Articoli di riviste: "Photometric"

1

Evans, D. W., M. Riello, F. De Angeli, J. M. Carrasco, P. Montegriffo, C. Fabricius, C. Jordi et al. "Gaia Photometric Catalogue: the calibration of the DR2 photometry". Proceedings of the International Astronomical Union 14, A30 (agosto 2018): 466–70. http://dx.doi.org/10.1017/s174392131900512x.

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AbstractGaia DR2 was released in April 2018 and contains a photometric catalogue of more than 1 billion sources. This release contains colour information in the form of integrated BP and RP photometry in addition to the latest G-band photometry. The level of uncertainty can be as good as 2 mmag with some residual systematics at the 10 mmag level. The addition of colour information greatly enhances the value of the photometric data for the scientific community. A high level overview of the photometric processing, with a focus on the improvements with respect to Gaia DR1, was given. The definition of the Gaia photometric system, a crucial part of the calibration of the photometry, was also explained. Finally, some of the photometric improvements expected for the next data release were described.

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2

Wittman, D., P. Riechers e V. E. Margoniner. "Photometric Redshifts and Photometry Errors". Astrophysical Journal 671, n. 2 (16 novembre 2007): L109—L112. http://dx.doi.org/10.1086/525020.

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3

Fotopoulou, S., e S. Paltani. "CPz: Classification-aided photometric-redshift estimation". Astronomy & Astrophysics 619 (30 ottobre 2018): A14. http://dx.doi.org/10.1051/0004-6361/201730763.

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Broadband photometry offers a time and cost effective method to reconstruct the continuum emission of celestial objects. Thus, photometric redshift estimation has supported the scientific exploitation of extragalactic multiwavelength surveys for more than twenty years. Deep fields have been the backbone of galaxy evolution studies and have brought forward a collection of various approaches in determining photometric redshifts. In the era of precision cosmology, with the upcoming Euclid and LSST surveys, very tight constraints are put on the expected performance of photometric redshift estimation using broadband photometry, thus new methods have to be developed in order to reach the required performance. We present a novel automatic method of optimizing photometric redshift performance, the classification-aided photometric redshift estimation (CPz). The main feature of CPz is the unified treatment of all classes of objects detected in extragalactic surveys: galaxies of any type (passive, starforming and starbursts), active galactic nuclei (AGN), quasi-stellar objects (QSO), stars and also includes the identification of potential photometric redshift catastrophic outliers. The method operates in three stages. First, the photometric catalog is confronted with star, galaxy and QSO model templates by means of spectral energy distribution fitting. Second, three machine-learning classifiers are used to identify 1) the probability of each source to be a star, 2) the optimal photometric redshift model library set-up for each source and 3) the probability to be a photometric redshift catastrophic outlier. Lastly, the final sample is assembled by identifying the probability thresholds to be applied on the outcome of each of the three classifiers. Hence, with the final stage we can create a sample appropriate for a given science case, for example favoring purity over completeness. We apply our method to the near-infrared VISTA public surveys, matched with optical photometry from CFHTLS, KIDS and SDSS, mid-infrared WISE photometry and ultra-violet photometry from the Galaxy Evolution Explorer (GALEX). We show that CPz offers improved photometric redshift performance for both normal galaxies and AGN without the need for extra X-ray information.

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Li, Xiao Pan, Cheng Yang, Li Zhou e Hai Tao Yang. "Photometric Data Procession of the Swift/UVOT Instrument". Advanced Materials Research 989-994 (luglio 2014): 3489–92. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.3489.

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The Ultraviolet/Optical Telescope (UVOT) which is one of three scientific instruments onboard the NASA-led Swift satellite provides simultaneous ultraviolet and optical photometric data. We present the installing procedures of HEASoft software and the detailed method for using the HEASoft in UVOT photometric data processions. We focus on the application of photometry processes, and present the photometry of Quasar PKS 0537-441. The analysis of the photometric data shows that this source has extreme variations in optical and ultraviolet bands and the shape of photometric flux curves in each band is excellently in agreement with each other.

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5

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 (agosto 2015): 159–70. http://dx.doi.org/10.1017/s1743921316000727.

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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.

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Tedesco, Edward F. "Archiving Asteroid Photometric Data". Highlights of Astronomy 9 (1992): 719–20. http://dx.doi.org/10.1017/s1539299600010169.

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AbstractCurrent programs which produce asteroid photometric data range from astrometry through visual and near-infrared photometry and spectrophotometry to thermal infrared (8 to 30 micrometers) photometry. These data are published in a variety of places including observatory publications, IAU Circulars, the Minor Planet Circulars, and various journals.

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7

Rufener, F. "Passbands and Photometric Systems". Highlights of Astronomy 7 (1986): 813–17. http://dx.doi.org/10.1017/s1539299600007334.

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AbstractSynthetic photometry must be used to accurately define the passbands which characterize a photometric system. On the one hand, the colour indices of the stars must be coherent with their absolute spectrophotometry; on the other hand, direct comparisons of model atmospheres with observations must be carried out without resorting to arbitrary transformations. A systematic evaluation procedure could be applied to various photometric systems.

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Pforr, Janine. "The Spitzer Extragalactic Representative Volume Survey - measuring photometric redshifts for ∼4 million galaxies - challenges and ways forward". Proceedings of the International Astronomical Union 15, S341 (novembre 2019): 157–61. http://dx.doi.org/10.1017/s1743921319002412.

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AbstractWe highlight the challenges as well as lessons learnt in the derivation of the photometric redshifts for ∼4 million galaxies at 0 < z ≲ 6 contained in the Spitzer Extragalactic Representative Volume Survey (SERVS) and summarise the photometric redshift results recently published in Pforr et al. (2019). The inhomogeneous nature of the ancillary photometry for SERVS presents a similar situation to the one future, large, extragalactic surveys with e.g. LSST and JWST will face. We employ template SED-fitting to determine photometric redshifts. Our comparison of photometric redshifts to ∼75.000 public, spectroscopic redshifts results in an average σNMAD of ∼0.038 and outlier fraction of 3.7% for sources with the best photometric coverage. We find that photometric redshifts are determined most robustly when filter bands are numerous and cover a wide wavelength range. We highlight some possible improvements for the photometric redshifts in SERVS in the future.

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9

Bessell, Michael S. "Photometric Systems". International Astronomical Union Colloquium 136 (1993): 22–39. http://dx.doi.org/10.1017/s025292110000734x.

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AbstractMulticolour photometry has historically been carried out within a variety of standard systems. With the advent of new detectors with different wavelength sensitivities to those of the original system and the use of subsets of secondary standards, many subtle and not so subtle changes have occurred to the original systems. However, by reverse engineering, the passbands of the modified standard systems can be determined which enables good realisation of theoretical colours and better passband matching for CCD-based photometry. In this paper, the various photometric systems will be discussed and compared and strategies will be outlined for ensuring that precise relative photometry is maintained in the future, in particular from area detectors.

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10

Zhou, Rongpu, Michael C. Cooper, Jeffrey A. Newman, Matthew L. N. Ashby, James Aird, Christopher J. Conselice, Marc Davis et al. "Deep ugrizY imaging and DEEP2/3 spectroscopy: a photometric redshift testbed for LSST and public release of data from the DEEP3 Galaxy Redshift Survey". Monthly Notices of the Royal Astronomical Society 488, n. 4 (25 luglio 2019): 4565–84. http://dx.doi.org/10.1093/mnras/stz1866.

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ABSTRACT We present catalogues of calibrated photometry and spectroscopic redshifts in the Extended Groth Strip, intended for studies of photometric redshifts (photo-z’s). The data includes ugriz photometry from Canada–France–Hawaii Telescope Legacy Survey (CFHTLS) and Y-band photometry from the Subaru Suprime camera, as well as spectroscopic redshifts from the DEEP2, DEEP3, and 3D-HST surveys. These catalogues incorporate corrections to produce effectively matched-aperture photometry across all bands, based upon object size information available in the catalogue and Moffat profile point spread function fits. We test this catalogue with a simple machine learning-based photometric redshift algorithm based upon Random Forest regression, and find that the corrected aperture photometry leads to significant improvement in photo-z accuracy compared to the original SExtractor catalogues from CFHTLS and Subaru. The deep ugrizY photometry and spectroscopic redshifts are well suited for empirical tests of photometric redshift algorithms for LSST. The resulting catalogues are publicly available at http://d-scholarship.pitt.edu/36064/. We include a basic summary of the strategy of the DEEP3 Galaxy Redshift Survey to accompany the recent public release of DEEP3 data.

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11

Whitten, D. D., V. M. Placco, T. C. Beers, A. L. Chies-Santos, C. Bonatto, J. Varela, D. Cristóbal-Hornillos et al. "J-PLUS: Identification of low-metallicity stars with artificial neural networks using SPHINX". Astronomy & Astrophysics 622 (febbraio 2019): A182. http://dx.doi.org/10.1051/0004-6361/201833368.

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Context. We present a new methodology for the estimation of stellar atmospheric parameters from narrow- and intermediate-band photometry of the Javalambre Photometric Local Universe Survey (J-PLUS), and propose a method for target pre-selection of low-metallicity stars for follow-up spectroscopic studies. Photometric metallicity estimates for stars in the globular cluster M15 are determined using this method. Aims. By development of a neural-network-based photometry pipeline, we aim to produce estimates of effective temperature, Teff, and metallicity, [Fe/H], for a large subset of stars in the J-PLUS footprint. Methods. The Stellar Photometric Index Network Explorer, SPHINX, was developed to produce estimates of Teff and [Fe/H], after training on a combination of J-PLUS photometric inputs and synthetic magnitudes computed for medium-resolution (R ~ 2000) spectra of the Sloan Digital Sky Survey. This methodology was applied to J-PLUS photometry of the globular cluster M15. Results. Effective temperature estimates made with J-PLUS Early Data Release photometry exhibit low scatter, σ(Teff) = 91 K, over the temperature range 4500 < Teff (K) < 8500. For stars from the J-PLUS First Data Release with 4500 < Teff (K) < 6200, 85 ± 3% of stars known to have [Fe/H] < −2.0 are recovered by SPHINX. A mean metallicity of [Fe/H] = − 2.32 ± 0.01, with a residual spread of 0.3 dex, is determined for M15 using J-PLUS photometry of 664 likely cluster members. Conclusions. We confirm the performance of SPHINX within the ranges specified, and verify its utility as a stand-alone tool for photometric estimation of effective temperature and metallicity, and for pre-selection of metal-poor spectroscopic targets.

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Lee, Bomee, e Ranga-Ram Chary. "Improved photometric redshifts with colour-constrained galaxy templates for future wide-area surveys". Monthly Notices of the Royal Astronomical Society 497, n. 2 (17 luglio 2020): 1935–45. http://dx.doi.org/10.1093/mnras/staa2100.

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ABSTRACT Cosmology and galaxy evolution studies with LSST, Euclid, and Roman, will require accurate redshifts for the detected galaxies. In this study, we present improved photometric redshift estimates for galaxies using a template library that populates three-colour space and is constrained by HST/CANDELS photometry. For the training sample, we use a sample of galaxies having photometric redshifts that allows us to train on a large, unbiased galaxy sample having deep, unconfused photometry at optical-to-mid infrared wavelengths. Galaxies in the training sample are assigned to cubes in 3D colour space, V − H, I − J, and z − H. We then derive the best-fitting spectral energy distributions of the training sample at the fixed CANDELS median photometric redshifts to construct the new template library for each individual colour cube (i.e. colour-cube-based template library). We derive photometric redshifts (photo-z) of our target galaxies using our new colour-cube-based template library and with photometry in only a limited set of bands, as expected for the aforementioned surveys. As a result, our method yields σNMAD of 0.026 and an outlier fraction of 6 per cent using only photometry in the LSST and Euclid/Roman bands. This is an improvement of ∼10 per cent on σNMAD and a reduction in outlier fraction of ∼13 per cent compared to other techniques. In particular, we improve the photo-z precision by about 30 per cent at 2 < z < 3. We also assess photo-z improvements by including K or mid-infrared bands to the ugrizYJH photometry. Our colour-cube-based template library is a powerful tool to constrain photometric redshifts for future large surveys.

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Davies, L. J. M., J. E. Thorne, A. S. G. Robotham, S. Bellstedt, S. P. Driver, N. J. Adams, M. Bilicki et al. "Deep Extragalactic VIsible Legacy Survey (DEVILS): consistent multiwavelength photometry for the DEVILS regions (COSMOS, XMMLSS, and ECDFS)". Monthly Notices of the Royal Astronomical Society 506, n. 1 (5 giugno 2021): 256–87. http://dx.doi.org/10.1093/mnras/stab1601.

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ABSTRACT The Deep Extragalactic VIsible Legacy Survey (DEVILS) is an ongoing high-completeness, deep spectroscopic survey of ∼60 000 galaxies to Y < 21.2 mag, over ∼6 deg2 in three well-studied deep extragalactic fields: D10 (COSMOS), D02 (XMMLSS), and D03 (ECDFS). Numerous DEVILS projects all require consistent, uniformly derived and state-of-the-art photometric data with which to measure galaxy properties. Existing photometric catalogues in these regions either use varied photometric measurement techniques for different facilities/wavelengths leading to inconsistencies, older imaging data and/or rely on source detection and photometry techniques with known problems. Here, we use the ProFound image analysis package and state-of-the-art imaging data sets (including Subaru-HSC, VST-VOICE, VISTA-VIDEO, and UltraVISTA-DR4) to derive matched-source photometry in 22 bands from the FUV to 500 $\mu$m. This photometry is found to be consistent, or better, in colour analysis to previous approaches using fixed-size apertures (which are specifically tuned to derive colours), but produces superior total source photometry, essential for the derivation of stellar masses, star formation rates, star formation histories, etc. Our photometric catalogue is described in detail and, after internal DEVILS team projects, will be publicly released for use by the broader scientific community.

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14

Ohta, Kouji. "Global Photometric Properties of Barred Galaxies". International Astronomical Union Colloquium 157 (1996): 37–43. http://dx.doi.org/10.1017/s0252921100049393.

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15

De Ridder, Joris, Conny Aerts e Marc-Antoine Dupret. "Mode Identification Using Photometry and Spectroscopy". International Astronomical Union Colloquium 193 (2004): 466–69. http://dx.doi.org/10.1017/s0252921100011155.

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AbstractWe tested a stepwise approach to combine photometry and spectroscopy for mode identification where we first used the photometric amplitude ratios to restrict the degree l, then did a spectroscopic mode identification, and finally fitted the photometric amplitudes to restrict the list of candidate modes. For the spectroscopic mode identification, we implemented an efficient multi-mode moment method variant. We conclude that this new variant works well, but that the photometric amplitudes are too model sensitive to do any additional mode discrimination.

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Kibblewhite, E. J., M. G. M. Cawson, S. Phillipps, J. I. Davies e M. J. Disney. "Automated galaxy surface photometry - IV. Photometric comparisons". Monthly Notices of the Royal Astronomical Society 236, n. 2 (1 gennaio 1989): 187–206. http://dx.doi.org/10.1093/mnras/236.2.187.

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Weaver, J. R., O. B. Kauffmann, O. Ilbert, H. J. McCracken, A. Moneti, S. Toft, G. Brammer et al. "COSMOS2020: A Panchromatic View of the Universe to z ∼ 10 from Two Complementary Catalogs". Astrophysical Journal Supplement Series 258, n. 1 (1 gennaio 2022): 11. http://dx.doi.org/10.3847/1538-4365/ac3078.

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Abstract The Cosmic Evolution Survey (COSMOS) has become a cornerstone of extragalactic astronomy. Since the last public catalog in 2015, a wealth of new imaging and spectroscopic data have been collected in the COSMOS field. This paper describes the collection, processing, and analysis of these new imaging data to produce a new reference photometric redshift catalog. Source detection and multiwavelength photometry are performed for 1.7 million sources across the 2 deg2 of the COSMOS field, ∼966,000 of which are measured with all available broadband data using both traditional aperture photometric methods and a new profile-fitting photometric extraction tool, The Farmer, which we have developed. A detailed comparison of the two resulting photometric catalogs is presented. Photometric redshifts are computed for all sources in each catalog utilizing two independent photometric redshift codes. Finally, a comparison is made between the performance of the photometric methodologies and of the redshift codes to demonstrate an exceptional degree of self-consistency in the resulting photometric redshifts. The i < 21 sources have subpercent photometric redshift accuracy and even the faintest sources at 25 < i < 27 reach a precision of 5%. Finally, these results are discussed in the context of previous, current, and future surveys in the COSMOS field. Compared to COSMOS2015, it reaches the same photometric redshift precision at almost one magnitude deeper. Both photometric catalogs and their photometric redshift solutions and physical parameters will be made available through the usual astronomical archive systems (ESO Phase 3, IPAC-IRSA, and CDS).

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Percy, John R., Nancy Wong, Dietmar Bohme, David R. Curott, Frank Dempsey, George L. Fortier, Matt Ganis et al. "Photometric surveys of suspected small-amplitude red variables. 3: an AAVSO photometric photometry survey". Publications of the Astronomical Society of the Pacific 106 (giugno 1994): 611. http://dx.doi.org/10.1086/133420.

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

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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.

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Evans, Dafydd Wyn, Marco Riello, Francesca De Angeli, Giorgia Busso, Floor van Leeuwen, Laurent Eyer, Carme Jordi et al. "Gaia Photometric Data: DR1 results and DR2 expectations". Proceedings of the International Astronomical Union 12, S330 (aprile 2017): 30–34. http://dx.doi.org/10.1017/s1743921317006329.

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AbstractGaia DR1 was released in September 2016 and contained a photometric catalogue of over 1 billion sources. At this stage, this only included mean G-band photometry and an estimate of the error. Even though this may sound limited in nature, interesting science can still be achieved with this data thanks to its quality. A high level overview of the photometric processing and some validation results will be presented. Additionally, epoch photometry in the G-band was released in Gaia DR1 for a small number of variable sources in the South Ecliptic Pole which covers the LMC. The second data release (Gaia DR2) is currently being prepared and, if available, some preliminary validation results will be presented. It is planned that this release will contain colour information in the form of integrated BP and RP photometry in addition to the latest G-band photometry.

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Riello, M., F. De Angeli, D. W. Evans, G. Busso, N. C. Hambly, M. Davidson, P. W. Burgess et al. "Gaia Data Release 2". Astronomy & Astrophysics 616 (agosto 2018): A3. http://dx.doi.org/10.1051/0004-6361/201832712.

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Context. The second Gaia data release is based on 22 months of mission data with an average of 0.9 billion individual CCD observations per day. A data volume of this size and granularity requires a robust and reliable but still flexible system to achieve the demanding accuracy and precision constraints that Gaia is capable of delivering. Aims. We aim to describe the input data, the treatment of blue photometer/red photometer (BP/RP) low-resolution spectra required to produce the integrated GBP and GRP fluxes, the process used to establish the internal Gaia photometric system, and finally, the generation of the mean source photometry from the calibrated epoch data for Gaia DR2. Methods. The internal Gaia photometric system was initialised using an iterative process that is solely based on Gaia data. A set of calibrations was derived for the entire Gaia DR2 baseline and then used to produce the final mean source photometry. The photometric catalogue contains 2.5 billion sources comprised of three different grades depending on the availability of colour information and the procedure used to calibrate them: 1.5 billion gold, 144 million silver, and 0.9 billion bronze. These figures reflect the results of the photometric processing; the content of the data release will be different due to the validation and data quality filters applied during the catalogue preparation. The photometric processing pipeline, PhotPipe, implements all the processing and calibration workflows in terms of Map/Reduce jobs based on the Hadoop platform. This is the first example of a processing system for a large astrophysical survey project to make use of these technologies. Results. The improvements in the generation of the integrated G–band fluxes, in the attitude modelling, in the cross-matching, and and in the identification of spurious detections led to a much cleaner input stream for the photometric processing. This, combined with the improvements in the definition of the internal photometric system and calibration flow, produced high-quality photometry. Hadoop proved to be an excellent platform choice for the implementation of PhotPipe in terms of overall performance, scalability, downtime, and manpower required for operations and maintenance.

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Bódi, Attila, Pál Szabó, Emese Plachy, László Molnár e Róbert Szabó. "Automated Extended Aperture Photometry of K2 Variable Stars". Publications of the Astronomical Society of the Pacific 134, n. 1031 (1 gennaio 2022): 014503. http://dx.doi.org/10.1088/1538-3873/ac4398.

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Abstract Proper photometric data are challenging to obtain in the K2 mission of the Kepler space telescope due to strong systematics caused by the two-wheel-mode operation. It is especially true for variable stars wherein physical phenomena occur on timescales similar to the instrumental signals. We originally developed a method with the aim to extend the photometric aperture to be able to compensate the motion of the telescope which we named Extended Aperture Photometry (EAP). Here we present the outline of the automatized version of the EAP method, an open-source pipeline called autoEAP. We compare the light curve products to other photometric solutions for examples chosen from high-amplitude variable stars. In addition to the photometry, we developed a new detrending method, which is based on phase dispersion minimization and is able to eliminate long-term instrumental signals for periodic variable stars.

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Evans, D. W., M. Riello, F. De Angeli, J. M. Carrasco, P. Montegriffo, C. Fabricius, C. Jordi et al. "Gaia Data Release 2". Astronomy & Astrophysics 616 (agosto 2018): A4. http://dx.doi.org/10.1051/0004-6361/201832756.

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Aims. We describe the photometric content of the second data release of the Gaia project (Gaia DR2) and its validation along with the quality of the data. Methods. The validation was mainly carried out using an internal analysis of the photometry. External comparisons were also made, but were limited by the precision and systematics that may be present in the external catalogues used. Results. In addition to the photometric quality assessment, we present the best estimates of the three photometric passbands. Various colour-colour transformations are also derived to enable the users to convert between the Gaia and commonly used passbands. Conclusions. The internal analysis of the data shows that the photometric calibrations can reach a precision as low as 2 mmag on individual CCD measurements. Other tests show that systematic effects are present in the data at the 10 mmag level.

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

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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.

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ČAVLOVIĆ, ANKA OZANA, e IVAN BEŠLIĆ. "APPLICATION OF PHOTOMETRY IN DETERMINING THE DUST MASS CONCENTRATION OF HARDWOODS". WOOD RESEARCH 66(4) 2021 66, n. 4 (9 settembre 2021): 678–88. http://dx.doi.org/10.37763/wr.1336-4561/66.4.678688.

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Given the carcinogenicity of hardwood dust, the aim of this study was to determine the effectiveness of the photometric method for different types of woodworking machines and its application in determining the mass concentration of inhalable dust for raw and dry hardwoods. In addition to the optical part of the device, the input part of the measuring device contains the Institute of Occupational Medicine (IOM) inhalable dust filter holder. This correlation of gravimetric and photometric methods in determining the dust mass concentration showed that photometry underestimates the mass concentration measured gravimetrically. The results of this study recommend the application of a correction factor 2 for a timber band saw and a correction factor 3 for circular saws in determining the mass concentration of hardwood dust by the photometric method. It was showed that photometry can be used if the correction factor of the optical device has been previously tested for specific wood processing place.

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Rios-Venegas, C., A. Contreras-Quijada, N. Vogt, F.-J. Hambsch, R. Hinojosa, J. Aranda, V. Gotta et al. "Revisiting the post-common-envelope binaries HZ 9, KV Vel and Abell 65". Monthly Notices of the Royal Astronomical Society 493, n. 1 (21 febbraio 2020): 1197–203. http://dx.doi.org/10.1093/mnras/staa331.

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ABSTRACT New time-resolved photometric observations of three close but detached white dwarf/red dwarf binaries have enabled an in-depth analysis of their properties, combining new data with known information. For HZ 9, time-resolved photometric data have not been published previously. Our data reveal sinusoidal variations, with the orbital period showing unusual phase shifts between expected and observed light maximum epochs when combining our photometry with the precise radial velocity ephemeris. There are also variations of the photometric amplitude between 0.04 and 0.11 mag. Phase shifts and amplitude variations could be the result of a relatively strong magnetic activity of the secondary M star component, which seems to superimpose the usual reflection effect. This effect is dominant in the two remaining targets of our study. We improve the accuracy of the photometric ephemeris of KV Vel, complementing published data with light curves from the All-Sky Automated Survey (ASAS) and ASAS-SN and with our own observations. Finally, we also add new data for the central star of the planetary nebula Abell 65, complementing and confirming its previously published photometric ephemeris.

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Zhang, F., L. Li e Z. Han. "Binary interactions and UV photometry on photometric redshift". Proceedings of the International Astronomical Union 5, S262 (agosto 2009): 452–53. http://dx.doi.org/10.1017/s1743921310003674.

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AbstractUsing the Hyperz code (Bolzonella et al. 2000) we present photometric redshift estimates for a random sample of galaxies selected from the SDSS/DR7 and GALEX/DR4, for which spectroscopic redshifts are also available.We confirm that the inclusion of ultraviolet photometry improves the accuracy of photo-zs for those galaxies with g* – r* ≤ 0.7 and zspec ≤ 0.2. We also address the problem of how binary interactions can affect photo-z estimates, and find that their effect is negligible.

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28

Tümer, O., C. Ibanoĝlu, S. Evren e Z. Tunca. "Photoelectric photometry and photometric elements of LX Persei". Astrophysics and Space Science 112, n. 2 (maggio 1985): 273–86. http://dx.doi.org/10.1007/bf00653510.

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29

H. Puzia, Thomas, Markus Kissler-Patig, Jean Brodie, Paul Goudfrooij, Michael Hilker, Dante Minniti e Steve Zepf. "Extragalactic Globular Cluster Systems in the Near-IR". Symposium - International Astronomical Union 207 (2002): 294–300. http://dx.doi.org/10.1017/s0074180900223887.

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Extragalactic Globular Clusters are useful tracers of galaxy formation and evolution. Photometric studies of globular cluster systems beyond the Local Group are still the most popular method to investigate their physical properties, such as their ages and metallicities. However, the limitations of optical photometry are well known. The better wavelength sampling of the underlying cluster's SED using K-band photometry combined with optical passbands allows us to create colors which reduce the age-metallicity degeneracy to the largest extent. Here we report on the very first results of our near-IR photometric survey of globular cluster systems in early-type galaxies outside the Local Group.

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30

Chrastina, Marek, Miloslav Zejda e Zdeněk Mikulášek. "The MUNI Photometric Archive". Proceedings of the International Astronomical Union 7, S282 (luglio 2011): 205–6. http://dx.doi.org/10.1017/s1743921311027372.

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AbstractIn the 1990s of the last century, CCD cameras became more reachable. Due to many advantages of CCD cameras, astronomers began using them as the primary detector for photometry of stellar objects. A typical observatory, which operates one telescope at a time, obtained 0.5 TB of raw data during two decades, that means one million about 500 kB-sized files. There are several observatories in the Czech Republic and Slovakia (taking into account all scientific, public as well as private ones). A rough estimate of the total amount of this photometric data is 10 TB, which could be a very interesting source of observational data. Unfortunately, these data are not available online. These data are stored in observatory archives in arbitrary format. Often it is not even possible to find requested data. We have decided to change this state by establishing a common archive of raw photometric data, which would be available online together with tools for searching, listing etc. We already defined the data format, file and directory structure of our archive. We developed sophisticated tools for archive maintenance as well. Our goal is to provide data storage with simple and straightforward access and we are ready to interconnect with the VO right after the IVOA Photometry Data Model will be released.

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31

Parimucha, Š., M. Vaňko e P. Mikloš. "SPHOTOM – Package for an Automatic Multicolour Photometry". Proceedings of the International Astronomical Union 7, S282 (luglio 2011): 81–82. http://dx.doi.org/10.1017/s1743921311026998.

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AbstractWe present basic information about package SPHOTOM for an automatic multicolour photometry. This package is in development for the creation of a photometric pipe-line, which we plan to use in the near future with our new instruments. It could operate in two independent modes, (i) GUI mode, in which the user can select images and control functions of package through interface and (ii) command line mode, in which all processes are controlled using a main parameter file. SPHOTOM is developed as a universal package for Linux based systems with easy implementation for different observatories. The photometric part of the package is based on the Sextractor code, which allows us to detect all objects on the images and perform their photometry with different apertures. We can also perform astrometric solutions for all images for a correct cross-identification of the stars on the images. The result is a catalogue of all objects with their instrumental photometric measurements which are consequently used for a differential magnitudes calculations with one or more comparison stars, transformations to an international system, and determinations of colour indices.

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32

Mantegazza, L., e E. Poretti. "Insights into the Pulsational Behaviour of δ Sct Stars". International Astronomical Union Colloquium 155 (1995): 337–38. http://dx.doi.org/10.1017/s0252921100037386.

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Abstract (sommario):

Extensive photometric monitoring of bright δ Scuti stars, made in the last years, allowed us to get reliable frequency determinations also in very complicated cases. Table 1 gives a full description of our photometric targets. Recently, we realized that combining photometry with simultaneous high resolution spectroscopy, in order to study line profile variations, offers the possibility to perform a much more reliable mode identification. Hence, the photometric runs of FG Vir, X Cae, HD 2724 were paired with spectroscopic ones obtained at the Coudé Auxiliary Telescope (ESO, La Silla, Chile). The stellar spectra are centred at 4508 Å and they cover a range of 37.6 Å; the resolving power is about 50000-60000 and the linear dispersion is 2.4 Å/mm.

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33

Laigle, C., I. Davidzon, O. Ilbert, J. Devriendt, D. Kashino, C. Pichon, P. Capak et al. "Horizon-AGN virtual observatory – 1. SED-fitting performance and forecasts for future imaging surveys". Monthly Notices of the Royal Astronomical Society 486, n. 4 (13 aprile 2019): 5104–23. http://dx.doi.org/10.1093/mnras/stz1054.

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Abstract Using the light-cone from the cosmological hydrodynamical simulation horizon-AGN, we produced a photometric catalogue over 0 < z < 4 with apparent magnitudes in COSMOS, Dark Energy Survey, Large Synoptic Survey Telescope (LSST)-like, and Euclid-like filters at depths comparable to these surveys. The virtual photometry accounts for the complex star formation history (SFH) and metal enrichment of horizon-AGN galaxies, and consistently includes magnitude errors, dust attenuation, and absorption by intergalactic medium. The COSMOS-like photometry is fitted in the same configuration as the COSMOS2015 catalogue. We then quantify random and systematic errors of photometric redshifts, stellar masses, and star formation rates (SFR). Photometric redshifts and redshift errors capture the same dependencies on magnitude and redshift as found in COSMOS2015, excluding the impact of source extraction. COSMOS-like stellar masses are well recovered with a dispersion typically lower than 0.1 dex. The simple SFHs and metallicities of the templates induce a systematic underestimation of stellar masses at z < 1.5 by at most 0.12 dex. SFR estimates exhibit a dust-induced bimodality combined with a larger scatter (typically between 0.2 and 0.6 dex). We also use our mock catalogue to predict photometric redshifts and stellar masses in future imaging surveys. We stress that adding Euclid near-infrared photometry to the LSST-like baseline improves redshift accuracy especially at the faint end and decreases the outlier fraction by a factor ∼2. It also considerably improves stellar masses, reducing the scatter up to a factor 3. It would therefore be mutually beneficial for LSST and Euclid to work in synergy.

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34

Katime-Santrich, Orlando J., Bruno V. Castilho, Carlos A. O. Torres e Germano R. Quast. "Photometric and spectroscopic analysis of the stellar association AB Doradus". Proceedings of the International Astronomical Union 5, S265 (agosto 2009): 370–71. http://dx.doi.org/10.1017/s1743921310000979.

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AbstractWe present the stellar parameters and lithium abundance for 23 stars of the young stellar association AB Doradus, determined by photometry and spectroscopy. The photometric data was obtained at OPD/LNA and/or from the literature and the spectroscopic data was obtained at La silla/ESO and at OPD/LNA. The parameters were determined using photometric calibrations, line ratios, curves of growth and spectral synthesis. Our results confirm that the selected stars are probably association members, showing an uniform metallicity and lithium depletion consistent with 50 Myears

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35

Zhang, X. B. "The eclipsing binary IU Per and its intrinsic oscillations". Proceedings of the International Astronomical Union 4, S252 (aprile 2008): 429–30. http://dx.doi.org/10.1017/s1743921308023417.

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AbstractThe results of a long-term time-series photometry of the short-period eclipsing binary IU Per are reported. The observation confirms the intrinsic δ Scuti-like pulsation of the star as discovered by previous authors. A photometric solution for the binary system was carried out with the new data. Based on which, the pure oscillation light variations from the mass-accreting primary component were extracted. A Fourier analysis reveals four pulsation modes. Combining with the photometric solution, a preliminary mode identification was given.

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36

Reed, B. Cameron, e Charles J. Peterson. "A New Survey of Globular Cluster Structural and Luminosity Parameters". Symposium - International Astronomical Union 126 (1988): 489–90. http://dx.doi.org/10.1017/s0074180900042753.

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Abstract (sommario):

We have made an analysis of the visual photometric data contained in the Catalogue of Concentric Aperture UBVRI Photoelectric Photometry of Globular Clusters (Peterson 1986). Structural parameters have been obtained by use of the Simplex algorithm of Caceci and Cacheris (1984) to fit the model curves of King (1966) to the run of cluster luminosity with radius. We find that concentric aperture photometry alone can be used to determine globular cluster core radii and central surface brigtnesses reliably. Application of this techique, however, is limited to about two-thirds of the known clusters of the Galaxy because no or inadequate numbers of photometric measurements exist for the remaining clusters. Accurate determination of cluster concentration classes still requires use of other types of data, such as star counts.

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37

Smith, R. C., J. Echevarrıa, J. V. Hernandez e P. Szkody. "SS Cygni Revisited". Acta Polytechnica CTU Proceedings 2, n. 1 (23 febbraio 2015): 148–51. http://dx.doi.org/10.14311/app.2015.02.0148.

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Abstract (sommario):

New spectroscopic and photometric observations of SS Cygni, the brightest dwarf nova system, have been obtained, with the aim of mapping starspots on the surface of the secondary star. Four nights of echelle spectroscopy in quiescence have been obtained using the 2.2-m telescope at San Pedro Martir (Mexico) in August 2012 and another two nights at the 3.5-m telescope at Apache Point Observatory, USA, in September 2012, but these data are still being reduced. Simultaneous CCD photometry was also obtained at the two sites, and the Mexican photometry was extended into the subsequent long outburst. This presentation reveals some interesting photometric behaviour in that outburst, but further data will be necessary before the nature of the behaviour can be determined.

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38

Cottrell, P. L., e W. A. Lawson. "Pulsations and declines of RCB stars". International Astronomical Union Colloquium 139 (1993): 212–13. http://dx.doi.org/10.1017/s0252921100117397.

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AbstractWe have continued to observe many of the R Coronae Borealis (RCB) stars and other related hydrogen-deficient carbon stars. We wish to more fully investigate the photometric and spectroscopic properties of these peculiar stars.The UBVRI photometric data (acquired at Mount John University Observatory, MJUO) are being used to investigate whether the periods determined by Lawson et al. (1990), based on time intervals of up to 1100 d, are still evident in the larger datasets which now cover time intervals of up to 2200 d.The long time baseline of photometric observations that we have been able to acquire has enabled us to accumulate an extensive database of decline photometry. These are used to investigate links with the pulsations at maximum light in order to get a better understanding of this remarkable phenomenon.

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39

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.

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Abstract (sommario):

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:

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40

Grenon, Michel. "Photometric Calibrations after HIPPARCOS or: The Fine Structure of the HR-Diagram Revealed". Highlights of Astronomy 12 (2002): 680–83. http://dx.doi.org/10.1017/s1539299600014659.

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AbstractThe Hipparcos parallaxes allow us to revisit photometric calibrations in terms ofMvand to evaluate the effects of the overall metallicity across the HR-diagram. For evolved stars the spread in mass remains the major and irreducible source of errors in the photometricMv. If the relative locations of open cluster main-sequences are fully explained by the ∆Mvversus ∆[M/H] relation, the residual scatter in the lower main sequence appears due to additional parameters such as rotation or gravitational settling of the heavy elements. These cannot readily be studied by a purely photometric approach.

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41

Surot, F., E. Valenti, S. L. Hidalgo, M. Zoccali, O. A. Gonzalez, E. Sökmen, D. Minniti, M. Rejkuba e P. W. Lucas. "Mapping the stellar age of the Milky Way bulge with the VVV". Astronomy & Astrophysics 629 (22 agosto 2019): A1. http://dx.doi.org/10.1051/0004-6361/201935730.

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Abstract (sommario):

Context. The bulge represents the best compromise between old and massive Galactic components, and as such its study is a valuable opportunity to understand how the bulk of the Milky Way formed and evolved. In addition, being the only bulge in which we can individually resolve stars in all evolutionary sequences, the properties of its stellar content provide crucial insights into the formation of bulges. Aims. We are providing a detailed and comprehensive census of the Milky Way bulge stellar populations by producing deep and accurate photometric catalogs of the inner ∼300 deg2 of the Galaxy. Methods. We performed DAOPHOT/ALLFRAME point spread function (PSF) fitting photometry of multi-epochs J and Ks images provided by the VISTA Variables in the Vía Láctea (VVV) survey to obtain deep photometric catalogs. Artificial star experiments have been conducted on all images to properly assess the completeness and the accuracy of the photometric measurements. Results. We present a photometric database containing nearly 600 million stars across the bulge area surveyed by the VVV. Through the comparison of derived color-magnitude diagrams of selected fields representative of different levels of extinction and crowding, we show the quality, completeness and depth of the new catalogs. With the exception of the fields located along the plane, this new photometry samples stars down to ∼1–2 mag below the old main sequence turnoff with unprecedented accuracy. To demonstrate the tremendous potential inherent to this new dataset, we give a few examples of possible applications, including (i) star count studies through the dataset completeness map; (ii) surface brightness map; and (iii) cross-correlation with Gaia DR2. Conclusions. The database presented here represents an invaluable collection for the whole community, and we encourage its exploitation. The photometric catalogs including completeness information are publicly available through the ESO Science Archive as part of the MW-BULGE-PSPHOT release.

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42

Brunner, Robert J., Andrew J. Connolly, Alexander S. Szalay e Matthew A. Bershady. "Toward More Precise Photometric Redshifts: Calibration via CCD Photometry". Astrophysical Journal 482, n. 1 (10 giugno 1997): L21—L24. http://dx.doi.org/10.1086/310674.

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43

Hillier, J., P. Helfenstein, A. Verbiscer e J. Veverka. "Voyager photometry of Triton: Haze and surface photometric properties". Journal of Geophysical Research 96, S01 (1991): 19203. http://dx.doi.org/10.1029/91ja01736.

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44

Picazzio, Enos, Elysandra Figueredo, Amaury Augusto de Almeida, Claudia Mendes de Oliveira e Klim Ivanovich Churyumov. "Near infrared photometry of comet C/2005 E2 (McNaught)". Proceedings of the International Astronomical Union 5, S263 (agosto 2009): 285–88. http://dx.doi.org/10.1017/s1743921310001948.

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AbstractWe present results of JHK photometry for comet C/2005 E2 (McNaught). Observations were made with the OSIRIS imager at the SOAR telescope, on Sept. 26-27, 2005. The dependence of the main parameters on the angular distance from the cometary photometric nucleus is discussed. We considered concentric rings around the photometric nucleus of the comet, with the radius determined by the aperture. Integrated flux in the ring, surface brightness, J-H and H-K color indices, and mean flux decay were obtained for each ring. A phometric radial profile was also obtained by tracing average values of the ace brightness for increasing values of radii in isophotes which allowed us to compute the azimuthally averaged surface brightness of the coma. The images centered on the photometric nucleus show three jets from active areas on the nucleus.

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45

Baransky, A., O. Lukina e S. Borysenko. "Astrometric and photometric observations of six brightest trans-Neptunian objects at the Kyiv comet station". Advances in Astronomy and Space Physics 10, n. 2 (2020): 48–54. http://dx.doi.org/10.17721/2227-1481.10.48-54.

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Abstract (sommario):

In this work we focused on observations of six trans-Neptunian objects (TNOs) whose apparent magnitudes are brighter than 20m. We present the results of astrometric and photometric observations of (134340) Pluto, (136108) Haumea, (136472) Makemake, (136199) Eris, (90482) Orcus, and (20000) Varuna obtained at the Kyiv comet station (Code MPC 585) in 2017-2019. For observations we used the 0.7-m (f/4) reflector AZT-8 with FLI PL4710 CCD camera and filters of Johnson-Cousins photometric system. From our images we measured the objects' astrometric positions, calculated apparent magnitudes in the BVRI (mostly R) bands using aperture photometry method, and found absolute magnitudes together with the colour indices in several bands. Analysing our results, we investigate the limitation on the astrometry and photometry of faint objects with the 0.7-m telescope.

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46

Stahl, Benjamin E., Thomas de Jaeger, WeiKang Zheng e Alexei V. Filippenko. "The snapshot distance method: estimating the distance to a Type Ia supernova from minimal observations". Monthly Notices of the Royal Astronomical Society 505, n. 2 (13 maggio 2021): 2300–2308. http://dx.doi.org/10.1093/mnras/stab1367.

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ABSTRACT We present the snapshot distance method (SDM), a modern incarnation of a proposed technique for estimating the distance to a Type Ia supernova (SN Ia) from minimal observations. Our method, which has become possible owing to recent work in the application of deep learning to SN Ia spectra (we use the deepSIP package), allows us to estimate the distance to an SN Ia from a single optical spectrum and epoch of 2 + passband photometry – one night’s worth of observations (though contemporaneity is not a requirement). Using a compilation of well-observed SNe Ia, we generate snapshot distances across a wide range of spectral and photometric phases, light-curve shapes, photometric passband combinations, and spectrum signal-to-noise ratios. By comparing these estimates to the corresponding distances derived from fitting all available photometry for each object, we demonstrate that our method is robust to the relative temporal sampling of the provided spectroscopic and photometric information, and to a broad range of light-curve shapes that lie within the domain of standard width–luminosity relations. Indeed, the median residual (and asymmetric scatter) between SDM distances derived from two-passband photometry and conventional light-curve-derived distances that utilize all available photometry is $0.013_{-0.143}^{+0.154}$ mag. Moreover, we find that the time of maximum brightness and light-curve shape (both of which are spectroscopically derived in our method) are only minimally responsible for the observed scatter. In a companion paper, we apply the SDM to a large number of sparsely observed SNe Ia as part of a cosmological study.

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47

Thanjavur, Karun, Željko Ivezić, Sahar S. Allam, Douglas L. Tucker, J. Allyn Smith e Stephen Gwyn. "Photometric cross-calibration of the SDSS Stripe 82 Standard Stars catalogue with Gaia EDR3, and comparison with Pan-STARRS1, DES, CFIS, and GALEX catalogues". Monthly Notices of the Royal Astronomical Society 505, n. 4 (22 maggio 2021): 5941–56. http://dx.doi.org/10.1093/mnras/stab1452.

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ABSTRACT We extend the SDSS Stripe 82 Standard Stars catalogue with post-2007 SDSS imaging data. This improved version lists averaged SDSS ugriz photometry for nearly a million stars brighter than r ∼ 22 mag. With 2–3 times more measurements per star, random errors are 1.4–1.7 times smaller than in the original catalogue, and about three times smaller than for individual SDSS runs. Random errors in the new catalogue are $\lesssim$0.01 mag for stars brighter than 20.0, 21.0, 21.0, 20.5, and 19.0 mag in u, g, r, i, and z-bands, respectively. We achieve this error threshold by using the Gaia Early Data Release 3 (EDR3) Gmag photometry to derive grey photometric zeropoint corrections, as functions of RA and Declination, for the SDSS catalogue, and use the Gaia BP–RP colour to derive corrections in the ugiz bands, relative to the r-band. The quality of the recalibrated photometry, tested against Pan-STARRS1, DES, CFIS, and GALEX surveys, indicates spatial variations of photometric zeropoints ≦ 0.01 mag (rms), with typical values of 3–7 millimag in the RA, and 1–2 millimag in the Declination directions, except for $\lesssim$6 millimag scatter in the u-band. We also report a few minor photometric problems with other surveys considered here, including a magnitude-dependent ∼0.01 mag bias between 16 ≤ GGaia ≤ 20 in the Gaia EDR3. Our new, publicly available catalogue offers robust calibration of ugriz photometry below 1 per cent level, and will be helpful during the commissioning of the Vera C. Rubin Observatory Legacy Survey of Space and Time.

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48

Maskoliunas, M., J. Zdanavičius, V. Čepas, A. Kazlauskas, R. P. Boyle, K. Zdanavičius, K. Černis, K. Milašius e M. Macijauskas. "New calibration of the Vilnius photometric system". Proceedings of the International Astronomical Union 14, A30 (agosto 2018): 486. http://dx.doi.org/10.1017/s1743921319005179.

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Abstract (sommario):

AbstractThe medium-band Vilnius photometric system with the mean wavelengths at 345 (U), 374 (P), 405 (X), 466 (Y), 516 (Z), 544 (V), and 656 (S) nm for many years was an important tool to determine interstellar reddenings and distances of single stars due to its ability to classify stars of all temperatures in spectral classes and luminosity classes in the presence of different interstellar reddenings. At present, Gaia DR2 presents distances to stars with an unprecedented accuracy at least up to 3 kpc. However, multicolor photometry, which allows the classification of stars as well as the preliminary determination of stellar temperatures, gravities, metallicities and interstellar reddenings, remains an important method for distant stars. Here we present an empirical calibration of the intrinsic color indices of the Vilnius system in terms of physical parameters of stars for dwarf and giant stars of spectral classes F-G-K-M. In any attempted photometric determination of physical parameters of stars it is important to have an extensive and homogeneous sample of spectroscopically determined parameters for stars for which there are also accurate photometric data. As a source catalogue for the Vilnius photometry the latest updated version of the Catalogue of Photoelectric Observations in the Vilnius System was used, which contains compilations from the published photometry for about 11 000 stars. The stars which had both the Gaia DR2 parallaxes and the determinations of stellar parameters from high-dispersion spectra were extracted from this catalogue. The final sample contains more than 1500 stars of spectral classes F-M. The majority of these stars (ca 70%) are not reddened, for others the values of interstellar reddening AV were determined using the regular techniques of photometric classification in the Vilnius system. The absolute magnitudes MV and consequently the luminosity classes were determined using Gaia DR2 parallaxes. We present the analytical expressions for the effective temperature Teff and surface gravity logg and evaluate the errors of solutions for dwarf and giant stars. To test the accuracy of the proposed method, we have compared our results with the stars observed by Gaia and with the stellar parameters available from the large spectroscopic surveys: APOGEE, Gaia-ESO, GALAH, LAMOST, RAVE and SEGUE. The results of comparison contain 5-6 % outliers.The proposed method allows the fast and straightforward evaluation of stellar physical parameters for the stars observed in the Vilnius photometric system. Despite the fact, that the accuracy of determination is significantly lower than in the case of spectroscopic methods, the method described may be useful for distant faint stars, which are still inaccessible for spectroscopic observations.

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49

Casagrande, Luca. "All sky photometric zero-points from stellar effective temperatures". Proceedings of the International Astronomical Union 14, A30 (agosto 2018): 465. http://dx.doi.org/10.1017/s1743921319005118.

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Abstract (sommario):

AbstractI use SkyMapper DR1.1 to explore the quality of its uvgriz photometry, and zero-points. I introduce a formalism to derive photometric zero-points across the sky by benchmarking against stars with well known effective temperatures, bypassing the need for absolute spectrophotometry.

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50

Jerzykiewicz, M. "Two Aspects of Using Hipparcos Data for Studying Multiperiodic Stellar Pulsations". International Astronomical Union Colloquium 176 (2000): 46–49. http://dx.doi.org/10.1017/s0252921100057043.

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Abstract (sommario):

AbstractTwo aspects of using Hipparcos data for studying multiperiodic stellar pulsations involve (1) deriving frequencies of multiperiodic pulsators from Hipparcos Epoch Photometry, and (2) using Hipparcos parallaxes together with other data, such as the frequencies, frequency ratios and multicolor photometry, to identify pulsation modes. Details are examined by looking at the δ Scuti star DK Virginis. From Hipparcos Epoch Photometry, two frequencies are derived. These frequencies are then verified by showing that they also fit all available ground-based observations of the star. In addition, Hipparcos parallax and a photometric effective temperature are used to compare the position of DK Vir in the HR diagram with evolutionary tracks. The star turns out to be at the end of core-hydrogen-burning stage of its evolution or slightly beyond, with a mass of 2.2 M⊙, or somewhat smaller. The observed frequencies indicate that the two detected modes are p3 and p2, while the relatively large photometric amplitudes imply ℓ ≲ 2.

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