefficients are derived from artificial variable star laboratory measurements. Saturation compensation significantly increases the number of meteors with measured intensity and improves the estimation of meteoroid mass distribution. Astrometry is automated to determine each image's plate coefficient using appropriate star catalogs. The images are simultaneously intensity calibrated from the contained stars to determine the photon sensitivity and the saturation level referenced above the atmosphere. The camera s spectral response is used to compensate for stellar color index and typical meteor spectra in order to report meteor light curves in traditional visual magnitude units. Recent efforts include improved camera calibration procedures, long focal length 'streak' meteor photometry and two-station track determination. Meteor44 has been used to analyze data from the 2001, 2002 and 2003 MSFC Leonid observational campaigns as well as several lesser showers. The software is interactive and can be demonstrated using data from recent Leonid campaigns.

  2. Eclipse of epsilon Aurigae

    NASA Astrophysics Data System (ADS)

    Templeton, Matthew R.

    2009-07-01

    The bright, long-period, eclipsing binary star epsilon Aurigae is predicted to begin its next eclipse late July or early August of 2009. Epsilon Aurigae is now past solar conjunction and has reappeared as a morning object. All observers -- both visual and instrumental -- are encouraged to contribute observations of the eclipse during the next two years, beginning immediately for morning observers. Observations are urgently requested right now because it is less likely to be observed in the morning, and the eclipse will begin within the next month. The AAVSO is participating in a global campaign to record this eclipse as part of the International Year of Astronomy 2009 celebrations, organized by the Citizen Sky project (http://www.citizensky.org). For experienced visual observers, please observe this star on a weekly basis, using charts available via VSP from the AAVSO website. For novice visual observers, we recommend participating in this observing program by following the Citizen Sky 10-Star tutorial program, which provides a simple training experience in variable star observing. Photoelectric observers belonging to the AAVSO PEP-V program may submit data as usual via the WebObs feature of the AAVSO website Blue&Gold section. Photoelectric observers may also contribute reduced observations in all filters (including infrared J- and H-bands) directly to the AAVSO via WebObs. Observers using wide-field CCD and DSLR systems are also encouraged to participate; avoid saturating the star. For those with narrower-field systems (D < 2 degrees), we recommend taking a large number (10-100) of very short exposures and then stacking the resulting images. Observations should be submitted to the AAVSO International Database. Aaron Price is coordinating Citizen Sky for the AAVSO, and Dr. Robert Stencel and Jeffrey Hopkins are co-leading the precision photometry efforts.

  3. Development and validation of the photoelectric effect concept inventory

    NASA Astrophysics Data System (ADS)

    Önder, Fatih

    2016-09-01

    This study aims to develop a multiple-choice instrument for determining students’ concepts about the photoelectric effect. To develop the instrument, 30 students taking the Modern Physics course were interviewed to determine their misconceptions about the photoelectric effect. These misconceptions were compared with the misconceptions set out in the literature so that a decision could be made to define the questions and distractors to be used in the instrument. The content validity of the inventory was achieved on the basis of the feedback received from ten experts. The inventory was administered to 295 students enrolled in the Physics Teaching and Science Teaching Departments and discrimination index, difficulty index, and point biserial coefficient values were determined for each item. Cronbach’s alpha coefficient was calculated for the whole of the test. The results of the analysis reveal that the inventory is both valid and reliable.

  4. A photoelectric photometer for the observation of occultation

    NASA Astrophysics Data System (ADS)

    Wang, C.-J.; Shi, X.-Z.

    1980-03-01

    The paper describes a simple photoelectric photometer for the observation of occultation. Also discussed are some design problems, including the relation between measurable magnitude, signal-noise ratio and integrating time, the effect due to brightness of background, and the requirement of frequency bandwidth of the photometer. As a test, the instrument was used to observe the occulted event of star AGK+19 deg 0599 by asteroid (65) Cybele on Oct. 18, 1979 and a successful result was obtained.

  5. A portable millisecond-integration-time photoelectric photometer.

    NASA Technical Reports Server (NTRS)

    Mcgraw, J. T.; Wells, D. C.; Wiant, J. R.

    1973-01-01

    Portable equipment for recording millisecond-integration-time photoelectric photometric data is described. Digital data are reliably recorded on standard 6.35 mm audio grade magnetic tape via a quadradial audio grade tape deck. The system is designed specifically for recording lunar occulations of stars, but the data recording technique is independent of the data source. Recovery of the data is made via minicomputer.

  6. Study on evaluation of photoelectric jamming effectiveness on ranging lidar

    NASA Astrophysics Data System (ADS)

    Che, Jinxi; Yang, Haiqiang; Gao, Bo

    2015-11-01

    Lidar (Light Detection and Range) is a brand-new field and research hotspot. Ranging lidar is studied in this paper. Specifically, its basic working principle and photoelectric jamming mechanism are introduced. Then, the ranging error jamming success rate rule is developed for laser distance deception jamming. And the effectiveness evaluation of laser blinding jamming is based on the influence level on ranging accuracy and ranging function. The results have some reference value to evaluation of jamming test effectiveness.

  7. A design of camera simulator for photoelectric image acquisition system

    NASA Astrophysics Data System (ADS)

    Cai, Guanghui; Liu, Wen; Zhang, Xin

    2015-02-01

    In the process of developing the photoelectric image acquisition equipment, it needs to verify the function and performance. In order to make the photoelectric device recall the image data formerly in the process of debugging and testing, a design scheme of the camera simulator is presented. In this system, with FPGA as the control core, the image data is saved in NAND flash trough USB2.0 bus. Due to the access rate of the NAND, flash is too slow to meet the requirement of the sytsem, to fix the problem, the pipeline technique and the High-Band-Buses technique are applied in the design to improve the storage rate. It reads image data out from flash in the control logic of FPGA and output separately from three different interface of Camera Link, LVDS and PAL, which can provide image data for photoelectric image acquisition equipment's debugging and algorithm validation. However, because the standard of PAL image resolution is 720*576, the resolution is different between PAL image and input image, so the image can be output after the resolution conversion. The experimental results demonstrate that the camera simulator outputs three format image sequence correctly, which can be captured and displayed by frame gather. And the three-format image data can meet test requirements of the most equipment, shorten debugging time and improve the test efficiency.

  8. Detection of Terrestrial Planets Using Transit Photometry

    NASA Technical Reports Server (NTRS)

    Koch, David; Witteborn, Fred; Jenkins, Jon; Dunham, Edward; Boruci, William; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    Transit photometry detection of planets offers many advantages: an ability to detect terrestrial size planets, direct determination of the planet's size, applicability to all main-sequence stars, and a differential brightness change of the periodic signature being independent of stellar distance or planetary orbital semi-major axis. Ground and space based photometry have already been successful in detecting transits of the giant planet HD209458b. However, photometry 100 times better is required to detect terrestrial planets. We present results of laboratory measurements of an end-to-end photometric system incorporating all of the important confounding noise features of both the sky and a space based photometer including spacecraft jitter. In addition to demonstrating an instrumental noise of less than 10 ppm (an Earth transit of a solar-like star is 80 ppm), the brightnesses of individual stars were dimmed to simulate Earth-size transit signals. These 'transits' were reliably detected as part of the tests.

  9. An Improved Method for Differential Photometry

    NASA Astrophysics Data System (ADS)

    Fernández Fernández, Javier; Chou, Dean-Yi; Pan, Yen-Chen; Wang, Li-Hang

    2012-05-01

    We developed a method to improve the conventional differential photometry by using many auxiliary stars to reduce noise in the reference light curve, which is used to calibrate the light curve of the target star. The data used in this study are taken with the Taiwan Automated Telescope network. The light curves of two δ Scuti, HD 163032 and V830 Her, are shown here as examples. The results are compared with four other methods: conventional differential photometry; ensemble photometry; the method of Tamuz, Mazeh, & Zucker; and trend filtering algorithm. The light curve computed with our method is smoother than the other four methods, while preserving the pulsational signals. The mode frequencies determined from the light curve from our method also has a higher S/N and lower error in comparison with other methods.

  10. Hertz and the Discovery of Radio Waves and the Photoelectric Effect.

    ERIC Educational Resources Information Center

    Spradley, Joseph L.

    1988-01-01

    Describes the discoveries by Hertz historically, such as photoelectric effect, radio waves, their impact on modern physics and some applications. Presents several diagrams and two chronological tables. (YP)

  11. Photometry of the old nova HZ Pup

    NASA Astrophysics Data System (ADS)

    Cassanelli, Tomas; Abbott, Tim

    2016-01-01

    This study of the old nova HZ Pup involved obtaining image data, removing the instrumental signature, performing photometry on the stellar images present, and generating light curves. Relative photometry between the target star and other stars in the image was used to remove atmospheric effects. A periodogram of this light curve shows the historically known periodicity close to 20 minutes. However, other periodicities are also present and it is not clear from the data which are real and which are artifacts of the sampling. These data will be combined with data from other telescopes collected contemporaneously in order to resolve this ambiguity.

  12. TRIPPy: Python-based Trailed Source Photometry

    NASA Astrophysics Data System (ADS)

    Fraser, Wesley C.; Alexandersen, Mike; Schwamb, Megan E.; Marsset, Michael E.; Pike, Rosemary E.; Kavelaars, JJ; Bannister, Michele T.; Benecchi, Susan; Delsanti, Audrey

    2016-05-01

    TRIPPy (TRailed Image Photometry in Python) uses a pill-shaped aperture, a rectangle described by three parameters (trail length, angle, and radius) to improve photometry of moving sources over that done with circular apertures. It can generate accurate model and trailed point-spread functions from stationary background sources in sidereally tracked images. Appropriate aperture correction provides accurate, unbiased flux measurement. TRIPPy requires numpy, scipy, matplotlib, Astropy (ascl:1304.002), and stsci.numdisplay; emcee (ascl:1303.002) and SExtractor (ascl:1010.064) are optional.

  13. Bioinspired smart gating of nanochannels toward photoelectric-conversion systems.

    PubMed

    Wen, Liping; Hou, Xu; Tian, Ye; Nie, Fu-Qiang; Song, Yanlin; Zhai, Jin; Jiang, Lei

    2010-03-01

    Learning from nature has inspired the creation of intelligent materials to better understand and imitate biology. Recent studies on bioinspired responsive surfaces that can switch between different states are shown, which open up new avenues for the development of smart materials in two dimensions. Based on this strategy, biomimetic nanochannel systems have been produced by introducing responsive molecules, which closely mimic the gating mechanism of biological nanochannels and show potential applications in many fields such as photoelectric-conversion systems demonstrated in this paper. PMID:20217833

  14. Photoelectrical properties of TiO2-Si structures

    NASA Astrophysics Data System (ADS)

    Petrova, Yu S.; Zarubin, A. N.; Kalygina, V. M.; Zupiy, S. Yu

    2014-10-01

    The effect of thermal annealing at 500 and 750°C as well as treatment in oxygen plasma on electrical and photoelectrical characteristics of TiO2-Si structures were investigated. TiO2 films were deposited on n-Si substrates by magnetron sputtering. It was found that in the structures annealed at 500°C and treated in oxygen plasma a substantial part of the enhanced photocurrent was observed over a long time after removing of illumination with λ = 400 nm.

  15. Corrections to fundamental constants from photoelectric observations of lunar occultations

    NASA Astrophysics Data System (ADS)

    Rossello, G.

    1982-12-01

    A catalog of photoelectric occultations, which are more accurate than visual observations, is presented along with an analysis of the occultations intended to correct the FK4 stellar reference frame and lunar theory constants. A constant correction at the epoch 1969.0 of plus 0.87 plus or minus 0.06 to the FK4 system is consistent with those obtained by other authors, and the corrections to the semidiameter and parallactic inequality are in accord with values recently obtained by Morrison and Appleby (1981).

  16. A photoelectric study of three southern Delta Scuti stars

    NASA Astrophysics Data System (ADS)

    Morris, S.; DuPuy, D. L.

    1980-06-01

    Differential photoelectric observations of three Delta Scuti stars AI Scl, WZ Scl, and XX Scl were obtained on ten nights during October 1978. Al Scl did not exhibit strictly periodic behavior, but showed a tendency to pulsate at 134 minutes. WZ Scl and XX Scl were both found to be multiperiodic, with period ratios of 0.6853 and 0.9522, respectively. As the period for radial fundamental and first overtone pulsation is 0.76, the observed period ratios are interpreted as caused by nonradial pulsation. A slightly modified Jurkevich period search method, used to obtain these results, is described.

  17. A method of studying the photoelectric properties of liquid semiconductors

    SciTech Connect

    Aivazov, A.A.; Budagyan, B.G.; Giorgadze, A.L.

    1985-09-01

    The authors propose a way of measuring the optical and photoelectric properties of liquid semiconductors. They have developed a high temperature apparatus with cuvettes that allow sufficient material to be loaded for heat treating the melt over the whole range of measurement temperatures. After fusion and heat treatment for 30 min, the melt is fed into the working chamber by the pressure exerted by the inert gas. The optical and photoeletric parameters are measured from the melt. This method has been used to measure the steady-state longitudinal photoconductivity of liquid selenium.

  18. Photoelectric and electric properties of four-component copper chalcogenides

    SciTech Connect

    Saipulaeva, L. A. Gabibov, F. S.; Mel'nikova, N. V.; Alibekov, A. G.; Kheifets, O. L.; Babushkin, A. N.; Kurochka, K. V.

    2012-11-15

    The results of investigation of the electrophysical and photoelectric properties of complex copper chalcogenides are presented, namely, the properties of CuSnAsSe{sub 3}, which exhibits ferroelectric properties, and CuInAsS{sub 3}, which exhibits ionic conductivity. The spectral and temperature regions of photosensitivity of these crystals are determined. The depth of the level of carrier trapping centers, which manifest themselves under thermal activation, are evaluated from the analysis of thermally stimulated conductivity (TSC) curves in CuInAsS{sub 3}.

  19. Photoelectric radar servo control system based on ARM+FPGA

    NASA Astrophysics Data System (ADS)

    Wu, Kaixuan; Zhang, Yue; Li, Yeqiu; Dai, Qin; Yao, Jun

    2016-01-01

    In order to get smaller, faster, and more responsive requirements of the photoelectric radar servo control system. We propose a set of core ARM + FPGA architecture servo controller. Parallel processing capability of FPGA to be used for the encoder feedback data, PWM carrier modulation, A, B code decoding processing and so on; Utilizing the advantage of imaging design in ARM Embedded systems achieves high-speed implementation of the PID algorithm. After the actual experiment, the closed-loop speed of response of the system cycles up to 2000 times/s, in the case of excellent precision turntable shaft, using a PID algorithm to achieve the servo position control with the accuracy of + -1 encoder input code. Firstly, This article carry on in-depth study of the embedded servo control system hardware to determine the ARM and FPGA chip as the main chip with systems based on a pre-measured target required to achieve performance requirements, this article based on ARM chip used Samsung S3C2440 chip of ARM7 architecture , the FPGA chip is chosen xilinx's XC3S400 . ARM and FPGA communicate by using SPI bus, the advantage of using SPI bus is saving a lot of pins for easy system upgrades required thereafter. The system gets the speed datas through the photoelectric-encoder that transports the datas to the FPGA, Then the system transmits the datas through the FPGA to ARM, transforms speed datas into the corresponding position and velocity data in a timely manner, prepares the corresponding PWM wave to control motor rotation by making comparison between the position data and the velocity data setted in advance . According to the system requirements to draw the schematics of the photoelectric radar servo control system and PCB board to produce specially. Secondly, using PID algorithm to control the servo system, the datas of speed obtained from photoelectric-encoder is calculated position data and speed data via high-speed digital PID algorithm and coordinate models. Finally, a

  20. ATel 7543: NIR photometry of SNhunt 275

    NASA Astrophysics Data System (ADS)

    Richardson, Noel; Artigau, Etienne

    2015-05-01

    SNhunt 275 (PSN J09093496+3307204) appears to be behaving similarly to SN 2009ip with an eruptive mass-loss event followed by a supernova explosion. We obtained a few epochs of NIR photometry using the Observatoire du Mont Megantic 1.6 m telescope and the CPAPIR instrument (Artigau et al. ...

  1. Photometry of Faint Wide Doubles in Hydra

    NASA Astrophysics Data System (ADS)

    Knapp, Wilfried; Thuemen, Chris; Gould, Ross

    2015-11-01

    Images of several double stars in Hydra published on the "Double Star Imaging Project" Yahoo Group page suggest magnitude issues compared with the corresponding WDS catalog data per end of 2014. Taking additional images with V and B filters enabled photometry for these pairs, suggesting significant corrections to the old data in WDS.

  2. Walraven photometry of nearby southern OB associations

    NASA Technical Reports Server (NTRS)

    De Geus, E. J.; Lub, J.; Van De Grift, E.

    1990-01-01

    Homogeneous Walraven (VBLUW) photometry is presented for 5260 stars in the regions of five nearby southern OB associations: Scorpio Centaurus (Sco OB2), Orion OB1, Canis Major OB1, Monoceros OB1, and Scutum OB2. Derived V and (B - V) in the Johnson system are included.

  3. TRIPP: Time Resolved Imaging Photometry Package

    NASA Astrophysics Data System (ADS)

    Geckeler, Ralf D.; Schuh, Sonja; Dreizler, Stefan; Deetjen, Jochen; Gleissner, Thomas; Risse, Patrick; Rauch, Thomas; Göhler, Eckart; Hügelmeyer, Simon; Husser, Tim-Oliver; Israel, Holger; Benlloch-Garcia, Sara; Pottschmidt, Katja; Wilms, Jörn

    2014-05-01

    Written in IDL, TRIPP performs CCD time series reduction and analysis. It provides an on-line check of the incoming frames, performs relative aperture photometry and provides a set of time series tools, such as calculation of periodograms including false alarm probability determination, epoc folding, sinus fitting, and light curve simulations.

  4. Precision Multiband Photometry with a DSLR Camera

    NASA Astrophysics Data System (ADS)

    Zhang, M.; Bakos, G. Á.; Penev, K.; Csubry, Z.; Hartman, J. D.; Bhatti, W.; de Val-Borro, M.

    2016-03-01

    Ground-based exoplanet surveys such as SuperWASP, HAT Network of Telescopes (HATNet), and KELT have discovered close to two hundred transiting extrasolar planets in the past several years. The strategy of these surveys is to look at a large field of view and measure the brightnesses of its bright stars to around half a percent per point precision, which is adequate for detecting hot Jupiters. Typically, these surveys use CCD detectors to achieve high precision photometry. These CCDS, however, are expensive relative to other consumer-grade optical imaging devices, such as digital single-lens reflex cameras (DSLRs). We look at the possibility of using a DSLR camera for precision photometry. Specifically, we used a Canon EOS 60D camera that records light in three colors simultaneously. The DSLR was integrated into the HATNet survey and collected observations for a month, after which photometry was extracted for 6600 stars in a selected stellar field. We found that the DSLR achieves a best-case median absolute deviation of 4.6 mmag per 180 s exposure when the DSLR color channels are combined, and 1000 stars are measured to better than 10 mmag (1%). Also, we achieve 10 mmag or better photometry in the individual colors. This is good enough to detect transiting hot Jupiters. We performed a candidate search on all stars and found four candidates, one of which is KELT-3b, the only known transiting hot Jupiter in our selected field. We conclude that the Canon 60D is a cheap, lightweight device capable of useful photometry in multiple colors.

  5. Portrayal of the History of the Photoelectric Effect in Laboratory Instructions

    ERIC Educational Resources Information Center

    Klassen, Stephen; Niaz, Mansoor; Metz, Don; McMillan, Barbara; Dietrich, Sarah

    2012-01-01

    The literature on the pedagogical aspects of the photoelectric effect as used in the undergraduate student laboratory shows that little research has been done in this area. Our current study is an analysis of the instructions in 38, electronically published laboratory manuals for the photoelectric effect. The analyses were based on history and…

  6. Measurement of image plane illumination uniformity of photoelectric imaging system

    NASA Astrophysics Data System (ADS)

    Kang, Deng-kui; Yang, Hong; Sha, Ding-guo; Jiang, Chang-lu; Chen, Min; Zhong, Xing-hui; Ma, Shi-bang; Yuan, Liang

    2014-09-01

    The image plane illumination nonuniformity caused by optical system or detector will affect the detection precision of photoelectric imaging system, especially in image guidance, positioning and recognition. An image plane illumination uniformity measurement device was set up, which was characteristiced of high uniformity and wide dynamic range. The device was composed of an asymmetric integrating sphere,the image collection and processing system, as well as the electrical control system.The asymmetric integrating sphere had two different radius,which was respectively 800mm and 1000mm.The spectral region was (0.4~1.1)μm, the illumination range was (1×10-4~2×104)lx. The image collection and processing system had two different acquisition card,which were respectively used for analog and digital signals. The software can process for dynamic image or static image. The TracePro software was used to make a internal ray tracing of integrating sphere, the illumination uniformity at the export was simulated for the size of 330mm×230mm and Φ 100mm export, the results were respectively 97.95% and 98.33%. Then,an illuminometer was used to measure the actual illumination uniformity of integrating sphere, the result was shown the actual illumination uniformity was 98.8%. Finally, a visible photoelectric imaging system was tested ,and three different uniformity indicators results were given.

  7. Photoelectric performance degradation of several laser-irradiated Si detectors

    NASA Astrophysics Data System (ADS)

    Moeglin, Jean-Pierre; Gautier, Bernard; Joeckle, Rene C.; Bolmont, Dominique

    1998-04-01

    The modifications of the basic photoelectric properties in visible Si photodiodes irradiated by laser pulses have been measured and an attempt to link them to the observed/computed dopant distribution has been performed. These detectors have been irradiated 'in band' with two types of lasers: 1) a Q-switched Nd:YAG laser, frequency doubled with a 'short' pulse duration of 4 ns and 2) dye laser R6G with a 'long' pulse of 2 microsecond(s) . The single pulse fluence range extended form 0.4 to 50 J/cm2 well above the surface melting fluence threshold. Specially manufactured detectors have been tested. These detectors have a linearly graded junction with different resistivities. The detector responsivity decrease (DRD) vs applied irradiation fluence has been measured for both irradiation types. SIMS has been used to measure the changes in the dopant profile. It has been shown that a large spreading with a 'plateau like shape' of the boron distribution is obtained, resulting from a gas phase diffusion of dopant during the vaporization/condensation cycle. A relationship between DRD and boron profile has been established for Si detectors irradiated by the dye laser. A local sensitivity drop of 70 percent inside the damaged area location has been measured. Furthermore, it has been shown that high irradiation fluences induce a sequential loss of the different photoelectric properties rather than a complete detector breakdown at a prescribed fluence threshold.

  8. Anomalous photoelectric effect of a polycrystalline topological insulator film.

    PubMed

    Zhang, Hongbin; Yao, Jiandong; Shao, Jianmei; Li, Hai; Li, Shuwei; Bao, Dinghua; Wang, Chengxin; Yang, Guowei

    2014-01-01

    A topological insulator represents a new state of quantum matter that possesses an insulating bulk band gap as well as a spin-momentum-locked Dirac cone on the surface that is protected by time-reversal symmetry. Photon-dressed surface states and light-induced surface photocurrents have been observed in topological insulators. Here, we report experimental observations of an anomalous photoelectric effect in thin films of Bi2Te3, a polycrystalline topological insulator. Under illumination with non-polarised light, transport measurements reveal that the resistance of the topological surface states suddenly increases when the polycrystalline film is illuminated. The resistance variation is positively dependent on the light intensity but has no relation to the applied electric field; this finding can be attributed to the gap opening of the surface Dirac cone. This observation of an anomalous photoelectric effect in polycrystalline topological insulators offers exciting opportunities for the creation of photodetectors with an unusually broad spectral range. Moreover, polycrystalline topological insulator films provide an attractive material platform for exploring the nature and practical application of topological insulators. PMID:25069391

  9. Design of a CAN bus interface for photoelectric encoder in the spaceflight camera

    NASA Astrophysics Data System (ADS)

    Sun, Ying; Wan, Qiu-hua; She, Rong-hong; Zhao, Chang-hai; Jiang, Yong

    2009-05-01

    In order to make photoelectric encoder usable in a spaceflight camera which adopts CAN bus as the communication method, CAN bus interface of the photoelectric encoder is designed in this paper. CAN bus interface hardware circuit of photoelectric encoder consists of CAN bus controller SJA 1000, CAN bus transceiver TJA1050 and singlechip. CAN bus interface controlling software program is completed in C language. A ten-meter shield twisted pair line is used as the transmission medium in the spaceflight camera, and speed rate is 600kbps.The experiments show that: the photoelectric encoder with CAN bus interface which has the advantages of more reliability, real-time, transfer rate and transfer distance overcomes communication line's shortcomings of classical photoelectric encoder system. The system works well in automatic measuring and controlling system.

  10. Photoelectric conversion and electrochromic properties of lutetium tetrakis(tert-butyl)bisphthalocyaninate

    SciTech Connect

    Hu, Andrew Teh; Hu Tenyi; Liu Lungchang

    2003-12-10

    Both photoelectric and electrochromic effects on lutetium tetrakis(tert-butyl)bisphthalocyaninate (Lu(TBPc){sub 2}) have been carried out in this study. Lu(TBPc){sub 2} is known for its electrochromic performance, but its photoelectric effect has not mentioned in the literature. The electrochromic properties of Lu(TBPc){sub 2} have been measured by cyclic voltammetry (CV) and UV-Vis spectrometer at the same time. It takes less than 1.5 s for the color to change from red to green under 0.9 V. Its cycle life is at least over 500 times. Furthermore, we also investigate its photoelectric conversion properties. Its photoelectric cell exhibits a positive photo-electricity conversion effect with a short-circuit photocurrent (46.4 {mu}A/cm{sup 2}) under illumination of white light (1.201 mW/cm{sup 2})

  11. Infrared Photometry for Automated Telescopes: Passband Selection

    NASA Astrophysics Data System (ADS)

    Milone, Gene; Young, Andrew T.

    2011-03-01

    The high precision that photometry in the near and intermediate infrared region can provide has not been achieved, partly because of technical challenges (including cryogenics, which most IR detectors require), and partly because the filters in common use are not optimized to avoid water-vapor absorptions, which are the principal impediment to precise ground-based IR photometry. We review the IRWG filters that achieve this goal, and the trials that were undertaken to demonstrate their superiority. We focus especially on the near IR set and, for high elevation sites, the passbands in the N window. We also discuss the price to be paid for the improved precision, in the form of lower throughput, and why it should be paid: to achieve not only higher precision (i.e., improved signal-to-noise ratio), but also lower extinction, thus producing higher accuracy in extra-atmospheric magnitudes. The edges of the IRWG passbands are not defined by the edges of the atmospheric windows: therefore, they admit no flux from these (constantly varying) edges. The throughput cost and the lack of a large body of data already obtained in these passbands are principal reasons why the IRWG filters are not in wide use at observatories around the world that currently do IR work. Yet a measure of the signal-to-noise ratio varies inversely with both extinction and with a measure of the Forbes effect. So, the small loss of raw throughput is recouped in signal-to-noise gain. We illustrate these points with passbands of both near and intermediate IR passbands. There is also the matter of cost for small production runs of these filters; reduced costs can be realized through bulk orders with uniform filter specifications. As a consequence, the near-IR IRWG passbands offer the prospect of being able to do photometry in those passbands at both high and low elevation sites that are capable of supporting precise photometry, thereby freeing infrared photometry from the need to access exclusively high and

  12. BVRI main-sequence photometry of the globular cluster M4

    SciTech Connect

    Alcaino, G.; Liller, W.

    1984-09-01

    We present BV and RI photographic photometry of 1421 and 189 stars, respectively, in the intermediate metallicity globular cluster M4 (NGC 6121). This investigation includes the first results of RI main-sequence photometry of a globular cluster. The use of longer wavelengths and longer color baselines provides the potential of improved isochrone fittings and underscores the urgent need for calculations of RI synthetic isochrones to be compared with observations. The Pickering-Racine wedge was used with the ESO 3.6 m telescope, the Las Campanas 2.5 m du Pont telescope, and the CTIO 1 m Yale telescope to extend the photoelectric limit from Vroughly-equal16.1 to Vroughly-equal19.1. We have determined the position of the main-sequence turnoff to lie at V = 16.6 +- 0.2 (m.e.) and B-V = 0.80 +- 0.03 (m.e.). A comparison of our BV observations with the CCD data of Richer and Fahlman shows excellent agreement: the two fifucial main sequences agree at all points to within 0.025 mag and, on average, to 0.013 mag. For the cluster we derive a distance modulus (m-M)/sub V/ = 12.52 +- 0.2 and reddening E(B-V) = 0.44 +- 0.03, results which confirm that at a distance of 2 kpc, M4 is the closest globular clusters to the Sun. Using the isochrones of VandenBerg, we deduce an age 13 +- 2 Gyr. As noted in several other investigations, there is a striking deficiency of stars in certain parts of the color-magnitude diagram; in M4 we find a pronounced gap over approx.0.6 mag at the base of the subgiant branch.

  13. UBV photometry of hot white dwarf stars

    NASA Astrophysics Data System (ADS)

    Cheselka, Mathew; Holberg, J. B.; Watkins, Ron; Collins, James; Tweedy, R. W.

    1993-12-01

    Johnson UBV photometry has been obtained for a set of hot degenerate stars, primarily DA and DO white dwarfs from among those detected in the Palomar-Green survey of UV excess objects. Most of our program stars have estimated effective temperatures (Teff) in the range 22,000 to 80,000 K and have no previous photometry. Some objects selected are also x-ray and extreme ultraviolet sources from the ROSAT all sky survey. The importance of precise photometric measurements in the analysis of x-ray data is discussed. A discrepancy between the observed colors and predicted colors is noted, and possibly accounted for by difficulties in defining the atmospheric cutoff of the U band and a general lack of hot stars used to define the photometric transformation between theoretical and observed colors.

  14. WISE Photometry for 400 Million SDSS Sources

    NASA Astrophysics Data System (ADS)

    Lang, Dustin; Hogg, David W.; Schlegel, David J.

    2016-02-01

    We present photometry of images from the Wide-Field Infrared Survey Explorer (WISE) of over 400 million sources detected by the Sloan Digital Sky Survey (SDSS). We use a “forced photometry” technique, using measured SDSS source positions, star-galaxy classification, and galaxy profiles to define the sources whose fluxes are to be measured in the WISE images. We perform photometry with The Tractor image modeling code, working on our “unWISE” coaddds and taking account of the WISE point-spread function and a noise model. The result is a measurement of the flux of each SDSS source in each WISE band. Many sources have little flux in the WISE bands, so often the measurements we report are consistent with zero given our uncertainties. However, for many sources we get 3σ or 4σ measurements; these sources would not be reported by the “official” WISE pipeline and will not appear in the WISE catalog, yet they can be highly informative for some scientific questions. In addition, these small-signal measurements can be used in stacking analyses at the catalog level. The forced photometry approach has the advantage that we measure a consistent set of sources between SDSS and WISE, taking advantage of the resolution and depth of the SDSS images to interpret the WISE images; objects that are resolved in SDSS but blended together in WISE still have accurate measurements in our photometry. Our results, and the code used to produce them, are publicly available at http://unwise.me.

  15. Narrow band photometry of selected asteroids

    NASA Technical Reports Server (NTRS)

    Rajamohan, R.; Bhargavi, S. G.

    1992-01-01

    The CCD photometry of selected asteroids was carried out to check for possible cometary activity in them. To distinguish the asteroids with possible cometary activity from those of the main belt, each object of interest was observed in two filters; one centered on the C2 emission band at 5140A (90A bandpass) and the other centered on the nearby continuum at 4845A (65A bandpass). None of the observed asteroids appear to have any C2 emission.

  16. Lightcurve Photometry Opportunities: 2016 July-September

    NASA Astrophysics Data System (ADS)

    Warner, Brian D.; Harris, Alan W.; Durech, Josef; Benner, Lance A. M.

    2016-07-01

    We present lists of asteroid photometry opportunities for objects reaching a favorable apparition and having either none or poorly-defined lightcurve parameters. Additional data on these objects will help with shape and spin axis modeling via lightcurve inversion. We also include lists of objects that will be the target of radar observations. Lightcurves for these objects can help constrain pole solutions and/or remove rotation period ambiguities that might not come from using radar data alone.

  17. Lightcurve Photometry Opportunities: 2016 April-June

    NASA Astrophysics Data System (ADS)

    Warner, Brian D.; Harris, Alan W.; Durech, Josef; Benner, Lance A. M.

    2016-04-01

    We present lists of asteroid photometry opportunities for objects reaching a favorable apparition and having either none or poorly-defined lightcurve parameters. Additional data on these objects will help with shape and spin axis modeling via lightcurve inversion. We also include lists of objects that will be the target of radar observations. Lightcurves for these objects can help constrain pole solutions and/or remove rotation period ambiguities that might not come from using radar data alone.

  18. Research and design of portable photoelectric rotary table data-acquisition and analysis system

    NASA Astrophysics Data System (ADS)

    Yang, Dawei; Yang, Xiufang; Han, Junfeng; Yan, Xiaoxu

    2015-02-01

    Photoelectric rotary table as the main test tracking measurement platform, widely use in shooting range and aerospace fields. In the range of photoelectric tracking measurement system, in order to meet the photoelectric testing instruments and equipment of laboratory and field application demand, research and design the portable photoelectric rotary table data acquisition and analysis system, and introduces the FPGA device based on Xilinx company Virtex-4 series and its peripheral module of the system hardware design, and the software design of host computer in VC++ 6.0 programming platform and MFC package based on class libraries. The data acquisition and analysis system for data acquisition, display and storage, commission control, analysis, laboratory wave playback, transmission and fault diagnosis, and other functions into an organic whole, has the advantages of small volume, can be embedded, high speed, portable, simple operation, etc. By photoelectric tracking turntable as experimental object, carries on the system software and hardware alignment, the experimental results show that the system can realize the data acquisition, analysis and processing of photoelectric tracking equipment and control of turntable debugging good, and measurement results are accurate, reliable and good maintainability and extensibility. The research design for advancing the photoelectric tracking measurement equipment debugging for diagnosis and condition monitoring and fault analysis as well as the standardization and normalization of the interface and improve the maintainability of equipment is of great significance, and has certain innovative and practical value.

  19. Lunar dust transport by photoelectric charging at sunset

    NASA Technical Reports Server (NTRS)

    Pelizzari, M. A.; Criswell, D. R.

    1978-01-01

    The motion of dust grains from a photoelectrically charged object at the moon's sunset terminator is studied with the aid of a simple model. It is shown that sunlit objects ranging in size from less than 0.01 cm to 5 cm in radius are responsible for the levitation of dust grains to heights of observed horizon glow. The transverse displacement of these grains is observed to be at least twice their maximum altitude, so that fitting the latter to horizon glow implies horizontal particle ranges typically 6 to 60 cm. Detachment of these grains from the sunlit areas takes place mainly along the contracting sunlight boundaries as the areas shrink during sunset. A high ratio of intergrain adhesion force to dust-grain weight is essential for the occurrence of horizon glow and significant dust transport from the subcentimeter sized sunlit areas.

  20. Curved-channel microchannel array plates. [photoelectric detectors

    NASA Technical Reports Server (NTRS)

    Timothy, J. G.

    1981-01-01

    The microchannel array plate (MCP) is a photoelectric detector with an imaging capability comparable to that of a photographic plate. Recently MCPs in which the channels are curved to inhibit ion feedback have become available. These devices represent a major advance in MCP technology, since a single curved-channel MCP can be operated stably at high gain in the pulse-counting mode without any of the problems of stability of response or short lifetime reported for 'chevron' MCP detectors. Attention is given to the mode of operation of channel electron multipliers (CEM) and MCP, curved-channel MCP, test procedures, and performance characteristics. The accumulated test data show that the fundamental operating characteristics of the curved-channel MCP are directly related to those for the CEM.

  1. Photo-induced anisotropic photoelectric response in oriented bacteriorhodopsin films

    NASA Astrophysics Data System (ADS)

    Xu, J.; Bhattacharya, P.; Váró, G.

    2003-06-01

    The photo-induced anisotropic properties of the chromophore protein bacteriorhodopsin (bR) are of interest for possible applications in optical image processing and spatial filtering. Here we report experimental results on the photo-induced anisotropic photoelectric response of dried oriented bR films. A polarization dependent photovoltage is measured across an ITO/bR/ITO photodetector. The anisotropy is introduced by a 632.8 nm linearly polarized pump beam and is detected with a 594.1 nm polarized probe beam. The influence of the pump light intensity on the photovoltage anisotropy has also been investigated. A model, based on the polarization dependent photoselection of the bR molecules reasonably explains the behavior of the measured data. The observed effect can be used to construct a polarization sensitive bR-based bio-photoreceiver.

  2. Optimization design and error analysis of photoelectric autocollimator

    NASA Astrophysics Data System (ADS)

    Gao, Lei; Yan, Bixi; Hu, Mingjun; Dong, Mingli

    2012-11-01

    A photoelectric autocollimator employing an area Charge Coupled Device (CCD) as its target receiver, which is specially used in numerical stage calibration is optimized, and the various error factors are analyzed. By using the ZEMAX software, the image qualities are optimized to ensure the spherical and coma aberrations of the collimating system are less than 0.27mm and 0.035mm respectively; the Root Mean Square (RMS) radius is close to 6.45 microns, which is identified with the resolution of the CCD, and the Modulation Transfer Function (MTF) is greater than 0.3 in the full field of view, 0.5 in the centre field at the corresponding frequency. The errors origin mainly from fabrication and alignment, which are all about 0.4" . The error synthesis shows that the instrument can meet the demands of the design accuracy, which is also consistent with the experiment.

  3. Photoelectric properties in metal ion modified DNA nanostructure.

    PubMed

    Kulkarni, Atul; Dugasani, Sreekantha Reddy; Jang Ah Kim; Kim; Sung Ha Park; Taesung Kim

    2015-08-01

    Due to specific or as designed self-assembly, DNA nanostructures gaining popularity in various nanoscale electronic applications. Herein, a novel divalent metal ion-DNA complex known as M-DNA have been investigated for its photoelectric characteristics. The increased conductivity of M-DNA thin films is attributed to the metal ion electrical and optical properties. The gate voltage effect along with illumination on the conductivity of M-DNA demonstrates that M-DNA can be used as an active element of a field-effect transistor. The Zn DNA shows maximum conductivity of 300μS/cm at 480 nm light illumination suggest that M-DNA can be utilized in nano-opto-electronics and bio-sensing applications. PMID:26737260

  4. Optimum detection of an optical image on a photoelectric surface

    NASA Technical Reports Server (NTRS)

    Helstrom, C. W.; Wang, L.

    1972-01-01

    The detection of an optical image in the presence of uniform background light is based on a likelihood ratio formed of the numbers of photoelectrons emitted from small elements of a photoelectric surface onto which the image is focused. When diffraction is negligible and the surface has unit quantum efficiency, this detector is equipollent with the optimum detector of the image forming light. Its performance is compared with that of the threshold detector and that of a detector basing its decisions on the total number of photoelectrons from a finite area of the image. The illuminance of the image is postulated to have a Gaussian spatial distribution. All three detectors exhibit nearly the same reliability.

  5. Saturn - UBV photoelectric pinhole scans of the disk. II

    NASA Technical Reports Server (NTRS)

    Price, M. J.; Franz, O. G.

    1980-01-01

    During the 1980 Saturn apparition, UBV pinhole scans of the disk were obtained with a photoelectric area-scanning photometer. An analysis of these data reveals that the atmosphere of Saturn can be represented by a finite clear H2 layer overlying a semiinfinite absorbent aerosol haze. The extent of the clear H2 region appears to be latitude-dependent; the H2 column density varies systematically from about 15 km-am over the equatorial and polar regions to about 31 km-am at temperate latitudes. A previous conclusion that the aerosol haze is strongly absorbent in the UV is confirmed; its effective U-band single-scattering albedo is about 0.4. Latitudinal disk structure at visual wavelengths appears to be the result of local variations in the volume density of absorbent particles in the aerosol layer.

  6. High-order multiphoton photoelectric effect at midinfrared laser wavelengths

    SciTech Connect

    Georges, A.T.

    2002-12-01

    A theoretical model that predicts the unexpectedly high photocurrents that were reported by Farkas et al. [J. Phys. B 31, L461 (1998)] for the photoelectric effect in gold at midinfrared laser wavelengths (12 {mu}m) is presented. It is shown that the observed effect, a nominally 46-photon process at threshold, is a stepwise and multiple-order process, which is strongly saturated at the moderate laser intensity of about {approx}10 MW/cm{sup 2}. The {approx_equal}30-photon-wide energy spectrum of the observed photoelectron current is due to above threshold photoemission. This relatively efficient above threshold effect is due to laser absorption in the long range Coulombic image surface potential.

  7. Surface photometry of WINGS galaxies with GASPHOT

    NASA Astrophysics Data System (ADS)

    D'Onofrio, M.; Bindoni, D.; Fasano, G.; Bettoni, D.; Cava, A.; Fritz, J.; Gullieuszik, M.; Kjærgaard, P.; Moretti, A.; Moles, M.; Omizzolo, A.; Poggianti, B. M.; Valentinuzzi, T.; Varela, J.

    2014-12-01

    Aims: We present the B, V, and K band surface photometry catalogs obtained by running the automatic software GASPHOT on galaxies from the WINGS cluster survey with isophotal areas larger than 200 pixels. The catalogs can be downloaded at the Centre de Données Astronomiques de Strasbourg. Methods: The luminosity growth curves of stars and galaxies in a given catalog relative to a given cluster image were obtained simultaneously by slicing the image with a fixed surface brightness step in several SExtractor runs. Then, using a single Sersic law convolved with a space-varying point spread function (PSF), GASPHOT performed a simultaneous χ2 best-fit of the major- and minor-axis luminosity growth curves of galaxies. We outline the GASPHOT performances and compare our surface photometry with that obtained by SExtractor, GALFIT, and GIM2D. This analysis is aimed at providing statistical information about the accuracy that is generally achieved by the softwares for automatic surface photometry of galaxies. Results: The GASPHOT catalogs provide the parameters of the Sersic law that fit the luminosity profiles for each galaxy and for each photometric band. They are the sky coordinates of the galaxy center (RA, Dec), the total magnitude (m), the semi-major axis of the effective isophote (Re), the Sersic index (n), the axis ratio (b/a), and a flag parameter (QFLAG) that generally indicates the fit quality. The WINGS-GASPHOT database includes 41 463 galaxies in the B band, 42 275 in the V band, and 71 687 in the K band. The bright early-type galaxies have higher Sersic indices and larger effective radii, as well as redder colors in their center. In general, the effective radii increase systematically from the K to the V and B band. Conclusions: The GASPHOT photometry agrees well with the surface photometry obtained by GALFIT and GIM2D, and with the aperture photometry provided by SExtractor. In particular, the direct comparison of structural parameters derived by different

  8. Spectroscopy and photometry of the symbiotic star V4018 Sgr in outburst

    NASA Astrophysics Data System (ADS)

    Munari, U.; Valisa, P.; Dallaporta, S.; Waagen, E. O.; Henden, A.

    2012-09-01

    Spectroscopy of the the symbiotic star V4018 Sgr (=AS 304), reported by AAVSO observers to be in outburst (cf. AAVSO Alert Notice 470), was obtained with the 0.6m telescope of the Schiaparelli Observatory in Varese (Italy). A low resolution, absolutely fluxed 4000-8650 Ang spectrum (4.24 Ang/pix) was recorded on Sept 13.90 UT. It shows the spectrum of the M giant overwhelmed by a blue continuum up to 6000 Ang, with only hydrogen Balmer and weak HeI lines visible in emission.

  9. VizieR Online Data Catalog: ubvy Photometry of magnetic CP stars (Adelman+, 2000)

    NASA Astrophysics Data System (ADS)

    Adelman, S. J.

    2000-05-01

    Differential Stroemgren uvby photometric observations from the Four College Automated Photoelectric Telescope (FCAPT) are presented for the magnetic CP stars HD 36668, 36 Lyn, HD 86592, and HR 8861. Using the FCAPT values, North's period for HD 36668 is refined to 2.11884 days. The 3.834 day period of Shore et al. (1990ApJ...348..242S) for 36 Lyn, which was found from magnetic field measurements, is confirmed by photometry. The FCAPT observations also support the 2.8867 day period of Babel & North (1997A&A...325..195B) for HD 86592, demonstrate that this star is a large amplitude variable in v (0.13 mag), and show that y varies crudely out of phase from u, v, and b which are in phase with one another. The variability of HR 8861 appears to be correlated with the meridional passages of regions of Si over- and underabundance as found by Piskunov et al. (1994A&A...291..910P) (5 data files).

  10. Photometry of Pluto-Charon mutual events and Hirayama family asteroids

    NASA Technical Reports Server (NTRS)

    Binzel, Richard P.

    1988-01-01

    Once every 124 years, nature provides earth-bound astronomers with the opportunity to observe occultation and transit phenomena between Pluto and its satellite, Charon. Ground-based observations of these events will allow precise physical parameters for the Pluto-Charon system to be derived which are unlikely to be improved upon until in situ spacecraft observations are obtained. The proposed program will continue to support photometry observations from McDonald Observatory, a critical location in an international Pluto Campaign network. Knowledge of the diameters, masses, densities, and compositions derived from these observations will augment our understanding of Pluto's origin and its context within the problem of solar system formation. A second task will continue to research the evolutionary processes which have occurred in the asteroid belt by measuring the physical properties of specific Hirayama family members. Photoelectric lightcurve observations of Koronis and Themis family members will be used to investigate the individual catastrophic collision events which formed each family. By comparing these properties with results of laboratory and numerical experiments, the outcomes of catastrophic disruptions and collisional evolution may be more precisely determined.

  11. Photometry of 50 suspected variable stars

    NASA Technical Reports Server (NTRS)

    Hooten, James T.; Hall, Douglas S.

    1990-01-01

    Fifty stars have been chosen as suspected variable stars and analyzed for variability. A large portion of this sample are stars that are either proved active chromosphere stars or are candidates for such activity. The photometric data base consists of differential V measurements of the Vanderbilt 16 inch (41 cm) automatic photoelectric telescope and 25 observers at 26 observatories worldwide. Published photometric data have also been utilized, with proper adjustments made to ensure that all magnitudes are differential. Searches for photometric period, amplitudes, and times of minimum light showed 68 percent of the sample to be photometrically variable with periods found for 34. Two stars were deemed norvariable for the period of observation. Conclusive statements could not be made concerning the photometric variability of the 14 remaining stars.

  12. A device for automatic photoelectric control of the analytical gap for emission spectrographs

    USGS Publications Warehouse

    Dietrich, John A.; Cooley, Elmo F.; Curry, Kenneth J.

    1977-01-01

    A photoelectric device has been built that automatically controls the analytical gap between electrodes during excitation period. The control device allows for precise control of the analytical gap during the arcing process of samples, resulting in better precision of analysis.

  13. Nanosized graphene sheets enhanced photoelectric behavior of carbon film on p-silicon substrate

    NASA Astrophysics Data System (ADS)

    Yang, Lei; Hu, Gaijuan; Zhang, Dongqing; Diao, Dongfeng

    2016-07-01

    We found that nanosized graphene sheets enhanced the photoelectric behavior of graphene sheets embedded carbon (GSEC) film on p-silicon substrate, which was deposited under low energy electron irradiation in electron cyclotron resonance plasma. The GSEC/p-Si photodiode exhibited good photoelectric performance with photoresponsivity of 206 mA/W, rise and fall time of 2.2, and 4.3 μs for near-infrared (850 nm) light. The origin of the strong photoelectric behavior of GSEC film was ascribed to the appearance of graphene nanosheets, which led to higher barrier height and photoexcited electron-collection efficiency. This finding indicates that GSEC film has the potential for photoelectric applications.

  14. A Correction to the Photoelectric Current in the Planck's Constant Experiment.

    ERIC Educational Resources Information Center

    Snyder, Evan S.

    1985-01-01

    Provides a method for correcting the photoemission from a collector when using the photoelectric effect experiment to determine Planck's constant. The problem results from a negative current through the cell and makes the measurement of the cutoff potential difficult. (DH)

  15. Photoelectric artefact from optogenetics and imaging on microelectrodes and bioelectronics: New Challenges and Opportunities

    PubMed Central

    Kozai, Takashi D.Y.; Vazquez, Alberto L.

    2015-01-01

    Bioelectronics, electronic technologies that interface with biological systems, are experiencing rapid growth in terms of technology development and applications, especially in neuroscience and neuroprosthetic research. The parallel growth with optogenetics and in vivo multi-photon microscopy has also begun to generate great enthusiasm for simultaneous applications with bioelectronic technologies. However, emerging research showing artefact contaminated data highlight the need for understanding the fundamental physical principles that critically impact experimental results and complicate their interpretation. This review covers four major topics: 1) material dependent properties of the photoelectric effect (conductor, semiconductor, organic, photoelectric work function (band gap)); 2) optic dependent properties of the photoelectric effect (single photon, multiphoton, entangled biphoton, intensity, wavelength, coherence); 3) strategies and limitations for avoiding/minimizing photoelectric effects; and 4) advantages of and applications for light-based bioelectronics (photo-bioelectronics). PMID:26167283

  16. Quick and Dirty WFPC2 Stellar Photometry

    NASA Technical Reports Server (NTRS)

    Mighell, Kenneth J.

    2001-01-01

    The latest release of the IRAF (Image Reduction and Analysis Facility) MXTOOLS package includes the new tasks QDWFPC2 (Quick and Dirty Wide Field and Planetary Camera, which does quick CCD (charge-coupled device) stellar photometry on two Hubble Space Telescope (HST) WFPC2 (Wide Field and Planetary Camera) observations: WFPC2COLOR, which converts HST WFPC2 instrumental magnitudes to standard colors using the Holtzman et al. color equations, and QDCMD (Quick and Dirty Color Magnitude Diagram), which reads the output of WFPC2COLOR and displays a color-magnitude diagram on a user-chosen graphics device.

  17. Photometry and polarimetry of V 1057 Cygni.

    NASA Technical Reports Server (NTRS)

    Rieke, G.; Lee, T.; Coyne, G.

    1972-01-01

    Evaluation of extensive photometric and polarimetric data over a six-month interval for V 1057 Cyg. The polarization appears to be constant and of interstellar origin; the photometry, which extends nearly six octaves from the ultraviolet to 22 microns in the infrared, indicates that the total observed luminosity is decreasing - having now declined about 10% from its earlier level. A model characterized by two circumstellar shells which absorb and reradiate short-wavelength stellar flux from an underlying A1-type star provides the best fit to the observational data. The present variability, however, cannot be due to circumstellar activity, but appears to originate in the star itself.

  18. Scintillation Noise in Exoplanet Transit Photometry

    NASA Astrophysics Data System (ADS)

    Föhring, Dóra; Wilson, Richard; Osborn, James; Dhillon, Vik

    2015-04-01

    Transit photometry is a powerful technique for studying exoplanets. Transit observations from the ground of targets of magnitude V= 10 or brighter, however, are limited by scintillation noise due to Earth's atmosphere. Through turbulence profiling using instruments such as the stereo-SCIDAR, we have shown to able to accurately model scintillation noise, which is essential in order to fully account for the error budget of the observation. Through numerical modelling we find that employing scintillation reducing techniques enables an improvement of a factor between 1.36 — 1.6 on the astrophysical parameters.

  19. The RINGS Survey: Optical Broadband Photometry

    NASA Astrophysics Data System (ADS)

    Kuzio de Naray, Rachel; Mitchell, Carl; Spekkens, Kristine; Sellwood, Jerry; Williams, Ted

    2016-01-01

    We have targeted a sample of 19 nearby spiral galaxies, the RSS Imaging and Spectroscopy Nearby Galaxy Survey (RINGS), for detailed study of their mass distributions. We have obtained Fabry-Perot Halpha velocity fields using the Southern African Large Telescope (SALT), 21-cm HI observations using the Very Large Array (VLA), and optical broadband BVRI photometry using the CTIO 0.9m and KPNO 2.1m telescopes. We present the results of the photometric component of the survey including multicolor images, surface brightness profiles, and DiskFit structural models.

  20. Charles Nordmann and Multicolour Stellar Photometry

    NASA Astrophysics Data System (ADS)

    Lequeux, James

    2010-11-01

    Charles Nordmann (1881-1940), an astronomer at the Paris Observatory, was the first to determine the effective temperature of stars with his photometre heterochrome, simultaneously and independently of Rosenberg, Wilsing and Scheiner in Germany. He is also the remote precursor of the multicolour photometry of Johnson and Morgan. In spite of the quality of his temperature determinations, which were as good or better than those made by spectrophotometry, he rapidly fell into oblivion because of some failures in his scientific work. We examine his activity in the international context of the time, and explain why he has been forgotten, to be rediscovered only recently.

  1. V photometry of Titania, Oberon, and Triton

    SciTech Connect

    Goguen, J.D.; Hammel, H.B.; Brown, R.H.

    1989-02-01

    The phase angle and orbital brightness variations of Titania, Oberon, and Triton are presently obtained through analysis of V filter photometry obtained at Mauna Kea in 1982-1983. While Titania and Oberon exhibit magnitude variations with phase angle comparable to those of low-to-moderate albedo asteroids observed within several deg of opposition, Triton's phase variation is distinctly different from these and has a phase coefficient consistent with either a high-albedo regolith or an optically thick nonparticulate scattering layer (perhaps an atmosphere, or an ocean). A low-albedo regolith cannot on the strength of these data be ruled out, however. 39 references.

  2. Time Series Photometry of KZ Lacertae

    NASA Astrophysics Data System (ADS)

    Joner, Michael D.

    2016-01-01

    We present BVRI time series photometry of the high amplitude delta Scuti star KZ Lacertae secured using the 0.9-meter telescope located at the Brigham Young University West Mountain Observatory. In addition to the multicolor light curves that are presented, the V data from the last six years of observations are used to plot an O-C diagram in order to determine the ephemeris and evaluate evidence for period change. We wish to thank the Brigham Young University College of Physical and Mathematical Sciences as well as the Department of Physics and Astronomy for their continued support of the research activities at the West Mountain Observatory.

  3. 13-Color Photometry of 16 Variable Be-Stars - Part One - Photometry

    NASA Astrophysics Data System (ADS)

    Alvarez, M.; Schuster, W. J.

    1982-07-01

    We present thirteen color photometry of 16 variable Be stars observed at the Observatorio Astronomico Nacional in San Pedro Martir in Baja California, Our data cover the years 1977 to 1979, and we include earlier measurements of Johnson and Mitchell from 1965 to 1968 that have been corrected in order to have a homogeneous set of data.

  4. Suppression of star formation in dwarf galaxies by photoelectric grain heating feedback

    NASA Astrophysics Data System (ADS)

    Forbes, John C.; Krumholz, Mark R.; Goldbaum, Nathan J.; Dekel, Avishai

    2016-07-01

    Photoelectric heating—heating of dust grains by far-ultraviolet photons—has long been recognized as the primary source of heating for the neutral interstellar medium. Simulations of spiral galaxies have shown some indication that photoelectric heating could suppress star formation; however, simulations that include photoelectric heating have typically shown that it has little effect on the rate of star formation in either spiral galaxies or dwarf galaxies, which suggests that supernovae are responsible for setting the gas depletion time in galaxies. This result is in contrast with recent work indicating that a star formation law that depends on galaxy metallicity—as is expected with photoelectric heating, but not with supernovae—reproduces the present-day galaxy population better than does a metallicity-independent one. Here we report a series of simulations of dwarf galaxies, the class of galaxy in which the effects of both photoelectric heating and supernovae are expected to be strongest. We simultaneously include space- and time-dependent photoelectric heating in our simulations, and we resolve the energy-conserving phase of every supernova blast wave, which allows us to directly measure the relative importance of feedback by supernovae and photoelectric heating in suppressing star formation. We find that supernovae are unable to account for the observed large gas depletion times in dwarf galaxies. Instead, photoelectric heating is the dominant means by which dwarf galaxies regulate their star formation rate at any given time, suppressing the rate by more than an order of magnitude relative to simulations with only supernovae.

  5. Photoelectric charging of dust particles: Effect of spontaneous and light induced field emission of electrons

    SciTech Connect

    Sodha, M. S.; Dixit, A.

    2009-09-07

    The authors have analyzed the charging of dust particles in a plasma, taking into account the electron/ion currents to the particles, electron/ion generation and recombination, electric field emission, photoelectric emission and photoelectric field emission of electrons under the influence of light irradiation; the irradiance has been assumed to be at a level, which lets the particles retain the negative sign of the charge. Numerical results and discussion conclude the papers.

  6. Suppression of star formation in dwarf galaxies by photoelectric grain heating feedback.

    PubMed

    Forbes, John C; Krumholz, Mark R; Goldbaum, Nathan J; Dekel, Avishai

    2016-07-28

    Photoelectric heating--heating of dust grains by far-ultraviolet photons--has long been recognized as the primary source of heating for the neutral interstellar medium. Simulations of spiral galaxies have shown some indication that photoelectric heating could suppress star formation; however, simulations that include photoelectric heating have typically shown that it has little effect on the rate of star formation in either spiral galaxies or dwarf galaxies, which suggests that supernovae are responsible for setting the gas depletion time in galaxies. This result is in contrast with recent work indicating that a star formation law that depends on galaxy metallicity--as is expected with photoelectric heating,but not with supernovae--reproduces the present-day galaxy population better than does a metallicity-independent one. Here we report a series of simulations of dwarf galaxies, the class of galaxy in which the effects of both photoelectric heating and supernovae are expected to be strongest. We simultaneously include space and time-dependent photoelectric heating in our simulations, and we resolve the energy-conserving phase of every supernova blast wave, which allows us to directly measure the relative importance of feedback by supernovae and photoelectric heating in suppressing star formation. We find that supernovae are unable to account for the observed large gas depletion times in dwarf galaxies. Instead, photoelectric heating is the dominant means by which dwarf galaxies regulate their star formation rate at any given time,suppressing the rate by more than an order of magnitude relative to simulations with only supernovae. PMID:27350244

  7. Near-infrared photometry of carbon stars

    NASA Astrophysics Data System (ADS)

    Whitelock, Patricia A.; Feast, Michael W.; Marang, Freddy; Groenewegen, M. A. T.

    2006-06-01

    Near-infrared, JHKL, photometry of 239 Galactic C-rich variable stars is presented and discussed. From these and published data, the stars were classified as Mira or non-Mira variables, and amplitudes and pulsation periods, ranging from 222 to 948 d for the Miras, were determined for most of them. A comparison of the colour and period relations with those of similar stars in the Large Magellanic Cloud indicates minor differences, which may be the consequence of sample selection effects. Apparent bolometric magnitudes were determined by combining the mean JHKL fluxes with mid-infrared photometry from IRAS and MSX. Then, using the Mira period luminosity relation to set the absolute magnitudes, distances were determined - to greater accuracy than has hitherto been possible for this type of star. Bolometric corrections to the K magnitude were calculated and prescriptions derived for calculating these from various colours. Mass-loss rates were also calculated and compared to values in the literature. Approximately one-third of the C-rich Miras and an unknown fraction of the non-Miras exhibit apparently random obscuration events that are reminiscent of the phenomena exhibited by the hydrogen-deficient R Coronae Borealis stars. The underlying cause of this is unclear, but it may be that mass loss, and consequently dust formation, is very easily triggered from these very extended atmospheres. Based on observations made at the South African Astronomical Observatory. E-mail: paw@saao.ac.za

  8. Photometry Of Pluto At Low Galactic Latitudes

    NASA Astrophysics Data System (ADS)

    George, Erin; Buie, M.; Bagenal, F.

    2012-10-01

    Our research is part of an ongoing project to continue the long-term photometric monitoring of Pluto in hopes to constrain volatile migration on the surface. As Pluto passes near the center of the galaxy, the fields are too crowded with stars for normal aperture photometry. We approached this problem by using Optimal Image Subtraction (OIS). We took images, both containing and not containing Pluto, using the 0.8m robotic telescope at Lowell Observatory, the 1m robotic telescope at New Mexico State University, and the Faulkes 2m robotic telescope at Siding Spring, part of Las Cumbres Observatory. We are presently gathering data, but our main focus was the data from 2010. We began by taking images of the star fields at the galactic center without Pluto to build catalogs of standard stars. These catalogs were applied to the Pluto images in order to make interpolated images and to cross check our results. We extracted the photometry of Pluto from differenced images where the background stars were subtracted, and we then applied the transformation equation to solve for Pluto’s standard magnitude. We will present the details of our data processing methodology, as well as the 2010 Pluto B, V, and B-V light curves in comparison to those from previous years. This work was supported by NASA Planetary Astronomy Grant NNX09AB43G.

  9. TRIPPy: Trailed Image Photometry in Python

    NASA Astrophysics Data System (ADS)

    Fraser, Wesley; Alexandersen, Mike; Schwamb, Megan E.; Marsset, Michaël; Pike, Rosemary E.; Kavelaars, J. J.; Bannister, Michele T.; Benecchi, Susan; Delsanti, Audrey

    2016-06-01

    Photometry of moving sources typically suffers from a reduced signal-to-noise ratio (S/N) or flux measurements biased to incorrect low values through the use of circular apertures. To address this issue, we present the software package, TRIPPy: TRailed Image Photometry in Python. TRIPPy introduces the pill aperture, which is the natural extension of the circular aperture appropriate for linearly trailed sources. The pill shape is a rectangle with two semicircular end-caps and is described by three parameters, the trail length and angle, and the radius. The TRIPPy software package also includes a new technique to generate accurate model point-spread functions (PSFs) and trailed PSFs (TSFs) from stationary background sources in sidereally tracked images. The TSF is merely the convolution of the model PSF, which consists of a moffat profile, and super-sampled lookup table. From the TSF, accurate pill aperture corrections can be estimated as a function of pill radius with an accuracy of 10 mmag for highly trailed sources. Analogous to the use of small circular apertures and associated aperture corrections, small radius pill apertures can be used to preserve S/Ns of low flux sources, with appropriate aperture correction applied to provide an accurate, unbiased flux measurement at all S/Ns.

  10. What was measured in Millikan's study of the photoelectric effect?

    NASA Astrophysics Data System (ADS)

    Lloyd, David R.

    2015-09-01

    Millikan's photoemission paper of 1916 is of great historical importance because it provided the first unambiguous experimental support for Einstein's theory of the photoelectric effect. His graphical presentation of the results, for the correlation of stopping potential with frequency of the incident light on a sodium surface, is widely reproduced in textbooks, both at the high school and undergraduate levels. By far the most significant result that emerged from the experiments is the slope of this graph, which provided an accurate value of the Planck constant h. However, some modern textbooks also emphasize the intercept on Millikan's graph, even though Millikan made little use of this. As previously emphasised, the intercept does not give a measure of the work function of the illuminated sample, but measures that of the collector surface. Millikan made this point very clear, and his experimental plots have been corrected for this, but it is still not generally realized that this is so. Even with Millikan's correction, his intercept does not give the true work function for sodium. Neither of his surfaces was metallic, though this was assumed by Millikan and is assumed in textbook accounts. It is shown here that the sodium surface was almost certainly heavily contaminated with sodium hydroxide. The consequences for the interpretation of the experiment, and for the use of these results in teaching, are explored.

  11. Photoelectric effect from observer's mathematics point of view

    NASA Astrophysics Data System (ADS)

    Khots, Boris; Khots, Dmitriy

    2014-12-01

    When we consider and analyze physical events with the purpose of creating corresponding models we often assume that the mathematical apparatus used in modeling is infallible. In particular, this relates to the use of infinity in various aspects and the use of Newton's definition of a limit in analysis. We believe that is where the main problem lies in contemporary study of nature. This work considers Physical aspects in a setting of arithmetic, algebra, geometry, analysis, topology provided by Observer's Mathematics (see www.mathrelativity.com). Certain results and communications pertaining to solution of these problems are provided. In particular, we prove the following Theorems, which give Observer's Mathematics point of view on Einstein photoelectric effect theory and Lamb-Scully and Hanbury-Brown-Twiss experiments: Theorem 1. There are some values of light intensity where anticorrelation parameter A ∈ [0,1). Theorem 2. There are some values of light intensity where anticorrelation parameter A = 1. Theorem 3. There are some values of light intensity where anticorrelation parameter A > 1.

  12. Optical system design of surface roughness photoelectric inspection instrument

    NASA Astrophysics Data System (ADS)

    Xiao, Ze-xin; Li, Peng; Cao, Jie; Xiao, Ran

    2010-11-01

    The light-section method for roughness measurement is one of the most classical measuring methods. According to light-section method which combine visual observation with photomicrography for testing surface roughness, domestic type of 9J is a traditional device. The surface roughness photoelectric inspection instrument which designed by the authors are also based on the theory of light-section, which integrates subjects of optics, mechanical, electronics and calculation. Surface roughness of object image can be obtained on the CCD sensor through the optical system. Using the autonomous software in the computer, the average height of workpiece unevenness Ra value can be measured and read in the monitor. Therefor, surface roughness level can be obtained. In order to design the optical system of device, there are three main aspects which should be finished: 1.Start with requirements of detective object, according to the detective range from Ra12.5 to Ra0.04 ruled by CNS(China National Standards) GB3505-83 the Surface Roughness Term Surface and the Parameters ,parameters on β(magnify power), NA(numerical aperture), WD(work distance), filed of object etc are defined and optimized. Meanwhile, good complementation and compatibility are noticed among three kinds magnification objectives. 2. Special type infinity image distance double telecentricity optical system is constructed. The main point is to design a set of objectives of long WD and infinity image distance flat field semi-apochromat. 3. How to match and optimize the CCD image sensor and lens.

  13. Electric and photoelectric properties of InAs photosensitive cells

    SciTech Connect

    Vlasova, E.O.; Martynov, V.N.; Morozov, V.A.

    1995-10-01

    Earlier we showed that InAs is a promising material for portable IR imagers employing arrays of charge coupled devices (CCD). The most important element of the array cell is the p-n junction. Electric and photoelectric properties of the p-n junction determine the characteristics of the array. In this work, we studied characteristics of photodiodes with autoepitaxial p{sup +}-n structure and passivating dielectric layers of anodic oxide and Si{sub 3}N{sub 4}. We also optimized the carrier concentration in the p{sup +}-layer and n-substrate and the thickness of the dielectric layers in order to increase the operating temperature of the CCD array, without affecting the signal-to-noise ratio in the signal detection mode. The temperature dependence of the differential resistance Rd of the diode; this dependence allows one to determine the generation regions and mechanisms of the reverse current of the diode I{sub rev}. The reverse current of the diode I{sub rev}, at zero bias is associated with two main processes: generation in the space-charge region (SCR) of the p-n junction I{sub SCR} and thermal generation in the neutral bulk I{sub bulk}. The corresponding contributions to the reverse current exhibit different temperature dependences.

  14. Photoelectric and luminescent properties of dysprosium-doped silver chloride

    SciTech Connect

    Novikov, G. F. Rabenok, E. V.; Bocharov, K. V.; Lichkova, N. V.; Ovchinnikov, O. V.; Latyshev, A. N.

    2011-02-15

    The influence of dysprosium doping on the photoelectric and luminescent properties of AgCl crystals is studied by methods of microwave photoconductivity and photoluminescence. Doping affects both the loss kinetics of photogenerated electrons and luminescence spectra and parameters of photostimulated burst of luminescence. It is shown that the charged [Dy{sub Ag}{sup {center_dot}{center_dot}} {center_dot} V Prime {sub Ag}]{sup {center_dot}} or neutral [Dy{sub Ag}{sup {center_dot}{center_dot}} {center_dot} 2V Prime {sub Ag}]{sup x} complexes are responsible for a new luminescence band peaked at 470 nm, which manifests itself at weight concentrations of the doping additive >10{sup -6}%. The long-wavelength shoulder at 570 nm in the photoluminescence spectra is attributed to intracenter transitions in the Dy{sup 3+} ions. The rate constant of the reaction of electron capture into the traps forming upon introduction of the dopant, k{sub t} = (3-5) Multiplication-Sign 10{sup -8} cm{sup 3} s{sup -1}, is evaluated. It is assumed that the traps are Dy{sup 3+} dysprosium ions.

  15. JHK photometry of selected Trojan and Hilda asteroids

    NASA Technical Reports Server (NTRS)

    Smith, Dale W.; Johnson, Paul E.; Buckingham, William L.; Shorthill, Richard W.

    1992-01-01

    No entirely satisfactory match has been established between the present JHK photometry of selected Hilda and Trojan asteroids and photometry for both main belt asteroids and laboratory samples. It is noted that while the leading Trojans and Hildas exhibit similar and homogeneous JHK colors, the trailing Trojans appear to be more heterogeneous. Charcoal and magnetite provide the best match in terms of JHK colors.

  16. Multiband Photometry of the Chromospherically Active & Spotted Binary System IM Peg—the Guide Star for the Gravity Probe B Mission

    NASA Astrophysics Data System (ADS)

    Zellem, Robert; Guinan, Edward F.; Messina, Sergio; Lanza, Antonino F.; Wasatonic, Richard; McCook, George P.

    2010-06-01

    We report on the starspot properties of IM Pegasi—the guide star of the Gravity Probe B (GP-B) satellite. GP-B's mission is to measure two predicted consequences of general relativity—the frame-dragging and geodetic effects—via its extremely precise onboard gyroscopes. However, IM Peg is a chomospherically active binary system with a luminous K2 III primary star showing rotationally modulated (Prot ≈ 24.5 days) light variations from starspots. The starspots can potentially cause problems as GP-B can erroneously interpret a change in starspot coverage (and corresponding shifts in the light center) as the star's movement. This apparent shift can also be exacerbated by possible changes in the light center (photocenter) of the binary system arising from changes in the light balance with the fainter ~1 Msolar (main-sequence early G-type star) component. Since 2000, we have carried out multiband high-precision photoelectric photometry of IM Peg to determine its activity and starspot coverage. Our photometry uses Strömgren uvby intermediate-band filters, VRI filters, and TiO (720/750 nm) narrowband filter sets. Measurements were made relative to nearby comparison and check stars using 0.8 m and 0.25 m telescopes. Analysis of TiO and multiband continuum photometry constrains the starspot areas, temperatures, and surface distributions. The photometry has been modeled using the maximum entropy and Tikhonov regularizations to determine the properties of starspots and to evaluate the effects of changing starspot areas and distributions on the light center of the binary. Our results indicate that IM Peg's activity should not affect the GP-B mission. We also present a study of IM Peg's long-term starspot cycle, which shows evidence of being 20 yr long. Lastly, we have determined the intrinsic (unspotted) brightness of the star to be V mag = 5.62 ± 0.03.

  17. Ten Recent Enhancements To Aperture Photometry Tool

    NASA Astrophysics Data System (ADS)

    Laher, Russ; Rebull, L. M.; Gorjian, V.

    2013-01-01

    Aperture Photometry Tool is free, multi-platform, easy-to-install software for astronomical research, as well as for learning, visualizing, and refining aperture-photometry analyses. This mature software has been under development for five years, and is a silent workhorse of the NASA/IPAC Teacher Archive Research Program. Software version 2.1.5 is described by Laher et al., Publications of the Astronomical Society of the Pacific, Vol. 124, No. 917, pp. 737-763, (July 2012). Four software upgrades have been released since the publication, which include new capabilities, increased speed, more user-friendliness, and some minor bug fixes. Visit www.aperturephotometry.org to download the latest version. The enhancements are as follows: 1) Added new Tools menu option to write selected primary-image data to a comma-separated-value file (for importing into Excel); 2) Added a new display of the color-table levels on a separate panel; 3) Added a new tool to measure the angular separation between positions on the thumbnail image, via mouse-cursor drag and release; 4) Added a new tool to overlay an aperture at user-specified coordinates (in addition to aperture overlay via mouse click); 5) Speeded up the source-list tool with optional multithreading in its automatic mode (allowed thread number is user-specifiable); 6) Added a new “Number” column to the output aperture-photometry-table file in order to track the input source order (multithreading reorders the output); 7) Upgraded the source-list tool to accept input source lists containing positions in sexagesimal equatorial coordinates (in addition to decimal degrees, or, alternatively, pixel coordinates); 8) Added a new decimal/sexagesimal converter; 9) Upgraded the source-list creation tool to compute the detection threshold using robust estimates of the local background and local data dispersion, where the user can select the grid and window sizes for these local calculations; and 10) Modified the batch mode to

  18. Photometry and Other Characteristics of Venus

    NASA Astrophysics Data System (ADS)

    Schmude, Richard W., Jr.; Dutton, James

    2001-12-01

    New photoelectric magnitude measurements are reported and these values have been combined with previously reported measurements in the selection of the photometric constants of Venus. The selected normalized magnitudes of Venus are: B(1,0) = -3.42, V(1,0) = -4.25, R(1,0) = -4.87 and I(1,0) = -5.14, while the selected solar phase angle coefficients for the B, V, R and I filters are: 0.0055, 0.0063, 0.0071 and 0.0062. Dichotomy measurements made between 1919 and 2001 have been reviewed and it is concluded that the Schroeter effect is real and that it is primarily due to two factors: 1) twilight scattering and 2) shading near the terminator. We also conclude that there is no correlation between the Schroeter effect and the 11-year solar cycle and that there is no difference in the magnitude of the Schroeter effect between eastern and western apparitions. There does, however, appear to be a ~35 year cycle in the magnitude of the Schroeter effect during most of the Twentieth Century. We also conclude that the cusp extensions of Venus may affect the observed phase of that planet and that irregularities near the terminator suggest large-scale vertical cloud relief of about 2-5 kilometers.

  19. TERMS PHOTOMETRY OF KNOWN TRANSITING EXOPLANETS

    SciTech Connect

    Dragomir, Diana; Kane, Stephen R.; Ciardi, David R.; Gelino, Dawn M.; Payne, Alan; Ramirez, Solange V.; Von Braun, Kaspar; Wyatt, Pamela; Pilyavsky, Genady; Mahadevan, Suvrath; Wright, Jason T.; Zachary Gazak, J.; Rabus, Markus

    2011-10-15

    The Transit Ephemeris Refinement and Monitoring Survey conducts radial velocity and photometric monitoring of known exoplanets in order to refine planetary orbits and predictions of possible transit times. This effort is primarily directed toward planets not known to transit, but a small sample of our targets consists of known transiting systems. Here we present precision photometry for six WASP (Wide Angle Search for Planets) planets acquired during their transit windows. We perform a Markov Chain Monte Carlo analysis for each planet and combine these data with previous measurements to redetermine the period and ephemerides for these planets. These observations provide recent mid-transit times which are useful for scheduling future observations. Our results improve the ephemerides of WASP-4b, WASP-5b, and WASP-6b and reduce the uncertainties on the mid-transit time for WASP-29b. We also confirm the orbital, stellar, and planetary parameters of all six systems.

  20. UBVRI photometry of W Ursae Majoris

    NASA Astrophysics Data System (ADS)

    Linnell, A. P.

    1985-03-01

    High speed UBVRI photometry of W Ursae Majoris produced 15,930 observations covering one complete cycle on 1984 March 5-6. For this epoch, total phase of primary minimum is flat in all spectral bands, while secondary minimum shows a substantial tilt during annual phases. The tilt correlates with a detectable O'Connell effect, indicates a transverse temperature gradient across the projected disk of the primary component, and is qualitatively consistent with a starspot origin for both effects. Gross characteristics of the color curves are consistent with those expected from the wavelength dependence of limb darkening. The observed greater color change at primary minimum as contrasted with secondary must have a different origin. There is qualitative consistency with a Rucinski hot secondary model. Whether consistency can also be achieved with a Mullan starspot model, or whether decisive discrimination between alterative physical models can be demonstrated must await detailed light synthesis simulation.

  1. Selecting M-giants with WISE photometry

    NASA Astrophysics Data System (ADS)

    Li, Jing

    2015-08-01

    We use M-giants, M-dwarfs and QSOs identified by LAMOST to assess how well WISE & 2MASS colour-cuts can separate these populations through photometry. We find that the WISE bands are very efficient to separate M-giants from M-dwarfs, especially for the early-type stars. We derive a new photometric relation to estimate [Fe/H] for M-giants. We show that previous photometric distance relations may be biased and devise a new empirical distance relation. We detect M-giants in the Sagittarius stream from the ALLWISE Source Archive. Our detection shows good agreement with the bright stream, although the leading tail appears to be misaligned by a couple of degrees. We have measured the metallicity distribution at four locations along the stream, finding a clear metallicity offset between the leading and trailing tails.

  2. Asteroid Maps From Photometry And Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Kaasalainen, Mikko; Marchis, F.; Carry, B.

    2007-10-01

    While disk-integrated photometry is the main source of information on most asteroids, adaptive optics can provide some disk-resolved data on many larger (main-belt) asteroids. Asteroid models from lightcurve inversion agree well with the obtained AO images (Marchis et al. 2006, Icarus 185,39), but even more detailed models can be obtained by combining the two sources in inversion. In addition to giving more detail to existing models, the approach can also be used to obtain models of asteroids for which the photometric data are yet insufficient alone. This also helps to calibrate the inversion and deconvolution processes related to the separate sources; e.g., whether features apparently revealed by AO post-processing are real or artificial. We present some examples and discuss the resolution level of topographic detail in the resulting models. Hundreds of asteroids can be mapped in this way in the near future.

  3. Multicolour Optical Photometry of Active Geostationary Satellites

    NASA Astrophysics Data System (ADS)

    Jolley, A.; Wade, G.; Bedard, D.

    Although broadband photometry has been used to infer information about artificial satellites since soon after the launch of Sputnik 1, the development of photometric techniques for non-resolved space object identification or characterisation has been hampered by the large number of variables involved. Many individual studies, and some long ongoing experiments, have used costly metre-class telescopes to obtain data despite other experiments demonstrating that much more flexible and affordable small aperture telescopes may be suitable for the task. In addition, due to the highly time consuming and weather dependent nature of obtaining photometric observations, many studies have suffered from data sets of limited size, or relied upon simulations to support their claims. With this in mind, an experiment was conducted with the aim of determining the utility of small aperture telescopes for conducting broadband photometry of satellites for the purpose of non-resolved space object identification and characterisation. A 14 inch Celestron CG-14 telescope was used to gain multiple night-long, high temporal resolution data sets of six active geostationary satellites. The results of the experiment cast doubt on the efficacy of some of the previous approaches to obtaining and analysing photometric data. It was discovered that geostationary satellite lightcurves can vary to a greater degree than has generally been recognised, and colour ratios vary considerably with changes in the illumination/observation geometry, making it difficult to use colour for satellite discrimination. Evidence was also detected of variations in the spectral energy distribution of sunlight reflected off satellite surface materials, which could have implications for surface material characterisation and techniques that aim to separate satellite body and solar panel contributions to the total observed spectra.

  4. International Observing Campaign: Photometry and Spectroscopy of P Cygni

    NASA Astrophysics Data System (ADS)

    Pollmann, E.; Bauer, T.

    2012-04-01

    In this combined campaign on the Luminous Blue Variable star P Cygni we are trying for the first time by way of contemporaneous measurements of photometric V brightness and Ha equivalent width (EW) to realize a longterm monitoring of the intrinsic Ha-line flux. The photometric observers of AAVSO and BAV (Germany) and a spectroscopic observer group (Japan, France, Spain, Germany) started observing for this campaign in November 2008 at the request of Bernd Hanisch and one of us (EP) in order to continue former investigations whose results were based on multi-daily averaging of V and EW. Additional data from literature enable us to represent the quantitative behavior of the Ha-line flux for the timespan August 2005 to December 2011, which behavior reflects variabilities in mass-loss rate, stellar wind density, and ionization structure.

  5. A new photoelectric ink based on nanocellulose/CdS quantum dots for screen-printing.

    PubMed

    Tang, Aimin; Liu, Yuan; Wang, Qinwen; Chen, Ruisong; Liu, Wangyu; Fang, Zhiqiang; Wang, Lishi

    2016-09-01

    CdS quantum dots with excellent photoelectrical properties embedded in nanocellulose could be exploited for use in photoelectrical ink. In this work, nanocellulose/CdS quantum dot composites were fabricated by controlling the carboxylate content of the nanocellulose and the molar ratio of Cd(2+)/-COOH. New photoelectric inks were prepared based on the composites, in which the CdS quantum dots acted as the pigment and the nanocellulose as the binder. The results of the photocurrent of the composites showed that the photocurrent could be tailored by the carboxylate content and the molar ratio of Cd(2+)/-COOH. And the photocurrent could be as high as 2μA. The surface tension of the photoelectric ink was 27.80±0.03mN/m and its viscosity was 30.3mPas. The photoelectric ink was stable with excellent fluidity and rheology, it could therefore be applied to screen-printing and three-dimensional (3D) printing. PMID:27185112

  6. Automated surface photometry for the Coma Cluster galaxies: The catalog

    NASA Technical Reports Server (NTRS)

    Doi, M.; Fukugita, M.; Okamura, S.; Tarusawa, K.

    1995-01-01

    A homogeneous photometry catalog is presented for 450 galaxies with B(sub 25.5) less than or equal to 16 mag located in the 9.8 deg x 9.8 deg region centered on the Coma Cluster. The catalog is based on photographic photometry using an automated surface photometry software for data reduction applied to B-band Schmidt plates. The catalog provides accurate positions, isophotal and total magnitudes, major and minor axes, and a few other photometric parameters including rudimentary morphology (early of late type).

  7. The TAOS Project: High-Speed Crowded Field Aperture Photometry

    NASA Astrophysics Data System (ADS)

    Zhang, Z.-W.; Kim, D.-W.; Wang, J.-H.; Lehner, M. J.; Chen, W. P.; Byun, Y.-I.; Alcock, C.; Axelrod, T.; Bianco, F. B.; Coehlo, N. K.; Cook, K. H.; Dave, R.; de Pater, I.; Giammarco, J.; King, S.-K.; Lee, T.; Lin, H.-C.; Marshall, S. L.; Porrata, R.; Protopapas, P.; Rice, J. A.; Schwamb, M. E.; Wang, S.-Y.; Wen, C.-Y.

    2009-12-01

    We have devised an aperture photometry pipeline for data reduction of image data from the Taiwanese-American Occultation Survey (TAOS). The photometry pipeline has high computational performance, and is capable of real-time photometric reduction of images containing up to 1000 stars, within the sampling rate of 5 Hz. The pipeline is optimized for both speed and signal-to-noise performance, and in the latter category it performs nearly as well as DAOPHOT. This paper provides a detailed description of the TAOS aperture photometry pipeline.

  8. Influence of ferroelectricity on the photoelectric effect of LiNbO{sub 3}

    SciTech Connect

    Dunn, S.; Tiwari, D.

    2008-09-01

    A comparison between domain dependent photochemical and photoelectric cation reduction in LiNbO{sub 3} is presented. The reduction in photoelectric threshold for LiNbO{sub 3} due to the depolarization field allows UV irradiation to produce free electrons that can participate in photochemical reduction in silver nitrate. This is in addition to domain directed photophysics, where influences on the space charge layer due to the internal dipole of a ferroelectric determine the carrier at the surface. We show that the interaction of photoelectric and domain dependent influences is observed in LiNbO{sub 3} due to the low electron affinity ({approx}1-1.5 eV) and band bending (0.3-0.8 eV)

  9. Photoelectric Property Modulation by Nanoconfinement in the Longitude Direction of Short Semiconducting Nanorods.

    PubMed

    Tang, Chaolong; Jiang, Chengming; Bi, Sheng; Song, Jinhui

    2016-05-01

    Photoelectric property change in half-dimensional (0.5D) semiconducting nanomaterials as a function of illumination light intensity and materials geometry has been systematically studied. Through two independent methods, conductive atomic force microscopy (C-AFM) direct current-voltage acquisition and scanning kelvin probe microscopy (SKPM) surface potential mapping, photoelectric property of 0.5D ZnO nanomaterial has been characterized with exceptional behaviors compared with bulk/micro/one-dimensional (1D) nanomaterial. A new model by considering surface effect, quantum effect, and illumination effect has been successfully built, which could more accurately predict the photoelectric characteristics of 0.5D semiconducting nanomaterials. The findings reported in this study could potentially impact three-dimensional (3D) photoelectronics. PMID:27057764

  10. Comparison of Metallicities Adopted for the Synthetic UBV Photometry with Those Evaluated by Means of RGU Photometry

    NASA Astrophysics Data System (ADS)

    Karaali, S.; Güngör, S.; Karatas, Y.

    1998-04-01

    Comparison of metallicities adopted for the synthetic UBV photometry with those evaluated by means of RGU photometry for 92 stars is presented. The agreement only for zero metallicity. The discrepancy increases to low metallicities which cover Intermediate population and Population II main-sequence star. U-G and G-R colour indices are transformed from UBV synthetic data and do not include any observational error. Therefore, the disagreement may orginate from a systematic error in the metallicity calibration of relatively metal-poor stars in RGU photometry.

  11. L' AND M' Photometry Of Ultracool Dwarfs

    NASA Technical Reports Server (NTRS)

    Marley, M. S.; Tsvetanov, Z. I.; Vrba, F. J.; Henden, A. A.; Luginbuhl, C. B.

    2004-01-01

    We have compiled L' (3.4-4.1 microns) and M' (4.6- 4.8 microns) photometry of 63 single and binary M, L, and T dwarfs obtained at the United Kingdom Infrared Telescope using the Mauna Kea Observatory filter set. This compilation includes new L' measurements of eight L dwarfs and 13 T dwarfs and new M' measurements of seven L dwarfs, five T dwarfs, and the M1 dwarf Gl 229A. These new data increase by factors of 0. 6 and 1.6, respectively, the numbers of ultracool dwarfs T (sub eff) photometry, and trigonometric parallaxes are available, and we estimate these quantities for nine other dwarfs whose parallaxes and flux-calibrated spectra have been obtained. BC(SUB K) is a well-behaved function of near-infrared spectral type with a dispersion of approx. 0.1 mag for types M6-T5 it is significantly more scattered for types T5-T9. T (sub eff) declines steeply and monotonically for types M6-L7 and T4-T9, but it is nearly constant at approx. 1450 K for types L7-T4 with assumed ages of approx. 3 Gyr. This constant T(sub eff) is evidenced by nearly unchanging values of L'-M' between types L6 and T3. It also supports recent models that attribute the changing near-infrared luminosities and spectral features across the L-T transition to the rapid migration, disruption, and/or thinning of condensate clouds over a narrow range of T(sub eff). The L' and M' luminosities of early-T dwarfs do not exhibit the pronounced humps or inflections previously noted in l through K bands, but insufficient data exist for types L6-T5 to assert that M(Sub L') and M(sub M') are strictly monotonic within this range of typew. We compare the observed K, L', and M' luminosities of L and T dwarfs in our sample with those predicted by precipitation-cloud-free models for varying surface gravities and sedimentation efficiencies.

  12. Detection of Extrasolar Planets by Transit Photometry

    NASA Technical Reports Server (NTRS)

    Borucki, William; Koch, David; Webster, Larry; Dunham, Edward; Witteborn, Fred; Jenkins, Jon; Caldwell, Douglas; Showen, Robert; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    A knowledge of other planetary systems that includes information on the number, size, mass, and spacing of the planets around a variety of star types is needed to deepen our understanding of planetary system formation and processes that give rise to their final configurations. Recent discoveries show that many planetary systems are quite different from the solar system in that they often possess giant planets in short period orbits. The inferred evolution of these planets and their orbital characteristics imply the absence of Earth-like planets near the habitable zone. Information on the properties of the giant-inner planets is now being obtained by both the Doppler velocity and the transit photometry techniques. The combination of the two techniques provides the mass, size, and density of the planets. For the planet orbiting star HD209458, transit photometry provided the first independent confirmation and measurement of the diameter of an extrasolar planet. The observations indicate a planet 1.27 the diameter of Jupiter with 0.63 of its mass (Charbonneau et al. 1999). The results are in excellent agreement with the theory of planetary atmospheres for a planet of the indicated mass and distance from a solar-like star. The observation of the November 23, 1999 transit of that planet made by the Ames Vulcan photometer at Lick Observatory is presented. In the future, the combination of the two techniques will greatly increase the number of discoveries and the richness of the science yield. Small rocky planets at orbital distances from 0.9 to 1.2 AU are more likely to harbor life than the gas giant planets that are now being discovered. However, new technology is needed to find smaller, Earth-like planets, which are about three hundred times less massive than Jupiter-like planets. The Kepler project is a space craft mission designed to discover hundreds of Earth-size planets in and near the habitable zone around a wide variety of stars. To demonstrate that the

  13. Vitold Ceraski and Vladimir Nikonov - founders of stellar photometry in Russia

    NASA Astrophysics Data System (ADS)

    Mironov, A.; Pustylnik, I.

    2002-07-01

    This paper is dedicated to two ``godfathers'' of astrophotometry in Russia - Vitold Karlovich Ceraski (1849-1925) and Vladimir Borisovich Nikonov (1905-1987). We discuss their scientific legacy and its impact on the formation of the school of stellar photometry in Russia and the USSR. A graduate of Moscow University in 1871, V. Ceraski started his scientific career at the University Astronomical Observatory. Already at the dawn of the 20th century, he was universally regarded as an indisputable authority in Russian astrophotometry. Ceraski introduced essential improvements to K.-F. Zöllner's visual polarimetric photometer. In 1903-1905 he measured with the photometer the stellar magnitude of the Sun with an accuracy close to its modern value (within a 5\\ Venus with that of the speck of sunlight reflected from a convex glass surface (during daytime) and by comparing the brightness of Venus with that of the brightest stars (during the night). V. Nikonov, a graduate of Leningrad University, embarked in 1925 on scientific investigations in the Leningrad Astronomical Institute. In 1937, he constructed the first photoelectric photometer in the USSR. Experiments indicated that its attainable precision for 4fm 5 stars amounted to 0fm 003. It was obvious that therefore one should exercise extreme care in the reduction of stellar magnitudes beyond the earth's upper atmosphere. In 1944 he elaborated a method to account for atmospheric extinction which is now universally known as Nikonov's method. Its underlying idea lies in the observations of all non-variable stars available in the program for different air masses.

  14. The principle of frequency interaction and photoelectric conversion of the mass wave

    NASA Astrophysics Data System (ADS)

    Cao, Dayong

    2007-08-01

    The experiment results show that human consciousness can change photoelectric signals such as Voc and Isc of solar cell at isolation air. First in the world, consciousness signal is able to be recorded through the experiment. (It succeed in 10,22,2002) Consciousness augment or reduce the Voc to the slow wave like the ERP of the brain wave. Photoelectrical signal converts to slow fluctuation signal without characteristics of sine fluctuation, Which proves that there is a "cause and effect" relationship between alterations of consciousness (active) and photoelectrical signal (passive); Under the standard limit optical source (AM1.5), consciousness changes a normal photoelectric signal above threshold value of I-V tester. The experiment proves that consciousness signal is a kind of unknown physical signal. With a characteristic of slow fluctuation, mass wave of the light is different from the Einstein's light quantum (energy wave). Frequency interaction principle of it and its photoelectric conversion equation are being put forward. It is rife hold true. Consequently, it is discovered that consciousness signal with a slow weak wave has such high power. Mass energy space and time system theory and Quantum microcosmics space and time are being put forward. It give a support to new Mass wave. Consciousness can produces the consciousness signal with the mass wave and use it to act on photoelectric system. The system magnifies it. Consciousness is independent and self-determined while brain signal is passive and driven. Consciousness is spiritual and Intelligence while brain signal is physical, corporality and mechanic.

  15. WIYN Open Cluster Study: UBVRI Photometry of NGC 2158

    NASA Astrophysics Data System (ADS)

    Taverne, Luke T.; Steinhauer, Aaron J.; Deliyannis, Constantine P.

    2015-01-01

    We present WIYN 0.9m HDI UBVRI photometry of NGC 2158, a very rich, intermediate-aged, open cluster located near the galactic anti-center. We report derived values for the cluster age, distance, reddening.

  16. From Maxwell to Millikan: A Little History and a Little Hands-on with the Photoelectric Effect.

    ERIC Educational Resources Information Center

    Gipps, John

    1993-01-01

    Provides an historical chronology of events related to understanding the photoelectric effect. Focuses on the early history, the mystery of the photoelectric effect, the contributions of Albert Einstein and Robert Millikan to the field, and hands-on activities that demonstrate the phenomenon to students. (DDR)

  17. Mechanical analysis of photo-electricity measure equipment shafting in mobile-platform

    NASA Astrophysics Data System (ADS)

    Jiang, Weiwei; Hu, Hongyi; Tan, Yi; Liu, Ruzhen

    2015-02-01

    Along with the development of technology, photo-electricity measure equipment has been from ground-fixed to mobile-platform borne, So it is need to mechanical analysis of shafting for adapt movement environment of mobile-platform. First listed three kinds of shafting form, then analysis mechanical station of the foremost component bearing in vertical load, radial load, swing load station, last work out the formulas, which was the theory for the shafting design in mobile-platforms photo-electricity equipment.

  18. BINARY STAR SYNTHETIC PHOTOMETRY AND DISTANCE DETERMINATION USING BINSYN

    SciTech Connect

    Linnell, Albert P.; DeStefano, Paul; Hubeny, Ivan E-mail: pdestefa@uw.edu

    2013-09-15

    This paper extends synthetic photometry to components of binary star systems. The paper demonstrates accurate recovery of single star photometric properties for four photometric standards, Vega, Sirius, GD153, and HD209458, ranging over the HR diagram, when their model synthetic spectra are placed in fictitious binary systems and subjected to synthetic photometry processing. Techniques for photometric distance determination have been validated for all four photometric standards.

  19. VizieR Online Data Catalog: Photometry of Cepheids in Magellanic Clouds (Moffett+ 1998)

    NASA Astrophysics Data System (ADS)

    Moffett, T. J.; Gieren, W. P.; Barnes, T. G., III; Gomez, M.

    2000-09-01

    In this paper we present the new photometric data, demonstrate the consistency among the data obtained from CCD and aperture photometry, and determine improved periods for all of the variables. In follow-up papers we will use these observations to determine individual Cepheid distances and radii from the visual surface brightness technique and also from the infrared surface brightness technique (Welch 1994AJ....108.1421W; Fouque & Gieren 1997A&A...320..799F). Table 1 gives our final photometric results. All entries in Table 1 having B magnitudes are CCD observations (CTIO), and the ones lacking B magnitudes are photoelectric observations (ESO). The uncertainties in the CCD results are dominated by the uncertainty in the aperture correction. The standard deviation in the comparison stars on a particular image is typically +/-0.004 mag and always less than +/-0.01 mag. The aperture correction to the zero point of each frame is estimated to be better than +/-0.01 mag. We adopt +/-0.01 mag as the typical uncertainty in all magnitudes. For the photoelectric observations, we inferred the uncertainties from scatter in the observations of the Cepheids themselves, finding +/-0.010 mag in V and +/-0.012 mag in R and I. We combined our new photometry with existing photoelectric photometry from the literature to determine a new period for each Cepheid. This was greatly aided by the McMaster Cepheid Data Archive maintained by Doug Welch at http://www.physics.mcmaster.ca/Cepheid/. (The data reported here will be added to the McMaster archive.) Periods were found using an algorithm due to T. Deeming given in Bopp et al. (1970MNRAS.147..355B) and are listed in Table 2. The uncertainty of each period is reflected in the number of digits given in the table. For most of the Cepheids in our sample, the new periods lead to excellent light curves of very low scatter, which indicates that the periods for these variables are both correct and stable over the time of our observations. For

  20. VizieR Online Data Catalog: UBVRI photometry of faint field stars (Skiff, 2007)

    NASA Astrophysics Data System (ADS)

    Skiff, B. A.

    2007-03-01

    This file, originally prepared for the needs of the Lowell Observatory Near-Earth Object Search (LONEOS), contains a rough working collection of Johnson-Cousins UBVRI photometry assembled mainly from the published literature or from publicly available datasets. The V-R and V-I colors are all on the Cousins system. Most of the stars are fainter than V=10.0; the median magnitude is V=13.9, and significant numbers of stars are listed below 20mag. Besides several large surveys, several hundred small sequences in the regions of variable stars, star clusters, galaxies hosting supernovae, quasars, etc were built by determining coordinates for the sequence stars using the published finder charts. At minimum the data include V magnitudes and at least one ordinary photometric color, most commonly B-V. The data were collected for use in determining approximate photometric zero-points in wide-field imaging, with external accuracy of 0.05 mag or better. Though each dataset was vetted for consistency in magnitude and colors, neither high accuracy nor high precision is guaranteed. Obvious variable stars were omitted, but some unknown variables are inevitably included. In any given field, it is advisable use all the available stars for calibration rather than a single comparison. Several large datasets are included. The Guide Star Photometric Catalogue (GSPC, Lasker et al 1988, Cat. II/143) provides BV sequences near the centers of all the Schmidt sky survey plates. At high latitudes in the southern sky, additional data on the 5-degree Schmidt grid were obtained by Platais et al (1998, Cat. I/277) that extend the GSPC sequences to V=~16. More southern fields were observed by Demers et al (1993A&AS...99..437D and 1993A&AS...99..461D); coordinates for these stars have been determined for the first time. Nearly a thousand high-quality sequences in the northern sky have been observed by Henden, partly published in relation to work on cataclysmic variables (e.g. Cat. J/PASP/107

  1. Recent Advances in Video Meteor Photometry

    NASA Technical Reports Server (NTRS)

    Swift, Wesley R.; Suggs, Robert M.; Meachem, Terry; Cooke, William J.

    2003-01-01

    One of the most common (and obvious) problems with video meteor data involves the saturation of the output signal produced by bright meteors, resulting in the elimination of such meteors from photometric determinations. It is important to realize that a "bright" meteor recorded by intensified meteor camera is not what would be considered "bright" by a visual observer - indeed, many Generation II or III camera systems are saturated by meteors with a visual magnitude of 3, barely even noticeable to the untrained eye. As the relatively small fields of view (approx.30 ) of the camera systems captures at best modest numbers of meteors, even during storm peaks, the loss of meteors brighter than +3 renders the determination of shower population indices from video observations even more difficult. Considerable effort has been devoted by the authors to the study of the meteor camera systems employed during the Marshall Space Flight Center s Leonid ground-based campaigns, and a calibration scheme has been devised which can extend the useful dynamic range of such systems by approximately 4 magnitudes. The calibration setup involves only simple equipment, available to amateur and professional, and it is hoped that use of this technique will make for better meteor photometry, and move video meteor analysis beyond the realm of simple counts.

  2. BVRI CCD photometry of Omega Centauri

    NASA Astrophysics Data System (ADS)

    Alcaino, Gonzalo; Liller, William

    1987-12-01

    The authors present the first CCD, BVRI main-sequence photometry for ω Cen, matched to the new BVRI isochrones of VandenBerg and Bell (1985). Their main conclusions are: (1) The main-sequence turnoffs as seen in the several colors are found to be at VTO = 18.3±0.15; the MSTO color indexes are at: B-V = 0.55±0.03, V-I = 0.73±0.03, and B-I = 1.28±0.03. (2) The magnitude difference between the main-sequence turnoff and the horizontal branch is ΔMV = 3.80±0.15, as derived from the color-magnitude diagrams. (3) The authors deduce a consistent age for ω Cen in all three color-magnitude diagrams of 17±1.5 Gyr. (4) The large scatter among the main-sequence stars demonstrates that the chemical inhomogeneity of about |Fe/H| = ≡1 dex persists as well in the unevolved stars, hence suggesting the composition to be primordial.

  3. The HST Milky Way Stellar Photometry Archive

    NASA Astrophysics Data System (ADS)

    Radburn-Smith, David

    2012-10-01

    The Hubble Legacy Archive has invested a significant effort into automatically generating photometry for point sources in all HST observations regardless of the target. We estimate that this archive contains up to 800,000 Milky Way {MW} stars, distributed across the whole sky, complete to some three magnitudes fainter than SDSS. Approximately half of these stars have color information, which is required for stellar population analysis. This considerable archive is thus in need of collation, analysis, and publication.Here we propose to compile such a catalog for public access and to use it for two science goals: 1} A test of existing MW stellar models, where we will in particular constrain the fainter and more distant stellar populations; and 2} Probe the shape and structure of the MW stellar halo with a deeper star catalog than is currently available. These science cases will be used to fully define the catalog, in particular by assessing the different populations present in the observations, and by assessing the level of noise from contaminants and the completeness of the survey

  4. BVRI PHOTOMETRY OF 53 UNUSUAL ASTEROIDS

    SciTech Connect

    Ye, Q.-Z.

    2011-02-15

    We present the results of BVRI photometry and classification of 53 unusual asteroids, including 35 near-Earth asteroids (NEAs), 6 high eccentricity/inclination asteroids, and 12 recently identified asteroid-pair candidates. Most of these asteroids were not classified prior to this work. For the few asteroids that have been previously studied, the results are generally in agreement. In addition to observing and classifying these objects, we merge the results from severalphotometric/spectroscopic surveys to create the largest-ever sample with 449 spectrally classified NEAs for statistical analysis. We identify a 'transition point' of the relative number of C/X-like and S-like NEAs at H {approx} 18 {r_reversible} D {approx} 1 km with confidence level at {approx}95% or higher. We find that the C/X-like:S-like ratio for 18 {<=} H < 22 is about twice as high as that of H < 18 (0.33 {+-} 0.04 versus 0.17 {+-} 0.02), virtually supporting the hypothesis that smaller NEAs generally have less weathered surfaces (therefore less reddish appearance) due to younger collision ages.

  5. BVI CCD photometry of 47 Tucanae

    SciTech Connect

    Alcaino, G.; Liller, W.

    1987-08-01

    CCD BVI main-sequence photometry of 47 Tuc is presented, matched to the recent BVI isochrones of VandenBerg and Bell (1985). The main-sequence turnoffs are found to be at V = 17.60 + or - 0.1, B-V = 0.56 + or - 0.02; V-I = 0.68 + or - 0.02, and B-I = 1.24 + or - 0.02. The magnitude difference between the main-sequence turnoff and the horizontal branch is 3.55 + or - 0.15 for all three color indices. A consistent age for 47 Tuc of 17 Gyr and a consistent distance modulus of (m-M)v = 13.2 are obtained for all three indices, and an absolute magnitude of Mv = 0.85 is determined for the horizontal branch stars. The results also favor the adoption of (Fe/H) near -0.5 as the best abundance value for 47 Tuc. 38 references.

  6. Time series photometry and starspot properties

    NASA Astrophysics Data System (ADS)

    Oláh, Katalin

    2011-08-01

    Systematic efforts of monitoring starspots from the middle of the XXth century, and the results obtained from the datasets, are summarized with special focus on the observations made by automated telescopes. Multicolour photometry shows correlations between colour indices and brightness, indicating spotted regions with different average temperatures originating from spots and faculae. Long-term monitoring of spotted stars reveals variability on different timescales. On the rotational timescale new spot appearances and starspot proper motions are followed from continuous changes of light curves during subsequent rotations. Sudden interchange of the more and less active hemispheres on the stellar surfaces is the so called flip-flop phenomenon. The existence and strength of the differential rotation is seen from the rotational signals of spots being at different stellar latitudes. Long datasets, with only short, annual interruptions, shed light on the nature of stellar activity cycles and multiple cycles. The systematic and/or random changes of the spot cycle lengths are discovered and described using various time-frequency analysis tools. Positions and sizes of spotted regions on stellar surfaces are calculated from photometric data by various softwares. From spot positions derived for decades, active longitudes on the stellar surfaces are found, which, in case of synchronized eclipsing binaries can be well positioned in the orbital frame, with respect to, and affected by, the companion stars.

  7. BVRI photometry of DQ Herculis in 2014

    NASA Astrophysics Data System (ADS)

    Dmitrienko, E. S.; Ibragimov, M. A.; Savanov, I. S.; Satovskii, B. L.; Egamberdiev, Sh. A.; Burkhanov, O. A.

    2015-09-01

    The results of BV RI photometry of the nova DQ Her 1934 performed at the Maidanak Observatory of the Astronomical Institute of the Uzbek Academy of Sciences in October 2014 are presented. The system's brightness, the out-of-eclipse color indices, and the shape of the minima in the BV RI light curves, which are due to eclipses of the white dwarf with its accreting disk-like envelope by the red dwarf, correspond to one of the lowest activity levels observed during the system's deepest relaxation after a nova outburst. The orbital-phase variations of the color indices indicate the presence of a considerably non-uniform brightness distribution for light coming from the disk-like envelope and other gaseous structures of DQ Her, which are observed at orbital phases of 0.85-1.15. The results can be qualitatively interpreted in a picture in which the gas flow structure is formed during mass exchange in an intermediate polar. The behavior found for the color indices could be due, for example, to the visibility in this phase interval of the passage of regions of shocks (tidal shocks, a hot line, and/or a detached shock) through the line of sight.

  8. NEW UBVRI PHOTOMETRY OF 234 M33 STAR CLUSTERS

    SciTech Connect

    Ma Jun

    2013-04-15

    This is the second paper of our series. In this paper, we present UBVRI photometry for 234 star clusters in the field of M33. For most of these star clusters, there is photometry in only two bands in previous studies. The photometry of these star clusters is performed using archival images from the Local Group Galaxies Survey, which covers 0.8 deg{sup 2} along the major axis of M33. Detailed comparisons show that, in general, our photometry is consistent with previous measurements, and in particular that our photometry is in good agreement with that of Zloczewski and Kaluzny. Combined with star cluster photometry in previous studies, we present some results: none of the M33 youngest clusters ({approx}10{sup 7} yr) have masses approaching 10{sup 5} M{sub Sun }, and comparisons with models of simple stellar populations suggest a large range of ages for M33 star clusters and some as old as the Galactic globular clusters.

  9. FIXING THE U-BAND PHOTOMETRY OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Krisciunas, Kevin; Bastola, Deepak; Suntzeff, Nicholas B.; Espinoza, Juan; Gonzalez, David; Gonzalez, Luis; Gonzalez, Sergio; Hsiao, Eric Y.; Morrell, Nidia; Phillips, Mark M.; Hamuy, Mario E-mail: suntzeff@physics.tamu.edu E-mail: hsiao@lco.cl E-mail: mmp@lco.cl

    2013-01-01

    We present previously unpublished photometry of supernovae 2003gs and 2003hv. Using spectroscopically derived corrections to the U-band photometry, we reconcile U-band light curves made from imagery with the Cerro Tololo 0.9 m, 1.3 m, and Las Campanas 1 m telescopes. Previously, such light curves showed a 0.4 mag spread at one month after maximum light. This gives us hope that a set of corrected ultraviolet light curves of nearby objects can contribute to the full utilization of rest-frame U-band data of supernovae at redshift {approx}0.3-0.8. As pointed out recently by Kessler et al. in the context of the Sloan Digital Sky Survey supernova search, if we take the published U-band photometry of nearby Type Ia supernovae at face value, there is a 0.12 mag U-band anomaly in the distance moduli of higher redshift objects. This anomaly led the Sloan survey to eliminate from their analyses all photometry obtained in the rest-frame U-band. The Supernova Legacy Survey eliminated observer frame U-band photometry, which is to say nearby objects observed in the U-band, but they used photometry of high-redshift objects no matter in which band the photons were emitted.

  10. Dithering Strategies and Point-Source Photometry

    SciTech Connect

    Samsing, Johan; Kim, Alex G

    2011-02-22

    The accuracy in the photometry of a point source depends on the point-spread function (PSF), detector pixelization, and observing strategy. The PSF and pixel response describe the spatial blurring of the source, the pixel scale describes the spatial sampling of a single exposure, and the observing strategy determines the set of dithered exposures with pointing offsets from which the source flux is inferred. In a wide-field imaging survey, sources of interest are randomly distributed within the field of view and hence are centered randomly within a pixel. A given hardware configuration and observing strategy therefore have a distribution of photometric uncertainty for sources of fixed flux that fall in the field. In this article we explore the ensemble behavior of photometric and position accuracies for different PSFs, pixel scales, and dithering patterns. We find that the average uncertainty in the flux determination depends slightly on dither strategy, whereas the position determination can be strongly dependent on the dithering. For cases with pixels much larger than the PSF, the uncertainty distributions can be non-Gaussian, with rms values that are particularly sensitive to the dither strategy. We also find that for these configurations with large pixels, pointings dithered by a fractional pixel amount do not always give minimal average uncertainties; this is in contrast to image reconstruction for which fractional dithers are optimal. When fractional pixel dithering is favored, a pointing accuracy of better than {approx}0.15 {approx}0.15 pixel width is required to maintain half the advantage over random dithers.

  11. Multicolor surface photometry of powerful radio galaxies

    SciTech Connect

    Smith, E.P.

    1988-01-01

    CCD images of 72 powerful radio galaxies have been obtained with the KPNO 2.1m, 4m and CTIO 4m telescopes utilizing B, V, and R filters to study the colors and other photometric properties of these large systems. The GASP software package was used for the data reduction and detailed 2-d surface photometry. In addition, image modeling techniques were employed to investigate the contributions to galaxy properties by point-like nuclear sources seen in some of these galaxies. It was found that powerful radio galaxies show a much higher frequency than normal bright ellipticals of having optical morphologies which deviate from elliptical symmetry. Approximately 50% of the sample exhibit non-elliptically symmetric isophotes. These prominent distortions are present at surface brightness levels of {le} 25 V mag/(arc sec){sup 2}. In addition, a large fraction ({approximately}50%) of the remaining radio galaxies without the aforementioned morphological peculiarities have large isophotal twists ({Delta}P.A. {ge} 10{degree}) or ellipticity gradients. Significantly {approximately}50% of the galaxies with strong optical emission lines in their spectra display optically peculiar structures very similar to those found by Toomre and Toomre (1972) in their simulations of interacting disk galaxies. The galaxies with weak emission lines in their spectra are less frequently ({approximately}10%) distorted from elliptical shape. Those that are exhibit features like isophote twists, double nuclei and close companion galaxies embedded in the radio galaxy optical isophotes. The (B-V) colors of many of the powerful radio galaxies with strong emission lines are blue relative to normal giant ellipticals at the same redshift.

  12. Effect of temperature on carbon nanoparticle collection efficiency using photoelectric ESP.

    PubMed

    Kim, Woojin; Jung, Jae Hee; Song, Dong Keun; Kim, Hakjoon; Kim, Yong Jin; Kim, Sang Soo

    2009-03-01

    The electrostatic precipitator (ESP) technique is a promising method for enhancing the particulate matter (PM) emission reduction efficiency of diesel engines, and is much better than the diesel particulate filter (DPF) technique. However, the ESP's low efficiency in collecting PM with diameters less than several tens of nanometers remains a problem because the particle charging efficiency decreases as the size of the nanoparticles decreases. To improve the collection efficiency of nanosized PM, we used a photoelectric charger to increase the charging efficiency of nanoparticles ahead of the ESP system. Carbon nanoparticles produced using a spark discharge generator were used to evaluate the collection efficiency of the combined photoelectric charger and ESP system. The particle sizes were measured using a scanning mobility particle sizer system at various experimental temperatures similar to the temperature of DPF systems commonly used in diesel engines. We succeeded in obtaining improved collection efficiencies at increased inner temperatures of the photoelectric charging chamber. As the temperature increased from 694 degrees C to 839 degrees C at the inlet of the photoelectric chamber, the efficiency of PM collection improved significantly to 28.5% for a particle diameter of 18.4 nm. PMID:19157512

  13. [Vision engineering--photoelectric dye-based retinal prostheses: Okayama University model].

    PubMed

    Matsuo, Toshihiko

    2007-04-01

    Patients with retinitis pigmentosa lose photoreceptor cells by genetic abnormalities and hence become blind. Neurons such as bipolar cells and ganglion cells still remain alive even in the retina of these patients, and ganglion cells send axons to the brain as the optic nerve. The replacement of dead photoreceptor cells with something artificial is the basic concept of retinal prostheses. The remaining retinal neurons can be stimulated by either electric current or electric potential. Photodiode array and electrode array are two main ways to stimulate retinal neurons as retinal prostheses. These retinal prostheses have problems such as low sensitivity and requiring outer electric sources (batteries). To overcome the problems, we are developing photoelectric dye-based retinal prostheses which absorb light and convert photon energy to electric potentials. The prototype, photoelectric dye-coupled polyethylene film, could generate intracellular calcium elevation in photoreceptor-lacking retinal tissues and also in cultured retinal neurons. The photoelectric dye-based retinal prostheses are thin and soft, and therefore, a sheet of the film in a large size, corresponding to wide visual field, can be inserted into the vitreous and then to the subretinal space through a small opening by rolling up the film. After the production control and the quality control have been established, clinical trials of the photoelectric dye-based retinal prostheses would be planned in concordance with the Drugs and Medical Devices Law to prove the safety and the efficacy. PMID:17447519

  14. Measurement of K Shell Photoelectric Cross Sections at a K Edge--A Laboratory Experiment

    ERIC Educational Resources Information Center

    Nayak, S. V.; Badiger, N. M.

    2007-01-01

    We describe in this paper a new method for measuring the K shell photoelectric cross sections of high-Z elemental targets at a K absorption edge. In this method the external bremsstrahlung (EB) photons produced in the Ni target foil by beta particles from a weak[superscript 90]Sr-[superscript 90]Y beta source are passed through an elemental target…

  15. Photoelectric Emission Measurements on the Analogs of Individual Cosmic Dust Grains

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Tankosic, D.; Craven, P. D.; Spann, J. F.; LeClair, A.; West, E. A.; Weingartner, J. C.; Tielens, A. G. G. M.; Nuth, J. a.; Camata, R. P.

    2006-01-01

    The photoelectric emission process is considered to be the dominant mechanism for charging of cosmic dust grains in many astrophysical environments. The grain charge and equilibrium potentials play an important role in the dynamical and physical processes that include heating of the neutral gas in the interstellar medium, coagulation processes in the dust clouds, and levitation and dynamical processes in the interplanetary medium and planetary surfaces and rings. An accurate evaluation of photoelectric emission processes requires knowledge of the photoelectric yields of individual dust grains of astrophysical composition as opposed to the values obtained from measurements on flat surfaces of bulk materials, as it is generally assumed on theoretical considerations that the yields for the small grains are much different from the bulk values. We present laboratory measurements of the photoelectric yields of individual dust grains of silica, olivine, and graphite of approx. 0.09-5 micrometer radii levitated in an electrodynamic balance and illuminated with ultraviolet radiation at 120-160 nm wavelengths. The measured yields are found to be substantially higher than the bulk values given in the literature and indicate a size dependence with larger particles having order-of-magnitude higher values than for submicron-size grains.

  16. Photoelectric UBVRI sequences in the Galactic globular clusters NGC 6752 and NGC 6864

    SciTech Connect

    Alvarado, F.; Wenderoth, E.; Alcaino, G.; Liller, W. )

    1990-05-01

    UBVRI photoelectric sequences for the Galactic globular clusters NGC 6752 and NGC 6864 are presented. Both of them include fields suitable for CCD exposures. From five UBV sequences in NGC 6572, only five stars are in common with the previous works. 15 refs.

  17. The Photoelectric Effect: Experimental Confirmation Concerning a Widespread Misconception in the Theory

    ERIC Educational Resources Information Center

    Wong, Darren; Lee, Paul; Shenghan, Gao; Xuezhou, Wang; Qi, Huan Yan; Kit, Foong See

    2011-01-01

    The photoelectric effect is widely taught in schools and institutions. It is common knowledge that in order for photoelectrons to be emitted, the energy of the incoming photons must be greater than the work function of the irradiated metal (i.e. hv greater than [phi][subscript emitter]). However, what may not be as commonly known is that the…

  18. Reconstruction of the History of the Photoelectric Effect and Its Implications for General Physics Textbooks

    ERIC Educational Resources Information Center

    Niaz, Mansoor; Klassen, Stephen; McMillan, Barbara; Metz, Don

    2010-01-01

    The photoelectric effect is an important part of general physics textbooks. To study the presentation of this phenomenon, we have reconstructed six essential, history and philosophy of science (HPS)-related aspects of the events that culminated in Einstein proposing his hypothesis of lightquanta and the ensuing controversy within the scientific…

  19. Extreme Sensitivity of Room-Temperature Photoelectric Effect for Terahertz Detection.

    PubMed

    Huang, Zhiming; Zhou, Wei; Tong, Jinchao; Huang, Jingguo; Ouyang, Cheng; Qu, Yue; Wu, Jing; Gao, Yanqing; Chu, Junhao

    2016-01-01

    Extreme sensitivity of room-temperature photoelectric effect for terahertz (THz) detection is demonstrated by generating extra carriers in an electromagnetic induced well located at the semiconductor, using a wrapped metal-semiconductor-metal configuration. The excellent performance achieved with THz detectors shows great potential to open avenues for THz detection. PMID:26542882

  20. The influence of mobile impurities on photoelectric properties of PbSe-based multiphase photosensitive structures

    NASA Astrophysics Data System (ADS)

    Belenkov, A. N.; Davydov, V. V.; Boyko, S. B.; Petrovskaya, Z. N.; Karseev, A. Yu

    2015-11-01

    The PbSe-based photoelectric sensor technology is considered. The polycrystalline PbSe films are used for the production. The influence of mobile impurities in a material on the mechanism of the photovoltaic effect is revealed and investigated. The experimental results of investigation of the photovoltaic effect are discussed.

  1. Experiments on the Photoelectric Effect and on the Diffusion of Electrons in Gases

    ERIC Educational Resources Information Center

    McClellan, G.; And Others

    1978-01-01

    Describes an apparatus for investigating the behavior of photoelectrons in a uniform magnetic field in either a vacuum or a low-pressure gas. Presents data and discusses some basic features of the photoelectric effect and the diffusion of free electrons in a gas. (GA)

  2. Thought waves remotely affect the performance (output voltage) of photoelectric cells

    NASA Astrophysics Data System (ADS)

    Cao, Dayong; Cao, Daqing

    2012-02-01

    In our experiments, thought waves have been shown to be capable of changing (affecting) the output voltage of photovoltaic cells located from as far away as 1-3 meters. There are no wires between brain and photoelectric cell and so it is presumed only the thought waves act on the photoelectric cell. In continual rotations, the experiments tested different solar cells, measuring devices and lamps, and the experiments were done in different labs. The first experiment was conducted on Oct 2002. Tests are ongoing. Conclusions and assumptions include: 1) the slow thought wave has the energy of space-time as defined by C1.00007: The mass, energy, space and time systemic theory- MEST. Every process releases a field effect electrical vibration which be transmitted and focussed in particular paths; 2) the thought wave has the information of the order of tester; 3) the brain (with the physical system of MEST) and consciousness (with the spirit system of the mind, consciousness, emotion and desire-MECD) can produce the information (a part of them as the Genetic code); 4) through some algorithms such as ACO Ant Colony Optimization and EA Evolutionary Algorithm (or genetic algorithm) working in RAM, human can optimize the information. This Optimizational function is the intelligence; 5) In our experiments, not only can thought waves affect the voltage of the output photoelectric signals by its energy, but they can also selectively increase or decrease those photoelectric currents through remote consciousness interface and a conscious-brain information technology.

  3. Revised Filter Profiles and Zero Points for Broadband Photometry

    NASA Astrophysics Data System (ADS)

    Mann, Andrew W.; von Braun, Kaspar

    2015-02-01

    Estimating accurate bolometric fluxes for stars requires reliable photometry to absolutely flux calibrate the spectra. This is a significant problem for studies of very bright stars, which are generally saturated in modern photometric surveys. Instead we must rely on photometry with less precise calibration. We utilize precisely flux-calibrated spectra to derive improved filter bandpasses and zero points for the most common sources of photometry for bright stars. In total, we test 39 different filters in the General Catalog of Photometric Data as well as those from Tycho-2 and Hipparcos. We show that utilizing inaccurate filter profiles from the literature can create significant color terms resulting in fluxes that deviate by gsim10% from actual values. To remedy this we employ an empirical approach; we iteratively adjust the literature filter profile and zero point, convolve it with catalog spectra, and compare to the corresponding flux from the photometry. We adopt the passband values that produce the best agreement between photometry and spectroscopy and are independent of stellar color. We find that while most zero points change by < 5%, a few systems change by 10-15%. Our final profiles and zero points are similar to recent estimates from the literature. Based on determinations of systematic errors in our selected spectroscopic libraries, we estimate that most of our improved zero points are accurate to 0.5-1%.

  4. Correlating Total Visual Magnitude Estimates and CCD Photometry for Comets

    NASA Astrophysics Data System (ADS)

    Kidger, Mark Richard

    2015-08-01

    A key facet of understanding the activity of comets is coverage of their light curve. For some comets such as 2P/Encke there is good light curve coverage from visual observers extending back over many returns over more than 2 centuries. However, in recent years, CCD photometry by amateur astronomers has become the dominant data source and the number of total visual magnitude estimates has reduced sharply, making comparison of recent and historical photometric data for comets increasingly difficult. The relationship between total visual magnitude estimates - dominated by the emission from the Swan bands of C2 - and CCD aperture photometry - dominated by the dust continuum - has been far from clear.This paper compares CCD aperture photometry and total visual magnitude for several recent well-observed bright comets, including C/2014 Q2 (Lovejoy), C/2012 S1 (ISON) and C/2011 L4 (PanSTARRS) using a consistent and homogeneous database of observations from (mainly) Spanish observers. For comets with a 1/r radial coma profile, good agreement is found between CCD aperture photometry and total visual magnitude estimates for a CCD aperture corresponding to a physical coma diameter of ≈105km.The relationship between the coma radial brightness slope and the equivalent physical aperture for CCD photometry to obtain agreement with total visual magnitude estimates is investigated.

  5. Photometry of the young open cluster Trumpler 37

    SciTech Connect

    Marschall, L.A.; Karshner, G.B.; Comins, N.F. Main, Univ., Orono )

    1990-05-01

    Photoelectric UBV observations of 120 stars in the young open cluster Trumpler 37 are presented, primarily in the magnitude range 10.0 - 13.5. An analysis of the color-magnitude diagram of the cluster yields an age of 6.7 million yr and reveals the presence of a number of possible pre-main-sequence stars in the cluster. 24 refs.

  6. HST photometry of the trapezium cluster

    NASA Technical Reports Server (NTRS)

    Prosser, Charles F.; Stauffer, John R.; Hartmann, Lee; Soderblom, David R.; Jones, Burton F.; Werner, Michael W.; Mccaughrean, Mark J.

    1994-01-01

    We have obtained images of 11 fields in the Trapezium cluster with the Planetary Camera (PC) of the Hubble Space Telescope (HST) in order to extend Herbig & Terndrup's (1986) study of this prototype, dense embedded cluster to fainter magnitudes than is possible from the ground. Using these images, we have identified 319 stars within an area of approximately 12 sq arc min corresponding roughly to a volume of approximately 0.065 cu pc assuming the cluster is approximately spherically symmetric. Our completeness limits for star identification in V-band and I-band images are V approximately = 20 and I(sub c) approximately = 19 respectively, corresponding to a mass limit of approximately 0.15 solar mass if the faintest stars have the same average A(sub v) as that estimated for the brighter stars in the cluster. We have compared the V versus V-I color-magnitude diagram derived from the HST photometry to new theoretical isochrones. Star formation in the Trapezium appears to be remarkably coeval, with greater than or = 80% of the stars having inferred ages less than 1 Myr. Over the somewhat limited mass range of the observations, there is no evidence for 'bimodal' star formation-the high- and low-mass stars appear to have the same ages. The sharp cores of the HST images and the small angular size of the PC pixels has allowed us to identify 35 new visual binaries in the cluster with separations from approximately 0.06 arc sec (approximately 26 AU) to approximately 1.0 arc sec (approximately 440 AU). For the range of binary separations that we are sensitive to, the observed binary frequency for the Trapezium is essentially identical to that estimated for field low-mass stars by Duquennoy & Mayor (1991). The most straightfoward inference from this result is that binaries in this separation are unlikely to be formed by a tidal capture process. We have also identified three stars which have associated compact nebulosity visible in the HST images. One of these star + nebulosity

  7. Sub-terahertz microsecond optically controlled switch with GaAs active element beyond the photoelectric threshold

    NASA Astrophysics Data System (ADS)

    Kulygin, M.; Denisov, G.; Vlasova, K.; Andreev, N.; Shubin, S.; Salahetdinov, S.

    2016-01-01

    We study an unusual working regime of a recently developed sub-terahertz microwave cavity-based switch. The resonator cavity includes a semiconductor plate which is illuminated by laser emission beyond the photoelectric threshold. Despite a significant change to the conventional process of photoelectric effect we have found that the switch works. Typical switching performance rate is about 1 μs for the regime. A process of carrier density relaxation beyond the photoelectric threshold is discussed. An idea of diagnostic method for the semiconductor's quality is proposed.

  8. Sub-terahertz microsecond optically controlled switch with GaAs active element beyond the photoelectric threshold.

    PubMed

    Kulygin, M; Denisov, G; Vlasova, K; Andreev, N; Shubin, S; Salahetdinov, S

    2016-01-01

    We study an unusual working regime of a recently developed sub-terahertz microwave cavity-based switch. The resonator cavity includes a semiconductor plate which is illuminated by laser emission beyond the photoelectric threshold. Despite a significant change to the conventional process of photoelectric effect we have found that the switch works. Typical switching performance rate is about 1 μs for the regime. A process of carrier density relaxation beyond the photoelectric threshold is discussed. An idea of diagnostic method for the semiconductor's quality is proposed. PMID:26827338

  9. Division B Commission 25: Astronomical Photometry and Polarimetry

    NASA Astrophysics Data System (ADS)

    Walker, Alistair; Adelman, Saul; Milone, Eugene; Anthony-Twarog, Barbara; Bastien, Pierre; Chen, Wen Ping; Howell, Steve; Knude, Jens; Kurtz, Donald; Magalhães, Antonio Mario; Menzies, John; Smith, Allyn; Volk, Kevin

    2016-04-01

    Commission 25 (C25) deals with the techniques and issues involved with the measurement of optical and infrared radiation intensities and polarization from astronomical sources. As such, in recent years attention has focused on photometric standard stars, atmospheric extinction, photometric passbands, transformation between systems, nomenclature, and observing and reduction techniques. At the start of the trimester C25 changed its name from Stellar Photometry and Polarization to Astronomical Photometry and Polarization so as to explicitly include in its mandate particular issues arising from the measurement of resolved sources, given the importance of photometric redshifts of distant galaxies for many of the large photometric surveys now underway. We begin by summarizing commission activities over the 2012-2014 period, follow with a report on Polarimetry, continue with Photometry topics that have been of interest to C25 members, and conclude with a Vision for the Future.

  10. CCD Photometry of bright stars using objective wire mesh

    SciTech Connect

    Kamiński, Krzysztof; Zgórz, Marika; Schwarzenberg-Czerny, Aleksander

    2014-06-01

    Obtaining accurate photometry of bright stars from the ground remains problematic due to the danger of overexposing the target and/or the lack of suitable nearby comparison stars. The century-old method of using objective wire mesh to produce multiple stellar images seems promising for the precise CCD photometry of such stars. Furthermore, our tests on β Cep and its comparison star, differing by 5 mag, are very encouraging. Using a CCD camera and a 20 cm telescope with the objective covered by a plastic wire mesh, in poor weather conditions, we obtained differential photometry with a precision of 4.5 mmag per two minute exposure. Our technique is flexible and may be tuned to cover a range as big as 6-8 mag. We discuss the possibility of installing a wire mesh directly in the filter wheel.

  11. CCD Photometry of Bright Stars Using Objective Wire Mesh

    NASA Astrophysics Data System (ADS)

    Kamiński, Krzysztof; Schwarzenberg-Czerny, Aleksander; Zgórz, Marika

    2014-06-01

    Obtaining accurate photometry of bright stars from the ground remains problematic due to the danger of overexposing the target and/or the lack of suitable nearby comparison stars. The century-old method of using objective wire mesh to produce multiple stellar images seems promising for the precise CCD photometry of such stars. Furthermore, our tests on β Cep and its comparison star, differing by 5 mag, are very encouraging. Using a CCD camera and a 20 cm telescope with the objective covered by a plastic wire mesh, in poor weather conditions, we obtained differential photometry with a precision of 4.5 mmag per two minute exposure. Our technique is flexible and may be tuned to cover a range as big as 6-8 mag. We discuss the possibility of installing a wire mesh directly in the filter wheel.

  12. Photoelectric-enhanced radiation therapy with quasi-monochromatic computed tomography

    SciTech Connect

    Jost, Gregor; Mensing, Tristan; Golfier, Sven; Lawaczeck, Ruediger; Pietsch, Hubertus; Huetter, Joachim; Cibik, Levent; Gerlach, Martin; Krumrey, Michael; Fratzscher, Daniel; Arkadiev, Vladimir; Wedell, Reiner; Haschke, Michael; Langhoff, Norbert; Wust, Peter; Luedemann, Lutz

    2009-06-15

    Photoelectric-enhanced radiation therapy is a bimodal therapy, consisting of the administration of highly radiation-absorbing substances into the tumor area and localized regional irradiation with orthovoltage x-rays. Irradiation can be performed by a modified computed tomography (CT) unit equipped with an additional x-ray optical module which converts the polychromatic, fan-shaped CT beam into a monochromatized and focused beam for energy-tuned photoelectric-enhanced radiotherapy. A dedicated x-ray optical module designed for spatial collimation, focusing, and monochromatization was mounted at the exit of the x-ray tube of a clinical CT unit. Spectrally resolved measurements of the resulting beam were performed using an energy-dispersive detection system calibrated by synchrotron radiation. The spatial photon fluence was determined by film dosimetry. Depth-dose measurements were performed and compared to the polychromatic CT and a therapeutic 6 MV beam. The spatial dose distribution in phantoms using a rotating radiation source (quasi-monochromatic CT and 6 MV, respectively) was investigated by gel dosimetry. The photoelectric dose enhancement for an iodine fraction of 1% in tissue was calculated and verified experimentally. The x-ray optical module selectively filters the energy of the tungsten K{alpha} emission line with an FWHM of 5 keV. The relative photon fluence distribution demonstrates the focusing characteristic of the x-ray optical module. A beam width of about 3 mm was determined at the isocenter of the CT gantry. The depth-dose measurements resulted in a half-depth value of approximately 36 mm for the CT beams (quasi-monochromatic, polychromatic) compared to 154 mm for the 6 MV beam. The rotation of the radiation source leads to a steep dose gradient at the center of rotation; the gel dosimetry yields an entrance-to-peak dose ratio of 1:10.8 for the quasi-monochromatic CT and 1:37.3 for a 6 MV beam of the same size. The photoelectric dose enhancement

  13. A Study of Dust Cloud Parameters by Vilnius Photometry

    NASA Astrophysics Data System (ADS)

    Smriglio, F.; Dasgupta, A. K.; Boyle, R. P.

    Three-dimensional classification of stars based on their seven-color CCD photometry in the Vilnius system has been succesfully applied to study the small scale structure of interstellar dust clouds. In the present paper the statistical equations of Munch are modified and applied to stars located beyond the galactic absorbing layer. This particular use of Munch's statistics and the properties of CCD photometry in the Vilnius system offer a better possibility of probing the small scale structure of interstellar medium outside of the solar vicinity. This new technique and the first results are discussed.

  14. The Structure of Galaxies I: Surface Photometry Techniques

    NASA Astrophysics Data System (ADS)

    Schombert, J.; Smith, A. K.

    2012-04-01

    This project uses the 2MASS all-sky image database to study the structure of galaxies over a range of luminosities, sizes and morphological types. This first paper in this series will outline the techniques, reliability and data products to our surface photometry program. Our program will analyze all acceptable galaxies (meeting our criteria for isolation from companions and bright stars) from the Revised Shapley-Ames and Uppsala galaxy catalogs. Resulting photometry and surface brightness profiles are released using a transparent scheme of data storage which includes not only all the processed data but knowledge of the processing steps and calibrating parameters.

  15. The spotted contact binary SS ARIETIS - Spectroscopy and infrared photometry

    NASA Astrophysics Data System (ADS)

    Rainger, P. P.; Bell, S. A.; Hilditch, R. W.

    1992-02-01

    The first infrared photometry for the W-UMa system SS Ari is presented. An analysis based on medium-resolution spectroscopy presented here shows that SS Ari is a W-type system with a mass ratio of 0.33. It seems certain that the asymmetry in the published light curves and those obtained for this study can be explained by the effect of spots on one or possibly both components of the system. The precise location, size and temperature of these spots require the use of Doppler Imaging techniques in conjunction with high-quality multiband photometry.

  16. A method for determining stellar parameters from multicolor photometry

    NASA Astrophysics Data System (ADS)

    Sichevskij, S. G.

    2012-09-01

    Amethod for determining the most probable spectral types, color excesses E B- V , and distances of stars from multicolor photometry is described. The main idea of the method is modeling the photometric data using various models for the stellar spectra and the interstellar extinction law, and applying the maximum likelihood method. The reliability of the method is estimated using stars with known spectral types and WBVR photometry, based on the empirical library of stellar spectra of Pickles and the model for the interstellar extinction law developed by Fluks et al.

  17. Galileo Photometry of Asteroid 951 Gaspra

    USGS Publications Warehouse

    Helfenstein, P.; Veverka, J.; Thomas, P.C.; Simonelli, D.P.; Lee, P.; Klaasen, K.; Johnson, T.V.; Breneman, H.; Head, J.W.; Murchie, S.; Fanale, F.; Robinson, M.; Clark, B.; Granahan, J.; Garbeil, H.; McEwen, A.S.; Kirk, R.L.; Davies, M.; Neukum, G.; Mottola, S.; Wagner, R.; Belton, M.; Chapman, C.; Pilcher, C.

    1994-01-01

    Galileo images of Gaspra make it possible for the first time to determine a main-belt asteroid's photometric properties accurately by providing surface-resolved coverage over a wide range of incidence and emission angles and by extending the phase angle coverage to phases not observable from Earth. We combine Earth-based telescopic photometry over phase angles 2?? ??? ?? ??? 25?? with Galileo whole-disk and disk-resolved data at 33?? ??? ?? ??? 51?? to derive average global photometric properties in terms of Hapke's photometric model. The microscopic texture and particle phase-function behavior of Gaspra's surface are remarkably like those of other airless rocky bodies such as the Moon. The macroscopic surface roughness parameter, ??̄ = 29??, is slightly larger than that reported for typical lunar materials. The particle single scattering albedo, ??́0 = 0.36 ?? 0.07, is significantly larger than for lunar materials, and the opposition surge amplitude, B0 = 1.63 ?? 0.07, is correspondingly smaller. We determine a visual geometric albedo pv = 0.22 ?? 0.06 for Gaspra, in close agreement with pv = 0.22 ?? 0.03 estimated from Earth-based observations. Gaspra's phase integral is 0.47, and the bolometric Bond albedo is estimated to be 0.12 ?? 0.03. An albedo map derived by correcting Galileo images with our average global photometric function reveals subdued albedo contrasts of ??10% or less over Gaspra's northern hemisphere. Several independent classification algorithms confirm the subtle spectral heterogeneity reported earlier (S. Mottola, M. DiMartino, M. Gonano-Beurer, H. Hoffman, and G. Neukum, 1993, Asteroids, Comets, Meteors, pp. 421-424; M. J. S. Belton et al., 1992, Science 257, 1647-1652). Whole-disk colors (0.41 ??? ?? ??? 0.99 ??m) vary systematically with longitude by about ??5%, but color differences as large as 30% occur locally. Colors vary continuously between end-member materials whose areal distribution correlates with regional topography. Infrared

  18. Infrared space observatory photometry of circumstellar dust in Vega-type systems

    NASA Technical Reports Server (NTRS)

    Fajardo-Acosta, S. B.; Stencel, R. E.; Backman, D. E.; Thakur, N.

    1998-01-01

    The ISOPHOT (Infrared Space Observatory Photometry) instrument onboard the Infrared Space Observatory (ISO) was used to obtain 3.6-90 micron photometry of Vega-type systems. Photometric data were calibrated with the ISOPHOT fine calibration source 1 (FCS1). Linear regression was used to derive transformations to make comparisons to ground-based and IRAS photometry systems possible. These transformations were applied to the photometry of 14 main-sequence stars. Details of these results are reported on.

  19. The photoelectric effect from CsI by polarized soft X-rays

    NASA Technical Reports Server (NTRS)

    Shaw, Ping S.; Church, Eric D.; Hanany, Shaul; Liu, Yee; Fleischman, Judith; Kaaret, Philip; Novick, Robert; Manzo, Giuseppe

    1991-01-01

    Studies of the polarization dependence of the photoelectric effect produced by soft X-rays from CsI indicate that the geometrical effects in these experiments can often mimic the polarization signature. This paper presents a detailed calculation of these geometrical effects that are produced when the X-ray beam is not precisely aligned on a rotatable plane photocathode. The experimentally observed geometrical effects were used to precisely determine the realignment of the incident beam of polarized X-rays on a rotatable photocathode. The results allow determinations of the true polarization dependence of the photoemission from CsI. It is shown that the photoelectric effect in CsI depends on the polarization state of the X-rays.

  20. Coronal transients in FE XIV 5303A: First two-dimensional photoelectric ground-based observations

    NASA Technical Reports Server (NTRS)

    Altrock, R. C.; Demastus, H. L.

    1983-01-01

    An observational program was undertaken at Sacramento Peak Observatory to photoelectrically detect coronal transients. Continuous observations are made in the Fe XIV 5303A green line, utilizing the 40 cm coronagraph and the Photoelectric Coronal Photometer. Scans at three heights above the limb are combined to form a low resolution picture of the greenline corona every 20 to 30 minutes. Difference pictures, relative to an initial scan, are generated to search for sudden changes in the corona. The first few days of operation of this program have yielded three low-lying events ( 1.55 solar radii) following minor chromospheric activity (a surge and eruptive prominences), which propagated up through the corona with velocities on the order of 100 km/s.

  1. A vehicle photoelectric detection system based on guidance of machine vision

    NASA Astrophysics Data System (ADS)

    Wang, Yawei; Liu, Yu; Chen, Wei; Chen, Jing; Guo, Jia; Zhou, Lijun; Zheng, Haotian; Zhang, Xuantao

    2015-04-01

    A vehicle photoelectric detection system based on guidance of machine vision is described in detail, which is composed of electric-optic turret, distributed perception module, position orientation system and data process terminal, etc. Simultaneously, a target detection method used in the system based on visual guide is also discussed in this paper. This method, based on the initial alignment of camera position and the precise alignment of target location, realizes the target acquisition and measurement by using the high-definition cameras of distributed perception module installed around the vehicle as the human eyes to guide the line of sight of optoelectronic devices on the turret to the field of view of one camera quickly and carry on small-scale target alignment operations. Simulation results show that the method could achieve the intelligent dynamic guide of photoelectric detection system, and improve the detection efficiency and accuracy.

  2. Ultraviolet fast-response photoelectric effects in LiTaO3 single crystal

    NASA Astrophysics Data System (ADS)

    Guo, Er-Jia; Xing, Jie; Lu, Hui-Bin; Jin, Kui-Juan; Wen, Juan; Yang, Guo-Zhen

    2010-01-01

    The photoelectric effects of LiTaO3 (LTO) single crystals are experimentally studied with two kinds of LTO wafers, 10° tilted and untilted, at room temperature. A transient open-circuit photoelectrical response of 143 ps rise time is observed in the 10° tilted LTO when a 266 nm pulsed laser with a duration of 25 ps is irradiated directly onto the LTO surface. The untilted LTO with interdigitated electrodes of 10 µm finger width and 10 µm interspacing exhibits a linear dependence on the applied bias and power density of incident light, a response peak at about 235 nm and a sharp cutoff at about 270 nm. The noise current is only 61 pA at 20 V bias under the illumination of sunlight outdoors at midday. The experimental results suggest the promising application of the LTO single crystal in UV detection, in particular, as a solar-blind fast-response photodetector.

  3. One-step electrochemical synthesis and photoelectric conversion of a ZnO/Se/RGO composite

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Zhang, Chunyan; Zhang, Shengyi; Niu, Helin; Song, Jiming; Mao, Changjie; Jin, Baokang; Tian, Yupeng

    2015-12-01

    Using Zn(NO3)2, H2SeO3 and graphene oxide as precursors, the zinc oxide/selenium/reduced graphene oxide (ZnO/Se/RGO) composite was facilely electrodeposited on the surface of indium tin oxide glass. The conditions for electrochemical synthesis such as electrodeposition potential and electrolyte composition were studied. The morphology and crystallization of the products as-prepared were characterized using scanning electron microscopy (SEM) and x-ray diffractometry (XRD) respectively. The light absorption and conductivity of the products were studied by UV-visible spectroscopy (UV-vis) and electrochemical impedance spectroscopy (EIS). Based on a series of experimental results, the photoelectrical conversion mechanism and effect factors of the products were explored. By means of synergistic action of n-type ZnO, p-type Se and conductive RGO, the ZnO/Se/RGO composite showed excellent photoelectric conversion under visible light irradiation.

  4. Comparison of glottal area changes as measured from ultrahigh-speed photographs and photoelectric glottographs.

    PubMed

    Harden, J

    1975-12-01

    To determine the relationship of information on glottal area function provided by deviations sensed by the photoelectric glottograph to that derived from a frame-by-frame analysis of ultrahigh-speed photographic film, simultaneous photographic and glottographic recordings were obtained from five subjects. From the investigation, the following results were obtained: (1) the measurements of the light deviations sensed by the photoelectric glottograph during laryngeal vibrations produced curves that approximated those developed from photographic film frame-by-frame measurements of the visual image in vocal fry, modal, and falsetto voice registers, and (2) the Fourier coefficients of the compared data indicated that there was no significant difference between the curves. PMID:1207103

  5. Electrical and photoelectric properties of nanostructures obtained by electroless etching of silicon

    SciTech Connect

    Bilenko, D. I. Galushka, V. V.; Jarkova, E. A.; Mysenko, I. B.; Terin, D. V.; Hasina, E. I.

    2011-07-15

    The electrical and photoelectric properties of nanostructures with porous silicon layers obtained by electroless etching of silicon have been investigated. It is found that the photoelectric and photovoltaic properties of these structures depend on their morphology and are determined by not only the properties of the modified layer, but also the presence of possible barriers in the layered porous silicon. The ratio of the photoconductivity to the dark conductivity reached 10{sup 2}-5 Multiplication-Sign 10{sup 2}. An open-circuit voltage V{sub oc} was detected that amounted to {approx}250 mV at an incident light power close to AM-1 ({approx}100 mW/cm{sup 2}). In this case, the density of short-circuit current I{sub sc} was about 20 {mu}A/cm{sup 2}.

  6. Research on the real-time calibration of the varifocal photoelectric imaging system

    NASA Astrophysics Data System (ADS)

    Zhou, Bing; Huang, Fu-yu; Chen, Yu-dan

    2012-11-01

    A real-time system for optical axis of the varifocal photoelectric reconnaissance and tracking system is designed in this paper. Two images are acquired by the DSP processing system before and after zooming the focal length, and the varifocal and shifting coefficients are calculated real-timely through extracting the feature points and affine transform, etc, while the rotation coefficient equals to zero basically. The shifting parameter can be used to calibrate the optical axis, and its calibration precision is less than one pixel. The system can reduce the requirement of mechanical processing technology and mechanical tolerance greatly in the production procedure of the photoelectric reconnaissance and tracking system with a long focal length, and can make the system easer to implement.

  7. Some features of the electrophysical and photoelectric properties of MOS structures

    SciTech Connect

    Loskutova, E.A.; Davydov, V.N.; Lezina, T.D.

    1985-11-01

    Indium arsenide appears to be a promising material for creating microelectronic devices. The authors of this article maintain that the electrophysical characteristics of the InAs MOS structures have been insufficiently studied in comparison with those of the other III-V compounds and that there is practically no knowledge of photoelectric characteristics for these MOS structures. Noted is the presence of intense interaction processes of free carriers with states in the anodic oxide film (AOF) and at the AOF-InAs interface which to a substantial degree determine the form of the electrophysical and photoelectric characteristics of the structures and their behavior with a change of the measurement conditions. It is proposed that the mechanism for carrier generation and recombination in the structure is multistep Shockley-Read-Hall processes with participation of multiply charged centers.

  8. A novel method for measuring K-shell photoelectric parameters of high-Z elements

    NASA Astrophysics Data System (ADS)

    Nayak, S. V.; Badiger, N. M.

    2006-06-01

    The K-shell jump ratio, jump factor and the ratio of total to K-shell photoelectric cross section at K edge have been determined for Hf, Ta, Au and Pb by adopting a novel method. In this method, continuous external bremsstrahlung (EB) photons are produced in a thin nickel elemental converter by beta particles from a 90Sr-90Y weak beta source. The spectrum of EB photons transmitted through the elemental targets of Hf, Ta, Au and Pb is recorded with an HPGe detector coupled to an 8K multichannel analyser. The transmitted spectrum shows a sharp decrease in intensity at the K-shell binding energy of the target atom. The region of sharp decrease is fitted to a sigmoidal function and the K-shell jump ratio, jump factor and the ratio of total to the K-shell photoelectric cross section at K edge are determined. The measured values are compared with the theoretical values.

  9. High precision relative attitude measurement for inner payload of new photoelectric platform

    NASA Astrophysics Data System (ADS)

    Wang, Y. Y.; Wang, L.; Bai, X. G.; Ma, T. W.; Dai, M.

    2016-03-01

    A new method for measuring the relative attitude of a load on an airborne photoelectric platform supported by three-axis universal joint structure is proposed. The mathematical model for angle measurement is established, based on which the linear relation between the angle and distance is derived by using the eccentric method. Furthermore, the relative attitude measurement method for a load rotating along the yaw and pitch directions is also proposed based on a unique eccentric structure. Finally, to validate the proposed new method, a comprehensive experiment for measurement angle from -5° to +5° in increments of 0.5° was performed by using the angular capacitive sensor. The experimental results show that the precision of the angular measurement is better than 15″ with maximum 1.24 kHz bandwidth, which meets the relative attitude measurement requirements of the internal load on the airborne photoelectric platform.

  10. Electrochemical synthesis of ZnO nanoflowers and nanosheets on porous Si as photoelectric materials

    NASA Astrophysics Data System (ADS)

    Kou, Huanhuan; Zhang, Xin; Du, Yongling; Ye, Weichun; Lin, Shaoxiong; Wang, Chunming

    2011-03-01

    Well-aligned ZnO nanoflowers and nanosheets were synthesized on porous Si (PS) at different applied potentials by electrodeposition approach. The deposits were grown using the optimized program and were characterized by means of cyclic voltammetry (CV), amperometry I-t (I-t), open-circuit potentiometry. X-ray diffraction (XRD) analysis proved a strong preferential orientation (1 0 0) on PS. Scanning electronic microscopy (SEM) observation showed the deposits consist of nanoflowers with uniform grain size of about 100 nm in diameter and nanosheets, which may have potential applications in nanodevices and nanotechnologies. Thus, ZnO grown on PS can be used as photoelectric materials due to its larger photoelectric effect compared to Si wafer according to open-circuit potential (OCP) study. Optical band gap measurements were made on samples using UV-visible spectrophotometer thus giving a band gap of 3.35 eV.

  11. High precision relative attitude measurement for inner payload of new photoelectric platform.

    PubMed

    Wang, Y Y; Wang, L; Bai, X G; Ma, T W; Dai, M

    2016-03-01

    A new method for measuring the relative attitude of a load on an airborne photoelectric platform supported by three-axis universal joint structure is proposed. The mathematical model for angle measurement is established, based on which the linear relation between the angle and distance is derived by using the eccentric method. Furthermore, the relative attitude measurement method for a load rotating along the yaw and pitch directions is also proposed based on a unique eccentric structure. Finally, to validate the proposed new method, a comprehensive experiment for measurement angle from -5° to +5° in increments of 0.5° was performed by using the angular capacitive sensor. The experimental results show that the precision of the angular measurement is better than 15″ with maximum 1.24 kHz bandwidth, which meets the relative attitude measurement requirements of the internal load on the airborne photoelectric platform. PMID:27036812

  12. Study on Fabrication and UV Photoelectric Property of TiO2 Nanotube Array Electrodes.

    PubMed

    Fu, Yao; Duan, Xiao-Long; Xing, Ming-Ming; Luo, Xi-Xian; Zhang, Ying-Hui; Liu, Wang

    2016-04-01

    Highly ordered TiO2 nanotube array electrodes were successfully fabricated by a two-step anodization method on Ti sheet substrates in an electrolyte composed of ammonium fluoride, deionized water, and glycol. The tube wall was smooth, and the average internal and external diameters, wall thickness, and tube length achieved were 80 nm, 90 nm, 10 nm, and 9 µm, respectively. X-ray diffraction and field emission scanning electron microscopy results revealed that the TiO2 nanotube arrays presented an amorphous structure. When calcined at 300 °C, the arrays crystallized into the anatase phase, and the crystallization degree of the oxide layer increased as the temperature rose. Calcinating at 400 °C did not obviously disrupt the porous structure of the highly ordered arrays. However, higher temperature enlarged the diameter of the nanotube array and roughened the tube wall. When the temperature reached 600 °C, the nanotube mouth broke because of the excessive stress, causing the oxide layer's thinness and nanotube mouth clogging. The photoelectric test showed that the electrode presented obvious photoresponse under 300-400 nm UV excitation (maximized at 360 nm). The degree of crystallization and the micro-structure of the oxide layer can significantly affect the photoelectric properties of the electrode. After calcination at 400 °C, the TiO2 nanotube arrays, with highly ordered tubular structure directly connected to the Ti substrate, can ensure the rapid transportation of photo-induced electrons to the Ti substrate, while the high crystallinity of the arrays can help reduce the defect density of the nanotube and extend the lifetime of the photo-induced carriers. The electrode showed the best photoelectric property, and the photocurrent intensity was maximized (29.6 µA). However, the calcination process with over-temperature resulted in substantial loss of the TiO2 oxide layer, mouth clogging, and a severe decline in the photoelectric properties. PMID:27451743

  13. Enhanced photoelectric activity of CdSe nanostructures with mixed crystalline phases

    NASA Astrophysics Data System (ADS)

    Tao, Leiming; Pang, Shan; An, Yanqing; Xu, Hongtao; Wu, Sixin

    2010-05-01

    CdSe nanostructures were synthesized by the hydrothermal process. The morphology and structures of as-prepared CdSe were seriously affected by adding an ionic liquid, lithium bis((trifluoromethyl)- sulfonyl)amide. The results illustrated that when the ionic liquid is added, CdSe nanorod-chain assemblies with the mixed cubic and hexagonal phases are obtained. The surface photovoltaic and photocurrent measurements demonstrated that CdSe nanorod-chain assemblies show a photoelectric response.

  14. Effect of ultrasonic treatment on photoelectric and luminescent properties of ZnSe crystals

    SciTech Connect

    Zobov, E. M. Zobov, M. E.; Gabibov, F. S.; Kamilov, I. K.; Manyakhin, F. I.; Naimi, E. K.

    2008-03-15

    The results of the effect of ultrasonic treatment of ZnSe crystals on the structure of the energy spectrum of electronic states of centers with deep levels forming photoelectric and luminescent properties of this compound are presented. It is for the first time proved experimentally that the climb of edge dislocations under the effect of ultrasound leads to regrouping and generation of defects forming deep levels, which manifest themselves in phenomena of photosensitivity and radiative recombination.

  15. Photoelectric properties of GaAs p-n-junction under illumination of intense laser radiation

    NASA Astrophysics Data System (ADS)

    Ašmontas, S.; Gradauskas, J.; Sužiedėlis, A.; Šilėnas, A.; Vaičikauskas, V.; Žalys, O.; Steikūnas, G.; Steikūnienė, A.

    2014-10-01

    Results of experimental investigation of photoelectric properties of GaAs p-n-junction illuminated by short laser pulses of 1.06 μm wavelength are presented. The influence of laser radiation intensity and external bias voltage on the formation of photoresponse voltage has been studied. Free carrier heating was recognized to influence significantly the magnitude of the measured photovoltage. Possibility to improve the conversion efficiency of solar cells is discussed.

  16. Photoelectric properties of an array of axial GaAs/AlGaAs nanowires

    NASA Astrophysics Data System (ADS)

    Grigor'ev, R. V.; Shtrom, I. V.; Grigor'eva, N. R.; Novikov, B. V.; Soshnikov, I. P.; Samsonenko, Yu. B.; Khrebtov, A. I.; Buravleuv, A. D.; Cirlin, G. E.

    2015-05-01

    The results of studies of photoelectric properties of an array of axial n-type GaAs/Al x Ga1 - x As ( x ≈ 0.3) nanowires grown using molecular beam epitaxy on a p-type silicon substrate are presented. The ability to separate charges efficiently in a wide spectral range (from 450 to 1100 nm) is demonstrated. Such properties are important for designing active elements of photodetectors and solar cells.

  17. Photoelectric properties of film heterostructures based on poly-N-Epoxypropylcarbazole and merocyanine dye

    NASA Astrophysics Data System (ADS)

    Davidenko, N. A.; Ishchenko, A. A.; Korotchenkov, O. A.; Mokrinskaya, E. V.; Podolian, A. O.; Studzinsky, S. L.; Tonkopieva, L. S.

    2012-10-01

    Heterostructures comprising a merocyanine dye (M1) film deposited onto a poly-N-epoxypropylcarbazole (PEPC) film have been created, and their photoconducting, photodielectric, and photovoltaic properties have been studied. The PEPC/M1 heterostructures exhibit the photodiode and photoelectric converter properties. It is concluded that the p- n junction in these heterostructures is ensured by the hole character of conductivity in the polymer and the bipolar conductivity of the deposited dye film.

  18. Photometry of Faint and Wide Doubles in Vulpecula

    NASA Astrophysics Data System (ADS)

    Knapp, Wilfried; Thuemen, Chris

    2016-04-01

    Images of several double stars in Vulpecula published on the "Double Star Imaging Project" Yahoo Group page suggest magnitude issues compared with the corresponding WDS catalog data per April 2015. Taking additional images with V-filter enabled photometry for these pairs, providing confirming results.

  19. Photometry of Faint and Wide Doubles in Sagitta

    NASA Astrophysics Data System (ADS)

    Knapp, Wilfried; Thuemen, Chris

    2016-02-01

    Images of several double stars in Sagitta published on the "Double Star Imaging Project" Yahoo Group page suggest magnitude issues compared with the corresponding WDS catalog data per April 2015. Taking additional images with V-filter enabled photometry for these pairs, provided confirming results.

  20. Photometry and Measurement of Faint and Wide Doubles in Eridanus

    NASA Astrophysics Data System (ADS)

    Knapp, Wilfried; Thuemen, Chris

    2015-07-01

    Images of several double stars in Eridanus published on the "Double Star Imaging Project" Yahoo Group page suggest magnitude issues compared with the corresponding WDS catalog data per 2014.12. Taking additional images with V-filter enabled photometry for these pairs with confirming results.

  1. Multiband photometry of PSNJ14102342-4318437 with OAUNI

    NASA Astrophysics Data System (ADS)

    Pereyra, A.; Cori, W.; Ricra, J.; Zevallos, M.; Tello, J.

    2016-01-01

    We report multiband photometry of Type Ib SN PSNJ14102342-4318437 (ATel #8415, ATel #8434, ATel #8437, ATel #8504) on 2016-01-10 (UT) gathered with the OAUNI 51cm telescope (Pereyra et al. 2015; arXiv:1512.03104) at Huancayo Observatory, Peru.

  2. Characterization of Transiting Exoplanets by Way of Differential Photometry

    ERIC Educational Resources Information Center

    Cowley, Michael; Hughes, Stephen

    2014-01-01

    This paper describes a simple activity for plotting and characterizing the light curve from an exoplanet transit event by way of differential photometry analysis. Using free digital imaging software, participants analyse a series of telescope images with the goal of calculating various exoplanet parameters, including size, orbital radius and…

  3. Research Note - Absolute UBV Photometry at the Zacatecas Observatory

    NASA Astrophysics Data System (ADS)

    Schuster, W. J.; Parrao, L.; Gonazlez-Bedolla, S. F.; Rios-Herrera, M.; Berumen, M. R.

    1985-12-01

    Atmospheric extinction data, color coefficients, errors of observation and a list of standard and comparison stars are given for UB V photometry at the Astronomical Observatory in Zacatecas. Our observing and reduction procedures are discussed briefly, and our extinction coefficients and observing errors compared with previous values. The uses of these results are mentioned.

  4. JCMT COADD: UKT14 continuum and photometry data reduction

    NASA Astrophysics Data System (ADS)

    Hughes, David; Oliveira, Firmin J.; Tilanus, Remo P. J.; Jenness, Tim

    2014-11-01

    COADD was used to reduce photometry and continuum data from the UKT14 instrument on the James Clerk Maxwell Telescope in the 1990s. The software can co-add multiple observations and perform sigma clipping and Kolmogorov-Smirnov statistical analysis. Additional information on the software is available in the JCMT Spring 1993 newsletter (large PDF).

  5. Iontophoresis and Flame Photometry: A Hybrid Interdisciplinary Experiment

    ERIC Educational Resources Information Center

    Sharp, Duncan; Cottam, Linzi; Bradley, Sarah; Brannigan, Jeanie; Davis, James

    2010-01-01

    The combination of reverse iontophoresis and flame photometry provides an engaging analytical experiment that gives first-year undergraduate students a flavor of modern drug delivery and analyte extraction techniques while reinforcing core analytical concepts. The experiment provides a highly visual demonstration of the iontophoresis technique and…

  6. BVRI Photometry of the Supernova Candidate Gaia16ath

    NASA Astrophysics Data System (ADS)

    Vinko, J.; Feher, T.; Gyurita, A.; Redli, M.; Sukolova, D.

    2016-07-01

    We report confirmation and photometry of the recently discovered Gaia Science Alerts transient Gaia16ath. CCD frames were taken with the 60/90 cm Schmidt telescope through Bessell B,V,R,I filters at Konkoly Observatory, Piszkesteto, Hungary on July 11.01 UT. The transient was detected with high significance (S/N > 20) in all bands.

  7. Photoelectric dust levitation around airless bodies revised using realistic photoelectron velocity distributions

    NASA Astrophysics Data System (ADS)

    Senshu, H.; Kimura, H.; Yamamoto, T.; Wada, K.; Kobayashi, M.; Namiki, N.; Matsui, T.

    2015-10-01

    The velocity distribution function of photoelectrons from a surface exposed to solar UV radiation is fundamental to the electrostatic status of the surface. There is one and only one laboratory measurement of photoelectron emission from astronomically relevant material, but the energy distribution function was measured only in the emission angle from the normal to the surface of 0 to about π / 4. Therefore, the measured distribution is not directly usable to estimate the vertical structure of a photoelectric sheath above the surface. In this study, we develop a new analytical method to calculate an angle-resolved velocity distribution function of photoelectrons from the laboratory measurement data. We find that the photoelectric current and yield for lunar surface fines measured in a laboratory have been underestimated by a factor of two. We apply our new energy distribution function of photoelectrons to model the formation of photoelectric sheath above the surface of asteroid 433 Eros. Our model shows that a 0.1 μm-radius dust grain can librate above the surface of asteroid 433 Eros regardless of its launching velocity. In addition, a 0.5 μm grain can hover over the surface if the grain was launched at a velocity slower than 0.4 m/s, which is a more stringent condition for levitation than previous studies. However, a lack of high-energy data on the photoelectron energy distribution above 6 eV prevents us from firmly placing a constraint on the levitation condition.

  8. Application of fuzzy evidence theory in a photo-electric measurement system

    NASA Astrophysics Data System (ADS)

    Song, Jianxun; Xiong, Maotao; Zhang, Jin; Wu, Qinzhang

    2009-05-01

    The photo-electric measurement system is a kind of high-precision measurement system for trajectory parameters and object identity parameters, and it can acquire the image information of flying objects by CCD camera. Due to subject to some kinds of reasons, the feature information of image is not integrated and imprecise, and it has uncertainty and fuzzy in some degree. The Dempster-Shafer evidence theory is an important approach of uncertainty reasoning. With evidences fused, the uncertainty of the feature information of the object is declined gradually by Dempster combination rule, so it can achieve the aim of object detection and object recognition. The conception of fuzzy mass is expanded in the way of the relation of absolute membership on the basis of normal mass conception. The fuzzy theory is very suitable for the description and processing of uncertainty to evidences in D-S evidence theory, so the Basic Probability Assignment Function (BPAF) of D-S evidence theory can be acquired according to fuzzy theory, and it resolves crucial problem in D-S evidence theory. It is shown that data fusion method of fuzzy evidence theory can deal with uncertainty and the fuzzy of photo-electric measurement system according to the analysis of theory and the result of experimentation, and it has a bright future in photo-electric measurement systems.

  9. SEMICONDUCTOR MATERIALS Photoelectric conversion characteristics of ZnO/SiC/Si heterojunctions

    NASA Astrophysics Data System (ADS)

    Xiaopeng, Wu; Xiaoqing, Chen; Lijie, Sun; Shun, Mao; Zhuxi, Fu

    2010-10-01

    A series of n-ZnO/n-SiC/p-Si and n-ZnO/p-Si heterojunctions were prepared by DC sputtering. Their structural properties, I—V curves, photovoltaic effects and photo-response spectra were studied. The photoelectric conversion characteristics of n-ZnO/n-SiC/p-Si and n-ZnO/p-Si heterojunctions were investigated. It is found that the photoelectric conversion efficiency of the n-ZnO/n-SiC/p-Si heterojunction is about four times higher than that of the n-ZnO/p-Si heterojunction. The photovoltaic response spectrum indicated that the photoresponse curve of n-ZnO/n-SiC/p-Si increased more strongly than that of n-ZnO/p-Si with the wavelength increasing. It shows that the photoresponse of n-ZnO/p-Si can be enhanced when inserting a 3C-SiC layer between ZnO and Si. There is one inflexion in the photocurrent response curve of the n-ZnO/p-Si heterojunction and two inflexions in that of the n-ZnO/n-SiC/p-Si heterojunction. It is clear that the 3C-SiC plays an important role in the photoelectric conversion of the n-ZnO/n-SiC/p-Si heterojunction.

  10. Development of a grain volumetric flow sensor based on photoelectrical principle

    NASA Astrophysics Data System (ADS)

    Wang, Bo; Li, Minzan

    2008-12-01

    Field information acquisition plays an important part in Precision Agriculture System. Spatial and temporal variation of grain yield in a field is important field information. It can guide farmers in a reasonable means of production in order to save input and improve efficiency. Thus a grain yield monitor is developed based on photoelectrical sensor. The monitor consists of a LED, a photoelectrical transducer, cables, signal processing circuit, acquisition circuit, etc. The LED and the photoelectrical transducer are equipped in the left and right sides of the clean grain elevator of the combine harvester, respectively. When harvested wheat is threshed, clean grain is lifted to the grain tank by the lifting plates of the elevator, and the grain in a plate will switch off the light from the LED to the transducer. The height of the grain in a plate has a high correlation with the switching off time of the transducer. To measure the switching off time makes it possible to estimate grain yield. The signal processing circuit and acquisition circuit are used to monitor whether the light from the LED is switched off and then to measure the switching off time. And the yield can be calculated from the measured time based on a calibration model. The performance test shows the developed grain yield monitor is practical.

  11. Vacuum-deposited diphenyl-diketo-pyrrolopyrroles structures with photoelectrical applications

    NASA Astrophysics Data System (ADS)

    Georgiev, Y.; Zhivkov, I.; Takov, T.; Angelov, G.; Prikryl, R.; Stritesky, S.; Honova, J.; Weiter, M.

    2014-05-01

    Modern organic semiconductor devices are designed as stacked organic/inorganic thin films. In such multilayer structures, strong requirements are set forth to the properties of the specific films, e.g., film homogeneity, thickness uniformity and roughness. The physical vacuum deposition (PVD) technique fulfils all of these requirements having even the capability of producing the whole multilayer structure in the same vacuum cycle. Diphenyl-diketo-pyrrolopyrroles (DPP) are low-molecular-weight materials with promising luminescence and photoelectrical properties. This study deals with PVD of thin DPP films and measurement of their properties. The organic films and inorganic electrodes of the multilayer structures were prepared in the same vacuum cycle, and then the structures were encapsulated in a glove box avoiding exposure to oxygen. ITO|composite|Al structures were prepared with active DPP-C60 composite films (ratio 60:40 mass %) of about 100 nm thicknesses. The surface morphology of the films was studied by SEM imaging, which revealed uniform films containing separate spherical structures. The dark current and the photoconductivity were measured and the photoelectrical behavior of the structures was estimated. It was found that the optimized preparation of the structures under the aforementioned conditions leads to an improvement of their photoelectrical properties.

  12. Titanium dioxide-coated fluorine-doped tin oxide thin films for improving overall photoelectric property

    NASA Astrophysics Data System (ADS)

    Li, Bao-jia; Huang, Li-jing; Ren, Nai-fei; Zhou, Ming

    2014-01-01

    Titanium (Ti) layers were deposited by direct current (DC) magnetron sputtering on commercial fluorine-doped tin oxide (FTO) glasses, followed by simultaneous oxidation and annealing treatment in a tubular furnace to prepare titanium dioxide (TiO2)/FTO bilayer films. Large and densely arranged grains were observed on all TiO2/FTO bilayer films. The presence of TiO2 tetragonal rutile phase in the TiO2/FTO bilayer films was confirmed by X-ray diffraction (XRD) analysis. The results of parameter optimization indicated that the TiO2/FTO bilayer film, which was formed by adopting a temperature of 400 °C and an oxygen flow rate of 15 sccm, had the optimal overall photoelectric property with a figure of merit of 2.30 × 10-2 Ω-1, higher than 1.78 × 10-2 Ω-1 for the FTO single-layer film. After coating a 500 nm-thick AZO layer by DC magnetron sputtering on this TiO2/FTO bilayer film, the figure of merit of the trilayer film achieved to a higher figure of merit of 3.12 × 10-2 Ω-1, indicating further improvement of the overall photoelectric property. This work may provide a scientific basis and reference for improving overall photoelectric property of transparent conducting oxide (TCO) films.

  13. The Guiding Light: Vri/uvby & Tio Photometry Of The Chromospherically Active & Spotted Binary System Im Peg - The Guide-star For The Gravity Probe-b Mission

    NASA Astrophysics Data System (ADS)

    Zellem, Robert; Guinan, E.; Messina, S.; Wasatonic, R.; McCook, G.

    2007-12-01

    We report on the starspot and chromospheric properties of IM Pegasi - the guide star of the Gravity Probe B (GP-B) satellite. GP-B's mission is to measure two predicted consequences of General Relativity - frame-dragging and geodetic effects, via its extremely precise onboard gyroscopes. IM Peg was selected as the mission's guide star as it is not only bright enough to be seen with GP-B's onboard optical telescope but it is also a bright radio source. Thus, ground-based radio telescope observations can easily and accurately correct for IM Peg's motions in space. However, IM Peg is a chomospherically active binary system with a luminous K2 III primary star showing rotationally modulated (Prot 24.5 days) light variations from starspots. The starspots can cause problems as GP-B can erroneously interpret a change in starspot coverage (and corresponding shifts in the light center) as the star's movement. This apparent shift can also be exacerbated by possible changes in the light-center of the binary system arising from changes in the light balance with the fainter dK component. Since 2000 we have carried out multi-band high-precision photoelectric photometry of IM Peg to determine its activity and starspot coverage. Our photometry uses Strömgren uvby filters, VRCIC filters and TiO (719/755 nm ) narrow-band filter sets. Measurements were made relative to neaby comparsion & check stars using a robotic 0.8-m telescope (located in AZ) and 0.25-m telescope (located in PA). The TiO- and multi-band continuum photometry constrains the starspot areas, temperatures and distributions. The photometry is being modeled to determine the effects of changing starspot areas and distributions on the light center of the binary. The results of our analysis and possible impacts on the GP-B Mission will be discussed. This research is supported by NSF/RUI Grants AST- 0507536 and AST- 0507542 which we gratefully acknowledge.

  14. Crowded Field Photometry in the CLASH Clusters: Measuring the Red Sequence of Cluster Galaxies with Robust Photometry

    NASA Astrophysics Data System (ADS)

    Connor, Thomas; Donahue, Megan; Moustakas, John; Kelson, Daniel; Coe, Dan A.; Postman, Marc; CLASH Team

    2016-01-01

    The Cluster Lensing And Supernova survey with Hubble (CLASH) is an HST multi-cycle treasury program investigating 25 massive clusters of galaxies with X-ray gas Tx > 5 keV, spanning ~5 to ~30 x 10^14 solar masses, and a redshift range of 0.15 < z < 0.9. With 500 orbits of HST time and 16-filter, ultraviolet to infrared photometry of each cluster, this survey offers an unprecedented dataset for cluster galaxy photometry across a span of age and mass, but obtaining robust photometry for the cluster members has been hampered by the crowded field. We have developed a new technique to detect and define objects despite the presence of overlapping light profiles and to measure photometry of galaxies overlapping the extended haloes of massive galaxies. Utilizing spectral energy distribution fitting, we infer the properties of the detected galaxies, including their abundances and the time since their first star formation. Here we will discuss our technique and results, including the role metallicity and age play in shaping the red sequence of cluster galaxies.

  15. Southern galaxies. VIII - Surface photometry of the SD spiral NGC 7793

    NASA Astrophysics Data System (ADS)

    de Vaucouleurs, G.; Davoust, E.

    1980-08-01

    Detailed surface photometry in blue light of the SA(s)d galaxy NGC 7793, the faintest of the five major members of the Sculptor group, is obtained from photoelectrically calibrated Mount Stromlo and McDonald photographs. The luminosity distribution is dominated by an exponential disk of effective radius αe = 2'.11 = 1.92 kpc contributing 98.6% of the total luminosity BT = 9.51 ± 0.06. The corrected face-on magnitude BT0 = 9.13 corresponds to MT0 = -18.35 at the revised distance Δ = 3.1 Mpc (Appendix C). The spheroidal component visible only in the vicinity of the nucleus can be represented by an r1/4 law of effective radius rIe = 6".0 = 91 pc and total magnitude BTI = 14.13 or 1.4% of the total luminosity of the galaxy. The position angle of the major axis is 97°, the mean axis ratio is q = b/a = 0.61, and the inclination = 53°. The concentration indices C21 = 1.68 and C32 = 1.48 are consistent with the Sd classification. The integrated colors from UBV aperture photometry are essentially constant at = 0.56 ± 0.02, = -0.07 ± 0.02, the corrected face-on colors are (B - V)T0 = 0.46, (U - B)T0 = -0.15 in close agreement with the colors of M33 and the mean values for type Scd. A decomposition of the disk into an underlying old component and a young arm component shows that 65.570 of the total luminosity comes from the old component which has a corrected central luminosity μcα(0) = 21.06 and an effective radius re = 1'.76 = 1.60 kpc. The neutral H I mass MH = 0.67 × 109 Msun corresponds to a hydrogen-luminosity ratio MH/LB = 0.14 which is less than half the average for the morphological type and luminosity class of NGC 7793. The large number of H ii regions and the strength of the Hα emission in the disk suggest that a large fraction of the hydrogen is ionized. The integrated magnitude of the brightest superassociation (Hodge Nr 20) B, = 16.0 ± 0.1 is derived in Appendix A. The effect of resolution on the apparent peak brightness is illustrated in Appendix B

  16. Time-series high-resolution spectroscopy and photometry of ɛ Aurigae from 2006-2013: Another brick in the wall

    NASA Astrophysics Data System (ADS)

    Strassmeier, K. G.; Weber, M.; Granzer, T.; Schanne, L.; Bartus, J.; Ilyin, I.

    2014-11-01

    We present continuous and time-resolved R = 55 000 optical échelle spectroscopy of ɛ Aurigae from 2006-2013. Data were taken with the STELLA Echelle Spectrograph of the robotic STELLA facility at the Observatorio del Teide in Tenerife. Contemporaneous photometry with the Automatic Photoelectric Telescopes at Fairborn Observatory in Arizona is presented for the years 1996-2013. Spectroscopic observations started three years prior to the photometric eclipse and are still ongoing. A total of 474 high-resolution échelle spectra are analyzed and made available in this paper. We identify 368 absorption lines of which 161 lines show the characteristic sharp disk lines during eclipse. Another 207 spectral lines appeared nearly unaffected by the eclipse. From spectrum synthesis, we obtained the supergiant atmospheric parameters T_eff = 7395±70 K, log g≈ 1, and [Fe/H] = +0.02±0.2 with ξ_t = 9 km s-1 , ζ_RT = 13 km s-1 , and v sin i = 28±3 km s-1 . The residual average line broadening expressed in km s-1 varies with a period of 62.6±0.7 d, in particular at egress and after the eclipse. Two-dimensional line-profile periodograms show several periods, the strongest with ≈110 d evident in optically thin lines as well as in the Balmer lines. Center-of-intensity weighted radial velocities of individual spectral lines also show the 110-d period but, again, additional shorter and longer periods are evident and are different in the Balmer lines. The two main spectroscopic Hα periods, ≈ 116 d from the line core and ≈ 150 d from the center-of-intensity radial velocities, appear at 102 d and 139 d in the photometry. The Hβ and Johnson VI photometry on the other hand shows two well-defined and phase-coherent periods of 77 d and 132 d. We conclude that Hα is contaminated by changes in the circumstellar environment while the Hβ and VI photometry stems predominantly from the non radial pulsations of the F0 supergiant. We isolate the disk-rotation profile from 61

  17. J, H, K photometry of 433 Eros and other asteroids

    NASA Technical Reports Server (NTRS)

    Chapman, C. R.; Morrison, D.

    1976-01-01

    Results are reported for IR photometry of nine bright asteroids, including 433 Eros, which was conducted in the J, H, K, and (for Eros) L bands with an InSb photometer on the 1.3-m Kitt Peak telescope. It is found that the J-H and H-K color indices of all nine asteroids are slightly redder than those of the sun and that three C-type objects are somewhat redder in the same color indices than four S-types and an E-type. Eros is shown to have an unusually red J-K index; the shape of its IR spectral reflectance curve is attributed in part to the presence of the weak 2-micron pyroxene absorption band in the spectrum. The results show that JHK photometry is less diagnostic of asteroidal composition than higher-resolution IR spectrophotometry.

  18. Copernicus spectra and infrared photometry of 42 Orionis

    NASA Technical Reports Server (NTRS)

    Johnson, H. M.; Snow, T. P., Jr.; Gehrz, R. D.; Hackwell, J. A.

    1977-01-01

    The Orion sword star 42 Ori is embedded in a nebula north of and separated from the Orion nebula. The B1 V star is probably normal. Other members of the multiple remain poorly defined, and the nebula may exhibit some peculiarities that may depend on them. Copernicus ultraviolet spectra of the star are described here, especially in the form of tables of wavelength identifications. The properties of the interstellar material in the line of sight are also discussed. Infrared photometry is presented which suggests that the ratio of total to selective extinction ranges from 3 to 3.5 for the interstellar matter in the direction of 42 Ori. The IR photometry provides no evidence for companion stellar or circumstellar components.

  19. An Aperture Photometry Pipeline for K2 Data

    NASA Astrophysics Data System (ADS)

    Buzasi, Derek L.; Carboneau, Lindsey; Lezcano, Andy; Vydra, Ekaterina

    2016-01-01

    As part of an ongoing research program with undergraduate students at Florida Gulf Coast University, we have constructed an aperture photometry pipeline for K2 data. The pipeline performs dynamic automated aperture mask definition for all targets in the K2 fields, followed by aperture photometry and detrending. Our pipeline is currently used to support a number of projects, including studies of stellar rotation and activity, red giant asteroseismology, gyrochronology, and exoplanet searches. In addition, output is used to support an undergraduate class on exoplanets aimed at a student audience of both majors and non-majors. The pipeline is designed for both batch and single-target use, and is easily extensible to data from other missions, and pipeline output is available to the community. This paper will describe our pipeline and its capabilities and illustrate the quality of the results, drawing on all of the applications for which it is currently used.

  20. High-speed multicolour photometry with CMOS cameras

    NASA Astrophysics Data System (ADS)

    Pokhvala, S. M.; Zhilyaev, B. E.; Reshetnyk, V. M.

    2012-11-01

    We present the results of testing the commercial digital camera Nikon D90 with a CMOS sensor for high-speed photometry with a small telescope Celestron 11'' at the Peak Terskol Observatory. CMOS sensor allows to perform photometry in 3 filters simultaneously that gives a great advantage compared with monochrome CCD detectors. The Bayer BGR colour system of CMOS sensors is close to the Johnson BVR system. The results of testing show that one can carry out photometric measurements with CMOS cameras for stars with the V-magnitude up to ≃14^{m} with the precision of 0.01^{m}. Stars with the V-magnitude up to ˜10 can be shot at 24 frames per second in the video mode.

  1. Absolute stellar photometry on moderate-resolution FPA images

    USGS Publications Warehouse

    Stone, T.C.

    2009-01-01

    An extensive database of star (and Moon) images has been collected by the ground-based RObotic Lunar Observatory (ROLO) as part of the US Geological Survey program for lunar calibration. The stellar data are used to derive nightly atmospheric corrections for the observations from extinction measurements, and absolute calibration of the ROLO sensors is based on observations of Vega and published reference flux and spectrum data. The ROLO telescopes were designed for imaging the Moon at moderate resolution, thus imposing some limitations for the stellar photometry. Attaining accurate stellar photometry with the ROLO image data has required development of specialized processing techniques. A key consideration is consistency in discriminating the star core signal from the off-axis point spread function. The analysis and processing methods applied to the ROLO stellar image database are described. ?? 2009 BIPM and IOP Publishing Ltd.

  2. TFIT: A Photometry Package for Mixed-Resolution Datasets

    NASA Astrophysics Data System (ADS)

    Laidler, V. G.; Grogin, N.; Clubb, K.; Ferguson, H.; Papovich, C.; Dickinson, M.; Idzi, R.; MacDonald, E.; Ouchi, M.; Mobasher, B.

    2006-07-01

    TFIT is a software package for measuring relative galaxy photometry between imaging data sets with different angular resolutions, such as the Hubble ACS and Spitzer IRAC images taken for the Great Observatories Origins Deep Survey (GOODS). It combines prior information about spatial position and morphology obtained from high angular resolution images with PSF information about both images to construct object templates, which it then fits to a lower-resolution image of the same field. Simulations demonstrate that this technique improves accuracy in uncrowded fields, with performance holding steady as crowding increases and object separation decreases to 1.5 PSF FWHM: outperforming SExtractor by a factor of two. Photometry is also measured, with < 10% degradation, for objects that SExtractor fails to deblend. On real GOODS data, TFIT produces results that are consistent with a traditional PSF subtraction method. TFIT is implemented in Python and C++.

  3. Astronomical Photometry and the Legacy of Arne Henden (Abstract)

    NASA Astrophysics Data System (ADS)

    Joner, M.

    2015-06-01

    (Abstract only) Arne Henden has helped provide a valuable resource to the photometric community with the publication of the 1982 book Astronomical Photometry. I will present a brief review of the topics covered in this handbook and recount some of the many times that it has been useful to myself and my students for answering a wide variety of questions dealing with the acquisition and reduction of photometric observations.

  4. Luminosities and temperatures of M dwarf stars from infrared photometry

    NASA Technical Reports Server (NTRS)

    Veeder, G. J.

    1974-01-01

    Bolometric magnitudes for a large number of M type dwarf stars, obtained by broadband infrared photometry at 1.65, 2.2, and 3.5 microns, are reviewed. The data obtained indicate that one parameter is sufficient to describe the blanketing in all of the UBVRI bands for all types of M dwarfs. In general, late M dwarfs seem to have lower effective temperatures than are predicted by theoretical models.

  5. One Percent Strömvil Photometry in M 67

    NASA Astrophysics Data System (ADS)

    Philip, A. G. D.; Boyle, R. P.; Janusz, R.

    2005-05-01

    The Vatican Advanced Technology Telescope on Mt. Graham is being used in a program of CCD photometry of open and globular clusters. We are using the Ströomvil System (Straižys et al. 1996), a combination of the Strömgren and Vilnius Systems. This system allows stars to be classified as to temperature, surface gravity, metallicity and reddening from the photometric measures alone. However, to make accurate estimates of the stellar parameters the photometry should be accurate to 1 or 1.5 percent. In our initial runs on the VATT we did not achieve this accuracy. The problem turned out to be scattered light in the telescope and this has now been reduced so we can do accurate photometry. Boyle has written a routine in IRAF which allows us to correct the flats for any differences. We take rotated frames and also frames which are offset in position by one third of a frame, east-west and north-south. Measures of the offset stars give us the corrections that need to be made to the flat. Robert Janusz has written a program, the CommandLog, which allows us to paste IRAF commands in the correct order to reduce measures made on a given observing run. There is an automatic version where one can test various parameters and get a set of solutions. Now we have a set of Strömvil frames in the open cluster, M 67 and we compare our color-magnitude diagram with those of BATC (Fan et al. 1996) and Vilnius (Boyle et al. 1998). A preliminary report of the M 67 photometry will be found in Laugalys et al. (2004). Here we report on a selected set of stars in the M 67 frames, those with errors 1 percent or less.

  6. Design and implementation of photoelectric rotary table data acquisition and analysis system host computer software based on VC++ and MFC

    NASA Astrophysics Data System (ADS)

    Yang, Dawei; Yang, Xiufang; Han, Junfeng; Yan, Xiaoxu

    2015-02-01

    Photoelectric rotary table is mainly used in the defense industry and military fields, especially in the shooting range, target tracking, target acquisition, aerospace aspects play an important one. For range photoelectric measuring equipment field test application requirements, combined with a portable photoelectric rotary table data acquisition hardware system, software programming platform is presented based on the VC++, using MFC prepared PC interface, the realization of photoelectric turntable data acquisition, analysis and processing and debugging control. The host computer software design of serial communication and protocol, real-time data acquisition and display, real-time data curve drawing, analog acquisition, debugging guide, error analysis program, and gives the specific design method. Finally, through the photoelectric rotary table data acquisition hardware system alignment, the experimental results show that host computer software can better accomplish with lower machine data transmission, data acquisition, control and analysis, and to achieve the desired effect, the entire software system running performance is stable, flexible, strong practicality and reliability, the advantages of good scalability.

  7. Modifying the photoelectric behavior of bacteriorhodopsin by site-directed mutagenesis: electrochemical and genetic engineering approaches to molecular devices

    NASA Astrophysics Data System (ADS)

    Hong, F. T.; Hong, F. H.; Needleman, R. B.; Ni, B.; Chang, M.

    1992-07-01

    Bacteriorhodopsins (bR's) modified by substitution of the chromophore with synthetic vitamin A analogues or by spontaneous mutation have been reported as successful examples of using biomaterials to construct molecular optoelectronic devices. The operation of these devices depends on desirable optical properties derived from molecular engineering. This report examines the effect of site-directed mutagenesis on the photoelectric behavior of bR thin films with an emphasis on their application to the construction of molecular devices based on their unique photoelectric behavior. We examine the photoelectric signals induced by a microsecond light pulse in thin films which contain reconstituted oriented purple membrane sheets isolated from several mutant strains of Halobacterium halobium. A recently developed expression system is used to synthesize mutant bR's in their natural host, H. halobium. We then use a unique analytical method (tunable voltage clamp method) to investigate the effect of pH on the relaxation of two components of the photoelectric signals, B1 and B2. We found that for the four mutant bR's examined, the pH dependence of the B2 component varies significantly. Our results suggest that genetic engineering approaches can produce mutant bR's with altered photoelectric characteristics that can be exploited in the construction of devices.

  8. Automatic CCD Imaging Systems for Time-series CCD Photometry

    NASA Astrophysics Data System (ADS)

    Caton, D. B.; Pollock, J. T.; Davis, S. A.

    2004-12-01

    CCDs allow precision photometry to be done with small telescopes and at sites with less than ideal seeing conditions. The addition of an automatic observing mode makes it easy to do time-series CCD photometry of variable stars and AGN/QSOs. At Appalachian State University's Dark Sky Observatory (DSO), we have implemented automatic imaging systems for image acquisition, scripted filter changing, data storage and quick-look online photometry two different telescopes, the 32-inch and 18-inch telescopes. The camera at the 18-inch allows a simple system where the data acquisition PC controls a DFM Engineering filter wheel and Photometrics/Roper camera. The 32-inch system is the more complex, with three computers communicating in order to make good use of its camera's 30-second CCD-read time for filter change. Both telescopes use macros written in the PMIS software (GKR Computer Consulting). Both systems allow automatic data capture with only tended care provided by the observer. Indeed, one observer can easily run both telescopes simultaneously. The efficiency and reliability of these systems also reduces observer errors. The only unresolved problem is an occasional but rare camera-read error (the PC is apparently interrupted). We also sometimes experience a crash of the PMIS software, probably due to its 16-bit code now running in the Windows 2000 32-bit environment. We gratefully acknowledge the support of the National Science Foundation through grants number AST-0089248 and AST-9119750, the Dunham Fund for Astrophysical Research, and the ASU Research Council.

  9. Night sky photometry with amateur-grade digital cameras

    NASA Astrophysics Data System (ADS)

    Mrozek, Tomasz; Gronkiewicz, Dominik; Kolomanski, Sylwester; Steslicki, Marek

    2015-08-01

    Measurements of night sky brightness can give us valuable information on light pollution. The more the measurements we have the better is our knowledge on the spatial distribution of the pollution on local and global scale.High accuracy professional photometry of night sky can be performed with dedicated instruments. The main drawbacks of this method are high price and low mobility. This limits an amount of observers and therefore amount of photometric data that can be collected. In order to overcome the problem of limited amount of data we can involve amateur astronomers in photometry of night sky. However, to achieve this goal we need a method that utilizes equipment which is usually used by amateur astronomers, e.g digital cameras.We propose a method that enables good accuracy photometry of night sky with a use of digital compact or DSLR cameras. In the method reduction of observations and standarization to Johnson UBV system are performed. We tested several cameras and compared results to Sky Quality Meter (SQM) measurements. The overall consistency for results is within 0.2 mag.

  10. M2K Planet Search: Spectroscopic Screening and Transit Photometry

    NASA Astrophysics Data System (ADS)

    Mann, Andrew; Gaidos, E.; Fischer, D.; Lepine, S.

    2010-10-01

    The M2K project is a search for planets orbiting nearby early M and late K dwarf drawn from the SUPERBLINK catalog. M and K dwarfs are highly attractive targets for finding low-mass and habitable planets because (1) close-in planets are more likely to orbit within their habitable zone, (2) planets orbiting them induce a larger Doppler signal and have deeper transits than similar planets around F, G, and early K type stars, (3) planet formation models predict they hold an abundance of super-Earth sized planets, and (4) they represent the vast majority of the stars close enough for direct imaging techniques. In spite of this, only 10% of late K and early M dwarfs are being monitored by current Doppler surveys. As part of the M2K project we have obtained low-resolution spectra for more than 2000 of our sample of 10,000 M and K dwarfs. We vet our sample by screening these stars for high metallicity and low chromospheric activity. We search for transits on targets showing high RMS Doppler signal and photometry candidates provided by SuperWASP project. By using "snapshot” photometry have been able to achieve sub-millimag photometry on numerous transit targets in the same night. With further follow-up observations we will be able to detect planets smaller than 10 Earth masses.

  11. Theory of wide-angle photometry from standard stars

    NASA Technical Reports Server (NTRS)

    Usher, Peter D.

    1989-01-01

    Wide angle celestial structures, such as bright comet tails and nearby galaxies and clusters of galaxies, rely on photographic methods for quantified morphology and photometry, primarily because electronic devices with comparable resolution and sky coverage are beyond current technological capability. The problem of the photometry of extended structures and of how this problem may be overcome through calibration by photometric standard stars is examined. The perfect properties of the ideal field of view are stated in the guise of a radiometric paraxial approximation, in the hope that fields of view of actual telescopes will conform. Fundamental radiometric concepts are worked through before the issue of atmospheric attenuation is addressed. The independence of observed atmospheric extinction and surface brightness leads off the quest for formal solutions to the problem of surface photometry. Methods and problems of solution are discussed. The spectre is confronted in the spirit of standard stars and shown to be chimerical in that light, provided certain rituals are adopted. After a brief discussion of Baker-Sampson polynomials and the vexing issue of saturation, a pursuit is made of actual numbers to be expected in real cases. While the numbers crunched are gathered ex nihilo, they demonstrate the feasibility of Newton's method in the solution of this overdetermined, nonlinear, least square, multiparametric, photometric problem.

  12. Multi-channel fiber photometry for population neuronal activity recording

    PubMed Central

    Guo, Qingchun; Zhou, Jingfeng; Feng, Qiru; Lin, Rui; Gong, Hui; Luo, Qingming; Zeng, Shaoqun; Luo, Minmin; Fu, Ling

    2015-01-01

    Fiber photometry has become increasingly popular among neuroscientists as a convenient tool for the recording of genetically defined neuronal population in behaving animals. Here, we report the development of the multi-channel fiber photometry system to simultaneously monitor neural activities in several brain areas of an animal or in different animals. In this system, a galvano-mirror modulates and cyclically couples the excitation light to individual multimode optical fiber bundles. A single photodetector collects excited light and the configuration of fiber bundle assembly and the scanner determines the total channel number. We demonstrated that the system exhibited negligible crosstalk between channels and optical signals could be sampled simultaneously with a sample rate of at least 100 Hz for each channel, which is sufficient for recording calcium signals. Using this system, we successfully recorded GCaMP6 fluorescent signals from the bilateral barrel cortices of a head-restrained mouse in a dual-channel mode, and the orbitofrontal cortices of multiple freely moving mice in a triple-channel mode. The multi-channel fiber photometry system would be a valuable tool for simultaneous recordings of population activities in different brain areas of a given animal and different interacting individuals. PMID:26504642

  13. Measurements of Photoelectric Yield and Physical Properties of Individual Lunar Dust Grains

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Tankosic, D.; Craven, P. D.; Spann, J. F.; LeClair, A.; West, F. A.; Taylor, L.; Hoover, R.

    2005-01-01

    Micron size dust grains levitated and transported on the lunar surface constitute a major problem for the robotic and human habitat missions for the Moon. It is well known since the Apollo missions that the lunar surface is covered with a thick layer of micron/sub-micron size dust grains. Transient dust clouds over the lunar horizon were observed by experiments during the Apollo 17 mission. Theoretical models suggest that the dust grains on the lunar surface are charged by the solar UV radiation as well as the solar wind. Even without any physical activity, the dust grains are levitated by electrostatic fields and transported away from the surface in the near vacuum environment of the Moon. The current dust charging and the levitation models, however, do not fully explain the observed phenomena. Since the abundance of dust on the Moon's surface with its observed adhesive characteristics is believed to have a severe impact on the human habitat and the lifetime and operations of a variety of equipment, it is necessary to investigate the phenomena and the charging properties of the lunar dust in order to develop appropriate mitigating strategies. We will present results of some recent laboratory experiments on individual micro/sub-micron size dust grains levitated in electrodynamic balance in simulated space environments. The experiments involve photoelectric emission measurements of individual micron size lunar dust grains illuminated with UV radiation in the 120-160 nm wavelength range. The photoelectric yields are required to determine the charging properties of lunar dust illuminated by solar UV radiation. We will present some recent results of laboratory measurement of the photoelectric yields and the physical properties of individual micron size dust grains from the Apollo and Luna-24 sample returns as well as the JSC-1 lunar simulants.

  14. The photoelectric heating mechanism for very small graphitic grains and polycyclic aromatic hydrocarbons

    NASA Technical Reports Server (NTRS)

    Bakes, E. L. O.; Tielens, A. G. G. M.

    1994-01-01

    We have theoretically modeled the gas heating associated with the photoelectric ejection of electrons from a size distribution of interstellar carbon grains which extends into the molecular domain. We have considered a wide range of physical conditions for the interstellar gas (1 less than G(sub 0) less than 10(exp 5), with G(sub 0) being the intensity of the incident far-UV field in units of the Habing interstellar radiation field; 2.5 x 10( exp -3) less than n(sub e) less than 75/cu cm, with n(sub e) being the electron density; 10 less than T less than 10,000 K, with T being the gas temperature). The results show that about half of the heating is due to grains less than 1500 C atoms (less than 15 A). The other half originates in somewhat larger grains (1500-4.5 x 10(exp 5) C atoms; 15 less than 100 A). While grains larger than this do absorb about half of the available far-UV photons, they do not contribute appreciably to the gas heating. This strong dependence of gas heating on size results from the decrease in yield and from the increased grain charge (hence larger Coulomb losses) with increasing grain size. We have determined the net photoelectric heating rate and evaluated a simple analytical expression for the heating efficiency, dependent only on G(sub 0), T, and n(sub e). This expression is accurate to 3% over the whole parameter range and is valid up to gas temperatures of 10(exp 4) K, at which point the dominant gas-dust heat exchange mechanism becomes the recombination of electrons with grains rather than photoelectric ejection. The calculated heating efficiency for neutral grains is in good agreement with that derived from observations of the diffuse interstellar clouds. Our results also agree well with the Far Infrared Absolute Spectrometer (FIRAS) observations on the Cosmic Background Explorer Satellite. Finally, our photoelectric heating efficiency is compared to previous studies.

  15. On the vectorial photoelectric effect at 2.69 keV

    NASA Technical Reports Server (NTRS)

    Shaw, P. S.; Hanany, S.; Liu, Y.; Church, E. D.; Fleischman, J.; Kaaret, P.; Novick, R.; Santangelo, A.

    1991-01-01

    Recent experiments conducted to study the vectorial photoelectric effect with CsI, Al2O3 and Si photocathodes at 2.69 keV indicate null results. Detailed analysis shows that previously measured modulation can be well explained by geometrical misalignment and a combination of the asymmetric shape of the incident X-ray beam and a small detection area of the photoelectron detector. After the elimination of the sources of spurious modulation, we observed a modulation factor of less than 3 percent for a grazing incidence angle as small as 5 deg. There is no observable difference in the pulse height distribution between s and p states.

  16. Observation of coherence in the time-reversed relativistic photoelectric effect.

    PubMed

    Tashenov, S; Banaś, D; Beyer, H; Brandau, C; Fritzsche, S; Gumberidze, A; Hagmann, S; Hillenbrand, P-M; Jörg, H; Kojouharov, I; Kozhuharov, Ch; Lestinsky, M; Litvinov, Yu A; Maiorova, A V; Schaffner, H; Shabaev, V M; Spillmann, U; Stöhlker, Th; Surzhykov, A; Trotsenko, S

    2014-09-12

    The photoelectric effect has been studied in the regime of hard x rays and strong Coulomb fields via its time-reversed process of radiative recombination (RR). In the experiment, the relativistic electrons recombined into the 2p_{3/2} excited state of hydrogenlike uranium ions, and both the RR x rays and the subsequently emitted characteristic x rays were detected in coincidence. This allowed us to observe the coherence between the magnetic substates in a highly charged ion and to identify the contribution of the spin-orbit interaction to the RR process. PMID:25259973

  17. New technology of photoelectric reconnaissance based on exploitation of quantum effects

    NASA Astrophysics Data System (ADS)

    Yang, Kai; Chen, Liang; Liu, Honglin

    2008-03-01

    A new high spectrum difference technique was discussed in this paper, which use exploitation of quantum effects to detect and warn low observable objects (include missile, stealth etc.). It is a new technique in photoelectric reconnaissance area, and has many advantages such as wide radiation regions and greatly strengthens signal intensity. In this paper radiation spectrum intensity, atmosphere attenuation and effect distance are studied. We found that high intensity of stimulated emission spectrum can be obtained in atmosphere transmit window. So the sensitiveness and distance of detect can be enormously improved.

  18. Photoelectric properties of Al/In2Se3 Schottky barriers

    NASA Astrophysics Data System (ADS)

    Bodnar', I. V.; Rud', V. Yu.; Rud', Yu. V.; Gorbachev, D. V.

    2008-05-01

    We used directional solidification of the melt to grow single crystals of the binary compound In2Se3 and then determined the composition of the crystals obtained and their structure. From Hall effect measurements, we determined the type of conductivity, the concentration, and the Hall mobility of the free electrons in the single crystals obtained, on which we developed photosensitive Al/In2Se3 Schottky barriers for the first time and determined their photoelectric properties. We established that the indicated barriers can be used to design broadband optical photoconverters based on In2Se3 single crystals.

  19. New potential for enhancing concomitant chemoradiotherapy with FDA approved concentrations of cisplatin via the photoelectric effect

    PubMed Central

    Altundal, Yucel; Cifter, Gizem; Detappe, Alexandre; Sajo, Erno; Tsiamas, Panagiotis; Zygmanski, Piotr; Berbeco, Ross; Cormack, Robert A.; Makrigiorgos, Mike; Ngwa, Wilfred

    2015-01-01

    We predict, for the first time, that by using United States Food and Drug Administration approved concentrations of cisplatin, major radiosensitization may be achieved via photoelectric mechanism during concomitant chemoradiotherapy (CCRT). Our analytical calculations estimate that radiotherapy (RT) dose to cancer cells may be enhanced via this mechanism by over 100% during CCRT. The results proffer new potential for significantly enhancing CCRT via an emerging clinical scenario, where the cisplatin is released in-situ from RT biomaterials loaded with cisplatin nanoparticles. PMID:25492359

  20. VizieR Online Data Catalog: Photoelectric absorption cross-sections (Balucinska-Church+, 1992)

    NASA Astrophysics Data System (ADS)

    Balucinska-Church, M.; McCammon, D.

    1994-03-01

    Polynomial fit coefficients have been obtained for the energy dependence of the photoelectric absorption cross sections of 17 astrophysically important elements. The aim of this work is to provide convenient fits to the photoelectric absorption cross sections for each of 17 elements separately, so that spectral modelling can be performed with an absorption term containing the abundances of some or all of the elements as adjustable parameters. The fits to the individual elements can also be used independently for calculating window transmissions, gas stopping efficiency, etc. The atomic absorption cross sections were taken from Henke et al. (1982). Polynomial fits have been made to the atomic absorption cross sections in the energy range of 0.03 -- 10 keV for seventeen elements: hydrogen, helium, carbon, nitrogen, oxygen, neon, sodium, magnesium, aluminium, silicon, sulphur, chlorine, argon, calcium, chromium, iron and nickel. In the case of elements with only the K-edge in this energy range, polynomial fits were made each side of the edge; with the L-edge also present three fits were made. Polynomials of up to degree 8 were required. The functions fit Henke's data points with a typical error of 2% and a maximum error of 7%, except for points below 40~eV for argon, calcium and sodium, where the errors are larger. The effective cross section per hydrogen atom for a particular set of elemental abundances may be simply calculated from the individual cross sections. A set of routines has been written in generic FORTRAN-77 to implement these polynomial fits. The file XSCTNS.FOR contains seventeen REAL functions that will return the photoelectric cross sections for H, He, C, N, O, Ne, Na, Mg, Al, Si, S, Cl, A, Ca, Cr, Fe, and Ni in cm**2/g, given the photon energy in eV. The file TOTLXS.FOR contains a single function that returns the effective cross section in cm**2/H atom, given the photon energy in eV and a set of seventeen relative abundances in log10. If standard

  1. Research on photoelectric test and measurment for form and position error

    NASA Astrophysics Data System (ADS)

    Xie, Jinsong

    2002-09-01

    Structure and principles of a photoelectric test and measurement system for form and position error are described. A special optical system using laser beam characteristics was designed to ensure the uniformity of the scanning speed. To meet the requirements of the system a precision mechanical system a servo-control system and an computing and data processing system are designed. As a result a high-speed efficiency and high precision non-contact auto-test is realized. This is a promotion to the development of "advanced manufacture technology".

  2. New potential for enhancing concomitant chemoradiotherapy with FDA approved concentrations of cisplatin via the photoelectric effect.

    PubMed

    Altundal, Yucel; Cifter, Gizem; Detappe, Alexandre; Sajo, Erno; Tsiamas, Panagiotis; Zygmanski, Piotr; Berbeco, Ross; Cormack, Robert A; Makrigiorgos, Mike; Ngwa, Wilfred

    2015-02-01

    We predict, for the first time, that by using United States Food and Drug Administration approved concentrations of cisplatin, major radiosensitization may be achieved via photoelectric mechanism during concomitant chemoradiotherapy (CCRT). Our analytical calculations estimate that radiotherapy (RT) dose to cancer cells may be enhanced via this mechanism by over 100% during CCRT. The results proffer new potential for significantly enhancing CCRT via an emerging clinical scenario, where the cisplatin is released in-situ from RT biomaterials loaded with cisplatin nanoparticles. PMID:25492359

  3. The effect of neutron radiation on the photoelectric parameters of ITO-GaSe structures

    SciTech Connect

    Kovalyuk, Z. D. Litovchenko, P. G.; Politanska, O. A.; Sydor, O. N.; Katerynchuk, V. N.; Lastovetsky, V. F.; Litovchenko, O. P.; Dubovoy, V. K.; Polivtsev, L. A.

    2007-05-15

    The effect of 1-MeV neutrons on the photoelectric parameters of ITO-GaSe heterostructures was studied. It is shown that the observed variations in the current-voltage characteristics are caused by the effect of penetrating radiation on both components of the structure, which brings about an increase in the resistance of the heterostructures. The presence of exciton fine structure in the photosensitivity spectra after irradiation indicates that GaSe retains high structural quality notwithstanding the introduced radiation defects. The results obtained are accounted for by spatial redistribution of doping impurity in GaSe and structural changes in the ITO films.

  4. Improving Kepler Pipeline Sensitivity with Pixel Response Function Photometry.

    NASA Astrophysics Data System (ADS)

    Morris, Robert L.; Bryson, Steve; Jenkins, Jon Michael; Smith, Jeffrey C

    2014-06-01

    We present the results of our investigation into the feasibility and expected benefits of implementing PRF-fitting photometry in the Kepler Science Processing Pipeline. The Kepler Pixel Response Function (PRF) describes the expected system response to a point source at infinity and includes the effects of the optical point spread function, the CCD detector responsivity function, and spacecraft pointing jitter. Planet detection in the Kepler pipeline is currently based on simple aperture photometry (SAP), which is most effective when applied to uncrowded bright stars. Its effectiveness diminishes rapidly as target brightness decreases relative to the effects of noise sources such as detector electronics, background stars, and image motion. In contrast, PRF photometry is based on fitting an explicit model of image formation to the data and naturally accounts for image motion and contributions of background stars. The key to obtaining high-quality photometry from PRF fitting is a high-quality model of the system's PRF, while the key to efficiently processing the large number of Kepler targets is an accurate catalog and accurate mapping of celestial coordinates onto the focal plane. If the CCD coordinates of stellar centroids are known a priori then the problem of PRF fitting becomes linear. A model of the Kepler PRF was constructed at the time of spacecraft commissioning by fitting piecewise polynomial surfaces to data from dithered full frame images. While this model accurately captured the initial state of the system, the PRF has evolved dynamically since then and has been seen to deviate significantly from the initial (static) model. We construct a dynamic PRF model which is then used to recover photometry for all targets of interest. Both simulation tests and results from Kepler flight data demonstrate the effectiveness of our approach. Kepler was selected as the 10th mission of the Discovery Program. Funding for this mission is provided by NASA’s Science

  5. Karl Schwarzschild's investigations of ``out-of-focus photometry'' between 1897-1899 and his contribution to photographic photometry

    NASA Astrophysics Data System (ADS)

    Habison, Peter

    From 1897 to 1899 Karl Schwarzschild was working at Kuffner Observatory in Vienna. During these years he developed new measuring techniques in the field of photographic photometry, where he particularly studied the quantitative determination of the departure of the reciprocity law during photographic exposures. During that time stellar magnitudes were almost exclusively determined by measuring the size of in-focus stellar disks. Photometry using out-of-focus exposures had been proposed, but had not yet been tried. Schwarzschild's very first paper in this context contains two important results: The intimation that estimating densities on out-of-focus plates could give an accuracy of better than 0.05 mag and the analysis of his photographic data indicated that the reciprocity law (S=Iṡ t), was not obeyed. >From the paper it is not clear how he came to set himself this double task. A series of singly exposed plates date from September 1897, whereas the series of exposures of particular relevance to the question of the time dependence of plate density all date from October 1897. It is remarkable how Schwarzschild succeeded in deriving a better approximation of the characteristic curve's dependence on intensity and time. The talk will focus on Schwarzschild's investigations of ``out-of-focus photometry'' between 1897 and 1899. A few selected original photographic plates will be presented and discussed.

  6. Enhanced photoelectric performance of PbS/CdS quantum dot co-sensitized solar cells via hydrogenated TiO2 nanorod arrays.

    PubMed

    Chen, Yanli; Tao, Qiang; Fu, Wuyou; Yang, Haibin; Zhou, Xiaoming; Su, Shi; Ding, Dong; Mu, Yannan; Li, Xue; Li, Minghui

    2014-08-28

    The enhanced photoelectric performance of quantum dot sensitized solar cells via hydrogenated TiO2 is proposed. The best energy conversion efficiency is 1.5 times higher than cells without hydrogen treatment. We demonstrated that introducing oxygen vacancies by hydrogenation is an effective and feasible method for enhanced photoelectric performance. PMID:25010989

  7. Photometry of the central region of the Andromeda Nebula

    SciTech Connect

    Sharov, A.S.; Liutyi, V.M.

    1980-05-01

    The photoelectric U, B, V observations of the central region of M81 made in 166 fields at distances of 54-351 arcsec from the center are used to explain the structure of the central condensation of the galaxy. The surface-brightness isophotes can be fit by ellipses varying in axial ratio from 0.9 to 0.6 and in position angle from 70 to 45 deg. The central condensation may include a bar in the form of a triaxial ellipsoid the nucleus occupies an asymmetric position in this condensation, shifted by 22 arcsec northwest relative to the most distant U isophote at a 368 arcsec. The apparent eccentricity with respect to the outlying isophotes is caused by distribution of dust, as shown by the colorimetric B - V, U - B color-index profiles reflecting the dust in the central condensation of M31.

  8. Exploiting the Photoelectric effect for X-ray Polarimetry using Time Projection Chamber

    NASA Technical Reports Server (NTRS)

    Jahoda, Keith; Black, Kevin; Deines-Jones, Philip; Hill, Joanne; Swank, Jean

    2008-01-01

    The promise of photoelectric X-ray polarimetry has now been realized in laboratory demonstrations and may soon be used for astrophysical observations. Photoelectric polarimetry in gas filled proportional counters achieves high sensitivity through a combination of broad band width and good modulation. The band can be tuned by careful choice of gas composition and pressure. The measurements rely on imaging the tracks of photoelectrons. The initial direction of each track carries information about the electric field of the X-ray photon, and an ensemble of such measurements thus measures the net polarization of the source. A novel readout geometry using time projection chambers (TPC) allows deep (i.e. high efficiency) detectors, albeit without the ability to image the sky. Polarimeters which exploit the TPC geometry can be optimized for use behind telescopes, to study faint persistent sources, or as wide field of view instruments, designed to study bright transient events such as gamma-ray bursts or solar flares. We present the conceptual design of both types of TPC polarimeter. Recent laboratory results demonstrate that these polarimeters can achieve substantial gains in the polarization sensitivity achievable in experiments of modest size.

  9. Electrical and photoelectrical characteristic investigation of a new generation photodiode based on bromothymol blue dye

    NASA Astrophysics Data System (ADS)

    Gencer Imer, A.; Tombak, A.; Korkut, A.

    2016-04-01

    Bromothymol blue (BTB) with the molecular formula of C27H28Br2O5S was grown onto p-Si substrate to fabricate heterojunction by spin coating technique. The current voltage (I-V) measurements of diode were carried out in dark and under different illumination intensity at room temperature. The photoelectrical properties of heterojunction based on BTB were investigated using the illumination intensity dependent I-V data. The results showed that photo current of diode increases with the increase in light intensity. Also, the electrical parameters of device were determined via I-V, and capacitance- voltage (C-V), conductance-voltage (G-V) measurements at different frequencies. It is observed that the excess capacitance is created at low frequencies due to the contribution of interface states charge which can follow the alternative current signal to capacitance. It is stated that, both the electrical & photoelectrical parameters of diode can be changed, and also the performance of the device could be affected by the organic thin film interlayer.

  10. Photoelectric detection of electron spin resonance of nitrogen-vacancy centres in diamond.

    PubMed

    Bourgeois, E; Jarmola, A; Siyushev, P; Gulka, M; Hruby, J; Jelezko, F; Budker, D; Nesladek, M

    2015-01-01

    The readout of negatively charged nitrogen-vacancy centre electron spins is essential for applications in quantum computation, metrology and sensing. Conventional readout protocols are based on the detection of photons emitted from nitrogen-vacancy centres, a process limited by the efficiency of photon collection. We report on an alternative principle for detecting the magnetic resonance of nitrogen-vacancy centres, allowing the direct photoelectric readout of nitrogen-vacancy centres spin state in an all-diamond device. The photocurrent detection of magnetic resonance scheme is based on the detection of charge carriers promoted to the conduction band of diamond by two-photon ionization of nitrogen-vacancy centres. The optical and photoelectric detection of magnetic resonance are compared, by performing both types of measurements simultaneously. The minima detected in the measured photocurrent at resonant microwave frequencies are attributed to the spin-dependent ionization dynamics of nitrogen-vacancy, originating from spin-selective non-radiative transitions to the metastable singlet state. PMID:26486014

  11. Photoelectric detection of electron spin resonance of nitrogen-vacancy centres in diamond

    PubMed Central

    Bourgeois, E.; Jarmola, A.; Siyushev, P.; Gulka, M.; Hruby, J.; Jelezko, F.; Budker, D.; Nesladek, M.

    2015-01-01

    The readout of negatively charged nitrogen-vacancy centre electron spins is essential for applications in quantum computation, metrology and sensing. Conventional readout protocols are based on the detection of photons emitted from nitrogen-vacancy centres, a process limited by the efficiency of photon collection. We report on an alternative principle for detecting the magnetic resonance of nitrogen-vacancy centres, allowing the direct photoelectric readout of nitrogen-vacancy centres spin state in an all-diamond device. The photocurrent detection of magnetic resonance scheme is based on the detection of charge carriers promoted to the conduction band of diamond by two-photon ionization of nitrogen-vacancy centres. The optical and photoelectric detection of magnetic resonance are compared, by performing both types of measurements simultaneously. The minima detected in the measured photocurrent at resonant microwave frequencies are attributed to the spin-dependent ionization dynamics of nitrogen-vacancy, originating from spin-selective non-radiative transitions to the metastable singlet state. PMID:26486014

  12. Synthesis, crystal structure, electronic structure, and photoelectric response properties of KCu2SbS3.

    PubMed

    Wang, Ruiqi; Zhang, Xian; He, Jianqiao; Zheng, Chong; Lin, Jianhua; Huang, Fuqiang

    2016-02-28

    Copper thioantimonates have received enormous attention due to their potential for applications in photovoltaic devices. In this work, a new layered compound KCu2SbS3 was synthesized via a reactive flux method using thiourea as a reactive flux. The compound crystallizes in the triclinic space group P1[combining macron]. The structure features two-dimensional [Cu2SbS3](-) layers stacking along the c axis with K(+) ions intercalated between the layers. Each [Cu2SbS3](-) layer is composed of two single graphene-like layers connected via interlayer Cu-S bonds and CuSb contacts. The optical measurements indicate that the compound has a band gap of 1.7 eV. The Hall effect measurement shows that KCu2SbS3 is a p-type semiconductor with a carrier concentration of 7 × 10(16) cm(-3). First-principles calculations reveal that the direct transition occurs between Cu-3d-S-3p orbitals (VBM) to Sb-5p-S-3p orbitals (CBM). The photoelectric response properties of KCu2SbS3 under visible light irradiation were analyzed. The photocurrent is 3.7 μA cm(-2) at 10 V bias, demonstrating its potential for applications in photoelectric devices. PMID:26794832

  13. Photoelectric detection of electron spin resonance of nitrogen-vacancy centres in diamond

    NASA Astrophysics Data System (ADS)

    Bourgeois, E.; Jarmola, A.; Siyushev, P.; Gulka, M.; Hruby, J.; Jelezko, F.; Budker, D.; Nesladek, M.

    2015-10-01

    The readout of negatively charged nitrogen-vacancy centre electron spins is essential for applications in quantum computation, metrology and sensing. Conventional readout protocols are based on the detection of photons emitted from nitrogen-vacancy centres, a process limited by the efficiency of photon collection. We report on an alternative principle for detecting the magnetic resonance of nitrogen-vacancy centres, allowing the direct photoelectric readout of nitrogen-vacancy centres spin state in an all-diamond device. The photocurrent detection of magnetic resonance scheme is based on the detection of charge carriers promoted to the conduction band of diamond by two-photon ionization of nitrogen-vacancy centres. The optical and photoelectric detection of magnetic resonance are compared, by performing both types of measurements simultaneously. The minima detected in the measured photocurrent at resonant microwave frequencies are attributed to the spin-dependent ionization dynamics of nitrogen-vacancy, originating from spin-selective non-radiative transitions to the metastable singlet state.

  14. Simulation Analysis on Photoelectric Conversion Characteristics of Silicon Nanowire Array Photoelectrodes.

    PubMed

    Zhao, Yong; Yu, Jin; Fang, Li-Guang; Zheng, Jun; Wang, Hui-Qin; Yuan, Ji-Ren; Wu, Shaolong; Cheng, Guo-An

    2015-12-01

    Semiconductor nanowire photoelectrochemical cells have attracted extensive attention in the light-conversion field owing to the low-cost preparation, excellent optical absorption, and short distance of carrier collection. Although there are numbers of experimental investigations to improve the device performance, the understanding of the detailed process of photoelectric conversion needs to be further improved. In this work, a thorough optoelectronic simulation is employed to figure out how the nanowire diameter, doping concentration, and illumination wavelength affect the photoelectric conversion characteristics of the silicon nanowire array photoelectrodes. We find that two balances should be carefully weighted between optical absorption and photogenerated-carrier collection, along with between short-circuit photocurrent density and open-circuit voltage. For the small-diameter nanowire array photoelectrodes, the overall absorption is higher than that of the larger-diameter ones with the most contribution from the nanowires. However, the substrate shows increasing absorption with increasing illumination wavelength. Higher doping density leads to a larger open-circuit voltage; while lower doping density can guarantee a relatively higher short-circuit photocurrent. To obtain high-light-conversion-efficiency photoelectrodes, the doping density should be carefully chosen with considerations of illumination wavelength and surface recombination. Suppressing the surface recombination velocity can effectively enhance the short-circuit photocurrent (open-circuit voltage) for the lightly (heavily) doped nanowire array photoelectrodes. Our systematical results provide a theoretical guidance for the photoelectrochemical devices based on semiconductor nanostructures. PMID:26123274

  15. Simulation Analysis on Photoelectric Conversion Characteristics of Silicon Nanowire Array Photoelectrodes

    NASA Astrophysics Data System (ADS)

    Zhao, Yong; Yu, Jin; Fang, Li-Guang; Zheng, Jun; Wang, Hui-Qin; Yuan, Ji-Ren; Wu, Shaolong; Cheng, Guo-An

    2015-06-01

    Semiconductor nanowire photoelectrochemical cells have attracted extensive attention in the light-conversion field owing to the low-cost preparation, excellent optical absorption, and short distance of carrier collection. Although there are numbers of experimental investigations to improve the device performance, the understanding of the detailed process of photoelectric conversion needs to be further improved. In this work, a thorough optoelectronic simulation is employed to figure out how the nanowire diameter, doping concentration, and illumination wavelength affect the photoelectric conversion characteristics of the silicon nanowire array photoelectrodes. We find that two balances should be carefully weighted between optical absorption and photogenerated-carrier collection, along with between short-circuit photocurrent density and open-circuit voltage. For the small-diameter nanowire array photoelectrodes, the overall absorption is higher than that of the larger-diameter ones with the most contribution from the nanowires. However, the substrate shows increasing absorption with increasing illumination wavelength. Higher doping density leads to a larger open-circuit voltage; while lower doping density can guarantee a relatively higher short-circuit photocurrent. To obtain high-light-conversion-efficiency photoelectrodes, the doping density should be carefully chosen with considerations of illumination wavelength and surface recombination. Suppressing the surface recombination velocity can effectively enhance the short-circuit photocurrent (open-circuit voltage) for the lightly (heavily) doped nanowire array photoelectrodes. Our systematical results provide a theoretical guidance for the photoelectrochemical devices based on semiconductor nanostructures.

  16. Improved photoelectrical performance of graphene supported highly crystallized anatase TiO2

    NASA Astrophysics Data System (ADS)

    Zhang, Min; Sun, Qiong; Zhao, Mei; Li, Yang; Liu, Qiuhong; Dong, Lifeng

    2015-08-01

    In this study, titanium oxysulfate (TiOSO4) and graphene were used as titanium source and supporter, respectively, to synthesize anatase TiO2-graphene (TiO2-G) composite. Crystal structure, morphology, and composition of TiO2-G were investigated by X-ray diffraction, scanning electron microscope, transmission electron microscope, and thermogravimetric analysis. Both TiO2-G and blank TiO2 powders exhibit spindle-shaped structure with the long axis along [001]. Compared to unsupported TiO2, TiO2 nanoparticles uniformly formed on graphene surface. When fabricated into dye-sensitized solar cells, photoelectrical conversion efficiency of TiO2-G (2.3 %) was much higher than that of blank TiO2 (0.89 %) prepared at the same conditions. Moreover, high sintering temperature enhanced photoelectrical performance of the composite. When the temperature was increased from 450 to 600 °C, the efficiency was improved from 1.5 to 2.6 %. The findings above demonstrate that TiO2-G has great potential for applications in dye-sensitized solar cells.

  17. Preparation and photoelectric property of TiO2 nanoparticles with controllable phase junctions

    NASA Astrophysics Data System (ADS)

    Wang, Hongmei; Tan, Xin; Yu, Tao

    2014-12-01

    To explore the effect of phase composition on the photoelectric property of anatase-rutile mixed crystal nanoparticles, a series of TiO2 nanoparticles with phase junctions controlling were synthetized by hydrolysis of TiCl4 in hydrochloric acid, an ionic liquid-assisted method was used during this process. Crystalline size and the ratio of anatase to rutile of as-prepared samples were calculated by the XRD. The surface area was measured by nitrogen sorption measurements using the BET method. The micro-structure of phase junctions was characterized by TEM. Optical transmittance properties of TiO2 with controllable phase junctions were examined via ultraviolet-visible diffuse reflection spectroscopy (UV-vis DRS). The particles were manufactured into films using the doctor-blade technique on FTO glasses. To test photocurrent density, and spatial separation capacity of electron-holes pairs, photo-electro method was employed. The photocatalytic activities of the resulting samples were examined in the degradation of methyl orange (MO) under artificial solar light irradiation. Mechanisms of separation and transfer of photogenerated charge and the effect of phase composition on photoelectric property of anatase-rutile nanoparticles were discussed.

  18. Photoelectric scanning-based method for positioning omnidirectional automatic guided vehicle

    NASA Astrophysics Data System (ADS)

    Huang, Zhe; Yang, Linghui; Zhang, Yunzhi; Guo, Yin; Ren, Yongjie; Lin, Jiarui; Zhu, Jigui

    2016-03-01

    Automatic guided vehicle (AGV) as a kind of mobile robot has been widely used in many applications. For better adapting to the complex working environment, more and more AGVs are designed to be omnidirectional by being equipped with Mecanum wheels for increasing their flexibility and maneuverability. However, as the AGV with this kind of wheels suffers from the position errors mainly because of the frequent slipping property, how to measure its position accurately in real time is an extremely important issue. Among the ways of achieving it, the photoelectric scanning methodology based on angle measurement is efficient. Hence, we propose a feasible method to ameliorate the positioning process, which mainly integrates four photoelectric receivers and one laser transmitter. To verify the practicality and accuracy, actual experiments and computer simulations have been conducted. In the simulation, the theoretical positioning error is less than 0.28 mm in a 10 m×10 m space. In the actual experiment, the performances about the stability, accuracy, and dynamic capability of this method were inspected. It demonstrates that the system works well and the performance of the position measurement is high enough to fulfill the mainstream tasks.

  19. Single-beam water vapor detection system with automatic photoelectric conversion gain control

    NASA Astrophysics Data System (ADS)

    Zhu, C. G.; Chang, J.; Wang, P. P.; Wang, Q.; Wei, W.; Liu, Z.; Zhang, S. S.

    2014-11-01

    A single-beam optical sensor system with automatic photoelectric conversion gain control is proposed for doing high reliability water vapor detection under relatively rough environmental conditions. Comparing to a dual-beam system, it can distinguish the finer photocurrent variations caused by the optical power drift and provide timely compensation by automatically adjusting the photoelectric conversion gain. This system can be rarely affected by the optical power drift caused by fluctuating ambient temperature or variation of fiber bending loss. The deviation of the single-beam system is below 1.11% when photocurrent decays due to fiber bending loss for bending radius of 5 mm, which is obviously lower than the dual-beam system (8.82%). We also demonstrate the long-term stability of the single-beam system by monitoring a 660 ppm by volume (ppmv) water vapor sample continuously for 24 h. The maximum deviation of the measured concentration during the whole testing period does not exceed 10 ppmv. Experiments have shown that the new system features better reliability and is more apt for remote sensing application which is often subject to light transmission loss.

  20. Deposition of Bacteriorhodopsin Protein in a Purple Membrane Form on Nitrocellulose Membranes for Enhanced Photoelectric Response

    PubMed Central

    Kim, Young Jun; Neuzil, Pavel; Nam, Chang-Hoon; Engelhard, Martin

    2013-01-01

    Bacteriorhodopsin protein (bR)-based systems are one of the simplest known biological energy converters. The robust chemical, thermal and electrochemical properties of bR have made it an attractive material for photoelectric devices. This study demonstrates the photoelectric response of a dry bR layer deposited on a nitrocellulose membrane with indium tin oxide (ITO) electrodes. Light-induced electrical current as well as potential and impedance changes of dried bR film were recorded as the function of illumination. We have also tested bR in solution and found that the electrical properties are strongly dependent on light intensity changing locally proton concentration and thus pH of the solution. Experimental data support the assumption that bR protein on a positively charged nitrocellulose membrane (PNM) can be used as highly sensitive photo- and pH detector. Here the bR layer facilitates proton translocation and acts as an ultrafast optoelectric signal transducer. It is therefore useful in applications related to bioelectronics, biosensors, bio-optics devices and current carrying junction devices. PMID:23271605

  1. Comparison of ozone determinations by ultraviolet photometry and gas-phase titration

    NASA Technical Reports Server (NTRS)

    Demore, W. B.; Patapoff, M.

    1976-01-01

    A comparison of ozone determinations based on ultraviolet absorption photometry and gas-phase titration (GPT) shows good agreement between the two methods. Together with other results, these findings indicate that three candidate reference methods for ozone, UV photometry, IR photometry, and GPT are in substantial agreement. However, the GPT method is not recommended for routine use by air pollution agencies for calibration of ozone monitors because of susceptibility to experimental error.

  2. Photometry and spectroscopy in the open cluster alpha Persei, 2.

    NASA Technical Reports Server (NTRS)

    Prosser, Charles F.

    1994-01-01

    Results from a combination of new spectroscopic and photometric observations in the lower main sequence and pre-main sequence of the open cluster alpha Persei are presented. New echelle spectroscopy has provided radial and rotational velocity information for thirteen candidate members, three of which are nonmembers based on radial velocity, absence of a Li 6707 A feature, and absence of H alpha emission. A set of revised rotational velocity estimates for several slowly rotating candidates identified earlier is given, yielding rotational velocities as low as 7 km/s for two apparent cluster members. VI photometry for several pre-main-sequence members is given; the new (V, V-I(sub K) photometry yields a more clearly defined pre-main sequence. A list of approximately 30 new faint candidate members based on the (V, V-I(sub K)), charge coupled device (CCD) photometry is presented in an effort to identify additional cluster members at very low masses. Low-dispersion spectra obtained for several of these candidates provide in some cases supporting evidence for cluster membership. The single brown dwarf candidate in this cluster is for the first time placed in a color-magnitude diagram with other cluster members, providing a better means for establishing its true status. Stars from among the list of new photometric candidates may provide the means for establishing a sequence of cluster members down to very faint magnitudes (V approximately 21) and consequently very low masses. New coordinate determinations for previous candidate members and finding charts for the new photometric candidates are provided in Appendices.

  3. High-precision photometry for K2 Campaign 1

    NASA Astrophysics Data System (ADS)

    Huang, C. X.; Penev, K.; Hartman, J. D.; Bakos, G. Á.; Bhatti, W.; Domsa, I.; de Val-Borro, M.

    2015-12-01

    The two reaction wheel K2 mission promises and has delivered new discoveries in the stellar and exoplanet fields. However, due to the loss of accurate pointing, it also brings new challenges for the data reduction processes. In this paper, we describe a new reduction pipeline for extracting high-precision photometry from the K2 data set, and present public light curves for the K2 Campaign 1 target pixel data set. Key to our reduction is the derivation of global astrometric solutions from the target stamps, from which accurate centroids are passed on for high-precision photometry extraction. We extract target light curves for sources from a combined UCAC4 and EPIC catalogue - this includes not only primary targets of the K2 campaign 1, but also any other stars that happen to fall on the pixel stamps. We provide the raw light curves, and the products of various detrending processes aimed at removing different types of systematics. Our astrometric solutions achieve a median residual of ˜0.127 arcsec. For bright stars, our best 6.5 h precision for raw light curves is ˜20 parts per million (ppm). For our detrended light curves, the best 6.5 h precision achieved is ˜15 ppm. We show that our detrended light curves have fewer systematic effects (or trends, or red-noise) than light curves produced by other groups from the same observations. Example light curves of transiting planets and a Cepheid variable candidate, are also presented. We make all light curves public, including the raw and detrended photometry, at http://k2.hatsurveys.org.

  4. Inferring planetary obliquity using rotational and orbital photometry

    NASA Astrophysics Data System (ADS)

    Schwartz, J. C.; Sekowski, C.; Haggard, H. M.; Pallé, E.; Cowan, N. B.

    2016-03-01

    The obliquity of a terrestrial planet is an important clue about its formation and critical to its climate. Previous studies using simulated photometry of Earth show that continuous observations over most of a planet's orbit can be inverted to infer obliquity. However, few studies of more general planets with arbitrary albedo markings have been made and, in particular, a simple theoretical understanding of why it is possible to extract obliquity from light curves is missing. Reflected light seen by a distant observer is the product of a planet's albedo map, its host star's illumination, and the visibility of different regions. It is useful to treat the product of illumination and visibility as the kernel of a convolution. Time-resolved photometry constrains both the albedo map and the kernel, the latter of which sweeps over the planet due to rotational and orbital motion. The kernel's movement distinguishes prograde from retrograde rotation for planets with non-zero obliquity on inclined orbits. We demonstrate that the kernel's longitudinal width and mean latitude are distinct functions of obliquity and axial orientation. Notably, we find that a planet's spin axis affects the kernel - and hence time-resolved photometry - even if this planet is east-west uniform or spinning rapidly, or if it is north-south uniform. We find that perfect knowledge of the kernel at 2-4 orbital phases is usually sufficient to uniquely determine a planet's spin axis. Surprisingly, we predict that east-west albedo contrast is more useful for constraining obliquity than north-south contrast.

  5. Preliminary results on interstellar reddening as deduced from filter photometry

    NASA Technical Reports Server (NTRS)

    Laget, M.

    1972-01-01

    Filter photometry has been used to derive the interstellar reddening law from stars through the study of a single spectral type, B0. The deficiency in the far ultraviolet flux of a supergiant relative to a main sequence star is compared with the difference in the flux distribution due to a change of one spectral class. Individual interstellar reddening curves show the general feature reported by Stecher (1969) and by Bless and Savage (1970). There is a large amount of scatter in the far ultraviolet which may be partially due to a real difference in interstellar extinction and partially due to observational inaccuracy.

  6. Optical photometry and spectroscopy of Nova Del 2013

    NASA Astrophysics Data System (ADS)

    Tomov, T.; Ilkiewicz, K.; Swierczynski, E.; Belcheva, M.; Dimitrov, D.

    2013-08-01

    We report optical BV photometry and spectroscopy of Nova Del 2013, carried out between August 14.88 UT and August 15.08 UT. Using a 60 cm Cassegrain telescope at the Nicolaus Copernicus University Observatory (Torun, Poland) we estimated the V brightness of the Nova to be 6.31+/-0.02 mag and 6.18+/-0.03 mag on Aug. 14.94 UT and Aug. 15.02 UT respectively. HD 194113 (F2, V=8.00 mag) was used as a comparison star.

  7. CCD Photometry of SW Ursae Majoris during the 1996 Superoutburst

    NASA Astrophysics Data System (ADS)

    Nogami, Daisaku; Baba, Hajime; Kato, Taichi; Novak, Rudolf

    1998-04-01

    Differential CCD photometry of the 1996 April superoutburst of SW UMa was performed both at the Nicholas Copernicus Observatory and at the Ouda Station, Kyoto University. Although superhumps with a period of 0.05818 (+/- 0.00002) d and possible small-amplitude quasi periodic oscillations (QPOs) were detected, we failed to find the so-called super-QPOs. SW UMa has been proved to be the fourth SU UMa-type dwarf nova, following AL Com, V1028 Cyg, and HV Vir, in which an analysis of the superhump maxima timings revealed an increase in the superhump period.

  8. CCD time-resolved photometry of faint cataclysmic variables. III

    NASA Technical Reports Server (NTRS)

    Howell, Steve B.; Szkody, Paula; Kreidl, Tobias J.; Mason, Keith O.; Puchnarewicz, E. M.

    1990-01-01

    CCD time-resolved photometry in V, B, and near-IR for 17 faint cataclysmic variables (CVs) is presented and analyzed. The data are obtained at Kitt Peak National Observatory, the Perkins reflector, Lowell Observatory, and the Observatorio del Roque de los Muchachos from April-June 1989. The degree of variability and periodicities for the CVs are examined. It is observed that the variability of most of the stars is consistent with CV class behavior. Orbital periods for five CVs are determined, and three potential eclipsing systems are detected.

  9. A digital imaging photometry system for cometary data acquisition

    NASA Technical Reports Server (NTRS)

    Clifton, K. S.; Benson, C. M.; Gary, G. A.

    1986-01-01

    This report describes a digital imaging photometry system developed in the Space Science Laboratory at the Marshall Space Flight center. The photometric system used for cometary data acquisition is based on an intensified secondary electron conduction (ISEC) vidicon coupled to a versatile data acquisition system which allows real-time interactive operation. Field tests on the Orion and Rosette nebulas indicate a limiting magnitude of approximately m sub v = 14 over the 40 arcmin field-of-view. Observations were conducted of Comet Giacobini-Zinner in August 1985. The resulting data are discussed in relation to the capabilities of the digital analysis system. The development program concluded on August 31, 1985.

  10. Spectroscopy and photometry for low-mass stars in Praesepe

    NASA Technical Reports Server (NTRS)

    Williams, Scott D.; Stauffer, John R.; Prosser, Charles F.; Herter, Terry

    1994-01-01

    We have obtained spectral types, H alpha equivalent widths, and optical photometry for a small sample of late K and M dwarf candidate members of the Praesepe open cluster. At least for the small sample of stars we have observed, all of the Paesepe members later than M2 have H alpha in emission. The chromospheric activity of the Praesepe satrs is essentially the same as that for Hyades members of the same mass, as expected since the two clusters are thought to be the same age.

  11. Eos, Koronis, and Maria Family Asteroids: Infrared (JHK) Photometry

    NASA Technical Reports Server (NTRS)

    Veeder, Glenn J.; Matson, Dennis L.; Owensby, Pamela D.; Gradie, Jonathan C.; Bell, Jeffrey F.; Tedesco, Edward F.

    1995-01-01

    Infrared photometry at 1.2, 1.6, and 2.2 micrometer (JHK) is reported for 56 asteroids in the Eos, Koronis and, Maria dynamical families. These data are consistent with similar surface composition for all of the asteroids of each family. The infrared colors within each family cluster in the region observed for the S taxonomic class, but Eos asteroids may belong to a separable K class. Asteroid 243 Ida, which was observed by the Galileo spacecraft, is a typical member of the Koronis family. The average infrared colors of the Maria family are slightly redder than those of the Eos and Koronis families.

  12. LEMON: an (almost) completely automated differential-photometry pipeline

    NASA Astrophysics Data System (ADS)

    Terrón, V.; Fernández, M.

    2011-11-01

    We present LEMON, the CCD differential-photometry pipeline, written in Python, developed at the Institute of Astrophysics of Andalusia (CSIC) and originally designed for its use at the 1.23 m CAHA telescope for automated variable stars detection and analysis. The aim of our tool is to make it possible to completely reduce thousands of images of time series in a matter of hours and with minimal user interaction, if not none at all, automatically detecting variable stars and presenting the results to the astronomer.

  13. uvby photometry in McCormick proper motion fields

    NASA Technical Reports Server (NTRS)

    Degewij, J.

    1982-01-01

    The Danish 50 cm telescope at the European Southern Observatory was used to obtain high-precision uvby photometry for 50 F2 to G2 stars, with V values in the 9.4-12.3 mag range, which were selected in the southern galactic polar regions of the McCormick proper motion fields and measured on six different nights. The brighter stars are found to systematically exhibit smaller m(1) indices, of about 0.02 mag, upon comparison with the earlier data of Blaauw et al (1976). Single measurements are given for 98 stars in eight McCormick fields at intermediate southern galactic latitudes.

  14. MYRaf: An Easy Aperture Photometry GUI for IRAF

    NASA Astrophysics Data System (ADS)

    Niaei, M. S.; KiliÇ, Y.; Özeren, F. F.

    2015-07-01

    We describe the design and development of MYRaf, a GUI (Graphical User Interface) that aims to be completely open-source under General Public License (GPL). MYRaf is an easy to use, reliable, and a fast IRAF aperture photometry GUI tool for those who are conversant with text-based software and command-line procedures in GNU/Linux OSs. MYRaf uses IRAF, PyRAF, matplotlib, ginga, alipy, and SExtractor with the general-purpose and high-level programming language Python, and uses the Qt framework.

  15. Additional photoelectric observations and analysis of the variability of the beta Cephei stars 12 and 16 Lacertae

    NASA Astrophysics Data System (ADS)

    Jarzebowski, T.; Jerzykiewicz, M.; Rios Herrera, M.; Rios Berumen, M.

    1980-04-01

    We present photoelectric observations of two Cephei variables - 12 and 16 Lacertae- made in 1977 in the Observatory of Zacatecas. The results of a frequency analysis made with these data and with the data obtained in the same year at the San Pedro Martir, Chiran and Bialkow Observatories are also given.

  16. Design and realization of a contact-less interaction system based on infrared reflection photoelectric detection array

    NASA Astrophysics Data System (ADS)

    Liu, Fei; Lei, Bing; Feng, Ying

    2015-10-01

    Due to the good performance of high sensitivity, quick response and low cost, infrared reflection detection technology is widely used in various fields. In this work, we present a novel contact-less interaction system which is based on infrared reflection detection technology. The system is mainly composed of a Micro Controller Unit (MCU), upper computer and photoelectric detection module. The MCU is utilized to control the photoelectric detection module and to make sure that the sensing unit is lighted one by one in a given order. When the interactive object appears upon the infrared reflection photoelectric detection array, its position information will be ensured and sent to the upper computer through MCU. In this system, every sensing unit is lighted for 1ms, and the detection array includes 8×8 units. It means that the photoelectric detection array will scan 15.6 times per-second. The experimental research results indicate that the factors affecting the detection range including the working current of transmitting diode, modulation frequency, and the reflectivity of the interactive object. When the working current is 10mA, and the modulation frequency is 80 KHz, the system has a detection range of 20 cm. Moreover, efficient modulation and demodulation of optical signal is quite necessary to remove the influence of surrounding light.

  17. Syntheses, structures and photoelectric properties of a series of Cd(II)/Zn(II) coordination polymers and coordination supramolecules

    SciTech Connect

    Jin Jing; Han Xiao; Meng Qin; Li Dan; Chi Yuxian; Niu Shuyun

    2013-01-15

    Five Cd(II)/Zn(II) complexes [Cd(1,2-bdc)(pz){sub 2}(H{sub 2}O)]{sub n} (1), [Cd1Cd2(btec)(H{sub 2}O){sub 6}]{sub n} (2), [Cd(3,4-pdc) (H{sub 2}O)]{sub n} (3), [Zn(2,5-pdc)(H{sub 2}O){sub 4}]{center_dot}2H{sub 2}O (4) and {l_brace} [Zn(2,5-pdc)(H{sub 2}O){sub 2}]{center_dot}H{sub 2}O{r_brace} {sub n} (5) (H{sub 2}bdc=1,2-benzenedicarboxylic acid, pz=pyrazole, H{sub 4}btec=1,2,4,5-benzenetetracarboxylic acid, H{sub 2}pdc=pyridine-dicarboxylic acid) were hydrothermally synthesized and characterized by single-crystal X-ray diffraction, surface photovoltage spectroscopy, XRD, TG analysis, IR and UV-vis spectra and elemental analysis. Structural analyses show that complexes 1-3 are 1D, 2D and 3D Cd(II) coordination polymers, respectively. Complex 4 is a mononuclear Zn(II) complex. Complex 5 is a 3D Zn(II) coordination polymer. The surface photoelectric properties of complexes were investigated by SPS. The results indicate that all complexes exhibit photoelectric responses in the range of 300-600 nm, which reveals that they all possess certain photoelectric conversion properties. By the comparative analyses, it can be found that the species and coordination micro-environment of central metal ion, the species and property of ligands affect the intensity and scope of photoelectric response. - Graphical abstract: Five Cd(II)/Zn(II) complexes have been hydrothermally synthesized and characterized. The photoelectric properties were studied with SPS. The species and coordination micro-environment of central metal ion, the species and property of ligands all affect the photoelectric responses. Highlights: Black-Right-Pointing-Pointer Five Cd/Zn complexes have been synthesized and characterized. Black-Right-Pointing-Pointer The SPS results indicate they possess obvious photoelectric conversion property. Black-Right-Pointing-Pointer The species and coordination environment of central metal ion affect SPS. Black-Right-Pointing-Pointer The species and property of ligands affect SPS

  18. High Precision Photometry for the K2 Mission

    NASA Astrophysics Data System (ADS)

    Huang, Xu; Soares-Furtado, Melinda; Penev, Kaloyan; Hartman, Joel; Bakos, Gaspar; Bhatti, Waqas; Domsa, Istvan; de Val-Borro, Miguel

    2015-12-01

    The two reaction wheel K2 mission brings new challenges for the data reduction processes. We developed a reduction pipeline for extracting high precision photometry from the K2 dataset and we use this pipeline to generate light curves for the K2 Campaign 0 super-stamps and K2 Campaign 1 target pixel dataset. Key to our reduction technique is the derivation of global astrometric solutions from the target stamps from which accurate centroids are passed on for high precision photometry extraction. We also implemented the image subtraction method to reduce the K2 Campaign 0 super-stamps containing open clusters M35 and NGC2158. We extract target light curvesfor sources from a combined UCAC4 and EPIC catalogue -- this includes not only primary targets of the K2 Mission, but also other stars that happen to fall on the pixel stamps. Our astrometric solutions achieve a median residual of ~0.127". For bright stars, our best 6.5 hour precision for raw light curves is ~20 parts per million (ppm). For our detrended light curves, the best 6.5 hour precision achieved is ~15 ppm. We show that our detrended light curves have fewer systematic effects (or trends, or red-noise) than light curves produced by other groups from the same observations. We highlight the measurements of rotation curves using the K2 light curves of stars within open cluster M35 and NGC2158.

  19. A new look at photometry of the Moon

    USGS Publications Warehouse

    Goguen, J.D.; Stone, T.C.; Kieffer, H.H.; Buratti, B.J.

    2010-01-01

    We use ROLO photometry (Kieffer, H.H., Stone, T.C. [2005]. Astron. J. 129, 2887-2901) to characterize the before and after full Moon radiance variation for a typical highlands site and a typical mare site. Focusing on the phase angle range 45??. ) to calculate the scattering matrix and solve the radiative transfer equation for I/. F. The mean single scattering albedo is ??=0.808, the asymmetry parameter is ???cos. ?????=0.77 and the phase function is very strongly peaked in both the forward and backward scattering directions. The fit to the observations for the highland site is excellent and multiply scattered photons contribute 80% of I/. F. We conclude that either model, roughness or multiple scattering, can match the observations, but that the strongly anisotropic phase functions of realistic particles require rigorous calculation of many orders of scattering or spurious photometric roughness estimates are guaranteed. Our multiple scattering calculation is the first to combine: (1) a regolith model matched to the measured particle size distribution and index of refraction of the lunar soil, (2) a rigorous calculation of the particle phase function and solution of the radiative transfer equation, and (3) application to lunar photometry with absolute radiance calibration. ?? 2010 Elsevier Inc.

  20. Deep photometry and integral magnitudes of 8 nearby galaxies

    NASA Astrophysics Data System (ADS)

    Georgiev, Ts. B.

    2016-02-01

    We estimated integral magnitudes of galaxies trying to include the contribution of the brightest part of their halos. We performed surface photometry based on (i) concentric elliptical rims, corresponding to the peripheral ellipticity of the image, (ii) median estimation of the mean value of the rim pixels, (iii) apparent radial brightness profiles, corresponding to the rim medians, and (iv) magnitude curves of growth, derived by numerical integrations of the apparent rim profiles, without preliminary background estimation and removal. Furthermore, we used the magnitude curves of growth to determine the integral magnitudes (limited by size and deepness of our frames) and compared them with the total magnitudes in the data base HyperLeda. Also, we used the rim-profiles to estimate the background level far enough from the galaxy center and we build (here—only for trial) the intrinsic radial profiles (with background removal). We apply this photometry on 8 nearby galaxies, observed with CCD in the system BVRC IC by the 50 cm Schmidt telescope of the Rozhen NAO in 2003-2004. We build radial profiles which occur to be as average 1.8 times (1.2-2.5 times) larger than in data base NED and of integral brightness that occurs to be about 1.4 times (1.2-1.7 times) higher than in data base HyperLeda. The relative brightness additions, found here, correlate with the color index and anti-correlate with the luminosity of the galaxy.

  1. Changes on Pluto's Surface Revealed with Long Timebase Photometry

    NASA Astrophysics Data System (ADS)

    George, Erin; Buie, M.

    2013-10-01

    We are continuing to monitor the long-term photometric behavior of Pluto in order to constrain volatile surface migration. As Pluto passes near the center of the galaxy, the fields are too crowded for normal aperture photometric techniques. We approached this problem with a combination of point-spread function (PSF) photometry and optimal image subtraction (OIS). Our data are from the 0.8-m robotic telescope at Lowell Observatory, the 1-m robotic telescope at New Mexico State Observatory, and the Faulkes 2-m robotic telescope at Siding Spring, part of Las Cumbres Observatory. Our latest results add photometric data up through 2012 to the data collected since discovery. Our new reduction scheme consists of background catalogs, image subtraction using deep templates, and Pluto photometry extraction. We also use the known photometric properties of Charon determined with HST to remove Charon's contribution from old and new data and compare these results with the HST data where Pluto is measured by itself. Data since 2002 show marked departures from the behavior prior to that time. These results provide clear evidence for time evolution of Pluto's surface albedo. We will present these results along with implications for present-day processes that are altering the surface of Pluto. This work also provides crucial insight into the effort required to provide ground-based support observations for the upcoming New Horizons flyby of Pluto in 2015. Support for this work was provided by NASA Planetary Astronomy Program, grant number NNX09AB43G.

  2. Infrared spectroscopy and photometry of Comet Austin 1990 V

    NASA Technical Reports Server (NTRS)

    Hanner, Martha S.; Russell, Ray W.; Lynch, David K.; Brooke, Timothy Y.

    1993-01-01

    3-micron and 10-micron spectra and IR photometry of the dynamically new Comet Austin 1990 V were obtained for March-May 1990. An unusual 9-11 micron emission feature 15-20 percent above the continuum is evident at 0.78 AU postperihelion. The shape, in particular a peak at 11.06 micron, differs from that seen in Halley and several other comets, suggesting a difference in the mineralogy of the silicate grains. The 3.1-7.7 micron spectrum at 0.35 AU shows no obvious feature; feature/continuum contrast of the 3.36 micron emission feature is less than about 5 percent. Based on the IR photometry and a dust model weighted toward small grains, the dust production rate on 6 May at 0.78 AU was about 3 x 10 exp 5 g/s. The corresponding dust/gas mass ratio was about 0.1, classifying Austin as a dust-poor comet. This designation refers only to the relative dust cross section, not to the total mass.

  3. UBV Photometry of the young open cluster Berkely 87

    NASA Astrophysics Data System (ADS)

    Akinyemi, Abolaji; Eskridge, Paul B.

    2015-01-01

    We obtained UBV imaging of a field in the young open cluster Berkeley 87. From these images, we measured the brightness of ~180 stars in the cluster. Our photometry was calibrated using published photometry (Turner & Forbes 1982 PASP 94, 789) of a subset of stars in our field. The cluster is in a region of the sky with strongly varying extinction. Therefore we made a (U-B)-(B-V) color-color diagram of the field and used this to de-redden the stars on a case by case basis. We de-reddened the stars using the unreddened supergiant and main sequence colors from Astrophysical Quantities (Cox 2000).The color-magnitude diagrams of the de-reddened stars are compared to the Padova isochrones(Marigo et al 2008 A&A 482 883). The isochrones are generated for a range of ages, with solar metalicity and no α enhancement. The best fit for the isochrones was the main sequence de-reddened stars from which the age of the cluster is estimated to be 20 million years. This is older than previous age estimates (1-5 million years) from earlier studies of the cluster. This may indicate age variation in the cluster.We acknowledge the support of the Physics and Astronomy department, and the College of Science and Engineering, Minnesota State University, Mankato.

  4. PHOTOMETRY OF VARIABLE STARS FROM DOME A, ANTARCTICA

    SciTech Connect

    Wang Lingzhi; Macri, Lucas M.; Krisciunas, Kevin; Wang Lifan; Ashley, Michael C. B.; Lawrence, Jon S.; Luong-Van, Daniel; Storey, John W. V.; Cui Xiangqun; Gong Xuefei; Yuan Xiangyan; Feng Longlong; Yang Ji; Zhu Zhenxi; Liu Qiang; Zhou Xu; Pennypacker, Carl R.; Shang Zhaohui; Yang Huigen; York, Donald G.

    2011-11-15

    Dome A on the Antarctic plateau is likely one of the best observing sites on Earth thanks to the excellent atmospheric conditions present at the site during the long polar winter night. We present high-cadence time-series aperture photometry of 10,000 stars with i < 14.5 mag located in a 23 deg{sup 2} region centered on the south celestial pole. The photometry was obtained with one of the CSTAR telescopes during 128 days of the 2008 Antarctic winter. We used this photometric data set to derive site statistics for Dome A and to search for variable stars. Thanks to the nearly uninterrupted synoptic coverage, we found six times as many variables as previous surveys with similar magnitude limits. We detected 157 variable stars, of which 55% were unclassified, 27% were likely binaries, and 17% were likely pulsating stars. The latter category includes {delta} Scuti, {gamma} Doradus, and RR Lyrae variables. One variable may be a transiting exoplanet.

  5. Differential Photometry of Asteroids 727 Nipponia and 741 Botolphia

    NASA Astrophysics Data System (ADS)

    Leake, M. A.; Rollins, C.; Wark, T. J.

    2004-11-01

    Differential photometry of the asteroids 727 Nipponia and 741 Botolphia yielded light curves and periods consistent with those available from observers of the Observatoire de Geneve. Data were collected with the SARA 0.9-m telescope at KPNO over the nights of April 27, 2003, May 14, 2004, and June 27-29, 2004, using an Apogee AP7p 511x512 CCD camera, and reduced with Mira 6.0 and IDL routines. This project will help find the rotation period of several primitive asteroids and follow up with spectral analyses to determine where on these asteroids water of hydration may be located. The Nipponia data cover a full rotation period (nominally 5.07h) and the phased light curve resembles those of Behrend et al. at the Ob. Geneve (http://obswww.unige.ch/ behrend/). The Botolphia data cover a quarter of the almost 24-h (provisional) period, and supplement light curves available from the Ob. Geneve groups. Both asteroids are small (about 30 km), mid-belt, of uncertain taxonomy (DT for Nipponia, X for Botolphia), and have slightly high albedo (0.14 to 0.24); whether they are "primitive" is uncertain. Continuing differential photometry at varying phase angles and spectral analyses are planned to examine the spectral heterogeneity of these objects and to search for water of hydration. This research was part of the summer REU program at the Southeastern Association for Research in Astronomy (SARA), made possible by National Science Foundation Grant AST-0097616.

  6. Far-ultraviolet stellar photometry: Fields in Sagittarius and Scorpius

    NASA Astrophysics Data System (ADS)

    Schmidt, Edward G.; Carruthers, George R.

    1995-02-01

    Far-ultraviolet photometry for 741 objects in a field in Sagittarius centered near M8 and 541 objects in a field centered near sigma Scorpii is presented. These data were extracted from electographic images obtained with two cameras during a shuttle flight in 1991 April/May. The cameras provided band passes with lambdaeff = 1375 A and lambdaeff = 1781 A. Synthetic colors show that these bands are sensitive to effective temperature for hot stars. Our measurements were placed on a quantitative far-ultraviolet magnitude scale by convolving the spectra of stars observed by IUE with our cameras' spectral response functions. Fifty-eight percent of the ultraviolet objects were identified with visible stars using the SIMBAD database while another 40% of the objects are blends of early type stars too close together to separate with our resolution. Our photometry is compared with that from the TD-1, OAO 2, and ANS satellites and the S201 (Apollo 16) far-ultraviolet camera and found to agree at the level of a few tenths of a magnitude. Unlike previous studies, almost half of the identified visual counterparts to the ultraviolet objects are early B stars. A plot of distance modulus against ultraviolet color excess reveals a significant population of stars with strong ultraviolet excess.

  7. The MOST Asteroseismology Mission: Ultraprecise Photometry from Space

    NASA Astrophysics Data System (ADS)

    Walker, Gordon; Matthews, Jaymie; Kuschnig, Rainer; Johnson, Ron; Rucinski, Slavek; Pazder, John; Burley, Gregory; Walker, Andrew; Skaret, Kristina; Zee, Robert; Grocott, Simon; Carroll, Kieran; Sinclair, Peter; Sturgeon, Don; Harron, John

    2003-09-01

    The Microvariablity and Oscillations of Stars (MOST) mission is a low-cost microsatellite designed to detect low-degree acoustic oscillations (periods of minutes) with micromagnitude precision in solar-type stars and metal-poor subdwarfs. There are also plans to detect light reflected from giant, short-period, extrasolar planets and the oscillations of roAp stars and the turbulent variability in the dense winds of Wolf-Rayet stars. This paper describes the experiment and how we met the challenge of ultraprecise photometry despite severe constraints on the mass, volume, and power available for the instrument. A side-viewing, 150 mm aperture Rumak-Maksutov telescope feeds two frame-transfer CCDs, one for tracking and the other for science. There is a single 300 nm wide filter centered at 525 nm. Microlenses project Fabry images of the brighter (V<=10) target stars onto the science CCD. Fainter target stars will be focused directly elsewhere on the CCD. MOST was launched on 2003 June 30 into a low-Earth, Sun-synchronous, polar orbit allowing stars between -19° and +36° declination to be viewed continuously for up to 60 days. Attitude is controlled by reaction wheels and magnetotorquers. A solar safety shutter over the telescope diagonal is the only other moving part. Accumulated photometry will be used to calibrate response across the target field stop, and data will be compressed and downloaded to three dedicated ground stations.

  8. From Spitzer Galaxy photometry to Tully-Fisher distances

    NASA Astrophysics Data System (ADS)

    Sorce, J. G.; Tully, R. B.; Courtois, H. M.; Jarrett, T. H.; Neill, J. D.; Shaya, E. J.

    2014-10-01

    This paper involves a data release of the observational campaign: Cosmicflows with Spitzer (CFS). Surface photometry of the 1270 galaxies constituting the survey is presented. An additional ˜400 galaxies from various other Spitzer surveys are also analysed. CFS complements the Spitzer Survey of Stellar Structure in Galaxies, that provides photometry for an additional 2352 galaxies, by extending observations to low galactic latitudes (|b| < 30°). Among these galaxies are calibrators, selected in the K band, of the Tully-Fisher relation. The addition of new calibrators demonstrates the robustness of the previously released calibration. Our estimate of the Hubble constant using supernova host galaxies is unchanged, H0 = 75.2 ± 3.3 km s-1 Mpc-1. Distance-derived radial peculiar velocities, for the 1935 galaxies with all the available parameters, will be incorporated into a new data release of the Cosmicflows project. The size of the previous catalogue will be increased by 20 per cent, including spatial regions close to the Zone of Avoidance.

  9. Catalogue of UBVRI photometry of T Tauri stars and analysis of the causes of their variability

    NASA Technical Reports Server (NTRS)

    Herbst, William; Herbst, Debra K.; Grossman, Elan J.; Weinstein, Daryl

    1994-01-01

    A computer-based catalogue of UBVRI photoelectric photometry of T Tauri stars and their earlier type analogs has been compiled. It presently includes over 10 000 entries on 80 stars and will be updated on a regular basis; it is available on Internet. The catalogue is used to analyze the sometimes bizarre light variations of pre-main-sequence stars on time scales of days to months in an attempt to illuminate the nature and causes of the phenomenon. It is useful in discussing their light variations to divide the stars into three groups according to their spectra. These are: weak T Tauri stars (WTTS; spectral class later than K0 and W(sub H-alpha less than 10 A), classical T Tauri stars (CTTS; spectral class later than K0 and W(sub H-alpha) greater than 10 A), and early type T Tauri stars (ETTS; spectral class of K0 or earlier). Three distinct types of variability are displayed by stars in the catalogue. Type I variations are periodic in VRI and undoubtedly caused by rotational modulation of a star with an asymmetric distribution of cool spots on its surface. Irregular flare activity is sometimes seen on such stars in U and B. Type I variations are easiest to see on WTTS but are clearly present on CTTS and ETTS as well. Type II variations are caused by hot 'spots' or zones and, it is argued, result from changes in the excess or 'veiling' continuum commonly attributed to an accretion boundary layer or impact zone of a magnetically channeled accretion flow. This type of variation is seen predominantly or solely in CTTS. A subcategory, designated Type IIp, consists of stars which display periodic variations caused by hot spots. Whereas cool spots may last for hundreds or thousands of rotations, hot spots appear to come and go on a much shorter time scale. This suggests that both unsteady accretion and rotation of the star contribute to Type II variations. It is shown that a third type of variation exists among ETTS, including stars as early as A type. UX Ori is a typical

  10. Differential photoelectric charging of nonconducting surfaces in space. [on sunlit strip

    NASA Technical Reports Server (NTRS)

    Pelizzari, M. A.; Criswell, D. R.

    1978-01-01

    The photoelectric charging caused by an infinitely long strip of sunlight across a nonconducting plane is studied by use of a model which contains an electrical cutoff radius, and the results of numerical calculations are presented. The model simulates charging of a sunlit area with dimensions equal to the strip's width, exposed to a plasma with a comparatively large Debye length. Uniform potential is quickly established on a uniformly sunlit strip as a result of charge redistribution by low-energy photoelectrons. The results are in accord with a theoretical surface conductivity derived for photoelectron sheaths above highly charged sunlit areas. The surface potential, which drops sharply across the sunlight-shadow boundary, is discussed.

  11. Chromatic analysis of burn scar based on ANN by using photoelectrical technology

    NASA Astrophysics Data System (ADS)

    Wan, Baikun; Qi, Hongzhi; Ming, Dong; Zhang, Mingjian; Wang, Qifang

    2005-01-01

    In this paper a novel method for the chromatic analysis of burn scar is proposed. The aim of the algorithm is to evaluate the curative effect and set up the treatment plan pertinently, because the scar color is an impersonal parameter reflects the degree of scar hypertrophy. The method is based on artificial neural network (ANN) by using photoelectrical technique, and composed of three main parts: firstly capture the digital color images of the burn scar using CCD camera, then change the RGB color data of the burn scar into that of HSB color space and emend it using ANN, lastly judge the degree of burn scar hypertrophy by chromatic analysis using ANN again. The experimental results were good conformed to the degrees of scar hypertrophy given by clinical evaluations. It suggests that the chromatic analysis technique of the burn scar is valuable for further study and apply to the clinical engineering.

  12. Diffusive superconductors beyond the Usadel approximation: Electron-hole asymmetry and large photoelectric effect

    NASA Astrophysics Data System (ADS)

    Kalenkov, Mikhail S.; Zaikin, Andrei D.

    2015-07-01

    We extend the quasiclassical formalism for diffusive superconductors by deriving anisotropic (gradient) corrections to the Usadel equation. We demonstrate that in a number of physical situations such corrections may play a crucial role, being responsible for the effects which cannot be recovered within the standard Usadel approximation. One of them is the so-called photoelectric effect in superconductors and superconducting-normal (SN) hybrid structures. Provided a superconducting part of the system is irradiated by an external ac electromagnetic field, the charge imbalance develops and a nonvanishing dc voltage is induced across the SN interface. In the presence of magnetic impurities in a superconductor the magnitude of this effect becomes large and can easily be detected in modern experiments.

  13. Photoelectric studies of the transmembrane charge transfer reactions in photosystem I pigment-protein complexes.

    PubMed

    Semenov, Alexey Yu; Mamedov, Mahir D; Chamorovsky, Sergey K

    2003-10-23

    The results of studies of charge transfer in cyanobacterial photosystem I (PS I) using the photoelectric method are reviewed. The electrogenicity in the PS I complex and its interaction with natural donors (plastocyanin, cytochrome c(6)), natural acceptors (ferredoxin, flavodoxin), or artificial acceptors and donors (methyl viologen and other redox dyes) were studied. The operating dielectric constant values in the vicinity of the charge transfer carriers in situ were calculated. The profile of distribution of the dielectric constant along the PS I pigment-protein complex (from plastocyanin or cytochrome c(6) through the chlorophyll dimer P700 to the acceptor complex) was estimated, and possible mechanisms of correlation between the local dielectric constant and electron transfer rate constant were discussed. PMID:14572628

  14. Deconvolving the temporal response of photoelectric x-ray detectors for the diagnosis of pulsed radiations

    NASA Astrophysics Data System (ADS)

    Zou, Shiyang; Song, Peng; Guo, Liang; Pei, Wenbing

    2013-09-01

    Based on the conjugate gradient method, a simple algorithm is presented for deconvolving the temporal response of photoelectric x-ray detectors (XRDs) to reconstruct the resolved time-dependent x-ray fluxes. With this algorithm, we have studied the impact of temporal response of XRD on the radiation diagnosis of hohlraum heated by a short intense laser pulse. It is found that the limiting temporal response of XRD not only postpones the rising edge and peak position of x-ray pulses but also smoothes the possible fluctuations of radiation fluxes. Without a proper consideration of the temporal response of XRD, the measured radiation flux can be largely misinterpreted for radiation pulses of a hohlraum heated by short or shaped laser pulses.

  15. Advanced photoelectric effect experiment beamline at Elettra: A surface science laboratory coupled with Synchrotron Radiation

    SciTech Connect

    Panaccione, G.; Vobornik, I.; Fujii, J.; Krizmancic, D.; Annese, E.; Giovanelli, L.; Maccherozzi, F.; Salvador, F.; De Luisa, A.; Benedetti, D.; Gruden, A.; Bertoch, P.; Rossi, G.; Polack, F.; Cocco, D.; Sostero, G.; Diviacco, B.; Hochstrasser, M.; Maier, U.; Pescia, D.; and others

    2009-04-15

    We report the main characteristics of the advanced photoelectric effect experiments beamline, operational at Elettra storage ring, featuring a fully independent double branch scheme obtained by the use of chicane undulators and able to keep polarization control in both linear and circular mode. The paper describes the novel technical solutions adopted, namely, (a) the design of a quasiperiodic undulator resulting in optimized suppression of higher harmonics over a large photon energy range (10-100 eV), (b) the thermal stability of optics under high heat load via cryocoolers, and (c) the end station interconnected setup allowing full access to off-beam and on-beam facilities and, at the same time, the integration of users' specialized sample growth chambers or modules.

  16. Ultraviolet-photoelectric effect for augmented contrast and resolution in electron microscopy

    NASA Astrophysics Data System (ADS)

    Seniutinas, Gediminas; Balčytis, Armandas; Juodkazis, Saulius

    2016-05-01

    A new tool providing material contrast control in scanning electron microscopy (SEM) is demonstrated. The approach is based on deep-UV illumination during SEM imaging and delivers a novel material based contrast as well as higher resolution due to the photoelectric effect. Electrons liberated from illuminated sample surface contribute to the imaging which can be carried out at a faster acquisition rate, provide material selective contrast, reduce distortions caused by surface charging, and can substitute metal coating in SEM. These features provide high fidelity SEM imaging and are expected to significantly improve the performance of electron beam instruments as well as to open new opportunities for imaging and characterization of materials at the nanoscale.

  17. Specific features of the photoelectric properties of structures based on mesoporous silicon with silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Bilenko, D. I.; Galushka, V. V.; Zharkova, E. A.; Mysenko, I. B.; Terin, D. V.; Khasina, E. I.

    2015-11-01

    Electrical and photoelectric properties of porous silicon with introduced silver nanoparticles have been studied. It is shown that in the "dark-light-dark" operation mode, an abrupt jump of the dark current is observed upon illumination (with light spectrally close to sunlight), which is three to five times the initial dark current and the photocurrent. The voltages at which these abrupt changes in current are observed correspond to the range of existence of traps formed when the starting mesoporous silicon is obtained. It was found that the increased value of the dark current exhibits a long-term memory effect. The "current jump" can be attributed to the maximum capture of the generated photocarriers by traps, followed by their release in an electric field after the illumination.

  18. Low dose hard x-ray contact microscopy assisted by a photoelectric conversion layer

    SciTech Connect

    Gomella, Andrew; Martin, Eric W.; Lynch, Susanna K.; Wen, Han; Morgan, Nicole Y.

    2013-04-15

    Hard x-ray contact microscopy provides images of dense samples at resolutions of tens of nanometers. However, the required beam intensity can only be delivered by synchrotron sources. We report on the use of a gold photoelectric conversion layer to lower the exposure dose by a factor of 40 to 50, allowing hard x-ray contact microscopy to be performed with a compact x-ray tube. We demonstrate the method in imaging the transmission pattern of a type of hard x-ray grating that cannot be fitted into conventional x-ray microscopes due to its size and shape. Generally the method is easy to implement and can record images of samples in the hard x-ray region over a large area in a single exposure, without some of the geometric constraints associated with x-ray microscopes based on zone-plate or other magnifying optics.

  19. Immobilizing ternary ZnXCd1-XS on graphene via solvothermal method for enhanced photoelectric properties

    NASA Astrophysics Data System (ADS)

    Lei, Yun; Chen, Feifei; Xu, Jun

    2015-12-01

    Ternary ZnXCd1-XS particles were directly immobilized on graphene sheets by a facile solvothermal route with zinc acetate, cadmium acetate and thiourea as precursors, ethylene glycol as reaction solvent and graphene oxide as support. The value of x could be adjusted by controlling the molar ratio of Zn and Cd precursors. The products were characterized by X-ray diffraction, scanning electron microscope and ultraviolet-visible absorption. The photoelectric properties of the graphene-ZnXCd1-XS composites were investigated by transient photocurrent responses and electrochemical impedance spectra, and the results show that the obvious increase in the photocurrent density and decrease in electron-transfer resistance can be seen for graphene-Zn0.8Cd0.2S composites as compared to graphene-ZnXCd1-XS composites with other Zn/Cd ratios.

  20. Creating electrochemical gradients by light: from bio-inspired concepts to photoelectric conversion.

    PubMed

    Xie, Xiaojiang; Bakker, Eric

    2014-10-01

    Light is harvested by natural photosynthetic systems to generate electrochemical gradients that power various reactions. Implementing nature's lessons in photosynthesis holds great promise for technological advances. With a focus on designs and concepts, recent progress in generating electrochemical gradients by light, mimicking the two general types of photosynthetic centers in nature that make use of either light-induced charge separation or photo-isomerization are summarized here. Light induced electrochemical gradients pave new ways for photoelectric conversion. While extensive research in this direction has focused on light-induced charge separation, recent work has shown that energy conversion based on photo-isomerization is very promising. Photoswitchable compounds have been found in nature, such as the retinal molecule in bacteriorhodopsin. These compounds may form an attractive molecular basis for future progress in this field. PMID:25116853

  1. Photoelectric conversion characteristics of c-Se-based thin-film photodiodes in imaging device

    NASA Astrophysics Data System (ADS)

    Imura, S.; Kikuchi, K.; Miyakawa, K.; Ohtake, H.; Kubota, M.

    2015-06-01

    Herein, we report the use of high-efficiency crystalline-selenium-based (c-Se-based) thin-film heterojunction photodiodes in imaging devices. As a novel experiment, we use an image pickup tube with a photoelectric conversion layer consisting of n-gallium oxide (Ga2O3)/p-c-Se heterojunction photodiodes to obtain high-resolution images at a relatively low applied voltage. We reduce the thickness of the Ga2O3 layer to expand the depletion layer into the c-Se layer at a lower applied voltage. In addition, Sn-doping of the Ga2O3 layer effectively increases the carrier concentration, thereby allowing the photodiode to operate at lower voltage.

  2. Enhanced photoelectric properties by the coordinating role of doping and modification.

    PubMed

    Wang, Feng-Rui; Su, Yu-Yun; Liu, Jin-Ku; Wu, Ying

    2016-02-14

    Dual technique design in this research has successfully enriched the complementation between doping and surface modification. Here, Co(2+) doped Ag-ZnO nanocomposites (CAZ NCs) are mass produced by the combustion method. The HRTEM image shows that the doped Co(2+) and the surface modified Ag nanoparticles on the ZnO NCs are influential on the preferential orientation. Based on the conductivity formula σ = nqμ and the actual verification, the improved photoelectric properties of CAZ NCs under visible light irradiation are attributed to the enhanced light absorption and the weakened recombination of photogenerated electron-hole pairs. It would be instructive for the sound design concept of subsequent material development. PMID:26804789

  3. Photoelectric properties of unsymmetrical metal-free phthalocyanine and C60 complex thin films

    NASA Astrophysics Data System (ADS)

    Yang, Zhigang; Shen, Yue; Zhang, Jiancheng

    2004-12-01

    In this paper, novel one amino-group substituted unsymmetrical metal-free phthalocyanine (AUMPc) was synthesized, then the complex of AUMPc with C60 (The Complex) was obtained in the mixed solvents. Ultraviolet-visible (Uv-vis) spectrophotometer, fluorescence spectrophotometer and home-made photoconductivity meter were used to study the photoelectric properties of AUMPc and the complex. It was found that the absorbance of The Complex was larger than that of the total of AUMPc and C60 in the B belt (333nm), the absorbance of The Complex in the Q belt (693nm) where C60 had no absorbance was also increased. C60 took the role as annihilation in AUMPc, the photoconductivity of the Complex thin film was clearly increased when the film was exposed in the light.

  4. Electromagnetic Spectrum Analysis and Its Influence on the Photoelectric Conversion Efficiency of Solar Cells.

    PubMed

    Hu, Kexiang; Ding, Enjie; Wangyang, Peihua; Wang, Qingkang

    2016-06-01

    The electromagnetic spectrum and the photoelectric conversion efficiency of the silicon hexagonal nanoconical hole (SiHNH) arrays based solar cells is systematically analyzed according to Rigorous Coupled Wave Analysis (RCWA) and Modal Transmission Line (MTL) theory. An ultimate efficiency of the optimized SiHNH arrays based solar cell is up to 31.92% in consideration of the absorption spectrum, 4.52% higher than that of silicon hexagonal nanoconical frustum (SiHNF) arrays. The absorption enhancement of the SiHNH arrays is due to its lower reflectance and more supported guided-mode resonances, and the enhanced ultimate efficiency is insensitive to bottom diameter (D(bot)) of nanoconical hole and the incident angle. The result provides an additional guideline for the nanostructure surface texturing fabrication design for photovoltaic applications. PMID:27427668

  5. Photoelectric Franck-Hertz experiment and its kinetic analysis by Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Magyar, Péter; Korolov, Ihor; Donkó, Zoltán

    2012-05-01

    The electrical characteristics of a photoelectric Franck-Hertz cell are measured in argon gas over a wide range of pressure, covering conditions where elastic collisions play an important role, as well as conditions where ionization becomes significant. Photoelectron pulses are induced by the fourth harmonic UV light of a diode-pumped Nd:YAG laser. The electron kinetics, which is far more complex compared to the naive picture of the Franck-Hertz experiment, is analyzed via Monte Carlo simulation. The computations provide the electrical characteristics of the cell, the energy and velocity distribution functions, and the transport parameters of the electrons, as well as the rate coefficients of different elementary processes. A good agreement is obtained between the cell's measured and calculated electrical characteristics, the peculiarities of which are understood by the simulation studies.

  6. Physicochemical and photoelectric properties of cadmium hexathio- and hexaselenogermanate crystals and solid solutions derived from them

    SciTech Connect

    Motrya, S.F.; Tkachenko, V.I.; Chereshnya, V.M.; Kikineshi, A.A.; Semrad, E.E.

    1987-03-01

    Single crystals of Cd/sub 4/GeS/sub 6/, Cd/sub 4/GeSe/sub 6/, and the derived solid solutions have been synthesized and grown. Investigation of physicochemical and photoelectric properties of the alloys showed the existence in the Cd/sub 4/GeS/sub 6/-Cd/sub 4/GeSe/sub 6/ system of a continuous series of solid solutions. The specific resistance and the photosensitivity of the alloys fall with increasing selenium content. For polycrystalline Cd/sub 4/GeS/sub 6/ and Cd/sub 4/GeSe/sub 6/, the average low-temperature heat capacity was determined, and the standard entropy, enthalpy, and entropy of formation were calculated.

  7. Fabrication and photoelectric properties of oxide/CuIn{sub 5}Se{sub 8} heterojunctions

    SciTech Connect

    Bodnar', I. V.; Vaipolin, A. A.; Rud', V. Yu.; Rud', Yu. V. Terukov, E. I.

    2007-02-15

    Single crystals of the n-CuIn{sub 5}Se{sub 8} compound of hexagonal modification have been grown by direct crystallization from melt. On the basis of the experimental study of its thermal interaction with air oxygen, a method for fabricating new oxide/n-CuIn{sub 5}Se{sub 8} heterojunctions is proposed. Electrical and photoelectric properties of the structures obtained have been investigated. It is shown that the interaction of n-CuIn{sub 5}Se{sub 8} of hexagonal modification with air oxygen makes it possible to obtain heterojunctions with high photosensitivity. The new technology can be used in the design of broadband optical radiation converters based on n-CuIn{sub 5}Se{sub 8} crystals.

  8. High Photoelectric Conversion Efficiency of Metal Phthalocyanine/Fullerene Heterojunction Photovoltaic Device

    PubMed Central

    Lin, Chi-Feng; Zhang, Mi; Liu, Shun-Wei; Chiu, Tien-Lung; Lee, Jiun-Haw

    2011-01-01

    This paper introduces the fundamental physical characteristics of organic photovoltaic (OPV) devices. Photoelectric conversion efficiency is crucial to the evaluation of quality in OPV devices, and enhancing efficiency has been spurring on researchers to seek alternatives to this problem. In this paper, we focus on organic photovoltaic (OPV) devices and review several approaches to enhance the energy conversion efficiency of small molecular heterojunction OPV devices based on an optimal metal-phthalocyanine/fullerene (C60) planar heterojunction thin film structure. For the sake of discussion, these mechanisms have been divided into electrical and optical sections: (1) Electrical: Modification on electrodes or active regions to benefit carrier injection, charge transport and exciton dissociation; (2) Optical: Optional architectures or infilling to promote photon confinement and enhance absorption. PMID:21339999

  9. Photoelectric covalent organic frameworks: converting open lattices into ordered donor-acceptor heterojunctions.

    PubMed

    Chen, Long; Furukawa, Ko; Gao, Jia; Nagai, Atsushi; Nakamura, Toshikazu; Dong, Yuping; Jiang, Donglin

    2014-07-16

    Ordered one-dimensional open channels represent the typical porous structure of two-dimensional covalent organic frameworks (COFs). Here we report a general synthetic strategy for converting these open lattice structures into ordered donor-acceptor heterojunctions. A three-component topological design scheme was explored to prepare electron-donating intermediate COFs, which upon click reaction were transformed to photoelectric COFs with segregated donor-acceptor alignments, whereas electron-accepting buckyballs were spatially confined within the nanochannels via covalent anchoring on the channel walls. The donor-acceptor heterojunctions trigger photoinduced electron transfer and allow charge separation with radical species delocalized in the π-arrays, whereas the charge separation efficiency was dependent on the buckyball content. This new donor-acceptor strategy explores both skeletons and pores of COFs for charge separation and photoenergy conversion. PMID:24963896

  10. VizieR Online Data Catalog: CU Vir Stroemgren differential photometry (Pyper+, 2013)

    NASA Astrophysics Data System (ADS)

    Pyper, D. M.; Stevens, I. R.; Adelman, S. J.

    2014-06-01

    Our data are from two sources: Stroemgren differential uvby photometry obtained using the Four College Automated Photometric Telescope (FCAPT) originally on Mt. Hopkins, AZ, and later at Fairborn Observatory, Washington Camp, AZ, and photometry from the Solar Mass Ejection Imager (SMEI). (1 data file).

  11. Surface photometry of a sample of elliptical and S0 galaxies

    SciTech Connect

    De carvalho, R.R.; Da costa, L.N.; Djorgovski, S. California Institute of Technology, Pasadena )

    1991-08-01

    The results are reported of surface photometry of 38 early-type galaxies, located mainly in the Fornax Cluster. Detailed comparisons with previously published work are given along with internal and external error estimates for all quantities, and some serious systematic discrepancies in the older aperture photometry of some of the galaxies in the present sample are pointed out. 15 refs.

  12. Electrostatic Charging of Lunar Dust by UV Photoelectric Emissions and Solar Wind Electrons

    NASA Technical Reports Server (NTRS)

    Abbas, Mian M.; Tankosic, Dragana; Spann, James f.; LeClair, Andre C.; Dube, Michael J.

    2008-01-01

    The ubiquitous presence of dust in the lunar environment with its high adhesive characteristics has been recognized to be a major safety issue that must be addressed in view of its hazardous effects on robotic and human exploration of the Moon. The reported observations of a horizon glow and streamers at the lunar terminator during the Apollo missions are attributed to the sunlight scattered by the levitated lunar dust. The lunar surface and the dust grains are predominantly charged positively by the incident UV solar radiation on the dayside and negatively by the solar wind electrons on the night-side. The charged dust grains are levitated and transported over long distances by the established electric fields. A quantitative understanding of the lunar dust phenomena requires development of global dust distribution models, based on an accurate knowledge of lunar dust charging properties. Currently available data of lunar dust charging is based on bulk materials, although it is well recognized that measurements on individual dust grains are expected to be substantially different from the bulk measurements. In this paper we present laboratory measurements of charging properties of Apollo 11 & 17 dust grains by UV photoelectric emissions and by electron impact. These measurements indicate substantial differences of both qualitative and quantitative nature between dust charging properties of individual micron/submicron sized dust grains and of bulk materials. In addition, there are no viable theoretical models available as yet for calculation of dust charging properties of individual dust grains for both photoelectric emissions and electron impact. It is thus of paramount importance to conduct comprehensive measurements for charging properties of individual dust grains in order to develop realistic models of dust processes in the lunar atmosphere, and address the hazardous issues of dust on lunar robotic and human missions.

  13. [Study on single-walled carbon nanotube thin film photoelectric device].

    PubMed

    Xie, Wen-bin; Zhu, Yong; Gong, Tian-cheng; Chen, Yu-lin; Zhang, Jie

    2015-01-01

    The single-walled carbon nanotube film photoelectric device was invented, and it can generate net photocurrent under bias voltage when it is illuminated by the laser. The influences of bias voltage, laser power and illuminating position on the net photocurrent were investigated. The experimental results showed that when the center of the film was illuminated, the photocurrent increased with the applied bias, but tended to saturate as the laser power increased. As the voltage and the laser power reached 0. 2 V and 22. 7 mW respectively, the photocurrent reached 0. 24 µA. When the voltage was removed, the photocurrent varied with the laser illuminating position on the film and its value was distributed symmetrically about the center of the device. The photocurrent reached maximum and almost zero respectively when the laser illuminated on two ends and the center of the film. Analysis proposes that the net photocurrent can be generated due to internal photoelectric effect when the device is under voltage and the laser illuminates on the center of the film. It can be also generated due to photo-thermoelectric effect when the device is under no voltage and the laser illuminates on the film, and the relation between the net photocurrent and the illuminating position was derived according to the nature of thermoelectric power of single-walled carbon nanotubes with the established temperature model, which coincides with experimental result. Two effects are the reasons for the generation and variety of the net photocurrent and they superimpose to form the result of the net photocurrent when the device is under general conditions of voltage and laser illuminating position. The device has potential applications in the areas of photovoltaic device and optical sensor for its characteristic. PMID:25993863

  14. Constraints on the Bulk Composition of Uranus from Herschel PACS and ISO LWS Photometry, SOFIA FORCAST Photometry and Spectroscopy, and Ground-Based Photometry of its Thermal Emission

    NASA Astrophysics Data System (ADS)

    Orton, Glenn; Mueller, Thomas; Burgdorf, Martin; Fletcher, Leigh; de Pater, Imke; Atreya, Sushil; Adams, Joseph; Herter, Terry; Keller, Luke; Sidher, Sunil; Sinclair, James; Fujiyoshi, Takuya

    2016-04-01

    We present thermal infrared observations of the disk of Uranus at 17-200 μm to deduce its global thermal structure and bulk composition. We combine 17-200 μm filtered photometric measurements by the Herschel PACS and ISO LWS instruments and 19-35 μm filtered photometry and spectroscopy by the SOFIA FORCAST instrument, supplemented by 17-25 μm ground-based photometric filtered imaging of Uranus. Previous analysis of infrared spectroscopic measurements of the disk of Uranus made by the Spitzer IRS instrument yielded a model for the disk-averaged temperature profile and stratospheric composition (Orton et al. 2014a Icarus 243,494; 2014b Icarus 243, 471) that were consistent with submillimeter spectroscopy by the Herschel SPIRE instrument (Swinyard et al. 2014, MNRAS 440, 3658). Our motivation to observe the 17-35 μm spectrum was to place more stringent constraints on the global para-H2 / ortho-H2 ratio in the upper troposphere and lower stratosphere than the ISO SWS results of Fouchet et al. (2003, Icarus 161, 127), who examined H2 quadrupole lines. We will discuss the consistency of these observations with a higher para-H2 fraction than implied by local thermal equilibrium, which would resolve a discrepancy between the Spitzer-based model and observations of HD lines by the Herschel PACS experiment (Feuchtgruber et al. 2013 Astron. & Astrophys. 551, A126). Constraints on the global para-H2 fraction allow for more precise analysis of the far-infrared spectrum, which is sensitive to the He:H2 ratio, a quantity that was not constrained by the Spitzer IRS spectra. The derived model, which assumed the ratio derived by the Voyager-2 IRIS/radio-science occultation experiment (Conrath et al. 1987 J. Geophys. Res. 92, 15003), is inconsistent with 70-200 μm PACS photometry (Mueller et al. 2016 Astron. & Astrophys. submittted) and ISO LWS photometric measurements. However, the model can be made consistent with the observations if the fraction of He relative to H2 were

  15. Time series photometry of faint cataclysmic variables with a CCD

    NASA Astrophysics Data System (ADS)

    Abbott, Timothy Mark Cameron

    1992-08-01

    I describe a new hardware and software environment for the practice of time-series stellar photometry with the CCD systems available at McDonald Observatory. This instrument runs suitable CCD's in frame transfer mode and permits windowing on the CCD image to maximize the duty cycle of the photometer. Light curves may be extracted and analyzed in real time at the telescope and image data are stored for later, more thorough analysis. I describe a star tracking algorithm, which is optimized for a timeseries of images of the same stellar field. I explore the extraction of stellar brightness measures from these images using circular software apertures and develop a complete description of the noise properties of this technique. I show that scintillation and pixelization noise have a significant effect on high quality observations. I demonstrate that optimal sampling and profile fitting techniques are unnecessarily complex or detrimental methods of obtaining stellar brightness measures under conditions commonly encountered in timeseries CCD photometry. I compare CCD's and photomultiplier tubes as detectors for timeseries photometry using light curves of a variety of stars obtained simultaneously with both detectors and under equivalent conditions. A CCD can produce useful data under conditions when a photomultiplier tube cannot, and a CCD will often produce more reliable results even under photometric conditions. I prevent studies of the cataclysmic variables (CV's) AL Com, CP Eri, V Per, and DO Leo made using the time series CCD photometer. AL Com is a very faint CV at high Galactic latitude and a bona fide Population II CV. Some of the properties of AL Com are similar to the dwarf nova WZ Sge and others are similar to the intermediate polar EX Hya, but overall AL Com is unlike any other well-studied cataclysmic variable. CP Eri is shown to be the fifth known interacting binary white dwarf. V Per was the first CV found to have an orbital period near the middle of the

  16. Results from a Program of Full Disk Solar Photometry

    NASA Astrophysics Data System (ADS)

    Chapman, G.; Cookson, A.; Dobias, J.; Preminger, D.; Walton, S.

    Photometry of the full solar disk has been carried out at the San Fernando Observatory since 1985. A number of quantities are computed from images obtained in the red, blue and K-line. Photometric irradiance deficits due to sunspots and excesses due to faculae and network are highly correlated with variations in the total solar irradiance (TSI) from spacecraft. Multiple correlation coefficients as high as 0.95 to 0.97, depending on spacecraft and interval, have been obtained. Recent work shows that the short-term rotation variation of the TSI is due to the coming and going of active regions whereas the solar cycle variations on the scale of the solar cycle are due to changes in line blanketing associated with faculae and network.

  17. Using Photometry to Probe the Circumstellar Environment of δ Scorpii

    NASA Astrophysics Data System (ADS)

    Jones, C. E.; Wiegert, P. A.; Tycner, C.; Henry, G. W.; Cyr, R. P.; Halonen, R. J.; Muterspaugh, M. W.

    2013-05-01

    We acquired Johnson BV photometry of the binary Be disk system δ Scorpii during its 2009, 2010, 2011, and 2012 observing seasons and used it to probe the innermost regions of the disk. We found that several disk building events have occurred during this time, resulting in an overall brightening in the V band and reddening of the system. In addition to these long-term trends, we found cyclical variability in each observing season on timescales between 60 and 100 days. We were able to reproduce the changes in the magnitude and color of δ Sco using our theoretical models and found that variable mass-loss rates in the range 2.5-7.0 × 10-9 M ⊙ yr-1 over ~35 days can reproduce the observed increase in brightness.

  18. USING PHOTOMETRY TO PROBE THE CIRCUMSTELLAR ENVIRONMENT OF {delta} SCORPII

    SciTech Connect

    Jones, C. E.; Wiegert, P. A.; Cyr, R. P.; Halonen, R. J.; Tycner, C.; Henry, G. W.; Muterspaugh, M. W.

    2013-05-15

    We acquired Johnson BV photometry of the binary Be disk system {delta} Scorpii during its 2009, 2010, 2011, and 2012 observing seasons and used it to probe the innermost regions of the disk. We found that several disk building events have occurred during this time, resulting in an overall brightening in the V band and reddening of the system. In addition to these long-term trends, we found cyclical variability in each observing season on timescales between 60 and 100 days. We were able to reproduce the changes in the magnitude and color of {delta} Sco using our theoretical models and found that variable mass-loss rates in the range 2.5-7.0 Multiplication-Sign 10{sup -9} M{sub Sun} yr{sup -1} over {approx}35 days can reproduce the observed increase in brightness.

  19. CCD photometry of globular clusters in NGC 3377

    NASA Astrophysics Data System (ADS)

    Harris, William E.

    1990-08-01

    New CCD photometry to a limit B = 24.3 is presented for a sample of globular clusters around NGC 337, an intermediate-size elliptical in the Leo group. Assuming that the luminosity function of its globular clusters follows the same log-normal form as in other galaxies, a peak frequency level (turnover magnitude) of B(0) = 23.35 + or - 0.40 is derived for a combined sample of clusters in NGC 3377 and NGC 3379. Matching this to the globular clusters in the Milky Way then gives a distance modulus (m - M)B (Leo) = 30.2, or d = (10.7 + or - 2.2) Mpc, in good agreement with other recent distance-scale methods. The clusters around NGC 3377 follow a highly ellipsoidal space distribution; two different tests show that their distribution is at least as flattened as the E6 shape of the galaxy itself.

  20. CCD photometry of globular clusters in NGC 3377

    SciTech Connect

    Harris, W.E. )

    1990-09-01

    New CCD photometry to a limit B = 24.3 is presented for a sample of globular clusters around NGC 337, an intermediate-size elliptical in the Leo group. Assuming that the luminosity function of its globular clusters follows the same log-normal form as in other galaxies, a peak frequency level (turnover magnitude) of B(0) = 23.35 + or - 0.40 is derived for a combined sample of clusters in NGC 3377 and NGC 3379. Matching this to the globular clusters in the Milky Way then gives a distance modulus (m - M)B (Leo) = 30.2, or d = (10.7 + or - 2.2) Mpc, in good agreement with other recent distance-scale methods. The clusters around NGC 3377 follow a highly ellipsoidal space distribution; two different tests show that their distribution is at least as flattened as the E6 shape of the galaxy itself. 31 refs.

  1. Interpretation of integrated-disk photometry of Callisto and Ganymede

    NASA Technical Reports Server (NTRS)

    Pang, K.; Ajello, J. M.; Lumme, K.; Bowell, E.

    1983-01-01

    The Lumme-Bowell (1981) theory has been used to interpret the integrated phase curves of Callisto and Ganymede, and it is noted that while the theory explains the brightness angles of these satellites up to about 80 deg solar phase angle, the observed brightness drops off at larger angles more rapidly than predicted. It is suggested that this discrepancy is due to the fact that single regolith particles must have phase functions which are much more elongated in the forward or backward scattering directions than is allowed for by the Lumme-Bowell theory. The hemispheric asymmetry in Callisto's surface texture can be explained by invoking the formation of an ice film on the trailing side, consistent with Voyager detailed photometry and thermometry of Callisto.

  2. Three years of photometry of IM Pegasi = HR 8703

    NASA Technical Reports Server (NTRS)

    Eaton, J. A.; Hall, D. S.; Henry, G. W.; Lovell, L. P.; Stephan, C. A.; Chambliss, C. R.; Detterline, P. K.; Landis, H. J.; Louth, H.; Renner, T. R.

    1983-01-01

    Differential photometry of this K1 IV-III p RS CVn-type binary in 1978-79, 1979-80, and 1980-81 at eight different observatories shows that the variability, discovered originally by Herbst, is periodic. The mean of three different determinations of the photometric period was 24(d).39 + or 0(d).03, about 1 percent shorter than the orbital period of 24(d).649 determined spectroscopically by Harper. The total range observed during these three years was for V from 5(m).60 to 5(m).85. The light curve was nearly sinusoidal but always noticieably asymmetric, with the sense reversing sometime between 1979-80 and 1980-81.

  3. Spitzer IRAC Photometry for Time Series in Crowded Fields

    NASA Astrophysics Data System (ADS)

    Calchi Novati, S.; Gould, A.; Yee, J. C.; Beichman, C.; Bryden, G.; Carey, S.; Fausnaugh, M.; Gaudi, B. S.; Henderson, C. B.; Pogge, R. W.; Shvartzvald, Y.; Wibking, B.; Zhu, W.; Spitzer Team; Udalski, A.; Poleski, R.; Pawlak, M.; Szymański, M. K.; Skowron, J.; Mróz, P.; Kozłowski, S.; Wyrzykowski, Ł.; Pietrukowicz, P.; Pietrzyński, G.; Soszyński, I.; Ulaczyk, K.; OGLE Group

    2015-12-01

    We develop a new photometry algorithm that is optimized for the Infrared Array Camera (IRAC) Spitzer time series in crowded fields and that is particularly adapted to faint or heavily blended targets. We apply this to the 170 targets from the 2015 Spitzer microlensing campaign and present the results of three variants of this algorithm in an online catalog. We present detailed accounts of the application of this algorithm to two difficult cases, one very faint and the other very crowded. Several of Spitzer's instrumental characteristics that drive the specific features of this algorithm are shared by Kepler and WFIRST, implying that these features may prove to be a useful starting point for algorithms designed for microlensing campaigns by these other missions.

  4. Towards photometry pipeline of the Indonesian space surveillance system

    NASA Astrophysics Data System (ADS)

    Priyatikanto, Rhorom; Religia, Bahar; Rachman, Abdul; Dani, Tiar

    2015-09-01

    Optical observation through sub-meter telescope equipped with CCD camera becomes alternative method for increasing orbital debris detection and surveillance. This observational mode is expected to eye medium-sized objects in higher orbits (e.g. MEO, GTO, GSO & GEO), beyond the reach of usual radar system. However, such observation of fast moving objects demands special treatment and analysis technique. In this study, we performed photometric analysis of the satellite track images photographed using rehabilitated Schmidt Bima Sakti telescope in Bosscha Observatory. The Hough transformation was implemented to automatically detect linear streak from the images. From this analysis and comparison to USSPACECOM catalog, two satellites were identified and associated with inactive Thuraya-3 satellite and Satcom-3 debris which are located at geostationary orbit. Further aperture photometry analysis revealed the periodicity of tumbling Satcom-3 debris. In the near future, it is not impossible to apply similar scheme to establish an analysis pipeline for optical space surveillance system hosted in Indonesia.

  5. The symbiosis of photometry and radial-velocity measurements

    NASA Technical Reports Server (NTRS)

    Cochran, William D.

    1994-01-01

    The FRESIP mission is optimized to detect the inner planets of a planetary system. According to the current paradigm of planet formation, these planets will probably be small Earth-sized objects. Ground-based radial-velocity programs now have the sensitivity to detect Jovian-mass planets in orbit around bright solar-type stars. We expect the more massive planets to form in the outer regions of a proto-stellar nebula. These two types of measurements will very nicely complement each other, as they have highest detection probability for very different types of planets. The combination of FRESIP photometry and ground-based spectra will provide independent confirmation of the existence of planetary systems in orbit around other stars. Such detection of both terrestrial and Jovian planets in orbit around the same star is essential to test our understanding of planet formation.

  6. Flaring on RS CVn systems: Results from EUVE Photometry

    NASA Astrophysics Data System (ADS)

    Osten, R. A.; Brown, A.; Ayres, T. R.

    We present broadband EUV photometry for a sample of RS CVn systems observed with the Deep Survey Spectrometer and Right Angle Program (RAP) Scanners on the Extreme Ultraviolet Explorer (EUVE). We have developed robust data analysis and light curve software for the interpretation of these data. Large-scale flaring activity is seen on 15 of the 18 systems studied. These binaries cover a range in orbital period of 0.7 days to 21 days and include a mixture of giant, subgiant, and dwarf luminosity classes. For many systems the photometric coverage extends over several orbital periods and flaring is unambiguously characterized. We present statistics on the distribution of variability in the survey. Correlations of flaring with binary properties are examined.

  7. FRAM telescope - monitoring of atmospheric extinction and variable star photometry

    NASA Astrophysics Data System (ADS)

    Jurysek, J.; Honkova, K.; Masek, M.

    2015-02-01

    The FRAM (F/(Ph)otometric Robotic Atmospheric Monitor) telescope is a part of the Pierre Auger Observatory (PAO) located near town Malargüe in Argentina. The main task of the FRAM telescope is the continuous night - time monitoring of the atmospheric extinction and its wavelength dependence. The current methodology of the measurement of a atmospheric extinction and for instrumentation properties also allows simultaneous observation of other interesting astronomical targets. The current observations of the FRAM telescope are focused on the photometry of eclipsing binaries, positional refinement of minor bodies of the Solar system and observations of optical counterparts of gamma ray bursts. In this contribution, we briefly describe the main purpose of the FRAM telescope for the PAO and we also present its current astrono mical observing program.

  8. Millisecond optical photometry of the DQ Herculis objects

    NASA Technical Reports Server (NTRS)

    Imamura, James N.; Steiman-Cameron, Thomas Y.

    1988-01-01

    The results of millisecond optical photometry of the DQ Herculis stars EX Hya, H2252-035, V1223 Sgr, and AE Aqr obtained at the Las Campanas Observatory and Cerro Tololo Inter-American Observatory during the years 1985, 1986, and 1987 are reported. The data for coherent and incoherent features are searched for. Coherent features (other than those previously known) were not detected for frequencies between 0.1 and 250 Hz at 4-sigma upper limits of 0.05-0.4 percent. Evidence is not found for 1-3 s, quasi-coherent features. Such features have been detected in the optical emission of the AM Her objects AN UMa, EF Eri, and E1405-451. Because of the similarities between AM Her and DQ Her objects, it was suggested that such quasi-coherent features might also be found in the DQ Her objects.

  9. Prelude to, and Nature of the Space Photometry Revolution

    NASA Astrophysics Data System (ADS)

    Gilliland, Ronald L.

    2015-09-01

    It is now less than a decade since CoRoT initiated the space photometry revolution with breakthrough discoveries, and five years since Kepler started a series of similar advances. I'll set the context for this revolution noting the status of asteroseismology and exoplanet discovery as it was 15-25 years ago in order to give perspective on why it is not mere hyperbole to claim CoRoT and Kepler fostered a revolution in our sciences. Primary events setting up the revolution will be recounted. I'll continue with noting the major discoveries in hand, and how asteroseismology and exoplanet studies, and indeed our approach to doing science, have been forever changed thanks to these spectacular missions.

  10. Asteroid models from photometry and complementary data sources

    NASA Astrophysics Data System (ADS)

    Kaasalainen, Mikko

    2016-05-01

    I discuss inversion methods for asteroid shape and spin reconstruction with photometry (lightcurves) and complementary data sources such as adaptive optics or other images, occultation timings, interferometry, and range-Doppler radar data. These are essentially different sampling modes (generalized projections) of plane-of-sky images. An important concept in this approach is the optimal weighting of the various data modes. The maximum compatibility estimate, a multi-modal generalization of the maximum likelihood estimate, can be used for this purpose. I discuss the fundamental properties of lightcurve inversion by examining the two-dimensional case that, though not usable in our three-dimensional world, is simple to analyze, and it shares essentially the same uniqueness and stability properties as the 3-D case. After this, I review the main aspects of 3-D shape representations, lightcurve inversion, and the inclusion of complementary data.

  11. An interactive modular design for computerized photometry in spectrochemical analysis

    NASA Technical Reports Server (NTRS)

    Bair, V. L.

    1980-01-01

    A general functional description of totally automatic photometry of emission spectra is not available for an operating environment in which the sample compositions and analysis procedures are low-volume and non-routine. The advantages of using an interactive approach to computer control in such an operating environment are demonstrated. This approach includes modular subroutines selected at multiple-option, menu-style decision points. This style of programming is used to trace elemental determinations, including the automated reading of spectrographic plates produced by a 3.4 m Ebert mount spectrograph using a dc-arc in an argon atmosphere. The simplified control logic and modular subroutine approach facilitates innovative research and program development, yet is easily adapted to routine tasks. Operator confidence and control are increased by the built-in options including degree of automation, amount of intermediate data printed out, amount of user prompting, and multidirectional decision points.

  12. Photometry of stars in the Cas OB5 Associations

    NASA Astrophysics Data System (ADS)

    Tanriver, Mehmet; Keskin, Ahmet

    2016-07-01

    OB associations are a grouping of very young associations, contain 10-100 very hot massive stars, spectral types O and B. Also, the OB associations contain low and intermediate mass stars, too. Association members are believed to form within the same small volume inside a giant molecular cloud. Once the surrounding dust and gas is blown away, the remaining stars become not tied up and begin to drift separately. It is believed that the majority of all stars in the Milky Way were formed in OB associations. O type stars are short-lived, and will be at an end as supernovae after roundly a million years. OB associations are generally only a few million years in age or less. In this study, the photometry of UU Cas and field star which been Cas OB5 association member was carried out. Light curves and color diagrams are given in the study.

  13. Results of the 2015 Mexican Asteroid Photometry Campaign

    NASA Astrophysics Data System (ADS)

    Sada, Pedro V.; Navarro-Meza, Samuel; Reyes-Ruiz, Mauricio; Olguin, Lorenzo L.; Saucedo, Julio C.; Loera-Gonzalez, Pablo

    2016-04-01

    The 2015 Mexican Asteroid Photometry Campaign was organized at the 2nd National Planetary Astrophysics Workshop held in 2015 March at the Universidad Autónoma de Nuevo León in Monterrey, México. Three asteroids were selected for coordinated observations from several Mexican observatories. We report full lightcurves for the main-belt asteroid 1084 Tamariwa (P = 6.195 ± 0.001 h) and near-Earth asteroid (NEA) 4055 Magellan (P = 7.479 ± 0.001 h). Asteroid 1466 Mundleria was also observed on eight nights but no lightcurve was obtained because of its faintness, a crowded field-of-view, and low amplitude (<0.03 mag).

  14. Photometry of AM Herculis - A slow optical pulsar

    NASA Technical Reports Server (NTRS)

    Priedhorsky, W. C.; Krzeminski, W.

    1978-01-01

    Multicolor photometry of the X-ray binary AM Her suggests that the red component of the optical flux is closely related to the source of optical circular polarization in the system. It is concluded from the periodic modulation of flux in the U through R bands, which is particularly well-defined when plotted as color curves, that the primary and secondary minima are neither eclipses by a secondary star nor eclipses by a hot spot. It is suggested that the primary minimum in the visual light curve is the eclipse of a region of intense optical emission in the magnetic field near the surface of a degenerate dwarf by that dwarf itself.

  15. SIT Vidicon photometry for four old Magellanic Cloud clusters

    NASA Astrophysics Data System (ADS)

    Harris, W. E.; Hesser, J. E.; Atwood, B.

    1983-12-01

    SIT Vidicon photometry in B and V from the CTIO 4-m telescope is presented for NGC 1466, NGC 2203, NGC 2210, and NGC 2257 in the Large Magellanic Cloud. The deepest data are for NGC 2257, where the main sequence turnoff is reached at V = 22.4, confirming Stryker's (1983) inference from photographic data that the cluster has an age comparable to those of the Galactic globular clusters. NGC 2203 is found to be an intermediate-age cluster with a C-M diagram similar to that of NGC 7789 in the Galaxy. For NGC 1466 and NGC 2210 the present data are compatible with previous studies that have found these to be genuinely old clusters in the Galactic globular cluster sense.

  16. Glory revealed in disk-integrated photometry of Venus

    NASA Astrophysics Data System (ADS)

    García Muñoz, A.; Pérez-Hoyos, S.; Sánchez-Lavega, A.

    2014-06-01

    Context. Reflected light from a spatially unresolved planet yields unique insight into the overall optical properties of the planet cover. Glories are optical phenomena caused by light that is backscattered within spherical droplets following a narrow distribution of sizes; they are well known on Earth as localised features above liquid clouds. Aims: Here we report the first evidence for a glory in the disk-integrated photometry of Venus and, in turn, of any planet. Methods: We used previously published phase curves of the planet that were reproduced over the full range of phase angles with model predictions based on a realistic description of the Venus atmosphere. We assumed that the optical properties of the planet as a whole can be described by a uniform and stable cloud cover, an assumption that agrees well with observational evidence. Results: We specifically show that the measured phase curves mimic the scattering properties of the Venus upper-cloud micron-sized aerosols, also at the small phase angles at which the glory occurs, and that the glory contrast is consistent with what is expected after multiple scattering of photons. In the optical, the planet appears to be brighter at phase angles of ~11-13° than at full illumination; it undergoes a maximum dimming of up to ~10% at phases in between. Conclusions: Glories might potentially indicate spherical droplets and, thus, extant liquid clouds in the atmospheres of exoplanets. A prospective detection will require exquisite photometry at the small planet-star separations of the glory phase angles. Appendices are available in electronic form at http://www.aanda.org

  17. Recovering physical properties from narrow-band photometry

    NASA Astrophysics Data System (ADS)

    Schoenell, W.; Cid Fernandes, R.; Benítez, N.; Vale Asari, N.

    2013-05-01

    Our aim in this work is to answer, using simulated narrow-band photometry data, the following general question: What can we learn about galaxies from these new generation cosmological surveys? For instance, can we estimate stellar age and metallicity distributions? Can we separate star-forming galaxies from AGN? Can we measure emission lines, nebular abundances and extinction? With what precision? To accomplish this, we selected a sample of about 300k galaxies with good S/N from the SDSS and divided them in two groups: 200k objects and a template library of 100k. We corrected the spectra to z = 0 and converted them to filter fluxes. Using a statistical approach, we calculated a Probability Distribution Function (PDF) for each property of each object and the library. Since we have the properties of all the data from the STARLIGHT-SDSS database, we could compare them with the results obtained from summaries of the PDF (mean, median, etc). Our results shows that we retrieve the weighted average of the log of the galaxy age with a good error margin (σ ≈ 0.1 - 0.2 dex), and similarly for the physical properties such as mass-to-light ratio, mean stellar metallicity, etc. Furthermore, our main result is that we can derive emission line intensities and ratios with similar precision. This makes this method unique in comparison to the other methods on the market to analyze photometry data and shows that, from the point of view of galaxy studies, future photometric surveys will be much more useful than anticipated.

  18. Far-ultraviolet photometry of the globular cluster omega Cen

    NASA Technical Reports Server (NTRS)

    Whitney, Jonathan H.; O'Connell, Robert W.; Rood, Robert T.; Dorman, Ben; Landsman, Wayne B.; Cheng, K.-P.; Bohlin, Ralph C.; Hintzen, Paul M. N.; Roberts, Morton S.; Smith, Andrew M.

    1994-01-01

    We present far-ultraviolet images of the globular cluster omega Centauri obtained with the Ultraviolet Imaging Telescope (UIT) during the 1990 December Astro-1 mission. A total of 1957 sources are detected at 1620 A to a limiting ultraviolet (UV) magnitude of 16.4 in the central 24 min diameter region of the field and a limit of 15.6 over the remainder of the 40 min diameter field. Over 1400 of these sources are matched with stars on a Stroemgren u band charge coupled devices (CCD) frame obtained with the Cerro Tololo Inter-American Observatory (CTIO) 0.9 m telescope to produce a (far-UV, u) color-magnitude diagram (CMD). Completeness of the sample and error estimates are determined by photometry of artificial stars added to the images. The horizontal branch (HB) of the CMD is heavily populated hotter than 9000 K. A large number of 'extreme HB' stars are found hotter than a conspicuous break in the HB at T(sub e) approximately 16000 K. There is also a significant population of stars above the HB, the brightest of which is 4 mag brighter than the HB. Most of the hotter of these appear to be 'AGB-manque' or 'Post-Early Asymptotic Giant Branch' stars. We compare the observations to recent theoretical evolutionary tracks for the zero-age HB and subsequent phases. The tracks match the data well, with the exception of the hotter HB stars, many of which fall below the zero-age horizontal branch. It is unclear as yet whether these are a special population or an artifact of errors in the models or photometry. We identify 33 stars with T(sub e) greater than or approximately = 50000 K, which are hotter than zero-age HB stars with envelope masses of 0.003 solar mass.

  19. Magnetic activity on V889 Herculis. Combining photometry and spectroscopy

    NASA Astrophysics Data System (ADS)

    Järvinen, S. P.; Korhonen, H.; Berdyugina, S. V.; Ilyin, I.; Strassmeier, K. G.; Weber, M.; Savanov, I.; Tuominen, I.

    2008-09-01

    Aims: In this paper we analyse photometric and spectroscopic observations of the young active dwarf V889 Her. We present new surface temperature maps, and compare them to earlier published Doppler maps, as well as to the results obtained from long-term photometry. Methods: The light curve inversions and surface temperature maps were obtained using the Occamian approach inversion technique. Results: The 12 years of photometric records on V889 Her suggest a possible photometric cycle of approximately 9 years. Variability on this time scale is detected in the maximum, minimum, and mean photometric magnitudes. The spots prefer to concentrate on two active longitudes that are approximately 180° apart. Furthermore, one flip-flop event, i.e., a sudden change of the dominant active longitude by 180°, is detected at the time of the global maximum activity. The wings of the Ca II 8662 Å indicate that the quiet photosphere of the V889 Her is similar to the one of the present Sun supporting earlier determined atmospheric parameters, while the chromosphere of V889 Her shows signs of much stronger activity. The temperature maps reveal that the polar regions are covered by spots, which are about 1500 K cooler than the quiet photosphere. The mean spot latitude varies slightly with time. It appears that the spot latitudes from our Doppler images and the spot migration rates revealed by photometry indicate a weaker differential rotation than reported earlier, but in the same (solar-like) direction. Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Table [see full textsee full textsee full text] and Figs. [see full textsee full textsee full text]-[see full textsee full textsee full text] are only available in electronic form at http://www.aanda.org

  20. Exoplanet Photometry and Spectroscopy with HII/L2

    NASA Astrophysics Data System (ADS)

    Tamura, M.

    2000-12-01

    With the recent discovery of extrasolar planets (exoplanets) around nearby stars by indirect methods, one of the next goals of the exoplanet study is to directly detect the giant exoplanets and to make photometry and spectroscopy. The next decade will be the time to move from discovery to characterization of exoplanet systems. This, however, requires all of high sensitivity, high spatial resolution, and high dynamic range observations at infrared wavelengths, which will be difficult to achieve from the ground. In this paper, we describe a coronagraphic camera and spectrometer for the HII/L2 mission for mid- and far-infrared astronomy and show the photometry and spectroscopy of exoplanets to be one of the most important scientific aims for this mission. The proposed HII/L2 coronagraph will cover the wavelength between 4 and 27 micron, optimized at 5 micron. The plate scale is about 0.06 arcsec, covering a field-of-view of about 1 arcmin by 1 arcmin with a 1024x1024 array detector. Occulting masks of diameter greater than 0.72 arcsec will be available, which enables the observations of exoplanets beyond ~2 AU around nearby (d~5 pc) stars. The coronagraph greatly takes advantage of the single (non-segmented) mirror of the HII/L2 telescope design. A high-efficiency Ge or CdTe grism with a resolution of a few hundreds will be installed for the coronagraphic spectroscopy of the exoplanet atmosphere. Rich spectral features at mid-infrared wavelengths enable us to study various atmospheric components and to make a comparative study of the exoplanets and our solar system planets.

  1. Infrared Photometry of Late-M, L, and T Dwarfs

    NASA Astrophysics Data System (ADS)

    Leggett, S. K.; Golimowski, David A.; Fan, Xiaohui; Geballe, T. R.; Knapp, G. R.; Brinkmann, J.; Csabai, István; Gunn, James E.; Hawley, Suzanne L.; Henry, Todd J.; Hindsley, Robert; Ivezić, Željko; Lupton, Robert H.; Pier, Jeffrey R.; Schneider, Donald P.; Smith, J. Allyn; Strauss, Michael A.; Uomoto, Alan; York, D. G.

    2002-01-01

    We present ZJHKL'M' photometry of a sample of 58 late M, L, and T dwarfs, most of which are identified from the Sloan Digital Sky Survey and the Two Micron All-Sky Survey. Near-infrared spectra and spectral classifications for most of this sample are presented in a companion paper by Geballe et al. We derive the luminosities of 18 dwarfs in the sample with known parallaxes, and the results imply that the effective temperature range for the L dwarfs in our sample is approximately 2200-1300 K and for the T dwarfs 1300-800 K. We obtained new photometric data at the United Kingdom Infrared Telescope for: 42 dwarfs at Z, 34 dwarfs at JHK, 21 dwarfs at L', as well as M' data for two L dwarfs and two T dwarfs. The M' data provide the first accurate photometry for L and T dwarfs in this bandpass-for a T2 and a T5 dwarf, we find K-M'=1.2 and 1.6, respectively. These colors are much bluer than predicted by published models, suggesting that CO may be more abundant in these objects than expected, as has been found for the T6 dwarf Gl 229B. We also find that K-L' increases monotonically through most of the M, L, and T subclasses, but it is approximately constant between types L6 and T5, restricting its usefulness as a temperature indicator. The degeneracy is probably due to the onset of CH4 absorption at the blue edge of the L' bandpass. The JHK colors of L dwarfs show significant scatter, suggesting that the fluxes in these bandpasses are sensitive to variations in photospheric dust properties. The H-K colors of the later T dwarfs also show some scatter, which we suggest is due to variations in pressure-induced H2 opacity, which is sensitive to gravity and metallicity.

  2. VizieR Online Data Catalog: Stroemgren-Crawford uvbyβ photometry catalog (Paunzen, 2015)

    NASA Astrophysics Data System (ADS)

    Paunzen, E.

    2015-07-01

    This catalogue includes very precise celestial coordinates, but is magnitude and spatial resolution limited. However, the loss of objects is only marginal and is compensated for by the gain of homogeneity. In total, 298639 measurements of 60668 stars were used to derive unweighted mean indices and their errors. Photoelectric and CCD observations were treated in the same way. For the new catalogue, the literature through the end of 2014 was searched for photoelectric and CCD uvbybeta measurements The contents will be updated regularly. The complete files with all references can be downloaded and queried from http://gcpd.physics.muni.cz/ (1 data file).

  3. EXTENDED PHOTOMETRY FOR THE DEEP2 GALAXY REDSHIFT SURVEY: A TESTBED FOR PHOTOMETRIC REDSHIFT EXPERIMENTS

    SciTech Connect

    Matthews, Daniel J.; Newman, Jeffrey A.; Coil, Alison L.; Cooper, Michael C.; Gwyn, Stephen D. J. E-mail: janewman@pitt.edu E-mail: m.cooper@uci.edu

    2013-02-15

    This paper describes a new catalog that supplements the existing DEEP2 Galaxy Redshift Survey photometric and spectroscopic catalogs with ugriz photometry from two other surveys: the Canada-France-Hawaii Legacy Survey (CFHTLS) and the Sloan Digital Sky Survey (SDSS). Each catalog is cross-matched by position on the sky in order to assign ugriz photometry to objects in the DEEP2 catalogs. We have recalibrated the CFHTLS photometry where it overlaps DEEP2 in order to provide a more uniform data set. We have also used this improved photometry to predict DEEP2 BRI photometry in regions where only poorer measurements were available previously. In addition, we have included improved astrometry tied to SDSS rather than USNO-A2.0 for all DEEP2 objects. In total this catalog contains {approx}27, 000 objects with full ugriz photometry as well as robust spectroscopic redshift measurements, 64% of which have r > 23. By combining the secure and accurate redshifts of the DEEP2 Galaxy Redshift Survey with ugriz photometry, we have created a catalog that can be used as an excellent testbed for future photo-z studies, including tests of algorithms for surveys such as LSST and DES.

  4. THE PANCHROMATIC HUBBLE ANDROMEDA TREASURY. X. ULTRAVIOLET TO INFRARED PHOTOMETRY OF 117 MILLION EQUIDISTANT STARS

    SciTech Connect

    Williams, Benjamin F.; Dalcanton, Julianne J.; Weisz, Daniel R.; Byler, Nell; Johnson, L. C. E-mail: jd@astro.washington.edu E-mail: lcjohnso@astro.washington.edu; and others

    2014-11-01

    We have measured stellar photometry with the Hubble Space Telescope Wide Field Camera 3 (WFC3) and Advanced Camera for Surveys in near ultraviolet (F275W, F336W), optical (F475W, F814W), and near infrared (F110W, F160W) bands for 117 million resolved stars in M31. As part of the Panchromatic Hubble Andromeda Treasury survey, we measured photometry with simultaneous point-spread function (PSF) fitting across all bands and at all source positions after precise astrometric image alignment (<5-10 mas accuracy). In the outer disk, the photometry reaches a completeness-limited depth of F475W ∼ 28, while in the crowded, high surface brightness bulge, the photometry reaches F475W ∼ 25. We find that simultaneous photometry and optimized measurement parameters significantly increase the detection limit of the lowest-resolution filters (WFC3/IR) providing color-magnitude diagrams (CMDs) that are up to 2.5 mag deeper when compared with CMDs from WFC3/IR photometry alone. We present extensive analysis of the data quality including comparisons of luminosity functions and repeat measurements, and we use artificial star tests to quantify photometric completeness, uncertainties and biases. We find that the largest sources of systematic error in the photometry are due to spatial variations in the PSF models and charge transfer efficiency corrections. This stellar catalog is the largest ever produced for equidistant sources, and is publicly available for download by the community.

  5. The Panchromatic Hubble Andromeda Treasury. X. Ultraviolet to Infrared Photometry of 117 Million Equidistant Stars

    NASA Astrophysics Data System (ADS)

    Williams, Benjamin F.; Lang, Dustin; Dalcanton, Julianne J.; Dolphin, Andrew E.; Weisz, Daniel R.; Bell, Eric F.; Bianchi, Luciana; Byler, Nell; Gilbert, Karoline M.; Girardi, Léo; Gordon, Karl; Gregersen, Dylan; Johnson, L. C.; Kalirai, Jason; Lauer, Tod R.; Monachesi, Antonela; Rosenfield, Philip; Seth, Anil; Skillman, Eva

    2014-11-01

    We have measured stellar photometry with the Hubble Space Telescope Wide Field Camera 3 (WFC3) and Advanced Camera for Surveys in near ultraviolet (F275W, F336W), optical (F475W, F814W), and near infrared (F110W, F160W) bands for 117 million resolved stars in M31. As part of the Panchromatic Hubble Andromeda Treasury survey, we measured photometry with simultaneous point-spread function (PSF) fitting across all bands and at all source positions after precise astrometric image alignment (<5-10 mas accuracy). In the outer disk, the photometry reaches a completeness-limited depth of F475W ~ 28, while in the crowded, high surface brightness bulge, the photometry reaches F475W ~ 25. We find that simultaneous photometry and optimized measurement parameters significantly increase the detection limit of the lowest-resolution filters (WFC3/IR) providing color-magnitude diagrams (CMDs) that are up to 2.5 mag deeper when compared with CMDs from WFC3/IR photometry alone. We present extensive analysis of the data quality including comparisons of luminosity functions and repeat measurements, and we use artificial star tests to quantify photometric completeness, uncertainties and biases. We find that the largest sources of systematic error in the photometry are due to spatial variations in the PSF models and charge transfer efficiency corrections. This stellar catalog is the largest ever produced for equidistant sources, and is publicly available for download by the community.

  6. Study of the polarization dependence of the photoelectric effect in the soft X-ray band - A focal plane photoelectric stellar X-ray polarimeter for the Spectrum-X-Gamma mission

    NASA Technical Reports Server (NTRS)

    Heckler, A.; Blaer, A.; Kaaret, P.; Novick, R.

    1989-01-01

    An experimental study of the polarization dependence of the photoelectric effect in cesium iodide in the soft X-ray band was started (Heckler et al., 1989). At a grazing angle of 10 degrees and a photon energy of 2.6 keV, it is found that the photoelectric yield from a thin layer of evaporated cesium iodide varies by 12.4 percent as the polarization vector of the incident X-ray beam is rotated about the line-of-sight. The rotation angle corresponding to the maximum photoyield is displaced by 16 degrees from the normal to the photocathode. This modulation and phase shift are in good agreement with the results recently reported by Fraser, et al. (1989) It is shown that a focal plane stellar X-ray polarimeter based on this photoelectric effect will be substantially more efficient than convential X-ray polarimeters such as those based on either Bragg reflection or scattering from low atomic number targets.

  7. Photoelectric effects of ultraviolet fast response and high sensitivity in LiNbO3 single crystal

    NASA Astrophysics Data System (ADS)

    Guo, Er-Jia; Xing, Jie; Jin, Kui-Juan; Lu, Hui-Bin; Wen, Juan; Yang, Guo-Zhen

    2009-07-01

    The photoelectric effects in LiNbO3 (LNO) single crystal have been systematically studied with the two kinds of LNO wafers of tilt of 10° and untilted at the ambient temperature. The ultrafast response photoelectric effect of 120 ps rise time was observed in 10° tilted LNO single crystal with a 266 nm laser pulse of 25 ps duration. The photocurrent responsivity of untilted LNO with an interdigitated electrode of 10 μm finger width and 10 μm interspacing is 17.1 mA/W under the irradiation of 300 nm wavelength UV light at 10 V bias. The noise current under sunlight is only 73 pA at 10 V bias. The experimental results suggest that the LNO single crystal is one of the promising materials for photodetectors working in UV region.

  8. Ultraviolet fast-response photoelectric effect in tilted orientation SrTiO{sub 3} single crystals

    SciTech Connect

    Zhao Kun; Jin Kuijuan; Huang Yanhong; Zhao Songqing; Lu Huibin; He Meng; Chen Zhenghao; Zhou Yueliang; Yang Guozhen

    2006-10-23

    Ultraviolet photoelectricity based on the vicinal cut as-supplied SrTiO{sub 3} single crystals has been experimentally studied in the absence of an applied bias at room temperature. An open-circuit photovoltage of 130 ps rise time and 230 ps full width at half maximum was observed under the irradiation of a 355 nm pulsed laser of 25 ps in duration. The dependence of the photoelectric effect on the tilting angles was studied, and the optimum angle is 20.9 deg. . Seebeck effect is proposed to elucidate the tilting angle dependence of laser-induced photovoltage. This work demonstrates the potential of SrTiO{sub 3} single crystals in ultraviolet detection.

  9. Photoelectric effects of ultraviolet fast response and high sensitivity in LiNbO{sub 3} single crystal

    SciTech Connect

    Guo Erjia; Jin Kuijuan; Lu Huibin; Wen Juan; Yang Guozhen; Xing Jie

    2009-07-15

    The photoelectric effects in LiNbO{sub 3} (LNO) single crystal have been systematically studied with the two kinds of LNO wafers of tilt of 10 deg. and untilted at the ambient temperature. The ultrafast response photoelectric effect of 120 ps rise time was observed in 10 deg. tilted LNO single crystal with a 266 nm laser pulse of 25 ps duration. The photocurrent responsivity of untilted LNO with an interdigitated electrode of 10 mum finger width and 10 mum interspacing is 17.1 mA/W under the irradiation of 300 nm wavelength UV light at 10 V bias. The noise current under sunlight is only 73 pA at 10 V bias. The experimental results suggest that the LNO single crystal is one of the promising materials for photodetectors working in UV region.

  10. Design and realization of test system for testing parallelism and jumpiness of optical axis of photoelectric equipment

    NASA Astrophysics Data System (ADS)

    Shi, Sheng-bing; Chen, Zhen-xing; Qin, Shao-gang; Song, Chun-yan; Jiang, Yun-hong

    2014-09-01

    With the development of science and technology, photoelectric equipment comprises visible system, infrared system, laser system and so on, integration, information and complication are higher than past. Parallelism and jumpiness of optical axis are important performance of photoelectric equipment,directly affect aim, ranging, orientation and so on. Jumpiness of optical axis directly affect hit precision of accurate point damage weapon, but we lack the facility which is used for testing this performance. In this paper, test system which is used fo testing parallelism and jumpiness of optical axis is devised, accurate aim isn't necessary and data processing are digital in the course of testing parallelism, it can finish directly testing parallelism of multi-axes, aim axis and laser emission axis, parallelism of laser emission axis and laser receiving axis and first acuualizes jumpiness of optical axis of optical sighting device, it's a universal test system.

  11. The rotation period of Epsilon Eri from photometry of its starspots

    NASA Technical Reports Server (NTRS)

    Frey, Gary J.; Hall, Douglas S.; Mattingly, Phil; Robb, Steve; Wood, Jim; Zeigler, Kenneth; Grim, Bruce

    1991-01-01

    BV photometry at six observatories in 1988/1989 and 1989/1990 shows variability resulting from five starspots which lived 1 or 2 months each, had rotation periods in the range P between 10.0d and 12.3d, and had amplitudes in the range 0.01 m - 0.03 m. From the range in P it was possible to estimate k greater than 0.20 +/- 0.05 for the differential rotation coefficient. Ca II K-line photometry, polarimetry, and earlier photometry reported in the literature has also shown variability with periodicities in the same 10 d -12 d range.

  12. A Pan-STARRS1-based recalibration of the Sloan Digital Sky Survey photometry

    NASA Astrophysics Data System (ADS)

    Finkbeiner, Douglas P.; Schlafly, E.; Green, G.

    2014-01-01

    We present a recalibration of the SDSS DR9 photometry with new flat fields and zero points derived from Pan-STARRS. Using PSF photometry of 60 million stars with 16 < r < 20, we obtain SDSS flat-field and amplifier gain corrections stable to 3 millimagnitudes (mmag) in g,r,i,z bands and 15 mmag in u band. We also identify transient non-photometric periods in SDSS ("contrails") based on photometric deviations co-temporal in SDSS bands. The recalibrated SDSS and PS1 photometry agree with systematics at the 7 mmag level.

  13. Influence of polymer:sensitizer ratio on photoelectric properties of organic composite photoconductor

    NASA Astrophysics Data System (ADS)

    Aleman, K.; Sanchez Juarez, A.; Kosarev, A.; Mansurova, S.; Koeber, S.; Meerholz, K.

    2010-06-01

    The results on characterization of the main photoelectric properties of the polymer:fulleren based composite material by using the non-steady-state photo-electromotive force (p-EMF) and modulated photocurrent technique are presented. By measuring this current under different experimental conditions, important material photoelectric parameters such as drift L0 and diffusion length LD, photocarrier's lifetime τ ; quantum efficiency of charge generation φ can be determined. The 50% of the composite weight consists of a mixture of the hole-conducting polymer PF6:TPD (poly-hexyle-triophene:N,N'-bis(4-methylphenyl)-N,N'-bis-(phenyl)-benzidine) sensitized with the highly soluble C60 derivative PCBM (phenyl-C61-butyric acid methyl ester) . Seven samples with varied polymer:sensitizer weight ratio (49:1wt.-%, 45:5wt.-%, 40:10wt.-%, 15:35wt.-%, 25:25wt.-%, 10:40wt.-%, 5:45wt.-%) where prepared. The remaining 50% were two azo-dyes 2,5-dimethyl-(4-p-nitrophenylazo)-anisole (DMNPAA) and 3- methoxy-(4-p-nitrophenylazo)-anisole (MNPAA) (25wt.-% each). Photoconductive composite film was sandwiched between two glass plates covered by transparent ITO electrodes. Two counter-propagating beams derived from a cw HeNe laser (λ = 633nm) intersected inside the detector creating an interference pattern. The output photo-EMF current (SEE MANUSCRIPT FOR EQUATION) was detected as a voltage drop by a lock-in amplifier. At polymer sensitizer ratio 25:25wt.-% the signal sign changes to the opposite revealing that the majority carriers at this and higher concentration of sensitizer are electrons. Our results show that the majority carrier's lifetime τ is only slightly affected by the variations of sensitizer concentration. Mobility-lifetime product μhτh of holes, on its turn decreases at the increasing sensitizer concentration, while μeτe of electrons keeps increasing. All this indicates that the carrier's mobility is strongly influenced by the changes on sensitizer concentrations.

  14. Photoelectric characteristics of CH3NH3PbI3/p-Si heterojunction

    NASA Astrophysics Data System (ADS)

    Yamei, Wu; Ruixia, Yang; Hanmin, Tian; Shuai, Chen

    2016-05-01

    Organic–inorganic hybrid perovskite CH3NH3PbI3 film is prepared on p-type silicon substrate using the one-step solution method to form a CH3NH3PbI3/p-Si heterojunction. The film morphology and structure are characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The photoelectric properties of the CH3NH3PbI3/p-Si heterojunction are studied by testing the current–voltage (I–V) with and without illumination and capacitance–voltage (C–V) characteristics. It turns out from the I–V curve without illumination that the CH3NH3PbI3/p-Si heterojunction has a rectifier feature with the rectification ratio over 70 at the bias of ±5 V. Also, there appears a photoelectric conversion phenomenon on this heterojunction with a short circuit current (Isc) of 0.16 μA and an open circuit voltage (Voc) of about 10 mV The high frequency C–V characteristic of the Ag/CH3NH3PbI3/p-Si heterojunction turns out to be similar to that of the metal–insulator–semiconductor (MIS) structure, and a parallel translation of the C–V curve along the forward voltage axis is found. This parallel translation means the existence of defects at the CH3NH3PbI3/p-Si interface and positive fixed charges in the CH3NH3PbI3 layer. The defects at the interface of the CH3NH3PbI3/p-Si heterojunction result in the dramatic decline of the Voc. Besides, the C–V test of CH3NH3PbI3 film shows a non-linear dielectric property and the dielectric value is about 4.64 as calculated. Project supported by the Hebei Province Natural Science Foundation of China (No. F2014202184) and the Tianjin Natural Science Foundation of China (No. 15JCZDJC37800).

  15. Observations of the eclipsing binary b Persei

    NASA Astrophysics Data System (ADS)

    Templeton, Matthew R.

    2015-01-01

    Dr. Robert Zavala (USNO-Flagstaff) et al. request V time-series observations of the bright variable star b Persei 7-21 January 2015 UT, in hopes of catching a predicted eclipse on January 15. This is a follow-up to the February 2013 campaign announced in Alert Notice 476, and will be used as a photometric comparison for upcoming interferometric observations with the Navy Precision Optical Interferometer (NPOI) in Arizona. b Per (V=4.598, B-V=0.054) is ideal for photoelectric photometers or DSLR cameras. Telescopic CCD observers may observe by stopping down larger apertures. Comparison and check stars assigned by PI: Comp: SAO 24412, V=4.285, B-V = -0.013; Check: SAO 24512, V=5.19, B-V = -0.05. From the PI: "[W]e wanted to try and involve AAVSO observers in a follow up to our successful detection of the b Persei eclipse of Feb 2013, AAVSO Alert Notice 476 and Special Notice 333. Our goal now is to get good time resolution photometry as the third star passes in front of the close ellipsoidal binary. The potential for multiple eclipses exists. The close binary has a 1.5 day orbital period, and the eclipsing C component requires about 4 days to pass across the close binary pair. The primary eclipse depth is 0.15 magnitude. Photometry to 0.02 or 0.03 mags would be fine to detect this eclipse. Eclipse prediction date (JD 2457033.79 = 2015 01 11 UT, ~+/- 1 day) is based on one orbital period from the 2013 eclipse." More information is available at PI's b Persei eclipse web page: http://inside.warren-wilson.edu/~dcollins/bPersei/. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details and information on the targets.

  16. High precision dual-axis tracking solar wireless charging system based on the four quadrant photoelectric sensor

    NASA Astrophysics Data System (ADS)

    Liu, Zhilong; Wang, Biao; Tong, Weichao

    2015-08-01

    This paper designs a solar automatic tracking wireless charging system based on the four quadrant photoelectric sensor. The system track the sun's rays automatically in real time to received the maximum energy and wireless charging to the load through electromagnetic coupling. Four quadrant photoelectric sensor responsive to the solar spectrum, the system could get the current azimuth and elevation angle of the light by calculating the solar energy incident on the sensor profile. System driver the solar panels by the biaxial movement mechanism to rotate and tilt movement until the battery plate and light perpendicular to each other. Maximize the use of solar energy, and does not require external power supply to achieve energy self-sufficiency. Solar energy can be collected for portable devices and load wireless charging by close electromagnetic field coupling. Experimental data show that: Four quadrant photoelectric sensor more sensitive to light angle measurement. when track positioning solar light, Azimuth deviation is less than 0.8°, Elevation angle deviation is less than 0.6°. Use efficiency of a conventional solar cell is only 10% -20%.The system uses a Four quadrant dual-axis tracking to raise the utilization rate of 25% -35%.Wireless charging electromagnetic coupling efficiency reached 60%.

  17. Photoelectric properties of the metamorphic InAs/InGaAs quantum dot structure at room temperature

    SciTech Connect

    Golovynskyi, S. L.; Seravalli, L.; Trevisi, G.; Frigeri, P.; Gombia, E.; Dacenko, O. I.; Kondratenko, S. V.

    2015-06-07

    We present the study of optical and photoelectric properties of InAs quantum dots (QDs) grown on a metamorphic In{sub 0.15}Ga{sub 0.85}As buffer layer: such nanostructures show efficient light emission in the telecom window at 1.3 μm (0.95 eV) at room temperature. We prepared a sample with vertical geometry of contacts isolated from the GaAs substrate. The structure is found to be photosensitive in the spectral range above 0.9 eV at room temperature, showing distinctive features in the photovoltage and photocurrent spectra attributed to QDs, InAs wetting layer, and In{sub 0.15}Ga{sub 0.85}As metamorphic buffer, while a drop in the photoelectric signal above 1.36 eV is related to the GaAs layer. No effect of defect centers on the photoelectrical properties is found, although they are observed in the absorption spectrum. We conclude that metamorphic QDs have a low amount of interface-related defects close to the optically active region and charge carriers can be effectively collected into InAs QDs.

  18. Consciousness Can Change the Output Signals of a Solar Cell and the Photoelectric Conversion Equation of Slow Mass Wave

    NASA Astrophysics Data System (ADS)

    Cao, Dayong

    2009-03-01

    The experiment's results show that human consciousness can change output signals such as Voc (open-circuit voltage) and Isc (short circuit current) of a solar cell placed some distance from a participant. For the first time, a consciousness signal is able to be recorded through the experiment conducted in Oct 2002. The order and rhythm of the changing wave pattern of Voc is related to the action of consciousness. The order and rhythm of slow brain signal of ERP and EEG are related to the cognized objects. Consciousness is independent and self-determined while brain signal is passive and driven. Consciousness is spiritual and Intelligence while brain signal is physical, corporality and mechanic. So consciousness is different from the brain signal. And consciousness effection is different from physical effection of light. Because consciousness can choose the object which it acts on. The light have a pairt of mass wave of low frequency and energy wave of high frequency. In photoelectric conversion process, We only use the energy wave to get the η (photoelectric transformation efficiency) which is little. If being used a pairt of wave, we will get a larger η. The photoelectric conversion equation of slow mass wave are being put forward.

  19. Significant effects of reaction temperature on morphology, crystallinity, and photoelectrical properties of rutile TiO2 nanorod array films

    NASA Astrophysics Data System (ADS)

    Sun, Xianmiao; Sun, Qiong; Zhang, Qian; Zhu, Qianqian; Dong, Hongzhou; Dong, Lifeng

    2013-03-01

    Oriented single-crystalline TiO2 nanorod arrays have been extensively studied as the electrode of photoelectrochemical cells due to their unique properties. In this study, oriented rutile TiO2 nanorod arrays were directly synthesized on fluorine-doped tin oxide glass substrates by a facile hydrothermal method, and the effects of growth conditions (i.e. reaction temperature, growth time and titanium precursor) on their morphologies, crystal structures and photoelectrical properties were investigated. Reaction temperature played a more critical role in tailoring the surface morphology, crystal structures (i.e. length, diameter and crystallinity of nanorods) and photoelectrical properties of the nanorods than growth time did. With the increase in reaction temperature from 140 °C to 200 °C, both photocurrent density and external quantum efficiency (EQE) increased initially and then decreased, with a maximum value of 5.6 × 10-2 mA cm-2 at 170 °C and 2.7% at 160 °C, respectively. In addition, photoelectric measurements demonstrated that TiO2 nanorod arrays synthesized from TiCl4 at a relatively low reaction temperature exhibited a much higher EQE value than those obtained from titanium isopropoxide.

  20. A new look at photometry of the Moon

    NASA Astrophysics Data System (ADS)

    Goguen, Jay D.; Stone, Thomas C.; Kieffer, Hugh H.; Buratti, Bonnie J.

    2010-08-01

    We use ROLO photometry (Kieffer, H.H., Stone, T.C. [2005]. Astron. J. 129, 2887-2901) to characterize the before and after full Moon radiance variation for a typical highlands site and a typical mare site. Focusing on the phase angle range 45° < α < 50°, we test two different physical models, macroscopic roughness and multiple scattering between regolith particles, for their ability to quantitatively reproduce the measured radiance difference. Our method for estimating the rms slope angle is unique and model-independent in the sense that the measured radiance factor I/ F at small incidence angles (high Sun) is used as an estimate of I/ F for zero roughness regolith. The roughness is determined from the change in I/ F at larger incidence angles. We determine the roughness for 23 wavelengths from 350 to 939 nm. There is no significant wavelength dependence. The average rms slope angle is 22.2° ± 1.3° for the mare site and 34.1° ± 2.6° for the highland site. These large slopes, which are similar to previous "photometric roughness" estimates, require that sub-mm scale "micro-topography" dominates roughness measurements based on photometry, consistent with the conclusions of Helfenstein and Shepard (Helfenstein, P., Shepard, M.K. [1999]. Icarus 141, 107-131). We then tested an alternative and very different model for the before and after full Moon I/ F variation: multiple scattering within a flat layer of realistic regolith particles. This model consists of a log normal size distribution of spheres that match the measured distribution of particles in a typical mature lunar soil 72141,1 (McKay, D.S., Fruland, R.M., Heiken, G.H. [1974]. Proc. Lunar Sci. Conf. 5, Geochim. Cosmochim. Acta 1 (5), 887-906). The model particles have a complex index of refraction 1.65-0.003 i, where 1.65 is typical of impact-generated lunar glasses. Of the four model parameters, three were fixed at values determined from Apollo lunar soils: the mean radius and width of the log normal

  1. Resolved photometry of extragalactic young massive star clusters

    NASA Astrophysics Data System (ADS)

    Larsen, S. S.; de Mink, S. E.; Eldridge, J. J.; Langer, N.; Bastian, N.; Seth, A.; Smith, L. J.; Brodie, J.; Efremov, Yu. N.

    2011-08-01

    Aims: We present colour-magnitude diagrams (CMDs) of young massive star clusters in several galaxies located well beyond the Local Group. The richness of these clusters allows us to obtain large samples of post-main sequence stars and test how well the observed CMDs are reproduced by canonical stellar isochrones. Methods: We use imaging of seven clusters in the galaxies NGC 1313, NGC 1569, NGC 1705, NGC 5236 and NGC 7793 obtained with the Advanced Camera for Surveys on board the Hubble Space Telescope and carry out PSF-fitting photometry of individual stars in the clusters. The clusters have ages in the range ~(5-50) × 106 years and masses of ~105 M⊙-106 M⊙. Although crowding prevents us from obtaining photometry in the inner regions of the clusters, we are still able to measure up to 30-100 supergiant stars in each of the richest clusters. The resulting CMDs and luminosity functions are compared with photometry of artificially generated clusters, designed to reproduce the photometric errors and completeness as realistically as possible. Results: In agreement with previous studies, our CMDs show no clear gap between the H-burning main sequence and the He-burning supergiant stars, contrary to predictions by common stellar isochrones. In general, the isochrones also fail to match the observed number ratios of red-to-blue supergiant stars, although the difficulty of separating blue supergiants from the main sequence complicates this comparison. In several cases we observe a large spread (1-2 mag) in the luminosities of the supergiant stars that cannot be accounted for by observational errors. We find that this spread can be reproduced by including an age spread of ~(10-30) × 106 years in the models. However, age spreads cannot fully account for the observed morphology of the CMDs and other processes, such as the evolution of interacting binary stars, may also play a role. Conclusions: Colour-magnitude diagrams can be successfully obtained for massive star

  2. Optical and near infrared photometry of Butcher-Oemler clusters

    NASA Technical Reports Server (NTRS)

    Shier, Lisa M.; Rieke, Marcia J.

    1993-01-01

    Rich clusters of galaxies at moderate redshifts (z approx. .3) have a larger proportion of optically blue galaxies than their low redshift counterparts. Spectroscopic examination of the blue galaxies by various authors has shown that the blue galaxies are generally Seyferts, show evidence for recent star formation, or are foreground objects. Unfortunately, spectroscopy is too time consuming to be used on large samples. Thus, we have looked for a way to separate Seyferts, starbursts, ellipticals and nonmembers using photometry alone. Five moderate redshift clusters, Abell numbers 777, 963, 1758, 1961 and 2218, have been observed in the V, R and K bands. We model the spectral energy distributions of various kinds of galaxies found in clusters and derive observed colors. We have modeled the spectral energy distributions (SED) of several kinds of galaxies and compute their colors as a function of redshift. We expect to see ellipticals, spirals, starbursts, post-starburst and Seyfert galaxies. The SED of elliptical and Sbc galaxies was observed by Rieke and Rieke. The SEDs for the starburst galaxies was created by adding a reddened 10(exp 8) year old burst to a spiral galaxy SED. The post-starburst (E+A) galaxy SEDs are composed of a slightly reddened 10(exp 9) year old burst and elliptical galaxy SED. SEDs for the Seyferts were created by adding a v(exp -1.1) power law, and a hot dust thermal spectrum to the Sbc. From the SEDs the colors of galaxies at various redshifts with assorted filters were computed. Lilly & Gunn (1985) have optical and infrared photometry for a sample of galaxies in CL0024+1654 observed spectroscopically by Dressler, Gunn and Schneider (1985). We have used this data to choose the most appropriate SEDs for our starburst and post-starburst models. The most likely explanation for the optically blue colors in most cluster galaxies is star formation. Very few galaxies lie in the Seyfert locus. Abel 1758 has more Seyfert candidates than the other

  3. The expected Gaia revolution in asteroid science: Photometry and spectroscopy

    NASA Astrophysics Data System (ADS)

    Cellino, A.

    2014-07-01

    Gaia is expected to produce a major revolution in our knowledge of the asteroids. Apart from a huge improvement in the accuracy of the orbital elements of these objects, something which is a ''natural'' consequence of the unprecedented astrometric accuracy of Gaia, we can also expect that the photometric and spectrophotometric performances of the Gaia detectors will be such to substantially move ahead the frontier of the domain of physical characterization of asteroids by means of remote observations. A list of physical properties, that will be derived from the analysis of the detections corresponding to different observed transits of each object in the Gaia focal plane during five years of operational activity, includes masses, sizes, average densities, spin properties, reflectance spectra, albedos, as well as a new taxonomic classification. In this review, the focus will be on Gaia photometry and spectrophotometry. The method of photometric inversion of sparse photometric data developed to reduce Gaia photometric data of asteroids will be described, and its expected performances will be discussed. In particular, the choice of assuming for the objects the shapes of ideal triaxial ellipsoids, fairly simplistic in an era in which much more refined shape models are currently used in photometric inversion methods, will be justified by the need of minimizing the CPU time needed to process data for hundreds of thousands of objects in a reasonable time. The processing of spectrophotometric data will be also described. These data will produce a huge data set of reflectance spectra of asteroids. A particular advantage of these data will be that of including also the blue part of the spectrum, which has been substantially lost since the epoch in which the CCD detectors have replaced the older photomultipliers used for UBVRI photometry. The big data set of new asteroid spectra will be also used to develop a new asteroid taxonomy, used new algorithms developed for this

  4. Infrared photometry and polarimetry of Cygnus X-3

    NASA Technical Reports Server (NTRS)

    Jones, Terry Jay; Gehrz, Robert D.; Kobulnicky, Henry A.; Molnar, Lawrence A.; Howard, Eric M.

    1994-01-01

    We present photometry and linear polarimetry of Cygnus X-3 at K (2.2 micrometers) obtained over a 5 yr period. Photometry and polarimetry at J, H, and K of nearby field stars is also presented. From an analysis of these data we find: (1) Using the x-ray ephemeris of Kitamoto et al. (ApJ, 384, 263 (1992), including the first and second derivatives of the period, the leading edge of the decline to minimum in the quiescent K light curve has not changed in phase since 1974. The duration of the minimum in the light curve has changed significantly between different epochs, becoming much broader in 1993 than it was previously. (2) In addition to an interstellar polarization component, it is likely Cyg X-3 has an intrinsic polarization component that is variable. The variations in the polarization do not show any diagnostic pattern with orbital phase. A crude analysis of the polarization suggests the intrinsic polarization of Cyg X-3 has a mean position angle of approximately 12 deg, nearly the same as the direction of the expanding radio lobes. This is consistent with circumstellar electrons scattering in an equatorial disk that is perpendicular to the lobe axis. (3) The mean position angle for the interstellar polarization in the direction of Cyg X-3 is 150 deg. This is nearly perpendicular to the axis of interstellar radio scattering seen in the extended (Very Long Baseline Inteferometry (VLBI) images. Since the position angle of interstellar polarization is the same as the projected magnetic field direction, this suggests the interstellar (not circumstellar) scattering must be taking place perpendicular to the interstellar magnetic field lines. (4) Cyg X-3 was observed at K during a flare on 1992 September 30 with a temporal resolution of 6 s. The flaring had rise and fall times of approximately 50 s with peak intensities up to 80 mJy. The flux between individual flare events never dropped to quiescent levels for the duration of our observations (approximately 2000 s).

  5. Infrared Passbands for Accurate IR Photometry : the IRWG set

    NASA Astrophysics Data System (ADS)

    Milone, E. F.; Young, A. T.

    2002-12-01

    The well-known past limitations in accuracy and precision of infrared photometry has been shown to be due primarily to atmospheric features within passbands and the use of the edges of the atmospheric windows to define those passbands. The saturation of portions of the passbands high in the atmosphere means, especially for the longer wavelength passbands, a large difference between a linearly extrapolated zero-air mass magnitude and the actual value. The rapid curvature of the extinction curve between 1 and 0 air mass is known as the Forbes effect. Since the strengths of atmospheric features vary with altitude and the circumstances of each site, different observatories have responded to the problem by redefining the Johnson system from J to Q to suit the needs of the site. The result has been a proliferation of systems, with filters having been selected for maximum throughput and so not necessarily placed, shaped, and narrowed to minimize optimally the effects of the absorption bands of the terrestrial atmosphere. Given this situation and in light of the tremendous promise of high precision presented by infrared photometry, and with the support of an important segment of the IR community, the Infrared Astronomy Working Group (IRWG) was created inside IAU Com. 25 to solve the problem. A subgroup of the IRWG consisting of Young, Milone, and Stagg set about examining the properties of existing passbands and in optimizing the placement and width of passbands within the atmospheric windows. Here we review the transformation properties of the recommended Z to Q passbands and of the IR filters produced by Custom Scientific Co. to approximate the near IR passbands of this set, their signal to noise ratios, and results of the standardization testing project at the Rothney Astrophysical Observatory over the past few years. The extinction coefficients determined with the manufactured filters demonstrate the usefulness of these passbands for transformation to the standard

  6. Photometry and Spectroscopy of BD+35 1111 in M38

    NASA Astrophysics Data System (ADS)

    Souza, Steven P.; Kwitter, Karen B.; Sami, Mona; Beltz-Mohrmann, Gillian

    2014-06-01

    BD+35 1111 is a ~10.5-magnitude star in the field of M38, an open cluster that has been a target of our ongoing study of Hα emission variability in massive stars via narrowband CCD photometry (e.g. Souza, Davis, and Teich 2013, BAAS. 45, PM354.22). BD+35 1111 has no MKK classification in the literature, and is not listed as variable in GCVS, VSX, or NSVS. It is included, with no further characterization, in both the Vatican and Kohoutek catalogs of emission line stars. Using inhomogeneous ensemble photometry (e.g. Bhatti, Richmond, Ford, and Petro 2010, ApJ Supp., 186, 233), we find it to be an irregular variable with a range of ~0.15 mag. To further understand this star we obtained a medium-resolution spectrum using the DIS spectrograph on the ARC 3.5-meter telescope at Apache Point Observatory. We classify BD+35 1111 as B2Ve, the only confirmed Be star in the field of M38. This raises the question of membership, since the age of M38 is likely 250 Ma or greater (Pandey et al. 2007, Publ. Astron. Soc. Japan 59, 547). From published B and V magnitudes we find a nominal distance to BD+35 1111 of 1.6 kpc, but with a range of 1.3 to 2.0 kpc, marginally consistent with distance estimates for M38 ranging from 1.0 to 1.4 kpc. If a member, BD+35 1111 is a candidate blue straggler. If not, it may have escaped from a nearby younger cluster, possibly Kronberger 1 (Kronberger et al. 2006, A&A 447, 921), which has the right heliocentric distance and age. The notion that BD+35 1111 is behind M38 is supported by its reddening of EB-V ~ 0.5, significantly higher than for M38 itself 0.24). We gratefully acknowledge support for student research from NSF grant AST-1005024 to the Keck Northeast Astronomy Consortium, Williams College, and NASA via an American Astronomical Society Small Research Grant.

  7. THE ANALYSIS OF BIOLUMINESCENCES OF SHORT DURATION, RECORDED WITH PHOTOELECTRIC CELL AND STRING GALVANOMETER.

    PubMed

    Harvey, E N; Snell, P A

    1931-03-20

    1. The rapid decay of luminescence in extracts of the ostracod crustacean Cypridina hilgendorfii, has been studied by means of a photoelectric-amplifier-string galvanometer recording system. 2. For rapid flashes of luminescence, the decay is logarithmic if ratio of luciferin to luciferase is small; logarithmic plus an initial flash, if ratio of luciferin to luciferase is greater than five. The logarithmic plot of luminescence intensity against time is concave to time axis if ratio of luciferin to luciferase is very large. 3. The velocity constant of rapid flashes of luminescence is approximately proportional to enzyme concentration, is independent of luciferin concentration, and varies approximately inversely as the square root of the total luciferin (luciferin + oxyluciferin) concentration. For large total luciferin concentrations, the velocity constant is almost independent of the total luciferin. 4. The variation of velocity constant with total luciferin concentration (luciferin + oxyluciferin) and its independence of luciferin concentration is explained by assuming that light intensity is a measure of the luciferin molecules which become activated to oxidize (accompanied with luminescence) by adsorption on luciferase. The adsorption equilibrium is the same for luciferin and oxyluciferin and determines the velocity constant. PMID:19872603

  8. A scanning measurement method of the pitch of grating based on photoelectric microscope

    NASA Astrophysics Data System (ADS)

    Gao, Hongtang; Wang, Zhongyu; Wang, Hao

    2015-10-01

    Grating is an important sensor widely used in CNC machine or equipment for length measurement with high precision. Special line scales with dense and micro lines are also widely used for the calibration of length measurement instrument. All the pitches of grating and spaces of dense lines of line scale are needed to be calibrated for a good measurement application. General methods for measurement of dense and micro lines include digital image processing method by CCD Microscope or line scanning method by AFM or SEM, and laser distraction method. There are some disadvantages to measure a long length grating with high precision and efficiently in these methods. A dynamic method based on Photoelectric Microscope is introduced, the lines of grating to be measured is moving uniformly when measuring, and the working distance is a bigger 65mm, the zoom of objective is low 10X. The principle of this dynamic method is discussed and the distortion of line signal is analyzed. The way to decrease the affection caused by distortion of line signal is also described. A special glass grating line scale with length 10mm, space 10μm and width 5μm is measured to verify the method. The measurement result and the uncertainty analysis demonstrate the expand measurement uncertainty (k=2) is less than 0.1μm.

  9. Photo-electrical and transport properties of hydrothermal ZnO

    NASA Astrophysics Data System (ADS)

    Onufrijevs, P.; Ščajev, P.; JarašiÅ«nas, K.; Medvid, A.; Korsaks, V.; Mironova-Ulmane, N.; Zubkins, M.; Mimura, H.

    2016-04-01

    We performed the studies of optical, photoelectric, and transport properties of a hydrothermal bulk n-type ZnO crystal by using the contactless optical techniques: photoluminescence, light-induced transient grating, and differential reflectivity. Optical studies revealed bound exciton and defect-related transitions between the donor states (at ˜60 meV and ˜240 meV below the conduction band) and the deep acceptor states (at 0.52 eV above the valence band). The acceptor state was ascribed to VZn, and its thermal activation energy of 0.43 eV was determined. A low value of carrier diffusion coefficient (˜0.1 cm2/s) at low excitations and temperatures up to 800 K was attributed to impact the recharged deep acceptors. Electron and hole mobilities of 140 and ˜80 cm2/Vs, correspondently, were determined at room temperature. The decrease of carrier lifetime with excitation was ascribed to increasing rate of radiative recombination at low temperatures and nonradiative recombination above the room temperature.

  10. Effect of Al Doping Concentration on Microstructure, Photoelectric Properties and Doped Mechanism of Azo Films

    NASA Astrophysics Data System (ADS)

    Xu, Ying; Cai, Yanqing; Hou, Linyan; Ma, Penghua

    2014-05-01

    Al doped ZnO (AZO) thin films were deposited on a glass substrate by atmospheric pressure chemical vapor deposition (APCVD) method. Effect of Al doping concentration on microstructure, photoelectric properties and doped mechanism of AZO thin films were investigated. The analysis results revealed that the structural properties of the films possessed crystalline structure with a preferred (002) orientation. The best crystallization quality and minimum electrical resistivity was obtained at 5 at.% Al doped films and the minimum resistivity was 6.6 × 10-4 Ω ṡ cm. Uniform granular grains were observed on the surface of AZO films, and the average optical transmittance was above 80% in the visible range. The doped mechanism of AZO films was analyzed as follows. With Al doping in ZnO films, AlZn substitute and Ali interstice were produced, which decreased the resistivity of films. While after the limit value and with the continuing increase of Al doping concentration, free electrons were consumed and the resistivity of films increased.

  11. Measuring system for cable length and diameter based on photoelectric technology

    NASA Astrophysics Data System (ADS)

    Zhu, WeiMin; Zhou, Zhou; Wei, Ping; Qi, Fang

    2012-10-01

    Precise online measurement of cable diameter and length will ensure stability of quality production and production speed. This paper describes a measuring device to measure cable length and diameter simultaneously, accomplish online production process control. The device consists mainly of a synchronous sampling part, calculation and control part. The synchronous sampling part consists of two parallel rollers one meter far from each other. A measuring band cinctures the rollers and move together with them. There are two electromagnetic chucks on the measuring band which are controlled by two photoelectric position switches to hold or release a cable, in order to make the cable move with measuring system synchronously. An optical encoder is connected to one of the rollers coaxially to measure cable length. For cable diameter measurement, two orthogonal CCD sensors are used. Accuracy of online diameter measurement is mainly affected by vibration of cable movement. In order to reduce the cable diameter measurement error caused by vibration, measuring system uses a mechanical damping device and high-speed CCD sensors which exposure time is up to microseconds. The calculation and control part of measuring device can filter, amplify and binarizate electrical signals from synchronous sampling part, then they are processed by microcontroller 8051 to complete cable length and diameter measurement. As well, the measuring device can set error limits and detect online whether cable length and diameter size are in default range , if not it would give corresponding alarm.

  12. Synthesis, Crystal Structure, and Photoelectric Properties of a New Layered Bismuth Oxysulfide.

    PubMed

    Meng, Sha; Zhang, Xian; Zhang, Ganghua; Wang, Yaoming; Zhang, Hui; Huang, Fuqiang

    2015-06-15

    [Bi2O2]-containing tetragonal compounds have received enormous attention due to unique functions including ferroelectricity, photocatalysis, and superconductivity. Here, a new layered compound Bi9O7.5S6 was synthesized via a facile hydrothermal route. The compound, belonging to a new structure type crystallizes in a rhombohedral system with space group R3̅m (a = 4.0685(1) Å, c = 31.029(5) Å, V = 444.8(1) Å(3), Z = 1). The overall crystal structure consists of alternatively packed unique [Bi2O2] and [BiS2] layers along [001] which are combined with each other by van der Waals interaction. The phase purity of the product is confirmed by powder X-ray diffraction. XPS analyses indicate +3 for Bi and -2 for S atoms. The temperature dependence of resistivity ρ(T) indicates that the semiconducting sample follows the mechanisms of variable range hopping (VRH) and adiabatic small polaron hopping (SPH). The direct-transition band gap, Eg = 1.27 eV derived from optical absorption spectrum, falls in the optimal region of solar absorber materials. Accordingly, the photoelectric measurement demonstrates the potential for applications for photovoltaic devices. PMID:26016620

  13. Comprehensive insights into the charge dynamics process and excellent photoelectric properties of heterojunction solar cells.

    PubMed

    Liu, Xiangyang; Wang, Shun; Zheng, Haiwu; Cheng, Xiuying; Gu, Yuzong

    2016-09-21

    Zn2SnO4 octahedron nanoparticles/Cu4Bi4S9 (ZTO/CBS) and ZTO octahedron nanoparticles/CBS-graphene nanoplatelets (ZTO/CBS-GNs), as well as two types of bulk heterojunction (BHJ) solar cells with high flexibility were prepared on stainless steel meshes (SSMs). The improved photovoltaic responses of CBS-GNs and ZTO/CBS-GNs with the incorporation of graphene nanoplatelets were determined using surface photovoltage spectroscopy (SPS). The signals of time-resolved fluorescence response (TFR) and transient surface photovoltage (TPV) can provide more detailed information on the transition, separation and transport of photogenerated carriers. Here, the ZTO/CBS-GNs cell exhibits a superior performance and the highest efficiency is 8.6%. The multichannel separation process from the TPV signals indicates that the macro-photoelectric signals can be attributed to photogenerated charges separated at the interface of CBS/GNs, rather than CBS/ZTO. The comprehensive signals of SPS, TFR and TPV not only provide insights into the transition, separation and shifting of photogenerated carriers, but also promote the exploration of charge dynamics from the picosecond to second range. Importantly, the BHJ flexible solar cells with excellent efficiency and facile, scalable production present significant potential for practical application. PMID:27531035

  14. Comprehensive Insights into Charge Dynamics and Improved Photoelectric Properties of Well-Designed Solar Cells.

    PubMed

    Liu, Xiangyang; Wang, Shun; Zheng, Haiwu; Cheng, Xiuying; Gu, Yuzong

    2016-08-17

    Here, Zn2SnO4 nanorods/Cu4Bi4S9 (ZTO/CBS) and ZTO nanorods/CBS-graphene nanosheets (ZTO/CBS-GNs), as well as two types of bulk heterojunction (BHJ) solar cells with high flexibility were fabricated on stainless steel meshes (SSMs). The excellent photovoltaic responses of CBS-GNs and ZTO/CBS-GNs with incorporation of GNs were determined using surface photovoltage spectroscopy (SPS). The signals of time-resolved fluorescence response (TFR) and transient surface photovoltage (TPV) can provide more detailed information for transition, separation, and transport of photoinduced carriers. Besides, the ZTO nanorods/CBS-GNs cell exhibits the superior performance and the highest efficiency is 11.2%. The multichannel separation process from the TPVs indicates that the macro-photoelectric signals can be attributed to the photogenerated charges separated at the interface of CBS/GNs, rather than CBS/ZTO. The multi-interfacial recombination is the major carrier loss with electrical impedance spectroscopy (EIS) and the hole selective NiO can efficiently accelerate the charge extraction to the external circuit. The comprehensive signals of SPS, EIS, TFR, and TPV provide insights into transition, separation, recombination and shifting of carriers. Importantly, the BHJ flexible solar cells with high efficiency and facile, scalable production present a potential for application. PMID:27455131

  15. Photoelectrical Stimulation of Neuronal Cells by an Organic Semiconductor-Electrolyte Interface.

    PubMed

    Abdullaeva, Oliya S; Schulz, Matthias; Balzer, Frank; Parisi, Jürgen; Lützen, Arne; Dedek, Karin; Schiek, Manuela

    2016-08-23

    As a step toward the realization of neuroprosthetics for vision restoration, we follow an electrophysiological patch-clamp approach to study the fundamental photoelectrical stimulation mechanism of neuronal model cells by an organic semiconductor-electrolyte interface. Our photoactive layer consisting of an anilino-squaraine donor blended with a fullerene acceptor is supporting the growth of the neuronal model cell line (N2A cells) without an adhesion layer on it and is not impairing cell viability. The transient photocurrent signal upon illumination from the semiconductor-electrolyte layer is able to trigger a passive response of the neuronal cells under physiological conditions via a capacitive coupling mechanism. We study the dynamics of the capacitive transmembrane currents by patch-clamp recordings and compare them to the dynamics of the photocurrent signal and its spectral responsivity. Furthermore, we characterize the morphology of the semiconductor-electrolyte interface by atomic force microscopy and study the stability of the interface in dark and under illuminated conditions. PMID:27480642

  16. Some aspects of selection of impurities improving photoelectric characteristics of chalcogenide vitreous semiconductors

    SciTech Connect

    Burdiyan, I. I.; Cosiuc, V. V. Pynzar', R. A.

    2008-02-15

    The effect of low concentrations of two groups of doping impurities (one group includes Sn, Pb, Dy, Ho, Y and the other group includes In, Cs, and Al) on photoelectric properties of As{sub 2}Se{sub 3} and (As{sub 2}S{sub 3}){sub 0.3}(As{sub 2}Se{sub 3}){sub 0.7} was investigated. Studies of spectral distributions of photoconductivity and optical absorption showed that there is a distinct increase in photoconductivity if the level of doping with elements of the first group is as high as 0.015%. Elements of the second group of impurities did not exert any significant effect on photoconductivity. The effect of impurities of the first group is attributed to occupation of vacant sites (formed as a result of removal of highly volatile Se and S atoms) by low concentrations of impurity atoms. The observed effect is related to the fact that substitutional atoms can preserve covalent bonds and to the small difference between atomic sizes and electron affinity for doping impurities and S and Se. Atoms of the second group of impurities lack these features.

  17. Validation of Cross Sections for Monte Carlo Simulation of the Photoelectric Effect

    NASA Astrophysics Data System (ADS)

    Han, Min Cheol; Kim, Han Sung; Pia, Maria Grazia; Basaglia, Tullio; Batic, Matej; Hoff, Gabriela; Kim, Chan Hyeong; Saracco, Paolo

    2016-04-01

    Several total and partial photoionization cross section calculations, based on both theoretical and empirical approaches, are quantitatively evaluated with statistical analyses using a large collection of experimental data retrieved from the literature to identify the state of the art for modeling the photoelectric effect in Monte Carlo particle transport. Some of the examined cross section models are available in general purpose Monte Carlo systems, while others have been implemented and subjected to validation tests for the first time to estimate whether they could improve the accuracy of particle transport codes. The validation process identifies Scofield's 1973 non-relativistic calculations, tabulated in the Evaluated Photon Data Library(EPDL), as the one best reproducing experimental measurements of total cross sections. Specialized total cross section models, some of which derive from more recent calculations, do not provide significant improvements. Scofield's non-relativistic calculations are not surpassed regarding the compatibility with experiment of K and L shell photoionization cross sections either, although in a few test cases Ebel's parameterization produces more accurate results close to absorption edges. Modifications to Biggs and Lighthill's parameterization implemented in Geant4 significantly reduce the accuracy of total cross sections at low energies with respect to its original formulation. The scarcity of suitable experimental data hinders a similar extensive analysis for the simulation of the photoelectron angular distribution, which is limited to a qualitative appraisal.

  18. PHOTOELECTRIC CROSS-SECTIONS OF GAS AND DUST IN PROTOPLANETARY DISKS

    SciTech Connect

    Bethell, T. J.; Bergin, Edwin A.

    2011-10-10

    We provide simple polynomial fits to the X-ray photoelectric cross-sections (0.03 keV < E < 10 keV) for mixtures of gas and dust found in protoplanetary disks. Using the solar elemental abundances of Asplund et al., we treat the gas and dust components separately, facilitating the further exploration of evolutionary processes such as grain settling and gain growth. We find that blanketing due to advanced grain growth (a{sub max} > 1 {mu}m) can reduce the X-ray opacity of dust appreciably at E{sub X} {approx} 1 keV, coincident with the peak of typical T Tauri X-ray spectra. However, the reduction of dust opacity by dust settling, which is known to occur in protoplanetary disks, is probably a more significant effect. The absorption of 1-10 keV X-rays is dominated by gas opacity once the dust abundance has been reduced to about 1% of its diffuse interstellar value. The gas disk establishes a floor to the opacity at which point X-ray transport becomes insensitive to further dust evolution. Our choice of fitting function follows that of Morrison and McCammon, providing a degree of backward compatibility.

  19. Photochemical charges separation and photoelectric properties of flexible solar cells with two types of heterostructures

    NASA Astrophysics Data System (ADS)

    Liu, Xiangyang; Wang, Shun; Zheng, Haiwu; Cheng, Xiuying; Gu, Yuzong

    2015-12-01

    Photochemical charges generation, separation, and transport at nanocrystal interfaces are central to energy conversion for solar cells. Here, Zn2SnO4 nanowires/Cu4Bi4S9 (ZTO/CBS), ZTO nanowires/CBS-reduced graphene oxide (ZTO/CBS-RGO), and bulk heterojunction (BHJ) solar cells were measured. The signals of steady state and electric field-induced surface photovoltage indicate that RGO with high electron mobility can evidently improve the photovoltaic response. Besides, ZTO/CBS and ZTO/CBS-RGO cells exhibit the excellent performance and the highest efficiencies of 1.2% and 2.8%, respectively. The internal relations of photoelectric properties to some factors, such as film thickness, direct paths, RGO conductive network, energy level matching, etc., were discussed in detail. Qualitative and quantitative analyses further verified the comprehensive effect of RGO and other factors. Importantly, the fine bendable characteristic of BHJ solar cells with excellent efficiency and facile, scalable production gives the as-made flexible solar cells device potential for practical application in future.

  20. Photoelectric return-stroke velocity and peak current estimates in natural and triggered lightning

    NASA Technical Reports Server (NTRS)

    Mach, Douglas M.; Rust, W. David

    1989-01-01

    Two-dimensional photoelectric return stroke velocities from 130 strokes are presented, including 86 negative natural, 41 negative triggered, one positive triggered, and two positive natural return strokes. For strokes starting near the ground and exceeding 500 m in length, the average velocity is 1.3 + or - 0.3 X 10 to the 8th m/s for natural return strokes and 1.2 + or - 0.3 X 10 to the 8th m/s for triggered return strokes. For strokes with lengths less than 500 m, the average velocities are slightly higher. Using the transmission line model (TLM), the shortest segment one-dimensional return stroke velocity, and either the maximum or plateau electric field, it is shown that natural strokes have a peak current distribution that is lognormal with a median value of 16 kA (maximum E) or 12 kA (plateau E). Triggered lightning has a medium peak current value of 21 kA (maximum E) or 15 kA (plateau E). Correlations are found between TLM peak currents and velocities for triggered and natural subsequent return strokes, but not between TLM peak currents and natural first return stroke velocities.