Journal articles: 'Photometry, astronomical'

1

Prokhorov, M. E., A. I. Zakharov, V. G. Moshkalev, N. L. Krusanova, and M. S. Tuchin. "Mass Computations of the Brightness of Stars in an Arbitrary Spectral Band." Астрономический журнал 100, no. 6 (June 1, 2023): 500–511. http://dx.doi.org/10.31857/s0004629923050092.

Full text

Abstract:

The problem of calculating the brightness of an array of stars in an arbitrary photometric band, which is not the standard band of astronomical photometry, is considered from their multicolor photometry in some other photometric system. A similar problem is to transfer photometric measurements of stars from one multicolor photometric system to another. This task includes methods for calculating and comparing magnitudes, as well as merging photometric catalogs. The questions of choice of various zero-points of photometry and reduction of measurements for the atmosphere are considered. The issues of reducing the error of the proposed methods are discussed. The article is partly based on a report presented at the conference “Modern Stellar Astronomy-2022”, held at the Caucasian Mountain Observatory of the Sternberg State Astronomical Institute, Moscow State University, in November 8–10, 2022.

APA, Harvard, Vancouver, ISO, and other styles

2

Walker, Alistair, Saul Adelman, Eugene Milone, Barbara Anthony-Twarog, Pierre Bastien, Wen Ping Chen, Steve Howell, et al. "DIVISION B COMMISSION 25: ASTRONOMICAL PHOTOMETRY AND POLARIMETRY." Proceedings of the International Astronomical Union 11, T29A (August 2015): 159–70. http://dx.doi.org/10.1017/s1743921316000727.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

3

Howell, Steve B. "CCD Time-Series Photometry of Astronomical Sources." Symposium - International Astronomical Union 167 (1995): 167–72. http://dx.doi.org/10.1017/s0074180900056400.

Full text

Abstract:

CCDs are essentially the only instrument available today for photometry at most observatories; they are also becoming more readily available to amateurs as well. Thus, obtaining good photometric data with these two-dimensional devices is something we all need to understand. The history of and recent developments in CCD time-series photometry will be reviewed with some comments on future directions.

APA, Harvard, Vancouver, ISO, and other styles

4

Jiang, Shiyang. "The Large-Field Bright-Star High-Precision CCD Photometer of BAO." Symposium - International Astronomical Union 167 (1995): 325–26. http://dx.doi.org/10.1017/s007418090005662x.

Full text

Abstract:

Time-series high-accuracy photometry is very important for research in stellar variability. For a long time photometry made by a photomultiplier was the only instrument for high precision stellar photometry. To overcome the atmospheric variation and instrumental problems, we must choose at least one stable star as a comparison star and move the telescope quickly between the targets. So the real efficiency is very low and one only can do it on photometric nights. To overcome this limitation, since 1989 we began to cooperate with the team of the STEPHI network. We used the Chevreton four-channel photometer which can observe the variable, two comparison stars and a chosen sky background simultaneously. The multi-channel photometer is much better than normal single channel photometer as we can see from the several STEPHI results. Now the very high quantum efficiency CCD becomes more and more popular, so we are trying to change to use CCDs. Here we give some general description of a large field high accuracy bright star CCD photometer being prepared for the Beijing Astronomical Observatory (BAO).

APA, Harvard, Vancouver, ISO, and other styles

5

Tinbergen, Jaap. "New Techniques." International Astronomical Union Colloquium 136 (1993): 130–46. http://dx.doi.org/10.1017/s025292110000748x.

Full text

Abstract:

AbstractRoutine millimagnitude photometry may require a new approach to reduction of photometric errors. Such an approach is outlined in this paper; it stresses elimination of each error as close to its source as possible. The possibilities provided by modern technology are reviewed in this light. An engineering design group dedicated to photometry is a prerequisite and an on-site photometric technician may be necessary. In this concept, observers are mainly remote users of a database. Implied is the idea of accurate photometry necessarily developing into a single but multi-site astronomical facility (cf. VLBI) and the communal discipline that goes with it.

APA, Harvard, Vancouver, ISO, and other styles

6

Warner, Brian. "Astronomy in South Africa." Highlights of Astronomy 10 (1995): 674–76. http://dx.doi.org/10.1017/s1539299600012545.

Full text

Abstract:

This note reviews those aspects of astronomy in South Africa that may be useful for the support of astronomical development on the rest of the African continent.Optical and infrared astronomy is largely consolidated at the Sutherland site of the South African Astronomical Observatory (SAAO), about 300 km from Cape Town. The administrative and technical headquarters of this institution occupy the buildings of the old Royal Observatory (founded in 1820) in Cape Town. In Cape Town there is a twin 18/24 inch (0.45/0.6m) refractor and an 18-inch (0.45m) photometric reflector still operational. At Sutherland the 74-inch (1.8m Radcliffe) reflector is equipped for spectroscopy, CCD imaging and IR photometry. Newtonian and coudé foci are available but rarely used. Also at Sutherland there are 40-inch, 30-inch and 20-inch telescopes (approx. 1m, 0.75m and 0.5m) used primarily for CCD imaging (40-inch), optical and infrared photometry (30-inch) and UVBRI standard photometry (20-inch). An automatic photoelectric telescope (30-inch aperture) is nearing completion. Observing conditions at Sutherland provide about 50% photometric time.

APA, Harvard, Vancouver, ISO, and other styles

7

Osborn, J., D. Föhring, V. S. Dhillon, and R. W. Wilson. "Atmospheric scintillation in astronomical photometry." Monthly Notices of the Royal Astronomical Society 452, no. 2 (July 16, 2015): 1707–16. http://dx.doi.org/10.1093/mnras/stv1400.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Hudson, Hugh S. "Astronomical photometry from the moon." Advances in Space Research 14, no. 6 (June 1994): 99–104. http://dx.doi.org/10.1016/0273-1177(94)90012-4.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Brennan, S. J., and M. Fraser. "The Automated Photometry of Transients pipeline (AutoPhOT)." Astronomy & Astrophysics 667 (November 2022): A62. http://dx.doi.org/10.1051/0004-6361/202243067.

Full text

Abstract:

We present the Automated Photometry of Transients (AutoPhOT) package, a novel automated pipeline that is designed for rapid, publication-quality photometry of astronomical transients. AutoPhOT is built from the ground up using Python 3 – with no dependencies on legacy software. Capabilities of AutoPhOT include aperture and point-spread-function photometry, template subtraction, and calculation of limiting magnitudes through artificial source injection. AutoPhOT is also capable of calibrating photometry against either survey catalogues, or using a custom set of local photometric standards, and is designed primarily for ground-based optical and infrared images. We show that both aperture and point-spread-function photometry from AutoPhOT is consistent with commonly used software, for example, DAOPHOT, and also demonstrate that AutoPhOT can reproduce published light curves for a selection of transients with minimal human intervention.

APA, Harvard, Vancouver, ISO, and other styles

10

Pagul, Amanda, F. Javier Sánchez, Iary Davidzon, Anton M. Koekemoer, Bahram Mobasher, Mathilde Jauzac, Charles L. Steinhardt, et al. "Self-consistent Combined HST, K-band, and Spitzer Photometric Catalogs of the BUFFALO Survey Fields." Astrophysical Journal Supplement Series 273, no. 1 (July 1, 2024): 10. http://dx.doi.org/10.3847/1538-4365/ad40a1.

Full text

Abstract:

Abstract This article presents new astronomical source catalogs using data from the BUFFALO Survey. These catalogs contain detailed information for over 100,000 astronomical sources in the six BUFFALO clusters: A370, A2744, AS1063, MACS 0416, MACS 0717, and MACS 1149 spanning a total of 240 arcmin2. The catalogs include positions and forced photometry measurements of these objects in the F275W, F336W, F435W, F606W, F814W, F105W, F125W, F140W, and F160W HST bands, Keck-NIRC2/VLT-HAWKI Ks band, and IRAC Channel 1 and 2 bands. Additionally, we include photometry measurements in the F475W, F625W, and F110W bands for A370. This catalog also includes photometric redshift estimates computed via template fitting using LePhare. When comparing to a spectroscopic reference, we obtain an outlier fraction of 8.6% and scatter, normalized median absolute deviation, of 0.059. The catalogs are publicly available for their use by the community (https://archive.stsci.edu/hlsp/buffalo/).

APA, Harvard, Vancouver, ISO, and other styles

11

Sterken, C., A. U. Landolt, M. Beaseli, M. Breger, I. Glass, J. Graham, H. Hensberge, et al. "Commission 25: Stellar Photometry and Polarimetry: (Photometrie et Polarimetrie Stellaire)." Transactions of the International Astronomical Union 24, no. 1 (2000): 328–35. http://dx.doi.org/10.1017/s0251107x00003278.

Full text

Abstract:

The work of Commission 25 covers a wide range of topics concerning the measurement of magnitude, colour and polarisation of astronomical objects. As such, the area of interest covers virtually every field of astrophysical research in the visual and infrared spectral domain. Our reports cover some aspects of photometry and polarimetry as a technique rather than being an account of research highlights over the last three years.

APA, Harvard, Vancouver, ISO, and other styles

12

Yuldoshev, Q., M. Muminov, V. Andruk, Sh Ehgamberdiev, and S. Turaev. "Test of the scanner for expression the astrometric and photometric parameters from the digitized plates." «Узбекский физический журнал» 24, no. 2 (June 7, 2022): 81–89. http://dx.doi.org/10.52304/.v24i2.324.

Full text

Abstract:

This paper performs to research in detail the Epson Expression 10000XL scanner for photographic astroplate archive of the Ulugh Beg Astronomical Institute (UBAI) of the Uzbekistan Academy of Sciences. For processing the astroplates, it is used special developed software in the LINUX/MIDAS/ROMAFOT. The test plate was digitized with grayscale 8 and 16 bits with various scanner resolutions. Astronomical and photometric parameters were carried out from the plate and an evaluation of the developed method accuracy for determining rectangular coordinates and photometry. The repeatability of astrometric and photometric errors of the scanner for the digitized resolutions, 6 successive scans of every plate with a spatial resolution 600, 900, 1200, 1500, 1800, 2100, 2400 and 2540 dpi were processed.

APA, Harvard, Vancouver, ISO, and other styles

13

Weiss, Werner W., Konstanze Zwintz, Rainer Kuschnig, Gerald Handler, Anthony F. J. Moffat, Dietrich Baade, Dominic M. Bowman, et al. "Space Photometry with Brite-Constellation." Universe 7, no. 6 (June 16, 2021): 199. http://dx.doi.org/10.3390/universe7060199.

Full text

Abstract:

BRITE-Constellation is devoted to high-precision optical photometric monitoring of bright stars, distributed all over the Milky Way, in red and/or blue passbands. Photometry from space avoids the turbulent and absorbing terrestrial atmosphere and allows for very long and continuous observing runs with high time resolution and thus provides the data necessary for understanding various processes inside stars (e.g., asteroseismology) and in their immediate environment. While the first astronomical observations from space focused on the spectral regions not accessible from the ground it soon became obvious around 1970 that avoiding the turbulent terrestrial atmosphere significantly improved the accuracy of photometry and satellites explicitly dedicated to high-quality photometry were launched. A perfect example is BRITE-Constellation, which is the result of a very successful cooperation between Austria, Canada and Poland. Research highlights for targets distributed nearly over the entire HRD are presented, but focus primarily on massive and hot stars.

APA, Harvard, Vancouver, ISO, and other styles

14

Campagnolo, Julio Cesar Neves. "ASTROPOP: the ASTROnomical POlarimetry and Photometry Pipeline." Publications of the Astronomical Society of the Pacific 131, no. 996 (December 13, 2018): 024501. http://dx.doi.org/10.1088/1538-3873/aaecc2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Weiler, Michael. "Revised Gaia Data Release 2 passbands." Astronomy & Astrophysics 617 (September 2018): A138. http://dx.doi.org/10.1051/0004-6361/201833462.

Full text

Abstract:

Context. The European Space Agency mission Gaia has published, with its second data release (DR2), a catalogue of photometric measurements for more than 1.3 billion astronomical objects in three passbands. The precision of the measurements in these passbands, denoted G, GBP, and GRP, reach down to the milli-magnitude level. The scientific exploitation of this data set requires precise knowledge of the response curves of the three passbands. Aims. This work aims to improve the exploitation of the photometric data by deriving an improved set of response curves for the three passbands, allowing for an accurate computation of synthetic Gaia photometry. Methods. This is achieved by formulating the problem of passband determination in a functional analytic formalism, and linking the photometric measurements with four observational, one empirical, and one theoretical spectral library. Results. We present response curves for G, GBP, and GRP that differ from the previously published curves, and which provide a better agreement between synthetic Gaia photometry and Gaia observations.

APA, Harvard, Vancouver, ISO, and other styles

16

Drlica-Wagner, A., P. S. Ferguson, M. Adamów, M. Aguena, S. Allam, F. Andrade-Oliveira, D. Bacon, et al. "The DECam Local Volume Exploration Survey Data Release 2." Astrophysical Journal Supplement Series 261, no. 2 (August 1, 2022): 38. http://dx.doi.org/10.3847/1538-4365/ac78eb.

Full text

Abstract:

Abstract We present the second public data release (DR2) from the DECam Local Volume Exploration survey (DELVE). DELVE DR2 combines new DECam observations with archival DECam data from the Dark Energy Survey, the DECam Legacy Survey, and other DECam community programs. DELVE DR2 consists of ∼160,000 exposures that cover >21,000 deg2 of the high-Galactic-latitude (∣b∣ > 10°) sky in four broadband optical/near-infrared filters (g, r, i, z). DELVE DR2 provides point-source and automatic aperture photometry for ∼2.5 billion astronomical sources with a median 5σ point-source depth of g = 24.3, r = 23.9, i = 23.5, and z = 22.8 mag. A region of ∼17,000 deg2 has been imaged in all four filters, providing four-band photometric measurements for ∼618 million astronomical sources. DELVE DR2 covers more than 4 times the area of the previous DELVE data release and contains roughly 5 times as many astronomical objects. DELVE DR2 is publicly available via the NOIRLab Astro Data Lab science platform.

APA, Harvard, Vancouver, ISO, and other styles

17

Landolt, A. U., P. Martinez, P. Bastien, S. Fabrika, R. Gilliland, F. Grundahl, C. Jordi, and U. Munari. "Commission 25: Stellar Photometry and Polarimetry." Proceedings of the International Astronomical Union 1, T26A (December 2005): 307–12. http://dx.doi.org/10.1017/s1743921306004753.

Full text

Abstract:

AbstractEven a brief glance at astronomical journals indicates the breadth and depth of observational projects making use of photometric and polarimetric techniques. Examples of ongoing photometric and polarimetric research as related by Commission Members follows. I thank the Commission Members, acknowledged below, for their input.

APA, Harvard, Vancouver, ISO, and other styles

18

Ricci, D., M. Reyes-Ruiz, R. Michel, C. Ayala-Loera, G. Ramón-Fox, L. Fox Machado, S. Navarro-Meza, S. Brown Sevilla, and S. Curiel. "Transit observations with the three San Pedro Mártir telescopes." Proceedings of the International Astronomical Union 9, S310 (July 2014): 101–3. http://dx.doi.org/10.1017/s1743921314007972.

Full text

Abstract:

AbstractExoplanetary transit observations were carried out for the first time with all the three telescopes at the San Pedro Mártir National Astronomical Observatory in Baja California, Mexico.We present preliminary results on WASP-39 and WASP-43, two Hot Jupiters known for the presence of a highly-inflated radius. Using the defocused photometry technique, we observed these systems, achieving photometric precision of ± 3–5mmag peak-to-valley. The preliminary fit of their lightcurves shows physical and orbital parameters consistent with published results.

APA, Harvard, Vancouver, ISO, and other styles

19

Bates, Brian, David R. Halliwell, Samuel McNoble, Yingcai Li, and Martin Catney. "Acoustooptic filters for astronomical photometry: design and fabrication." Applied Optics 26, no. 22 (November 15, 1987): 4783. http://dx.doi.org/10.1364/ao.26.004783.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Howell, Steve B. "CCD Time-Series Photometry of Faint Astronomical Sources." International Astronomical Union Colloquium 136 (1993): 318–24. http://dx.doi.org/10.1017/s0252921100007715.

Full text

Abstract:

AbstractUsing CCDs to obtain time-series light curve information is an increasing area of interest in astronomy. For brighter, high signal-to-noise sources, the data collection and reduction procedures are very robust and easy to use. However, for fainter, low signal-to-noise objects we must resort to new methods. These include the use of optimum data extraction techniques, a fuller understanding of the CCD itself, and a more complete error model. This paper will provide a brief introduction to CCD time-series photometry and then explore the above new methods in relation to real observational situations.

APA, Harvard, Vancouver, ISO, and other styles

21

Kisley, Marina, Yu-Jing Qin, Ann Zabludoff, Kobus Barnard, and Chia-Lin Ko. "Classifying Astronomical Transients Using Only Host Galaxy Photometry." Astrophysical Journal 942, no. 1 (January 1, 2023): 29. http://dx.doi.org/10.3847/1538-4357/aca532.

Full text

Abstract:

Abstract The Legacy Survey of Space and Time (LSST) at the Vera C. Rubin Observatory will discover tens of thousands of extragalactic transients each night. The high volume of alerts demands immediate classification of transient types in order to prioritize observational follow-ups before events fade away. We use host galaxy features to classify transients, thereby providing classification upon discovery. In contrast to past work that focused on distinguishing Type Ia and core-collapse supernovae (SNe) using host galaxy features that are not always accessible (e.g., morphology), we determine the relative likelihood across 12 transient classes based on only 19 host apparent magnitudes and colors from 10 optical and IR photometric bands. We develop both binary and multiclass classifiers, using kernel density estimation to estimate the underlying distribution of host galaxy properties for each transient class. Even in this pilot study, and ignoring relative differences in transient class frequencies, we distinguish eight transient classes at purities significantly above the 8.3% baseline (based on a classifier that assigns labels uniformly and at random): tidal disruption events (TDEs; 48% ± 27%, where ± indicates the 95% confidence limit), SNe Ia-91bg (32% ± 18%), SNe Ia-91T (23% ± 11%), SNe Ib (23% ± 13%), SNe II (17% ± 2%), SNe IIn (17% ± 6%), SNe II P (16% ± 4%), and SNe Ia (10% ± 1%). We demonstrate that our model is applicable to LSST and estimate that our approach can accurately classify 59% of LSST alerts expected each year for SNe Ia, Ia-91bg, II, Ibc, SLSN-I, and TDEs. Our code and data set are publicly available.

APA, Harvard, Vancouver, ISO, and other styles

22

Lattis, Anthony. "Constructing the Electric Eye: Situating the Smithsonian National Air and Space Museum’s Wisconsin Collection of Photoelectric Detectors in Historical Context." Journal for the History of Astronomy 51, no. 4 (November 2020): 423–60. http://dx.doi.org/10.1177/0021828620942409.

Full text

Abstract:

Between 2017 and 2019, the Smithsonian National Air and Space Museum acquired a collection of photoelectric tubes used in the earliest program of astronomical photoelectric photometry at the University of Wisconsin. The Wisconsin Collection of Photoelectric Detectors represents a unique look inside the development of a pioneering research project and a fledgling technology. The process by which techniques and technologies related to photoelectric photometry developed in the early twentieth century involved a variety of academic disciplines and commercial actors, and this process is reflected in the variety and specific features of the tubes in the collection. This paper attempts to situate the Wisconsin Collection within the wider development of photoelectric tubes as a technology, the development of observation techniques at Wisconsin, and their contributions to astronomical knowledge.

APA, Harvard, Vancouver, ISO, and other styles

23

Vovchyk, Jeva, Jaroslav Blagodyr, and Olexandr Logvinenko. "Observations of Artificial Space Objects in Lviv Astronomical Observatory." Symposium - International Astronomical Union 196 (2001): 193–95. http://dx.doi.org/10.1017/s0074180900164101.

Full text

Abstract:

Space debris is the price which humankind must pay for entering space. And as this debris is dangerous in different ways, there must be ways to identify, catalogue, and predict the positions of, these cosmic bodies. That is why it is necessary to observe all artificial cosmic objects that are in space. One way of observing debris is by photometry. Photometric observations give light-curves from which one may deduce information about the position in space, the form, size, and other parameters of the object. Since 1975 a research group at Lviv Astronomical Observatory has been working at the problem of recording light-curves of different artificial cosmic objects. Four electrophotometers were constructed and developed. Many light curves of different artificial objects were measured with these electrophotometers. All light curves are collected in the local computer data bank and are available for use by anybody who needs such information.

APA, Harvard, Vancouver, ISO, and other styles

24

Sterken, Christiaan. "IAU Commission 25, and the development of early photometric systems." Proceedings of the International Astronomical Union 13, S349 (December 2018): 357–73. http://dx.doi.org/10.1017/s1743921319000486.

Full text

Abstract:

AbstractThe International Astronomical Union was conceived in 1918, and was formed one year later in Brussels. One of the 32 initial Commissions was the Committee on Stellar Photometry that later on became IAU Commission 25 Astronomical Photometry and Polarimetry, and since 2015 Commission B6 with the same name. The initial functions to be exercised by the Committee were (a)to advise in the matter of notation, nomenclature, definitions, conventions, etc., and(b)to plan and execute investigations requiring the cooperation of several observers or institutions.The basic philosophy was that IAU Commission 25 was to be an advisory body, rather than a decision-making committee that imposes its regulations. This position was reconfirmed at the 10th IAU General Assembly in 1958.From the early days on, the Commission members engaged in the teaching of the principles of photometric measurement – either via the Commission meetings and the ensuing reports, or via external means, such as lectures and publications. The topics of instruction dealt with absorption of light in the atmosphere, the modification imposed by the character of the receiving apparatus, the unequal response of different receivers to a same stimulus, and variations in the data-recorder response from one experiment to another.From the 1930s on it was suggested that IAU Commission 25 takes responsibility in matters of standard stars, standard filters and standard calibration methods.During the first half-century since its foundation, Commission 25 was an active forum for discussions on the basic principles of astronomical photometry, including the associated problems of transformability of magnitudes and colour indices from one instrumental configuration to another. During the second half-century of its existence, the Commission has served as a sort of news agency reporting on the developments in detector engineering, filter technology and data reduction. All along the Commission members were committed to accuracy and precision, a struggle that was primarily driven by the jumps forward in performance and sensitivity of every new detector that was introduced.The development over one century shows that the Commission was continuously touching on the philosophy of precise measurement, where accurate measuring – for a select group of pioneers – was an end in itself.This presentation looks back on the opinions of key players in the photometric standardisation debate, and briefly presents two case studies that illustrate the illusionary accuracy reached over a century in determining, as Commission member Ralph Allan Sampson put it, “a detail like magnitude”.

APA, Harvard, Vancouver, ISO, and other styles

25

Zhi, Hui, Xiaojun Jiang, and Jianfeng Wang. "Multicolour photometry of LEO mega-constellations Starlink and OneWeb." Monthly Notices of the Royal Astronomical Society 530, no. 4 (May 6, 2024): 5006–15. http://dx.doi.org/10.1093/mnras/stae693.

Full text

Abstract:

ABSTRACT The development of low earth orbit (LEO) mega-constellation fundamentally threatens ground-based optical astronomical observations. To study the photometric properties of the LEO mega-constellations, we used the Xinglong 50 cm telescope to conduct a large-sample, high-precision, and multicolour target-tracking photometry of two typical LEO mega-constellations: Starlink and OneWeb. Over a three-month observation period starting on 2022 January 1, we collected 1447 light curves of 404 satellites in four typical versions: Starlink v1.0, DarkSat, VisorSat, Starlink v1.5, and OneWeb. According to data statistics, Starlink v1.0 has the smallest median magnitude at clear and Sloan Digital Sky Survey gri band, and OneWeb is the dimmest bus. The brightness of Starlink v1.5 is slightly brighter than VisorSat. We construct a detailed photometric model with solar phase angle variations by calculating the illumination-visibility geometry based on the orbital parameters. Our data analysis shows that the solar phase angle is the significant characteristic which influencing Starlink satellites’ brightness, but it is not sensitive to OneWeb satellites. VisorSat and Starlink v1.5 versions, which are equipped with deployable visors, have significantly reduced scattered light compared to the previous Starlink v1.0 version. The multiband LOWESS and colour index are analysed in characterizing the energy and colour features of LEO mega-constellation satellites. This work found that the proportion of scattered sunlight mitigation achieved with VisorSat and Starlink v1.5 was 55.1 and 40.4 per cent, respectively. The colour index of different buses shows an evident clustering feature. Our observation and analysis could provide valuable quantitative data and photometric models, which can contribute to assessing the impact of LEO mega-constellations on astronomical observations.

APA, Harvard, Vancouver, ISO, and other styles

26

Arkhipova, V. P., A. V. Zasov, R. I. Noskova, and O. K. Silchenko. "Nests of Interacting Galaxies: What is It?" Symposium - International Astronomical Union 121 (1987): 579–86. http://dx.doi.org/10.1017/s0074180900155627.

Full text

Abstract:

Kinematical and photometric studies of nests of interacting galaxies are described. Velocity fields of 22 nests were obtained using the 6-meter telescope of the Special Astronomical Observatory of Sciences Academy of USSR. UBV-photometry carried out with 125-cm telescope of Sternberg Institute has shown that the majority of nests is blue and undergoes intense star formation. Nests are found to be of different types:among them there are single SB and dwarf Irr galaxies with super-giant HII -regions as well as tight pairs and multiple systems of galaxies. Multiple systems classified as nests are shown to be dynamically stable.

APA, Harvard, Vancouver, ISO, and other styles

27

Markov, Harry, Zlatan Tsvetanov, Ilian Iliev, Ivanka Stateva, and Nevena Markova. "Characterizing New Eclipsing Binaries Identified from STEREO Photometry." Proceedings of the International Astronomical Union 7, S282 (July 2011): 335–36. http://dx.doi.org/10.1017/s1743921311027785.

Full text

Abstract:

AbstractSince 2010, a program to explore new eclipsing binary systems identified from STEREO photometry has been in progress. Our first results are presented here: light curves and high resolution spectra taken with Coudé spectrograph (National Astronomical Observatory Rozhen) and ARC Échelle spectrometer (ARCES, Apache Point Observatory).

APA, Harvard, Vancouver, ISO, and other styles

28

Merlin, E., S. Pilo, A. Fontana, M. Castellano, D. Paris, V. Roscani, P. Santini, and M. Torelli. "A-PHOT: a new, versatile code for precision aperture photometry." Astronomy & Astrophysics 622 (February 2019): A169. http://dx.doi.org/10.1051/0004-6361/201833991.

Full text

Abstract:

Aims. We present A-PHOT, a new publicly available code for performing aperture photometry on astronomical images, that is particularly well suited for multi-band extragalactic surveys. Methods.A-PHOT estimates the fluxes emitted by astronomical objects within a chosen set of circular or elliptical apertures. Unlike other widely used codes, it runs on predefined lists of detected sources, allowing for repeated measurements on the same list of objects on different images. This can be very useful when forced photometric measurement on a given position is needed. A-PHOT can also estimate morphological parameters and a local background flux, and compute on-the-fly individual optimized elliptical apertures, in which the signal-to-noise ratio is maximized. Results. We check the performance of A-PHOT on both synthetic and real test datasets: we explore a simulated case of a space-based high-resolution imaging dataset, investigating the input parameter space to optimize the accuracy of the performance, and we exploit the CANDELS GOODS-South data to compare the A-PHOT measurements with those from the survey legacy catalogs, finding good agreement overall. Conclusions.A-PHOT proves to a useful and versatile tool for quickly extracting robust and accurate photometric measurements and basic morphological information of galaxies and stars, with the advantage of allowing for various measurements of fluxes at any chosen position without the need of a full detection run, and for determining the basic morphological features of the sources.

APA, Harvard, Vancouver, ISO, and other styles

29

Ball, Bill, and Gordon Bromage. "New EUV Selected Flare Stars." International Astronomical Union Colloquium 151 (1995): 67–68. http://dx.doi.org/10.1017/s0252921100034618.

Full text

Abstract:

The ROSAT Wide Field Camera all-sky EUV survey of 1990-91 identified over 200 active late-type stars (Pounds et al. 1993). Most of these were not known to be active prior to the survey and follow-up optical spectroscopy has been successful in selecting the most active dMe stars. These stars are characterized by their Balmer line emission which is direct evidence for an active chromosphere. We present photometric monitoring data for 4 new dMe stars, including the discovery of flaring activity on all 4 stars.The observations were made at the South African Astronomical Observatory at Sutherland near Capetown in October 1994, using the 0.5m and 1.9m telescopes for photometry and spectrometry, respectively. The 0.5m telescope is equipped with an automated, pulse-counting photometer. Flare monitoring of all the stars was done in the U-band with either 5 or 10 s integration times. All the stars monitored were between magnitude V = 11 and 13. A total of 15 flares were detected, including at least one on each star (Table 1). Comparison stars were measured in standard UBVRI photometric bands for each star.

APA, Harvard, Vancouver, ISO, and other styles

30

Agar, Jon, and J. B. Hearnshaw. "The Measurement of Starlight: Two Centuries of Astronomical Photometry." Technology and Culture 39, no. 4 (October 1998): 764. http://dx.doi.org/10.2307/1215853.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

D., Bhavana, S. Vig, S. K. Ghosh, and Rama Krishna Sai S. Gorthi. "A classifier to detect elusive astronomical objects through photometry." Monthly Notices of the Royal Astronomical Society 488, no. 2 (July 3, 2019): 2263–74. http://dx.doi.org/10.1093/mnras/stz1823.

Full text

Abstract:

ABSTRACT The application of machine learning principles in the photometric search of elusive astronomical objects has been a less-explored frontier of research. Here, we have used three methods, the neural network and two variants of k-nearest neighbour, to identify brown dwarf candidates using the photometric colours of known brown dwarfs. We initially check the efficiencies of these three classification techniques, both individually and collectively, on known objects. This is followed by their application to three regions in the sky, namely Hercules (2° × 2°), Serpens (9° × 4°), and Lyra (2° × 2°). Testing these algorithms on sets of objects that include known brown dwarfs show a high level of completeness. This includes the Hercules and Serpens regions where brown dwarfs have been detected. We use these methods to search and identify brown dwarf candidates towards the Lyra region. We infer that the collective method of classification, also known as ensemble classifier, is highly efficient in the identification of brown dwarf candidates.

APA, Harvard, Vancouver, ISO, and other styles

32

Ferradas-Alva, C., G. Ferrero, M. Huamán, W. Guevara-Day, E. Meza, J. Samanes, and P. Becerra. "Seeing measurement on Sasahuine mountain, Moquegua, Perú." Proceedings of the International Astronomical Union 7, S286 (October 2011): 448–51. http://dx.doi.org/10.1017/s174392131200525x.

Full text

Abstract:

AbstractOne of the greatest factors that significantly affect the quality of astronomical images is the atmospheric turbulence causing what we call “seeing”. We present results of the reduction and photometry of astronomical images obtained at the Sasahuine mountain astronomical site (4511 m.a.s.l.), located in the Southern Peruvian Andes, in the department of Moquegua, near the town of Cambrune. These data show preliminary seeing measurements for this site. The present work is part of a bigger investigation program called JANAX which seeks to evaluate potential astronomical observation sites in Peruvian territory through a series of observation missions. The program's aim is to gather data to validate the site for the future construction of a National Astronomical Observatory. The observations were made using an SBIG ST-7MX CCD camera and a BVR standard filter set, attached to a MEADE LX200 356mm telescope.

APA, Harvard, Vancouver, ISO, and other styles

33

Panov, K. P. "Long-Term Spot Photometry and Differential Rotation of the Spotted Flare Stars Ev Lac and by Dra." Symposium - International Astronomical Union 157 (1993): 157–59. http://dx.doi.org/10.1017/s0074180900174030.

Full text

Abstract:

Ev Lac = Gliese 873 (dM4.5e) is a well-known flare star with hydrogen Balmer lines as well as with Ca II lines in emission. Rotational modulation by starspots has been discovered by Pettersen (1980) who determined the photometric (rotational) period P = 4.378 d. Spot photometry of EV Lac was obtained with the 60 cm telescope of the Bulgarian National Astronomical Observatory in the years 1983–87 and 1989–91. For these years (except for 1989 and 1990) light curves are available in the V and B bands. From the BNAO-data and the data published by Pettersen (1980) a new ephemerishas been derived which shows a slight revision of the period.

APA, Harvard, Vancouver, ISO, and other styles

34

Polińska, M., K. Kamiński, W. Dimitrov, M. Fagas, W. Borczyk, T. Kwiatkowski, R. Baranowski, P. Bartczak, and A. Schwarzenberg–Czerny. "Global Astrophysical Telescope System – GATS." Proceedings of the International Astronomical Union 9, S301 (August 2013): 475–76. http://dx.doi.org/10.1017/s1743921313015123.

Full text

Abstract:

AbstractThe Global Astronomical Telescope System is a project managed by the Astronomical Observatory Institute of Adam Mickiewicz University in Poznań (Poland) and it is primarily intended for stellar medium/high resolution spectroscopy. The system will be operating as a global network of robotic telescopes. The GATS consists of two telescopes: PST 1 in Poland (near Poznań) and PST 2 in the USA (Arizona). The GATS project is also intended to cooperate with the BRITE satellites and supplement their photometry with spectroscopic observations.

APA, Harvard, Vancouver, ISO, and other styles

35

Weiler, M., C. Jordi, C. Fabricius, and J. M. Carrasco. "Passband reconstruction from photometry." Astronomy & Astrophysics 615 (July 2018): A24. http://dx.doi.org/10.1051/0004-6361/201732489.

Full text

Abstract:

Context. Based on an initial expectation from laboratory measurements or instrument simulations, photometric passbands are usually subject to refinements. These refinements use photometric observations of astronomical sources with known spectral energy distribution. Aims. This work investigates the methods for and limitations in determining passbands from photometric observations. A simple general formalism for passband determinations from photometric measurements is derived. The results are applied to the passbands of HIPPARCOS, Tycho, and Gaia DR1. Methods. The problem of passband determination is formulated in a basic functional analytic framework. For the solution of the resulting equations, functional principal component analysis is applied. Results. We find that, given a set of calibration sources, the passband can be described with respect to the set of calibration sources as the sum of two functions, one which is uniquely determined by the set of calibration sources, and one which is entirely unconstrained. The constrained components for the HIPPARCOS, Tycho, and Gaia DR1 passbands are determined, and the unconstrained components are estimated.

APA, Harvard, Vancouver, ISO, and other styles

36

Deng, Licai, Yu Xin, Xiaobin Zhang, Yan Li, Xiaojun Jiang, Guomin Wang, Kun Wang, Jilin Zhou, Zhengzhou Yan, and Zhiquan Luo. "SONG China project – participating in the global network." Proceedings of the International Astronomical Union 8, S288 (August 2012): 318–19. http://dx.doi.org/10.1017/s1743921312017115.

Full text

Abstract:

AbstractSONG (Stellar Observations Network Goup) is a low-cost ground based international collaboration aimed at two cutting edge problems in contemporary astrophysics in the time-domain: 1) Direct diagnostics of the internal structure of stars and 2) looking for and studying extra solar planets, possibly in the habitable zone. The general plan is to set up a network of 1m telescopes uniformly distributed in geographic latitude (in both hemispheres). China jointed the collaboration (initiated by Danish astronomers) at the very beginning. In addition to SONG's original plan (http://song.phys.au.dk), the Chinese team proposed a parallel photometry subnet work in the northern hemisphere, namely 50BiN (50cm Binocular Network, previously known as mini-SONG), to enable a large field photometric capability for the network, therefore maximising the potential of the network platform. The network will be able to produce nearly continuous time series observations of a number of selected objects with high resolution spectroscopy (SONG) and accurate photometry (50BiN), and to produce ultra-high accuracy photometry in dense field to look for micro-lensing events caused by planetary systems. This project has great synergy with Chinese Astronomical activities in Antarctica (Dome A), and other similar networks (e.g. LCOGT). The plan and current status of the project are overviewed in this poster.

APA, Harvard, Vancouver, ISO, and other styles

37

Bowman, Dominic M., and Daniel L. Holdsworth. "Adaptive elliptical aperture photometry: A software package for high-cadence ground-based photometry." Astronomy & Astrophysics 629 (August 28, 2019): A21. http://dx.doi.org/10.1051/0004-6361/201935640.

Full text

Abstract:

Context. Modern space telescopes are currently providing high-precision light curves for a large fraction of the sky, such that many new variable stars are being discovered. However, some stars have periodic variability with periods on the order of minutes and require high-cadence photometry to probe the physical mechanisms responsible. A cadence of less than a minute is often required to remove Nyquist ambiguities and confirm rapid variability, which forces observers to obtain high-cadence ground-based photometry. Aims. We aim to provide a modern software package to reduce ground-based photometric time series data and deliver optimised (differential) light curves. To produce high-quality light curves, which maximise the amplitude signal-to-noise ratio of short-period variability in a Fourier spectrum, we require adaptive elliptical aperture photometry as this represents a significant advantage compared to aperture photometry using circular apertures of fixed radii. Methods. The methodology of our code and its advantages are demonstrated using high-cadence ground-based photometry from the South African Astronomical Observatory (SAAO) of a confirmed rapidly oscillating Ap (roAp) star. Furthermore, we employed our software package to search for rapid oscillations in three candidate roAp stars. Results. We demonstrate that our pipeline represents a significant improvement in the quality of light curves, and we make it available to the community for use with different instruments and observatories. We search for and demonstrate the lack of high-frequency roAp pulsations to a limit of ∼1 mmag using B data in the three Ap stars HD 158596, HD 166542, and HD 181810. Conclusions. We demonstrate the significant improvement in the extraction of short-period variability caused by high-frequency pulsation modes, and discuss the implication of null detections in three Ap stars.

APA, Harvard, Vancouver, ISO, and other styles

38

Meade, Marilyn R. "A Second Catalog of [ITAL]ORBITING ASTRONOMICAL OBSERVATORY 2[/ITAL][ITAL]Orbiting Astronomical Observatory 2[/ITAL] Filter Photometry: Ultraviolet Photometry of 614 Stars." Astronomical Journal 118, no. 2 (August 1999): 1073–85. http://dx.doi.org/10.1086/300955.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Petrov, G., L. Slavcheva, R. Bachev, and B. Mihov. "Surface Photometry of Barred AGN Arakelian 564." Symposium - International Astronomical Union 194 (1999): 84–86. http://dx.doi.org/10.1017/s0074180900161790.

Full text

Abstract:

The Seyfert 1.5 galaxy Akn564 [1] is a well known X-ray active galactic nucleus (AGN) included in our list of selected barred AGN. The galaxy was observed during the August 1996 season at the 2-m RCC telescope of the Astronomical Observatory “Rozhen” of the Bulgarian Academy of Sciences. ST-6 with standard Schott V, R, I filters were used. MIDAS'96 package was used for the data reduction with teh Richter's expansion for the surface photometry [2]. Most of the basic data for the galaxy are shown in the Table 1 below.

APA, Harvard, Vancouver, ISO, and other styles

40

Toyozumi, Hiroyuki, and Michael C. B. Ashley. "Intra-Pixel Sensitivity Variation and Charge Transfer Inefficiency — Results of CCD Scans." Publications of the Astronomical Society of Australia 22, no. 3 (2005): 257–66. http://dx.doi.org/10.1071/as05013.

Full text

Abstract:

AbstractThe efficiency with which a charge-coupled device (CCD) detects photons depends, amongst other factors, on where within a pixel the photon hits. To explore this effect we have made detailed scans across a pixel for a front-illuminated three-phase EEV05-20 CCD using the standard astronomical B, V, R, and I colour filters. Pixel response functions and photometric sensitivity maps are derived from the scan images. Nonlinear charge transfer inefficiency (CTI) effects were observed and corrected for. The resulting images clearly show the intra-pixel sensitivity variations (IPSVs) due to the CCD electrode structure, and its dependence on wavelength. We briefly comment on the implications of IPSVs and CTI for high-precision photometry and astrometry.

APA, Harvard, Vancouver, ISO, and other styles

41

Agar, Jon. "The Measurement of Starlight: Two Centuries of Astronomical Photometry (review)." Technology and Culture 39, no. 4 (1998): 764–66. http://dx.doi.org/10.1353/tech.1998.0076.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Dick, J. S. B., and D. H. P. Jones. "A new data acquisition system for high-speed astronomical photometry." Journal of Physics E: Scientific Instruments 21, no. 9 (September 1988): 853–56. http://dx.doi.org/10.1088/0022-3735/21/9/007.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Tang, Z.-H., J.-H. Zhao, Y. Yu, and Z.-J. Shang. "Progress of the Chinese Plate-Digitizing Project." Proceedings of the International Astronomical Union 14, S339 (November 2017): 69–76. http://dx.doi.org/10.1017/s1743921318002259.

Full text

Abstract:

AbstractAbout 30,000 astronomical photographic plates were digitised between 2012–2017 with a special digitising machine that has high precision in both astrometry and photometry. All the images from the plates, together with plate information and measured coordinates of all the objects on the plates, have been stored in the Chinese Virtual Observatory.

APA, Harvard, Vancouver, ISO, and other styles

44

Markov, H. "Peculiarities of the Internal Photometrical Calibration Method Using Density Stellar Profiles." Symposium - International Astronomical Union 161 (1994): 309–10. http://dx.doi.org/10.1017/s0074180900047549.

Full text

Abstract:

On photographic plates taken for the purposes of classical stellar photometry (using a standard stellar sequence) there usually is no external photometrical calibration scale, neither a wedge nor spots; and hence the transition to relative intensity is a problem. The construction of a characteristic curve D(I) (hereafter CHC) by combining density profiles of several standard stars is a perfect solution of this task (Agnelli et al. 1979; de Vaucouleurs 1984). We have developed this method in order to obtain internal photometric calibrations for a large number of plates taken at the RC focus of the 2m telescope (F/8, scale 12.86) at the National Astronomical Observatory (NAO); these do not have any photometrical calibration. Our long term project provides UBV stellar photometry in the central regions of some globular clusters — M5, M10, M12, M56, M71, for which we have good collections of short exposure plates. The task also requires a background determination which can be done precisely only in relative intensities. We apply the method using Arp's UBV standard sequence in M5 globular cluster. In our investigation we demonstrate some peculiarities of the method:

APA, Harvard, Vancouver, ISO, and other styles

45

Walker, Alistair R. "CCD Photometry — Present and Future." Symposium - International Astronomical Union 167 (1995): 123–30. http://dx.doi.org/10.1017/s0074180900056369.

Full text

Abstract:

I will briefly treat some of the developments relating to CCD photometry which have taken place over the last two to three years, and speculate on those which can be anticipated to take place in the near future. CCDs have been in widespread use as astronomical detectors for slightly more than a decade. For the majority of visual-light projects they have displaced the photographic plate and the photomultiplier as the detector-of-choice, except in applications requiring large area coverage or high time resolution, but even here the development of arrays and the use of more sophisticated electronics has permitted encroachment into these domains. The use of large, low-noise detectors for CCD photometry places stringent demands on telescope optics, instruments, controllers, calibration procedures, data reduction methods and data storage, and forces a holistic approach to managing the data flow from detector to final storage medium.For an earlier review on this field see Walker (1993); other papers presented at IAU Colloquium No. 136 and IAU Symposium 167 (these proceedings) should be consulted for different topics, alternative viewpoints, and more in-depth discussions of specific subjects.

APA, Harvard, Vancouver, ISO, and other styles

46

Ambrosino, F., P. Cretaro, F. Meddi, C. Rossi, S. Sclavi, and I. Bruni. "The Latest Version of SiFAP: Beyond Microsecond Time Scale Photometry of Variable Objects." Journal of Astronomical Instrumentation 05, no. 03 (September 2016): 1650005. http://dx.doi.org/10.1142/s2251171716500057.

Full text

Abstract:

Technical improvements of the Silicon Fast optical Astronomical Photometer (SiFAP) allow the instrumentation to integrate photons coming from the target in time windows down to 20[Formula: see text]s. Further hardware improvement has been implemented to tag the Time of Arrival ([Formula: see text]) of each single photon. In addition, a new commercial GPS unit has replaced the older commercial unit improving time resolution. The latest version of SiFAP has been calibrated to check photometric sensitivity and linearity through observations of several standard stars. SiFAP has been also successfully tested by observing the HZ/Her X-1 Binary System estimating the spin period of the pulsar (Her X-1). Our results have been then compared to data available in literature.

APA, Harvard, Vancouver, ISO, and other styles

47

Sterken, Christiaan. "On the impact of an ultimate metrological reform in astronomical photometry." Vistas in Astronomy 35 (January 1992): 263–72. http://dx.doi.org/10.1016/0083-6656(92)90008-t.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Hagen-Thorn, V. A., and V. A. Yacovleva. "Polarimetric and Photometric Investigations of Lacertids." Symposium - International Astronomical Union 121 (1987): 325–27. http://dx.doi.org/10.1017/s0074180900155317.

Full text

Abstract:

At the Astronomical Observatory of Leningrad State University two observational programs of investigation of lacertids - photographic photometry and photoelectric polarimetry - are in progress for many years. Some results for OJ 287 and BL Lac are of interest: (1) existence of preferable direction of polarization, (2) correlations between the brightness and polarization parameters, and (3) high degree of polarization (~50%) of individual sources responsible for variability.

APA, Harvard, Vancouver, ISO, and other styles

49

Jockers, Klaus. "Astronomical Observations of Comets and the Io Torus Using Fabry-Perot-Interferometry." International Astronomical Union Colloquium 149 (1995): 182–87. http://dx.doi.org/10.1017/s0252921100022910.

Full text

Abstract:

AbstractFabry-Perot interferometers have been applied in a focal reducer to observe radiation from atoms and molecules in comets and in the Io torus. Tunable Fabry-Perot interferometers have been used as narrowband filters, and an etalon with fixed airgap in classical arrangement was employed for the measurement of Doppler shifts and for narrow-line photometry.

APA, Harvard, Vancouver, ISO, and other styles

50

Alcaino, Gonzalo, and William Liller. "The Ages of Globular Clusters Derived from BVRI CCD Photometry." Symposium - International Astronomical Union 126 (1988): 633–34. http://dx.doi.org/10.1017/s0074180900043400.

Full text

Abstract:

Main sequence photometry has been obtained in the BV system for at least 36 galactic globular clusters (Peterson 1986). One of the most important objectives for these continued researches by several astronomical groups has been that of determining the ages of globular clusters. During the past five years, a general consensus has emerged that the spread in age among the known galactic globular clusters could be as small as 1 billion years; Burstein (1985) suggests that the average age of these objects lies between 14 and 17 Gys.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Photometry, astronomical'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles