Journal articles on the topic 'WISE All-Sky catalogue'
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Shu, Yiping, Sergey E. Koposov, N. Wyn Evans, Vasily Belokurov, Richard G. McMahon, Matthew W. Auger, and Cameron A. Lemon. "Catalogues of active galactic nuclei from Gaia and unWISE data." Monthly Notices of the Royal Astronomical Society 489, no. 4 (September 5, 2019): 4741–59. http://dx.doi.org/10.1093/mnras/stz2487.
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ABSTRACT We present two catalogues of active galactic nucleus (AGN) candidates selected from the latest data of two all-sky surveys – Data Release 2 of the Gaia mission and the unWISE catalogue of the Wide-field Infrared Survey Explorer (WISE). We train a random forest classifier to predict the probability of each source in the Gaia–unWISE joint sample being an AGN, PRF, based on Gaia astrometric and photometric measurements and unWISE photometry. The two catalogues, which we designate C75 and R85, are constructed by applying different PRF threshold cuts to achieve an overall completeness of 75 per cent (≈90 per cent at GaiaG ≤ 20 mag) and reliability of 85 per cent, respectively. The C75 (R85) catalogue contains 2734 464 (2182 193) AGN candidates across the effective 36 000 deg2 sky, of which ≈0.91 (0.52) million are new discoveries. Photometric redshifts of the AGN candidates are derived by a random forest regressor using Gaia and WISE magnitudes and colours. The estimated overall photometric redshift accuracy is 0.11. Cross-matching the AGN candidates with a sample of known bright cluster galaxies, we identify a high-probability strongly lensed AGN candidate system, SDSS J1326+4806, with a large image separation of 21${^{\prime\prime}_{.}}$06. All the AGN candidates in our catalogues will have ∼5-yr long light curves from Gaia by the end of the mission, and thus will be a great resource for AGN variability studies. Our AGN catalogues will also be helpful in AGN target selections for future spectroscopic surveys, especially those in the Southern hemisphere. The C75 catalogue can be downloaded at https://www.ast.cam.ac.uk/~ypshu/AGN_Catalogues.html.
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Krakowski, T., K. Małek, M. Bilicki, A. Pollo, A. Kurcz, and M. Krupa. "Machine-learning identification of galaxies in the WISE × SuperCOSMOS all-sky catalogue." Astronomy & Astrophysics 596 (November 28, 2016): A39. http://dx.doi.org/10.1051/0004-6361/201629165.
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Wen, Z. L., J. L. Han, and F. Yang. "A catalogue of clusters of galaxies identified from all sky surveys of 2MASS, WISE, and SuperCOSMOS." Monthly Notices of the Royal Astronomical Society 475, no. 1 (December 9, 2017): 343–52. http://dx.doi.org/10.1093/mnras/stx3189.
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Zhang, Yanxia, Yongheng Zhao, and Xue-Bing Wu. "Classification of 4XMM-DR9 sources by machine learning." Monthly Notices of the Royal Astronomical Society 503, no. 4 (April 17, 2021): 5263–73. http://dx.doi.org/10.1093/mnras/stab744.
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ABSTRACT The ESA’s X-ray Multi-mirror Mission (XMM–Newton) created a new high-quality version of the XMM–Newton serendipitous source catalogue, 4XMM-DR9, which provides a wealth of information for observed sources. The 4XMM-DR9 catalogue is correlated with the Sloan Digital Sky Survey (SDSS) DR12 photometric data base and the AllWISE data base; we then get X-ray sources with information from the X-ray, optical, and/or infrared bands and obtain the XMM–WISE, XMM–SDSS, and XMM–WISE–SDSS samples. Based on the large spectroscopic surveys of SDSS and the Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST), we cross-match the XMM–WISE–SDSS sample with sources of known spectral classes, and obtain known samples of stars, galaxies, and quasars. The distribution of stars, galaxies, and quasars as well as all spectral classes of stars in 2D parameter space is presented. Various machine-learning methods are applied to different samples from different bands. The better classified results are retained. For the sample from the X-ray band, a rotation-forest classifier performs the best. For the sample from the X-ray and infrared bands, a random-forest algorithm outperforms all other methods. For the samples from the X-ray, optical, and/or infrared bands, the LogitBoost classifier shows its superiority. Thus, all X-ray sources in the 4XMM-DR9 catalogue with different input patterns are classified by their respective models that are created by these best methods. Their membership of and membership probabilities for individual X-ray sources are assigned. The classified result will be of great value for the further research of X-ray sources in greater detail.
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Spiniello, C., and A. Agnello. "VEXAS: VISTA EXtension to Auxiliary Surveys." Astronomy & Astrophysics 630 (October 2019): A146. http://dx.doi.org/10.1051/0004-6361/201936311.
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Context. We present the first public data release of the VISTA EXtension to Auxiliary Surveys (VEXAS), comprising nine cross-matched multi-wavelength photometric catalogues where each object has a match in at least two surveys. Aims. Our aim is to provide spatial coverage that is as uniform as possible in the multi-wavelength sky and to provide the astronomical community with reference magnitudes and colours for various scientific uses: object classification (e.g. quasars, galaxies, and stars; high-z galaxies, white dwarfs); photometric redshifts of large galaxy samples; searches of exotic objects (e.g. extremely red objects and lensed quasars). Methods. We cross-matched the wide-field VISTA catalogues (the VISTA Hemisphere Survey and the VISTA Kilo Degree Infrared Galaxy Survey) with the AllWISE mid-infrared Survey, requiring a match within 10″. We have further matched this table with X-ray and radio data (ROSAT, XMM, SUMSS). We also performed a second cross-match between VISTA and AllWISE, with a smaller matching radius (3″), including WISE magnitudes. We then cross-matched this resulting table (≈138 × 106 objects) with three photometric wide-sky optical deep surveys (DES, SkyMapper, PanSTARRS). We finally included matches to objects with spectroscopic follow-up by the SDSS and 6dFGS. Results. To demonstrate the power of all-sky multi-wavelength cross-match tables, we show two examples of scientific applications of VEXAS, in particular using the publicly released tables to discover strong gravitational lenses (beyond the reach of previous searches) and to build a statistically large sample of extremely red objects. Conclusions. The VEXAS catalogue is currently the widest and deepest public optical-to-IR photometric and spectroscopic database in the southern hemisphere.
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Solarz, A., R. Thomas, F. M. Montenegro-Montes, M. Gromadzki, E. Donoso, M. Koprowski, L. Wyrzykowski, C. G. Diaz, E. Sani, and M. Bilicki. "Spectroscopic observations of the machine-learning selected anomaly catalogue from the AllWISE Sky Survey." Astronomy & Astrophysics 642 (October 2020): A103. http://dx.doi.org/10.1051/0004-6361/202038439.
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We present the results of a programme to search and identify the nature of unusual sources within the All-sky Wide-field Infrared Survey Explorer (WISE) that is based on a machine-learning algorithm for anomaly detection, namely one-class support vector machines (OCSVM). Designed to detect sources deviating from a training set composed of known classes, this algorithm was used to create a model for the expected data based on WISE objects with spectroscopic identifications in the Sloan Digital Sky Survey. Subsequently, it marked as anomalous those sources whose WISE photometry was shown to be inconsistent with this model. We report the results from optical and near-infrared spectroscopy follow-up observations of a subset of 36 bright (gAB < 19.5) objects marked as “anomalous” by the OCSVM code to verify its performance. Among the observed objects, we identified three main types of sources: (i) low redshift (z ∼ 0.03 − 0.15) galaxies containing large amounts of hot dust (53%), including three Wolf-Rayet galaxies; (ii) broad-line quasi-stellar objects (QSOs) (33%) including low-ionisation broad absorption line (LoBAL) quasars and a rare QSO with strong and narrow ultraviolet iron emission; (iii) Galactic objects in dusty phases of their evolution (3%). The nature of four of these objects (11%) remains undetermined due to low signal-to-noise or featureless spectra. The current data show that the algorithm works well at detecting rare but not necessarily unknown objects among the brightest candidates. They mostly represent peculiar sub-types of otherwise well-known sources. To search for even more unusual sources, a more complete and balanced training set should be created after including these rare sub-species of otherwise abundant source classes, such as LoBALs. Such an iterative approach will ideally bring us closer to improving the strategy design for the detection of rarer sources contained within the vast data store of the AllWISE survey.
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Marton, G., P. Ábrahám, E. Szegedi-Elek, J. Varga, M. Kun, Á. Kóspál, E. Varga-Verebélyi, et al. "Identification of Young Stellar Object candidates in the Gaia DR2 x AllWISE catalogue with machine learning methods." Monthly Notices of the Royal Astronomical Society 487, no. 2 (May 14, 2019): 2522–37. http://dx.doi.org/10.1093/mnras/stz1301.
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ABSTRACT The second Gaia Data Release (DR2) contains astrometric and photometric data for more than 1.6 billion objects with mean Gaia G magnitude <20.7, including many Young Stellar Objects (YSOs) in different evolutionary stages. In order to explore the YSO population of the Milky Way, we combined the Gaia DR2 data base with Wide-field Infrared Survey Explorer (WISE) and Planck measurements and made an all-sky probabilistic catalogue of YSOs using machine learning techniques, such as Support Vector Machines, Random Forests, or Neural Networks. Our input catalogue contains 103 million objects from the DR2xAllWISE cross-match table. We classified each object into four main classes: YSOs, extragalactic objects, main-sequence stars, and evolved stars. At a 90 per cent probability threshold, we identified 1 129 295 YSO candidates. To demonstrate the quality and potential of our YSO catalogue, here we present two applications of it. (1) We explore the 3D structure of the Orion A star-forming complex and show that the spatial distribution of the YSOs classified by our procedure is in agreement with recent results from the literature. (2) We use our catalogue to classify published Gaia Science Alerts. As Gaia measures the sources at multiple epochs, it can efficiently discover transient events, including sudden brightness changes of YSOs caused by dynamic processes of their circumstellar disc. However, in many cases the physical nature of the published alert sources are not known. A cross-check with our new catalogue shows that about 30 per cent more of the published Gaia alerts can most likely be attributed to YSO activity. The catalogue can be also useful to identify YSOs among future Gaia alerts.
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Bonjean, V., N. Aghanim, P. Salomé, A. Beelen, M. Douspis, and E. Soubrié. "Star formation rates and stellar masses from machine learning." Astronomy & Astrophysics 622 (February 2019): A137. http://dx.doi.org/10.1051/0004-6361/201833972.
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Star-formation activity is a key property to probe the structure formation and hence characterise the large-scale structures of the universe. This information can be deduced from the star formation rate (SFR) and the stellar mass (M⋆), both of which, but especially the SFR, are very complex to estimate. Determining these quantities from UV, optical, or IR luminosities relies on complex modeling and on priors on galaxy types. We propose a method based on the machine-learning algorithm Random Forest to estimate the SFR and the M⋆ of galaxies at redshifts in the range 0.01 < z < 0.3, independent of their type. The machine-learning algorithm takes as inputs the redshift, WISE luminosities, and WISE colours in near-IR, and is trained on spectra-extracted SFR and M⋆ from the SDSS MPA-JHU DR8 catalogue as outputs. We show that our algorithm can accurately estimate SFR and M⋆ with scatters of σSFR = 0.38 dex and σM⋆ = 0.16 dex for SFR and stellar mass, respectively, and that it is unbiased with respect to redshift or galaxy type. The full-sky coverage of the WISE satellite allows us to characterise the star-formation activity of all galaxies outside the Galactic mask with spectroscopic redshifts in the range 0.01 < z < 0.3. The method can also be applied to photometric-redshift catalogues, with best scatters of σSFR = 0.42 dex and σM⋆ = 0.24 dex obtained in the redshift range 0.1 < z < 0.3.
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De Rosa, R. J., B. Smith, J. Bulger, J. Patience, C. Marois, I. Song, B. Macintosh, J. Graham, R. Doyon, and M. Bessell. "Debris Disks and Multiplicity within the 75pc Volume-limited A-Star (VAST) Survey." Proceedings of the International Astronomical Union 8, S299 (June 2013): 334–35. http://dx.doi.org/10.1017/s174392131300882x.
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AbstractWe present the preliminary findings of an investigation of the multiplicity of debris disk stars identified within our Volume-limited A-star (VAST) multiplicity survey. Previous studies have produced conflicting results regarding the multiplicity fraction of debris disk-hosting stars compared with non-excess stars. By combining our large-scale volume-limited AO survey of A-type stars with the all-sky WISE catalogue, we have investigated the frequency of binary companions to a large sample of A-type stars with and without measured 22μm excess. The results of this study will allow for a greater understanding of the interaction between a companion star and a circumstellar debris disk, informing future study into the formation and stability of planetary-mass companions within binary systems.
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Ross, Nicholas P., and Nicholas J. G. Cross. "The near and mid-infrared photometric properties of known redshift z ≥ 5 quasars." Monthly Notices of the Royal Astronomical Society 494, no. 1 (March 13, 2020): 789–803. http://dx.doi.org/10.1093/mnras/staa544.
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ABSTRACT We assemble a catalogue of 488 spectroscopically confirmed very high (z ≥ 5.00) redshift quasars (VHzQ) and report their near- (ZYJHKs/K) and mid- (WISE W1234) infrared properties. 97 per cent of the VHzQ sample is detected in one or more near-infrared (NIR) band, with lack of coverage rather than lack of depth being the reason for the non-detections. 389 (80 per cent) of the very high redshift quasars are detected at 3.4 μm in the W1 band from the unWISE catalogue and all of the z ≥ 7 quasars are detected in both unWISE W1 and W2. Using archival Wide Field Camera (WFCAM)/United Kingdom Infrared Telescope (UKIRT) and VISTA Infrared Camera (VIRCAM)/Visible and Infrared Survey Telescope for Astronomy (VISTA) data we check for photometric variability that might be expected from super-Eddington accretion. We find 28 of the quasars have sufficient NIR measurements and signal-to-noise ratio to look for variability. Weak variability was detected in multiple bands of Sloan Digital Sky Survey (SDSS) J0959+0227, and very marginally in the Y-band of MMT J0215-0529. Only one quasar, SDSS J0349+0034, shows significant differences between WFCAM and VISTA magnitudes in one band. With supermassive black hole accretion likely to be redshift invariant up to very high redshift, further monitoring of these sources is warranted. All the data, analysis codes and plots used and generated here can be found at: github.com/d80b2t/VHzQ.
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Kilerci Eser, Ece, T. Goto, T. Güver, A. Tuncer, and O. H. Ataş. "Infrared colours and spectral energy distributions of hard X-ray selected obscured and Compton-thick active galactic nuclei." Monthly Notices of the Royal Astronomical Society 494, no. 4 (May 12, 2020): 5793–810. http://dx.doi.org/10.1093/mnras/staa956.
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ABSTRACT We investigate the infrared colours and spectral energy distributions (SEDs) of 338 X-ray selected active galactic nuclei (AGNs) from the Swift/Burst Alert Telescope (BAT) 105-month survey catalogue, which have been detected using AKARI, in order to find new selection criteria for Compton-thick AGNs. By combining data from the Galaxy Evolution Explorer (GALEX), the Sloan Digital Sky Survey (SDSS) Data Release 14 (DR14), the Two-Micron All Sky Survey (2MASS), the Wide-field Infrared Survey Explorer (WISE), AKARI and Herschel for the first time, we perform ultraviolet (UV) to far-infrared (FIR) SEDs, fitting 158 Swift/BAT AGNs using cigale and constraining the AGN model parameters of obscured and Compton-thick AGNs. The comparison of average SEDs shows that while the mid-infrared (MIR) SEDs are similar for the three AGN populations, the optical/UV and FIR regions have differences. We measure the dust luminosity, the pure AGN luminosity and the total infrared luminosity. We examine the relationships between the measured infrared luminosities and the hard X-ray luminosity in the 14–195 keV band. We show that the average covering factor of Compton-thick AGNs is higher compared with the obscured and unobscured AGNs. We present new infrared selection criteria for Compton-thick AGNs based on MIR and FIR colours ([9–22 μm] > 3.0 and [22–90 μm] < 2.7) from WISE and AKARI. We find two known Compton-thick AGNs that are not included in the Swift/BAT sample. We conclude that MIR colours covering 9.7-μm silicate absorption and the MIR continuum could be promising new tools to identify Compton-thick AGNs.
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Kuijken, K., C. Heymans, A. Dvornik, H. Hildebrandt, J. T. A. de Jong, A. H. Wright, T. Erben, et al. "The fourth data release of the Kilo-Degree Survey: ugri imaging and nine-band optical-IR photometry over 1000 square degrees." Astronomy & Astrophysics 625 (April 30, 2019): A2. http://dx.doi.org/10.1051/0004-6361/201834918.
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Context. The Kilo-Degree Survey (KiDS) is an ongoing optical wide-field imaging survey with the OmegaCAM camera at the VLT Survey Telescope, specifically designed for measuring weak gravitational lensing by galaxies and large-scale structure. When completed it will consist of 1350 square degrees imaged in four filters (ugri). Aims. Here we present the fourth public data release which more than doubles the area of sky covered by data release 3. We also include aperture-matched ZYJHKs photometry from our partner VIKING survey on the VISTA telescope in the photometry catalogue. We illustrate the data quality and describe the catalogue content. Methods. Two dedicated pipelines are used for the production of the optical data. The ASTRO-WISE information system is used for the production of co-added images in the four survey bands, while a separate reduction of the r-band images using the THELI pipeline is used to provide a source catalogue suitable for the core weak lensing science case. All data have been re-reduced for this data release using the latest versions of the pipelines. The VIKING photometry is obtained as forced photometry on the THELI sources, using a re-reduction of the VIKING data that starts from the VISTA pawprints. Modifications to the pipelines with respect to earlier releases are described in detail. The photometry is calibrated to the Gaia DR2 G band using stellar locus regression. Results. In this data release a total of 1006 square-degree survey tiles with stacked ugri images are made available, accompanied by weight maps, masks, and single-band source lists. We also provide a multi-band catalogue based on r-band detections, including homogenized photometry and photometric redshifts, for the whole dataset. Mean limiting magnitudes (5σ in a 2″ aperture) and the tile-to-tile rms scatter are 24.23 ± 0.12, 25.12 ± 0.14, 25.02 ± 0.13, 23.68 ± 0.27 in ugri, respectively, and the mean r-band seeing is 0.″70.
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Bellstedt, Sabine, Simon P. Driver, Aaron S. G. Robotham, Luke J. M. Davies, Cameron R. J. Bogue, Robin H. W. Cook, Abdolhosein Hashemizadeh, et al. "Galaxy And Mass Assembly (GAMA): assimilation of KiDS into the GAMA database." Monthly Notices of the Royal Astronomical Society 496, no. 3 (June 3, 2020): 3235–56. http://dx.doi.org/10.1093/mnras/staa1466.
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ABSTRACT The Galaxy And Mass Assembly Survey (GAMA) covers five fields with highly complete spectroscopic coverage (>95 per cent) to intermediate depths (r < 19.8 or i < 19.0 mag), and collectively spans 250 deg2 of equatorial or southern sky. Four of the GAMA fields (G09, G12, G15, and G23) reside in the European Southern Observatory (ESO) VST KiDS and ESO VISTA VIKING survey footprints, which combined with our GALEX, WISE, and Herschel data provide deep uniform imaging in the $FUV/NUV/u/g/r/i/Z/Y/J/H/K_s/W1/W2/W3/W4/P100/P160/S250/S350/S500$ bands. Following the release of KiDS DR4, we describe the process by which we ingest the KiDS data into GAMA (replacing the SDSS data previously used for G09, G12, and G15), and redefine our core optical and near-infrared (NIR) catalogues to provide a complete and homogeneous data set. The source extraction and analysis is based on the new ProFound image analysis package, providing matched-segment photometry across all bands. The data are classified into stars, galaxies, artefacts, and ambiguous objects, and objects are linked to the GAMA spectroscopic target catalogue. Additionally, a new technique is employed utilizing ProFound to extract photometry in the unresolved MIR–FIR regime. The catalogues including the full FUV–FIR photometry are described and will be fully available as part of GAMA DR4. They are intended for both standalone science, selection for targeted follow-up with 4MOST, as well as an accompaniment to the upcoming and ongoing radio arrays now studying the GAMA 23h field.
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Mickaelian, Areg M., Hayk V. Abrahamyan, Gurgen M. Paronyan, and Gohar S. Harutyunyan. "Multiwavelength data for bright active galaxies." Proceedings of the International Astronomical Union 7, S284 (September 2011): 237–39. http://dx.doi.org/10.1017/s1743921312009143.
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AbstractThe spectral energy distribution (SED) gives a complete picture of the radiation of space objects and may result in correct classifications compared to those based only on optical (or other local) spectra. This is especially crucial for active galaxies, both AGN and Starbursts (SB). For this, multiwavelength (MW) data are needed taken from available surveys and catalogs. We have cross-correlated the Catalogue of quasars and active galaxies with all-sky or large-area MW catalogues, such as X-ray ROSAT (BSC and FSC), UV GALEX (MIS and AIS), optical APM, MAPS, USNO-B1.0, GSC 2.3.2, and SDSS DR8, NIR 2MASS, MIR/FIR WISE, IRAS (PSC and FSC) and AKARI (IRC and FIS), radio GB6, NVSS, FIRST, and WENSS. We have established accurate positions and photometry for a few thousands of objects that appeared in the catalog with poor data, as well as achieved the best astrometric and photometric data for all objects. This allowed correct cross-correlations and establishing correct MW data for these objects. As a result, we obtained 34 photometric points from X-rays to radio and using VO tools built SEDs for some 10,000 bright objects. Some data from other surveys were also used, such as Chandra, XMM, Spitzer, etc. All objects were grouped into several forms of SED and were compared to the known optical classes given in the catalog (QSO, BLL, Sy1, Sy1.2–1.9, Sy2, LINER, SB, and HII). This allowed reveal obscured AGN, as well as find previously misclassified objects. A homogeneous classification for these objects was established. The first part of this project is presented; establishment of accurate positions and photometry and cross-correlations with MW catalogs.
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Kovács, András, and István Szapudi. "Star–galaxy separation strategies for WISE-2MASS all-sky infrared galaxy catalogues." Monthly Notices of the Royal Astronomical Society 448, no. 2 (February 12, 2015): 1305–13. http://dx.doi.org/10.1093/mnras/stv063.
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Pye, John P. "Results from the ROSAT EUV Wide Field Camera." International Astronomical Union Colloquium 152 (1996): 1–4. http://dx.doi.org/10.1017/s0252921100035661.
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I review some of the major achievements of the ROSAT extreme-ultraviolet all-sky survey, including the results of the recently completed 2RE source catalogue and associated study of temporal variability in EUV sources.
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Żywucka, Natalia, Dorota Koziel-Wierzbowska, and Arti Goyal. "Catalogue with visual morphological classification of 32,616 radio galaxies with optical hosts." Proceedings of the International Astronomical Union 15, S356 (October 2019): 361–63. http://dx.doi.org/10.1017/s174392132000335x.
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AbstractWe present the catalogue of Radio sources associated with Optical Galaxies and having Unresolved or Extended morphologies I (ROGUE I). It was generated by cross-matching galaxies from the Sloan Digital Sky Survey Data Release 7 (SDSS DR 7) as well as radio sources from the First Images of Radio Sky at Twenty Centimetre (FIRST) and the National Radio Astronomical Observatory VLA Sky Survey (NVSS) catalogues. We created the largest handmade catalogue of visually classified radio objects and associated with them optical host galaxies, containing 32,616 galaxies with a FIRST core within 3 arcsec of the optical position. All listed objects possess the good quality SDSS DR 7 spectra with the signal-to-noise ratio > 10 and spectroscopic redshifts up to z = 0.6. The radio morphology classification was performed by a visual examination of the FIRST and the NVSS contour maps overlaid on a DSS image, while an optical morphology classification was based on the 120 arcsec snapshot images from SDSS DR 7.The majority of radio galaxies in ROGUE I, i.e. ∼ 93%, are unresolved (compact or elongated), while the rest of them exhibit extended morphologies, such as Fanaroff-Riley (FR) type I, II, and hybrid, wide-angle tail, narrow-angle tail, head-tail sources, and sources with intermittent or reoriented jet activity, i.e. double–double, X–shaped, and Z–shaped. Most of FR IIs have low radio luminosities, comparable to the luminosities of FR Is. Moreover, due to visual check of all radio maps and optical images, we were able to discover or reclassify a number of radio objects as giant, double–double, X–shaped, and Z–shaped radio galaxies. The presented sample can serve as a database for training automatic methods of identification and classification of optical and radio galaxies.
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Knowles, Kenda, Sinah Manaka, Michael F. Bietenholz, William D. Cotton, Matthew Hilton, Konstantinos Kolokythas, S. Ilani Loubser, and Nadeem Oozeer. "Searching for High-z Radio Galaxies with the MGCLS." Galaxies 9, no. 4 (November 2, 2021): 89. http://dx.doi.org/10.3390/galaxies9040089.
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We present the results from a search for high-redshift radio galaxy (HzRG) candidates using 1.28 GHz data in the Abell 2751 field drawn from the MeerKAT Galaxy Cluster Legacy Survey (MGCLS). We used the HzRG criteria that a radio source is undetected in all-sky optical and infrared catalogues and that it has a very steep radio spectrum. We used the likelihood ratio method for cross-matching the radio catalogue against multi-wavelength galaxy catalogues from the Dark Energy Camera Legacy Survey (DECaLS) and the All-sky Wide Infrared Survey Explorer (AllWISE). For those radio sources with no multi-wavelength counterpart, we further implemented a radio spectral index criterium of α<−1, using in-band spectral index measurements from the wide-band MeerKAT data. Using a 5σ signal-to-noise cut on the radio flux densities, we found a total of 274 HzRG candidates: 179 ultra-steep spectrum sources and 95 potential candidates, which could not be ruled out as they had no spectral information available. The spectral index assignments in this work were complete above a flux density of 0.3 mJy, which is at least an order of magnitude lower than existing studies in this frequency range or when extrapolating from lower frequency limits. Our faintest HzRG candidates with and without an in-band spectral index measurement had a 1.28 GHz flux density of 57 ± 8 μJy and 68 ± 13 μJy, respectively. Although our study is not complete down to these flux densities, our results indicate that the sensitivity and bandwidth of the MGCLS data make them a powerful radio resource to search for HzRG candidates in the Southern sky, with 20 of the MGCLS pointings having similar image quality as the Abell 2751 field and full coverage in both DECaLS and AllWISE. Data at additional radio frequencies will be needed for the faintest source populations, which could be provided in the near future by the MeerKAT UHF band (580–1015 MHz) at a similar resolution (∼8–10″).
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Barghini, D., D. Gardiol, A. Carbognani, and S. Mancuso. "Astrometric calibration for all-sky cameras revisited." Astronomy & Astrophysics 626 (June 2019): A105. http://dx.doi.org/10.1051/0004-6361/201935580.
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Context. Several fireball networks deploy all-sky cameras for the observation of bright meteors and bolides. Because the field is heavily distorted, a dedicated astrometric reduction is needed. A precise computation of the astrometric solution is essential to determine reliable orbital elements of the parent body and to recover possible fragments on ground. Aims. The purpose of this article is to assess the astrometric performances of this type of instruments, which is characterized by a wide field of view and small apertures. The currently available parametric models show a high level of complexity and generally suffer from parameter crosstalk and local minimum confinement if the initial estimates are not precisely provided. We address these issues here and propose a solution by adopting a new explicit parametrisation. Methods. The mismatch between the optical axis and the local zenith direction requires a geometric description that includes two centres of symmetry that lie very close to each other on the focal plane, causing an unreliable estimate of the related parameters. The introduction of new physical coordinates overcomes these issues, allowing a direct and independent estimation. We assessed the performances of different centroiding algorithms in the experimental conditions of an undersampled point spread function of reference stars and saturated bolides on video records. We implemented the algorithm for an automatic identification of bright sources on calibration frames and subsequent correlation with catalogue positions using astrometric projections of increasing complexity. Results. The algorithm and the new parametrisation of the astrometric solution are tested against real data from the PRISMA Italian fireball network and ensure good convergence properties for all cameras we tested so far. By processing astrometric data with a few months’ statistics, we can achieve a random projection indeterminacy of the order of 10 arcsec, which is negligible with respect to single measurement errors on the bolide position.
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McGale, P. A., D. J. Allan, C. R. Barber, D. Bertram, M. Denby, C. G. Page, J. P. Pye, et al. "The ROSAT Wide Field Camera all-sky survey of extreme-ultraviolet sources — The 2RE source catalogue." Advances in Space Research 16, no. 3 (January 1995): 69–72. http://dx.doi.org/10.1016/0273-1177(95)00046-h.
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Pounds, K. A., D. J. Allan, C. Barber, M. A. Barstow, D. Bertram, G. Branduardi-Raymont, G. E. C. Brebner, et al. "The ROSAT Wide Field Camera all-sky survey of extreme-ultraviolet sources – I. The Bright Source Catalogue." Monthly Notices of the Royal Astronomical Society 260, no. 1 (January 1993): 77–102. http://dx.doi.org/10.1093/mnras/260.1.77.
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Bilir, S., S. Karaali, N. D. Dağtekin, Ö. Önal, S. Ak, T. Ak, and A. Cabrera-Lavers. "Transformations from WISE to 2MASS, SDSS and BVI Photometric Systems: II. Transformation Equations for Red-Clump Stars." Publications of the Astronomical Society of Australia 29, no. 2 (2012): 121–31. http://dx.doi.org/10.1071/as11078.
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AbstractWe present colour transformations for the conversion of Wide-Field Survey Explorer W1, W2, and W3 magnitudes to the Johnson–Cousins BVIc, Sloan Digital Sky Survey gri, and Two Micron All Sky Survey JHKs photometric systems, for red clump (RC) stars. RC stars were selected from the Third Radial Velocity Experiment Data Release. The apparent magnitudes were collected by matching the coordinates of this sample with different photometric catalogues. The final sample (355 RC stars) was used to obtain metallicitydependent and free-of-metallicity transformations. These transformations combined with known absolute magnitudes at shorter wavelengths can be used in space density determinations for the Galactic (thin and thick) discs at distances larger than the ones evaluated with JHKs photometry alone, hence providing a powerful tool in the analysis of Galactic structure.
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Duncan, Kenneth J. "All-purpose, all-sky photometric redshifts for the Legacy Imaging Surveys Data Release 8." Monthly Notices of the Royal Astronomical Society 512, no. 3 (March 8, 2022): 3662–83. http://dx.doi.org/10.1093/mnras/stac608.
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ABSTRACT In this paper, we present photometric redshift (photo-z) estimates for the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys, currently the most sensitive optical survey covering the majority of the extragalactic sky. Our photo-z methodology is based on a machine-learning approach, using sparse Gaussian processes augmented with Gaussian mixture models (GMMs) that allow regions of parameter space to be identified and trained separately in a purely data-driven way. The same GMMs are also used to calculate cost-sensitive learning weights that mitigate biases in the spectroscopic training sample. By design, this approach aims to produce reliable and unbiased predictions for all parts of the parameter space present in wide area surveys. Compared to previous literature estimates using the same underlying photometry, our photo-zs are significantly less biased and more accurate at z > 1, with negligible loss in precision or reliability for resolved galaxies at z < 1. Our photo-z estimates offer accurate predictions for rare high-value populations within the parent sample, including optically selected quasars at the highest redshifts (z > 6), as well as X-ray or radio continuum selected populations across a broad range of flux (densities) and redshift. Deriving photo-z estimates for the full Legacy Imaging Surveys Data Release 8, the catalogues provided in this work offer photo-z estimates predicted to be of high quality for ≳9 × 108 galaxies over ${\sim}19\, 400\, \text{deg}^{2}$ and spanning 0 < z ≲ 7, offering one of the most extensive samples of redshift estimates ever produced.
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Kovlakas, K., A. Zezas, J. J. Andrews, A. Basu-Zych, T. Fragos, A. Hornschemeier, K. Kouroumpatzakis, B. Lehmer, and A. Ptak. "The Heraklion Extragalactic Catalogue (HECATE): a value-added galaxy catalogue for multimessenger astrophysics." Monthly Notices of the Royal Astronomical Society 506, no. 2 (June 25, 2021): 1896–915. http://dx.doi.org/10.1093/mnras/stab1799.
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ABSTRACT We present the Heraklion Extragalactic Catalogue, or HECATE, an all-sky value-added galaxy catalogue, aiming to facilitate present and future multiwavelength and multimessenger studies in the local Universe. It contains 204 733 galaxies up to a redshift of 0.047 (D${\lesssim }200\, \text{Mpc}{}$), and it is >50 per cent complete in terms of the B-band luminosity density at distances in the 0–170 Mpc range. By incorporating and homogenizing data from astronomical data bases and multiwavelength surveys, the catalogue offers positions, sizes, distances, morphological classifications, star formation rates, stellar masses, metallicities, and nuclear activity classifications. This wealth of information can enable a wide range of applications, such as (i) demographic studies of extragalactic sources, (ii) initial characterization of transient events, and (iii) searches for electromagnetic counterparts of gravitational-wave events. The catalogue is publicly available to the community at a dedicated portal, which will also host future extensions in terms of the covered volume and data products.
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Saxton, Richard D. "The Role of Wide Field X-ray Surveys in Astronomy." Proceedings of the International Astronomical Union 10, H16 (August 2012): 669–70. http://dx.doi.org/10.1017/s1743921314012824.
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AbstractWe review the history of X-ray sky surveys from the early experiments to the catalogues of 105 sources produced by ROSAT, Chandra and XMM-Newton. At bright fluxes the X-ray sky is shared between stars, accreting binaries and extragalactic sources while deeper surveys are dominated by AGN and clusters of galaxies. The X-ray background, found by the earliest missions, has been largely resolved into discrete sources at soft (0.3-2 keV) energies but at higher energies an important fraction still escapes detection. The possible identification of the missing flux with Compton-thick AGN has been probed in recent years by Swift and Integral.Variability seen in objects observed at different epochs has proved to be an excellent discriminator for rare classes of objects. The comparison of ROSAT All Sky Survey (RASS) and ROSAT pointed observations identified several Novae and high variability AGN as well as initiating the observational study of Tidal Disruption events. More recently the XMM-Newton slew survey, in conjunction with archival RASS data, has detected further examples of flaring objects which have been followed-up in near-real time at other wavelengths.
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Ivanov, G. A., V. S. Kislyuk, L. K. Pakulyak, A. V. Sergeev, T. P. Sergeeva, and A. I. Yatsenko. "New Measurements of Positions for the Astrographic Catalogue Stars." Symposium - International Astronomical Union 166 (1995): 356. http://dx.doi.org/10.1017/s0074180900228398.
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Six observatories of the former USSR carry out photographic observations within the FON project (the fourfold coverage of the northern sky) since 1982. The same type wide-angle Zeiss astrographs (D=400 mm, F=2000 and 3000 mm) are used. At present Golosiiv Observatory almost finished the Kiev observational part of the project and the measurements of onefold coverage plates have been started. The special measuring machine PARSEC (Programming Automatic Radial-Scanning Coordinatometer) has recently been constructed for this purpose.We intend to apply the measurements of the FON project plates to the determination of new positions and proper motions of all stars in the Astrographic Catalogue (AC) using the last one as the first epoch of observations. AC is applied also as input catalogue for PARSEC. About 500 plates have been measured at the moment and proper motions for more than 500000 stars in different areas of the northern sky have been obtained.The accuracy of the FON positions and proper motions of stars from the measurements of onefold coverage plates is estimated to be 0.35 arcsec and 0.006 arcsec/yr, respectively.Futher investigations will be carried out in cooperation with Sternberg Astronomical Institute (Moscow, Russia) and Astronomisches Rechen-Institut (Heidelberg, Germany).The above-described reasearches became possible partly by Grant N V41000 from the International Science Foundation.
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Cannon, Russell. "High Density Requirements." Highlights of Astronomy 11, no. 1 (1998): 297–99. http://dx.doi.org/10.1017/s1539299600020797.
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I will consider here some practical astrometric requirements, from the perspective of an optical astronomer working on objects much fainter than the limits of the primary catalogues, i.e., from 15 mag down to 20 mag and fainter. I take ‘high density’ to mean surface densities of order 100 or more stars per square degree; these two criteria are roughly equivalent (Bahcall & Soneira, 1980). The positions of such objects are routinely available to an accuracy of around 0.5-1.0 arcsec, e.g. from various digitised versions of the Schmidt Telescope photographic sky surveys. However, these sky surveys themselves readily yield internal accuracies at the 0.1 arcsec level, as demonstrated by repeated measures of the same plates. The problem is that the discrepancies can be ten times larger than this when different machines or plates are used, when a wide magnitude range is covered, when relative positions are compared over distances of a degree or more, or when absolute positions are needed for comparison with, say, radio catalogues. The challenge now is to improve this accuracy; we should to be able to specify the absolute positions of all well-defined optical objects to better than 250 mas, anywhere in the sky, at any epoch and regardless of magnitude or colour.
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Pryer, Dan, Robert E. Smith, Robin Booth, Chris Blake, Alexander Eggemeier, and Jon Loveday. "The galaxy power spectrum on the lightcone: deep, wide-angle redshift surveys and the turnover scale." Journal of Cosmology and Astroparticle Physics 2022, no. 08 (August 1, 2022): 019. http://dx.doi.org/10.1088/1475-7516/2022/08/019.
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Abstract We derive expressions for the survey-window convolved galaxy power spectrum in real space for a full sky and deep redshift survey, but taking into account the geometrical lightcone effect. We investigate the impact of using the standard mean redshift approximation as a function of survey depth, and show that this assumption can lead to both an overall amplitude suppression and scale-dependent error when compared to the 'true' spectrum. However, we also show that by using a carefully chosen 'effective fixed-time', one can find a range of scales where the approximation to the full model is highly accurate, but only on a more restricted set of scales. We validate the theory by constructing dark matter and galaxy lightcone mock surveys from a large N-body simulation with a high cadence of snapshots. We do this by solving the light cone equation exactly for every particle, where the particle worldlines are obtained in a piecewise fashion with cubic interpolation between neighbouring snapshots. We find excellent agreement between our measurements and the theory (∼ ±5%) over scales (0.004 h Mpc-1 ≤ k ≤ 0.54 h Mpc-1) and for a variety of magnitude limits. Finally, we look to see how accurately we can measure the turnover scale of the galaxy power spectrum k 0. Using the lightcone mocks we show that one can detect the turnover scale with a probability P ≥ 95% in an all-sky catalogue limited to an apparent magnitude m lim ∼ 21. We also show that the detection significance would remain high for surveys with m lim ∼ 22 and 20% sky coverage.
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Reid, I. N. "Photographic Sky Surveys." Symposium - International Astronomical Union 179 (1998): 41–48. http://dx.doi.org/10.1017/s0074180900128190.
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Photographic surveys have played a vital role in virtually every area of astronomical research over the last 50 years. Indeed, one can make a strong case that Schmidt telescopes in general, and the Palomar 48-inch Schmidt in particular, have made the most substantial contribution to our understanding of the Universe—at least at optical wavelengths. The all-sky atlases compiled since the initiation of the POSS I O/E survey in 1949 will continue to provide fundamental reference catalogues and potent research tools for many years to come (for our children's children's children), particularly when combined with the second epoch surveys currently under way. However, as far as undertaking new, large-scale sky surveys are concerned, it is clear that we have reached the end of an era. Alternative detector technology and new instrumentation (i.e., CCD mosaics) can now match and, indeed, exceed the capabilities of the photographic Schmidt telescopes in undertaking effective wide-field photometric surveys.In this review, I report on the progress being made in completing the all-hemisphere photographic surveys currently being undertaken from Siding Spring with the UK Schmidt and from Palomar with the Oschin Schmidt. I also provide a summary of the availability of machine scans and/or object catalogues derived from the various surveys. Photographic survey work is not confined to these atlases, however, and section 3 provides discussion of other more specialised projects currently being undertaken. Finally, I consider the future possibilities for photographic Schmidt surveys.
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Koulouridis, E., N. Clerc, T. Sadibekova, M. Chira, E. Drigga, L. Faccioli, J. P. Le Fèvre, et al. "The X-CLASS survey: A catalogue of 1646 X-ray-selected galaxy clusters up to z ∼ 1.5." Astronomy & Astrophysics 652 (August 2021): A12. http://dx.doi.org/10.1051/0004-6361/202140566.
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Context. Cosmological probes based on galaxy clusters rely on cluster number counts and large-scale structure information. X-ray cluster surveys are well suited for this purpose because they are far less affected by projection effects than optical surveys, and cluster properties can be predicted with good accuracy. Aims. The XMM Cluster Archive Super Survey, X-CLASS, is a serendipitous search of X-ray-detected galaxy clusters in 4176 XMM-Newton archival observations until August 2015. All observations are clipped to exposure times of 10 and 20 ks to obtain uniformity, and they span ∼269 deg2 across the high-Galactic latitude sky (|b| > 20°). The main goal of the survey is the compilation of a well-selected cluster sample suitable for cosmological analyses. Methods. We describe the detection algorithm, the visual inspection, the verification process, and the redshift validation of the cluster sample, as well as the cluster selection function computed by simulations. We also present the various metadata that are released with the catalogue, along with two different count-rate measurements, an automatic one provided by the pipeline, and a more detailed and accurate interactive measurement. Furthermore, we provide the redshifts of 124 clusters obtained with a dedicated multi-object spectroscopic follow-up programme. Results. With this publication, we release the new X-CLASS catalogue of 1646 well-selected X-ray-detected clusters over a wide sky area, along with their selection function. The sample spans a wide redshift range, from the local Universe up to z ∼ 1.5, with 982 spectroscopically confirmed clusters, and over 70 clusters above z = 0.8. The redshift distribution peaks at z ∼ 0.1, while if we remove the pointed observations it peaks at z ∼ 0.3. Because of its homogeneous selection and thorough verification, the cluster sample can be used for cosmological analyses, but also as a test-bed for the upcoming eROSITA observations and other current and future large-area cluster surveys. It is the first time that such a catalogue is made available to the community via an interactive database which gives access to a wealth of supplementary information, images, and data.
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Shirley, Raphael, Yannick Roehlly, Peter D. Hurley, Veronique Buat, María del Carmen Campos Varillas, Steven Duivenvoorden, Kenneth J. Duncan, et al. "HELP: a catalogue of 170 million objects, selected at 0.36–4.5 μm, from 1270 deg2 of prime extragalactic fields." Monthly Notices of the Royal Astronomical Society 490, no. 1 (September 10, 2019): 634–56. http://dx.doi.org/10.1093/mnras/stz2509.
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ABSTRACT We present an optical to near-infrared (NIR) selected astronomical catalogue covering 1270 deg2. This is the first attempt to systematically combine data from 23 of the premier extragalactic survey fields – the product of a vast investment of telescope time. The fields are those imaged by the Herschel Space Observatory that form the Herschel Extragalactic Legacy Project (HELP). Our catalogue of 170 million objects is constructed by a positional cross-match of 51 public surveys. This high-resolution optical, NIR, and mid-infrared catalogue is designed for photometric redshift estimation, extraction of fluxes in lower resolution far-infrared maps, and spectral energy distribution modelling. It collates, standardizes, and provides value added derived quantities including corrected aperture magnitudes and astrometry correction over the Herschel extragalactic wide fields for the first time. $grizy$ fluxes are available on all fields with g-band data reaching $5\sigma$ point-source depths in a 2 arcsec aperture of 23.5, 24.4, and 24.6 (AB) mag at the 25th, 50th, and 75th percentiles, by area covered, across all HELP fields. It has K or $K_s$ coverage over 1146 deg2 with depth percentiles of 20.2, 20.4, and 21.0 mag, respectively. The IRAC Ch 1 band is available over 273 deg2 with depth percentiles of 17.7, 21.4, and 22.2 mag, respectively. This paper defines the ‘masterlist’ objects for the first data release (DR1) of HELP. This large sample of standardized total and corrected aperture fluxes, uniform quality flags, and completeness measures provides large well-understood statistical samples over the full Herschel extragalactic sky.
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Shamir, Lior, and Robert J. Nemiroff. "A Fuzzy Logic Based Algorithm for Finding Astronomical Objects in Wide-Angle Frames." Publications of the Astronomical Society of Australia 22, no. 2 (2005): 111–17. http://dx.doi.org/10.1071/as04072.
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AbstractAccurate automatic identification of astronomical objects in an imperfect world of non-linear wide-angle optics, imperfect optics, inaccurately pointed telescopes, and defect-ridden cameras is not always a trivial first step. In the past few years, this problem has been exacerbated by the rise of digital imaging, providing vast digital streams of astronomical images and data. In the modern age of increasing bandwidth, human identifications are many times impracticably slow. In order to perform an automatic computer-based analysis of astronomical frames, a quick and accurate identification of astronomical objects is required. Such identification must follow a rigorous transformation from topocentric celestial coordinates into image coordinates on a CCD frame. This paper presents a fuzzy logic based algorithm that estimates needed coordinate transformations in a practical setting. Using a training set of reference stars, the algorithm statically builds a fuzzy logic model. At runtime, the algorithm uses this model to associate stellar objects visible in the frames to known cataloged objects, and generates files that contain photometry information of objects visible in the frame. Use of this algorithm facilitates real-time monitoring of stars and bright transients, allowing identifications and alerts to be issued more reliably. The algorithm is being implemented by the Night Sky Live all-sky monitoring global network and has shown itself significantly more reliable than the previously used non-fuzzy logic algorithm.
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Keeling, Jeffrey James. "An annotated vascular flora and floristic analysis of the southern half of the Nature Conservancy Davis Mountains Preserve, Jeff Davis County, Texas, U.S.A." Journal of the Botanical Research Institute of Texas 11, no. 2 (November 29, 2017): 563–618. http://dx.doi.org/10.17348/jbrit.v11.i2.1091.
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The Nature Conservancy Davis Mountains Preserve (DMP) is located 40 km northwest of Fort Davis, Texas, in the northeastern region of the Chihuahuan Desert and consists of some of the most complex topography of the Davis Mountains, including their summit, Mount Livermore, at 8378 ft (2554 m). The cool, temperate, "sky island" ecosystem caters to the requirements that are needed to accommodate a wide range of unique diversity, endemism, and vegetation patterns, including desert grasslands and montane savannahs. The current study began in May of 2011 and aimed to catalogue the entire vascular flora of the 18,360 acres of Nature Conservancy property south of Highway 118 and directly surrounding Mount Livermore. Previous botanical investigations are presented, as well as biogeographic relationships of the flora. The numbers from herbaria searches and from the recent field collections combine to a total of 2,153 voucher specimens, representing 483 species and infraspecies, 287 genera, and 87 families. The best-represented families are Asteraceae (89 species, 18.4% of the total flora), Poaceae (76 species, 15.7% of the total flora), and Fabaceae (21 species, 4.3% of the total flora). The current study represents a 25.44% increase in vouchered specimens and a 9.7% increase in known species from the study area’s 18,360 acres and describes four endemic and fourteen non-native species (four invasive) on the property. The subsequent analysis of the results, compared to those of previous regional-flora catalogues, presents the flora of the DMP as one that is unique to the higher elevations and igneous substrates of western Texas and the northern Chihuahuan Desert. Multiple influences from overlapping and neighboring ecoregions, including the Great Plains, Madrean, and Sonoran provinces, are all seen to have varying degrees of authority in regards to the shaping of the modern-day vegetation.
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Driver, Simon P. "The GAMA Panchromatic Survey." Proceedings of the International Astronomical Union 8, S295 (August 2012): 155–58. http://dx.doi.org/10.1017/s1743921313004559.
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AbstractThe Galaxy And Mass Assembly Survey (GAMA) has now been operating for almost 5 years gathering spectroscopic redshifts for five regions of sky spanning 300 sq degrees in total to a depth of r < 19.8 mag. The survey has amassed over 225,000 redshifts making it the third largest redshift campaign after the SDSS and BOSS surveys. The survey has two novel features that set it apart: (1) complete and uniform sampling to a fixed flux limit (r < 19.8 mag) regardless of galaxy clustering due to multiple-visits to each sky region, enabling the construction of high-fidelity catalogues of groups and pairs, (2) co-ordination with diverse imaging campaigns which together sample an extremely broad range along the electro-magnetic spectrum from the UV (GALEX) through optical (VST KIDs), near-IR (VISTA VIKING), mid-IR (WISE), far-IR (Herschel-Atlas), 1m (GMRT), and eventually 20cm continuum and rest-frame 21cm line measurements (ASKAP DINGO). Apart from the ASKAP campaign all multi-wavelength programmes are either complete or in the final stages of observations and the UV-far-IR data are expected to be fully merged by the end of 2013. This article provides a brief flavour of the coming panchromatic database which will eventually include measurements or upper-limits across 27 wavebands for 380,000 galaxies. GAMA DR2 is scheduled for the end of January 2013.
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Krivonos, R., V. Arefiev, I. Lapshov, E. Filippova, R. Burenin, A. Semena, S. Grebenev, et al. "Wide-field X-ray observations of the supernova remnant Puppis A with the SRG/ART-XC telescope." Monthly Notices of the Royal Astronomical Society 510, no. 3 (December 16, 2021): 3113–18. http://dx.doi.org/10.1093/mnras/stab3647.
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ABSTRACT The Spectrum-Roentgen-Gamma (SRG) observatory is currently conducting its 4-yr all-sky X-ray survey, started on 2019 December 12. The survey is periodically interrupted for technological operations with the spacecraft. These time intervals are usually used by the Mikhail Pavlinsky ART-XC telescope to perform calibrations. In this context, SRG carried out scanning observations of the Puppis A supernova remnant (SNR) with the aim to check the imaging performance of ART-XC and to optimize the technique of image reconstruction for extended objects. Using the unique imaging capabilities of ART-XC and its uniform coverage of the entire Puppis A region, we attempted to investigate the morphology of this SNR at energies ≳ 4 keV, and to search for previously unknown X-ray sources. Puppis A was observed in 2019–2020, conducting 1.5° × 1.5° shallow surveys with an exposure of 36 h. Additional deep pointed observations of the central part of Puppis A were carried out in 2021 lasted 31 h to highlight the morphology of the extended emission. The X-ray emission of the Puppis A was significantly detected as an extended structure in the 4–6 keV energy band. The morphology of the emission is in general agreement with that observed in soft X-rays previously. The deep sky image of Puppis A obtained with the ART-XC telescope is characterized by a typical SNR shell rim morphology, an extended emission and a bright emission knot in the north-eastern part of the supernova shell. Also, four point X-ray sources have been detected, including three objects identified in catalogues, and one newly discovered X-ray emitter.
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Barclay, T. "The Space-Based Photometry Revolution." Proceedings of the International Astronomical Union 14, S339 (November 2017): 21. http://dx.doi.org/10.1017/s1743921318002120.
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AbstractThe Transiting Exoplanet Survey Satellite (TESS) is a NASA Astrophysics Explorer-class mission that will perform an all-sky survey to search for planets transiting nearby bright stars. The primary goal is to search for planets smaller than Neptune that are amenable to follow-up spectroscopic observations that will yield planet masses, thereby providing prime targets for future atmospheric characterization studies. In its two-year prime mission, TESS will monitor more than 200,000 stars with four wide-field optical CCD cameras that will tile more than 90% of the sky. TESS will also obtain full-frame images (FFIs) of the entire field of view with a cadence of 30 minutes to facilitate additional science. These FFIs will provide photometry for more than 30 million objects brighter than magnitude I =16 during the two-year prime mission. The TESS legacy will be a catalogue of the nearest and brightest main-sequence stars hosting transiting exoplanets. The TESS Mission will also have a robust Guest Investigator (GI) Programme that will be managed by the TESS Science Support Center at NASA Goddard Space Flight Center. Under the GI programme, the astrophysics community may propose new 2-minute cadence targets and investigations using the 30-minute cadence FFI data. TESS GI calls for proposals will occur once per year, and about 20,000 targets will be available for each GI programme cycle.TESS was launched in April 2018, and will observe from a unique elliptical high-Earth orbit that will provide an unobstructed view of its field to obtain continuous light-curves.
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Piskunov, A. E., A. Just, N. V. Kharchenko, P. Berczik, R. D. Scholz, S. Reffert, and S. X. Yen. "Global survey of star clusters in the Milky Way." Astronomy & Astrophysics 614 (June 2018): A22. http://dx.doi.org/10.1051/0004-6361/201732337.
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Context. The all-sky Milky Way Star Clusters (MWSC) survey provides uniform and precise ages, along with other relevant parameters, for a wide variety of clusters in the extended solar neighbourhood. Aims. In this study we aim to construct the cluster age distribution, investigate its spatial variations, and discuss constraints on cluster formation scenarios of the Galactic disk during the last 5 Gyrs. Methods. Due to the spatial extent of the MWSC, we have considered spatial variations of the age distribution along galactocentric radius RG, and along Z-axis. For the analysis of the age distribution we used 2242 clusters, which all lie within roughly 2.5 kpc of the Sun. To connect the observed age distribution to the cluster formation history we built an analytical model based on simple assumptions on the cluster initial mass function and on the cluster mass-lifetime relation, fit it to the observations, and determined the parameters of the cluster formation law. Results. Comparison with the literature shows that earlier results strongly underestimated the number of evolved clusters with ages t ≳ 100 Myr. Recent studies based on all-sky catalogues agree better with our data, but still lack the oldest clusters with ages t ≳ 1 Gyr. We do not observe a strong variation in the age distribution along RG, though we find an enhanced fraction of older clusters (t > 1 Gyr) in the inner disk. In contrast, the distribution strongly varies along Z. The high altitude distribution practically does not contain clusters with t < 1 Gyr. With simple assumptions on the cluster formation history, the cluster initial mass function and the cluster lifetime we can reproduce the observations. The cluster formation rate and the cluster lifetime are strongly degenerate, which does not allow us to disentangle different formation scenarios. In all cases the cluster formation rate is strongly declining with time, and the cluster initial mass function is very shallow at the high mass end.
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de Gasperin, F., W. L. Williams, P. Best, M. Brüggen, G. Brunetti, V. Cuciti, T. J. Dijkema, et al. "The LOFAR LBA Sky Survey." Astronomy & Astrophysics 648 (April 2021): A104. http://dx.doi.org/10.1051/0004-6361/202140316.
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Context. The LOw Frequency ARray (LOFAR) is the only radio telescope that is presently capable of high-sensitivity, high-resolution (i.e. < 1 mJy beam−1 and < 15″) observations at ultra-low frequencies (< 100 MHz). To utilise these capabilities, the LOFAR Surveys Key Science Project is undertaking a large survey to cover the entire northern sky with Low Band Antenna (LBA) observations. Aims. The LOFAR LBA Sky Survey (LoLSS) aims to cover the entire northern sky with 3170 pointings in the frequency range between 42 − 66 MHz, at a resolution of 15″ and at a sensitivity of 1 mJy beam−1 (1σ). In this work, we outline the survey strategy, the observational status, and the calibration techniques. We also briefly describe several of our scientific motivations and present the preliminary public data release. Methods. The preliminary images were produced using a fully automated pipeline aimed at correcting all direction-independent effects in the data. Whilst the direction-dependent effects, such as those from the ionosphere, have not yet been corrected, the images presented in this work are still ten times more sensitive than previous available surveys at these low frequencies. Results. The preliminary data release covers 740 deg2 around the HETDEX spring field region at an angular resolution of 47″ with a median noise level of 5 mJy beam−1. The images and the catalogue of 25 247 sources have been publicly released. We demonstrate that the system is capable of reaching a root mean square (rms) noise of 1 mJy beam−1 and an angular resolution of 15″ once direction-dependent effects are accounted for. Conclusions. LoLSS will provide the ultra-low-frequency information for hundreds of thousands of radio sources, providing critical spectral information and producing a unique data set that can be used for a wide range of science topics, such as the search for high redshift galaxies and quasars, the study of the magnetosphere of exoplanets, and the detection of the oldest populations of cosmic-rays in galaxies, clusters of galaxies, as well as those produced by active galactic nuclei.
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Szécsényi-Nagy, Gábor. "On the Applicability of Fibre-Fed Multi-Object Spectrographs in Flare Star Research." International Astronomical Union Colloquium 148 (1995): 85–89. http://dx.doi.org/10.1017/s0252921100021758.
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AbstractThe use of optical fibres has recently allowed the full field of some Schmidt telescopes to be accessed for multi-object spectroscopy. The new device: the MOS (multi-object spectrograph) is to revolutionize the field of astronomical spectroscopy. Cosmic objects grouped into aggregates having apparent angular diameters of 1 to 6 degrees and similar apparent brightness in the visual or near infrared spectral range are to be the most probable future targets of MOSs. Flare stars — as it has been demonstrated convincingly by various authors (see Szecsenyi-Nagy 1986, and references therein) — are the most abundant type of variable stars but because of their low luminosity and relatively late discovery we have only very limited amount of spectroscopic data about most of these objects. It is a real bonanza that most of the catalogued flare stars are associated with young open clusters and this fact of course suggests them as really promising targets for wide-field Schmidt cameras equipped with MOSs. In an average open cluster scrutinized for its flare star members some dozen or some hundred representatives of this species are known which are distributed over a sky field of 10–20 square degrees. Fortunately, they are never packed into unresolvable concentrations and even short focal length cameras are able to produce separate images of all cluster member flare stars for an accurate photographic photometry of the objects. The apparent visual brightness of these stars most often fits a 5–7 magnitude range. This seems to be profitable also for the effectiveness of using fibre-fed MOSs in flare star spectroscopy. The first steps of such a program should be the study of radial velocities and the comparison of the measured values with the accepted radial velocity of the cluster. These measurements could provide new and independent arguments for (or against?) the cluster membership of the flare stars observed in the fields of catalogued open clusters. Later, more detailed spectral studies should collect information about the time dependent features of the spectra of flare stars.
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Akras, Stavros, Lizette Guzman-Ramirez, and Denise R. Gonçalves. "Compact planetary nebulae: improved IR diagnostic criteria based on classification tree modelling." Monthly Notices of the Royal Astronomical Society 488, no. 3 (July 11, 2019): 3238–50. http://dx.doi.org/10.1093/mnras/stz1911.
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Abstract Planetary nebulae (PNe) are strong H α line emitters and a lot of new PNe discoveries have been made by the SuperCOSMOS AAO/UKST H α Survey (SHS) and the Isaac Newton Telescope Photometric H α Survey (IPHAS). However, their resulting list of candidates turned out to be heavily contaminated from H α-line mimics like young stellar objects (YSOs) and/or H ii regions. The aim of this work is to find new infrared criteria that can better distinguish compact PNe from their mimics using a machine learning approach and the photometric data from the Two-Micron All-Sky Survey and Wide-field Infrared Survey Explorer. Three classification tree models have been developed with the following colour criteria: W1 − W4 ≥ 7.87 and J − H < 1.10; H − W2 ≥ 2.24 and J − H < 0.50; and Ks− W3 ≥ 6.42 and J − H < 1.31 providing a list of candidates, characterized by a high probability to be genuine PNe. The contamination of this list of candidates from H α mimics is low but not negligible. By applying these criteria to the IPHAS list of PN candidates and the entire IPHAS and VPHAS+ DR2 catalogues, we find 141 sources, from which 92 are known PNe, 39 are new very likely compact PNe (without an available classification or uncertain) and 10 are classified as H ii regions, Wolf–Rayet stars, AeBe stars, and YSOs. The occurrence of false-positive identifications in this technique is between 10 and 15 per cent.
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Fernandez, L., M. M. Cueli, J. González-Nuevo, L. Bonavera, D. Crespo, J. M. Casas, and A. Lapi. "Galaxy cluster mass density profile derived using the submillimetre galaxies magnification bias." Astronomy & Astrophysics 658 (January 26, 2022): A19. http://dx.doi.org/10.1051/0004-6361/202141905.
Full textAbstract:
Context. The magnification bias is a gravitational lensing effect that produces an increase or decrease in the detection probability of background sources near the position of a lense. The special properties of the submillimetre galaxies (SMGs; steep source number counts, high redshift, and a very low cross-contamination with respect to the optical band) makes them the optimal background sample for magnification bias studies. Aims. We want to study the average mass density profile of tens to hundreds of clusters of galaxies acting as lenses that produce a magnification bias on the SMGs, and to estimate their associated masses and concentrations for different richness ranges. The cluster richness is defined as R = L200/L* with L200 as the total r-band luminosity within the radius r200. Methods. The background sample is composed of SMGs observed by Herschel with 1.2 < z < 4.0 (mean redshift at ∼2.3) while the foreground sample is made up of galaxy clusters extracted from the Sloan Digital Sky Survey III with photometric redshifts of 0.05 < z < 0.8 (mean redshift at ∼0.38). Measurements are obtained by stacking the SMG–cluster pairs to estimate the cross-correlation function using the Davis-Peebles estimator. This methodology allows us to derive the mass density profile for a wide range of angular scales, ∼2 − 250 arcsec or ∼10 − 1300 kpc for z = 0.38, with a high radial resolution, and in particular to study the inner part of the dark matter halo (< 100 kpc). In addition, we also divide the cluster sample into five bins of richness and we analyse the estimated cross-correlation data using different combinations of the most common theoretical mass density profiles. Results. It is impossible to fit the data with a single mass density profile at all scales: in the inner part there is a clear excess in the mass density profile with respect to the outer part that we interpret as the galactic halo of the big central galaxy. As for the outer part, the estimated average masses increase with richness from M200c = 5.8 × 1013 M⊙ to M200c = 51.5 × 1013 M⊙ (M200c = 7.1 × 1013 M⊙ for the total sample). With respect to the concentration parameter, its average also increases with richness from C = 0.74 to C = 1.74 (C = 1.72 for the total sample). In the small-scale regions, the obtained average masses fluctuate around M200c = 3 − 4 × 1013 M⊙ with average concentration values of around C ∼ 4. Conclusions. The total average masses are in perfect agreement with the mass–richness relationship estimated from the cluster catalogue. In the bins of lowest richness, the central galactic halo constitutes ∼40% of the total mass of the cluster and its relevance decreases for higher richness values. While the estimated average concentration values of the central galactic halos are in agreement with traditional mass–concentration relationships, we find low concentrations for the outer part. Moreover, the concentrations decrease for lower richness values, probably indicating that the group of galaxies cannot be considered to be relaxed systems. Finally, we notice a systematic lack of signal at the transition between the dominance of the cluster halo and the central galactic halo (∼100 kpc). This feature is also present in previous studies using different catalogues and/or methodologies, but is never discussed.
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Goja, Bojan. "Maestro di Pico i iluminacije u inkunabuli De Civitate Dei (Nicolas Jenson, Venecija, 1475.) u samostanu Sv. Duje u Kraju na Pašmanu." Ars Adriatica, no. 4 (January 1, 2014): 235. http://dx.doi.org/10.15291/ars.497.
Full textAbstract:
The Franciscan Monastery of St Domnius at Kraj on the island of Pašman houses an incunable edition of Augustine’s The City of God (De Civitate Dei) which was printed in Venice by Nicolas Jenson in 1475. The incunable features beautiful Renaissance multi-coloured illuminations painted in tempera, sepia, ink and water colours while gold foils and gold dust were used on fol. 17 (the page number is not original but was subsequently added in pencil; this folio contains the beginning of Book 1) and a number of other folios. The illumination on fol. 17 consists of two phytomorphic initials, a decorative border and independent figural scenes while a number of other folios are decorated with phytomorphic initials of the littera notabilior type, the height of which corresponds to two lines, painted in red or blue. The top and left margin of the first page of Book 1 are filled with a decorative border terminating in trilobes on each end. The ornamental scheme of the border consists of a band made up of five thin lines which undulates in a spiral and thus forms circles. These are filled with flowers, leaves and berries painted in blue, green and cyclamen purple but also with gold stylized burdock flowers (Lat. Arctium lappa; some scholars call them gold dots, that is, bottoni dorati). The remaining fields are filled with bent scrolls. In the upper left corner of the frame is a goldfinch. The initial I, composed of phytomorphic motifs in blue, green and cyclamen purple and their shades, is painted against a gold background of the rectangular field situated at the beginning of the text column on the left-hand side. Inside the decorative border, placed at the height which corresponds to the centre of the initial, is a medallion with the bust of St Augustine depicted in the open sky with elongated white clouds and no other details. The illusion of the spatial depth was achieved through the use of tonal gradations: the shades of blue are darker at the top and lighter in the lower half of the sky. St Augustine is dressed in a white robe and a red cloak with a black hood. He is wearing a white mitre with a horizontal and perpendicular band highlighted with gold dust. The shadows and folds of his clothes were articulated with black and white lines. His right hand is pointing to the open book which was painted at the height of his chest. The fingers on his right hand are elongated and thin. St Augustine’s gold nimbus was painted as a full circle the left half of which was outlined in white and the right half in black. St Augustine is directing his gentle and sad gaze upwards. His head is slightly bent. His round and bony head is marked by the large round eyes with prominent sclera and dark circles underneath while the arched eyebrows are thinner at their ends. The nose is small and the mouth is turned downwards. The plasticity of the face and its complexion were articulated with white and pink shades. The trimmed dark beard is depicted with short lines in lighter and darker shades. The ornamental frame which fills the top margin corresponds to the one in the left margin but was decorated more modestly because the miniaturist placed the scroll bearing the printer’s name and the scroll identifying the text as belonging to Book 1 at the centre of the frame which left only the beginning and the end of the frame to be decorated. The scroll with the printer’s name is emphasized by a golden burdock flower at the top of the frame and a golden teasel flower (Lat. Dipsacus fullonum) at the bottom. The lower margin features two symmetrical angels, rendered in a somewhat imprecise drawing, who kneel on the ground painted in the shades of green and brown. The physiognomy of the angels is similar to that of St Augustine. Their round heads have small eyes and noses, shaded circles under the eyes and arched eyebrows. The mouths are depicted as thin lines with pronounced ends and are further accentuated by a dot beneath the lower lip. The plasticity of their faces was achieved through the tonal gradation of pink and white. The angels’ hair, ochre in colour and highlighted with gold dust, is thick and short and covers the tops of their heads like a helmet. The outspread wings were painted in dark and light shades of blue. Two wide red scrolls with white highlights emerge symmetrically from behind the angels at their waist height. Wavy tendrils and gold stylized teasel flowers extend from the red scroll. The angels hold a laurel wreath between them. The colour of the circular field inside the wreath is cyclamen purple. The wreath is formed by three rows of leaves which are bound by four regularly spaced ties. The leaves’ edges and tips were painted in light and dark shades of green. Inside the wreath is a Renaissance crest surrounded by thin white wiggly tendrils with sprouting leaves. The shield, in the shape of a horse’s head, is divided horizontally into the dark blue upper half and the red lower half. It features a gold lion with his mouth wide open who is facing right and holding a tree with his front paws. The tree’s pyramidal top is decorated with small dots indicating leaves and fruit. The shield’s right half is outlined in white and the left one in black. The second text column on the first page of Book 1 is decorated with the painted initial letter G. It consists of phytomorphic motifs in blue, red, yellow and cyclamen purple and their shades. Two small leaves are attached to the initial on its left-hand side. As is the case with the crest, the initial was additionally decorated with elegant white tendrils sprouting leaves and highlighted with gold dust. The background is also gold while the rectangular field around the initial is outlined in a thin black line. Two wavy tendrils and two gold stylized teasel flowers emerge from the corners of the frame on the left-hand side while a green leaf appears at the centre. Apart from these illuminations and initials on fol. 17, the incunable contains other initials, one for the beginning of each of the remaining twenty one book, and all of them consist of blue, green and cyclamen pink phytomorphic motifs painted against a gold background inside a black rectangular frame. The plasticity of these initials was achieved through tonal gradation and the use of yellow while thin white undulating tendrils with variations in width and highlights in gold dust enriched the decoration. Some sentences in the text were emphasized by numerous initials in red or blue of the littera notabilior type the height of which corresponds to two lines of the text. The illuminations of this incunable edition of the De Civitate Dei belong to north Italian or Venetian Renaissance painting and they demonstrate numerous significant similarities with the works of the well-known Venetian miniaturist whom the scholarly literature identified as Maestro del Plinio di Giovanni Pico della Mirandola (Maestro del Plinio di Pico or, more commonly, Maestro di Pico). The attribution of the illuminations in this incunable to Maestro di Pico, who may have been helped by his workshop and assistants especially during the painting of the decorative frame and initials, is based on the figure of St Augustine and the angels who support the crest. Their features display the same typology which characterizes the works of Maestro di Pico. Identical angels appear in the bottom margin of Brunetto Latini’s Il Tesoro (Gerardus de Lisa, Treviso, 1474; Cambridge, Mass., Harvard, Houghton Library, Inc. 6459, c. 7). The figure of St Augustine shows pronounced similarities with the figure of a Dominican monk, set inside the initial O of the littera historiata type, in Nicolaus de Auximo’s Supplementum (Franciscus Renner et Nicolaus de Frankofordia, Venice, 1474; Biblioteca Marciana, Inc. Ven. 494, c.2). Identical angels and putti can be found in the bottom margins of Strabo’s Geographica (Minneapolis, Univ. of Minnesotta Library, Ms. 1460/f St., c.1), and in two copies of Pliny’s Historia Naturalis (Venice, N. Jenson, 1472, Paris, Bibliothèque Nationale, Vèlins 498 and Venice, N. Jenson, 1472, San Marino, CA, Huntington Library, n. 2289). A beautiful comparative example is the Biblia Latina (Franciscus Renner & Nicolaus de Frankfordia, 1475, Dallas, Texas, Southern Methodist University, Bridwell Library) and its first page which has a similar composition to that in the incunable from Kraj. The figure of St Jerome, depicted inside a littera historiata provides a plethora of specific Morellian details which are essential for the attribution of the illuminations in the incunable from Kraj to Maestro di Pico. Striking similarities in the depictions of saints, phytomorphic initials and decorative frames can also be found in two psalters (one in Venice, Biblioteca Querini Stampaglia, Inc. 6, the other in Siena, Biblioteca S. Bernardino del Convento dell’Osservanza) and in the first page of the Psalms in a breviary from Paris (Bibliothèque Ste-Geneviève, OE XV 147 Rés). Similar saints and angels all of which belong to the same figural typology were used to decorate three copies from the Commissioni series made for Doge Agostino Barbarigo (Commissione del doge Agostino Barbarigo a Girolamo Capello, 1487, Venice, Bib. Del Museo Correr, MS Cl. III. 33 (fig. 15); Commissione del doge Agostino Barbarigo a Paolo di Canale, 1489, Paris, Bibliothèque Nationale, Lat. 4729, c.2, and Commissione del doge Agostino Barbarigo a Tommaso Loredano, 1490, Paris, Bibliothèque Nationale, Lat. 4730, c.1). Further parallels can be found in the illuminations of a breviary from Augsburg (c. 1480, Universitätsbibl., Cod. I.2.2o 35) the first page of which has a lettera istoriata with the figure of St Paul whose physiognomy closely resembles that of St Augustine in the incunabule from Kraj, while the bottom margin features centrally placed angels which are identical to those at Kraj. Equally important comparative material is found in three Paduan incunables (Biblioteca del Seminario Vescovile) which contain illuminations attributed to Maestro di Pico. The distinctive features of the angels, putti and saints as well as the type of decoration used in the margins of these incunables also demonstrate striking similarities with the illuminations from Kraj. Other examples include Lattanzi’s Opera (Giovanni da Colonia and Johannes Manthen, Venice, 1478; Forc. M. 3.2), Jacopo da Varagine’s Legenda aurea (Gabriele di Pietro, Venice, 1477, with a likely contribution of his workshop; Forc. M. 2.22) and Cipriano’s Opera (Vindelino da Spira, Venice, 1471; Forc. K. 2.12). On the basis of the comparative analyses outlined above and the similarities which have been noted, it can be concluded that the illuminations in the incunable of St Augustine’s De Civitate Dei (Nicolas Jenson, Venice, 1475), housed in the Monastery of St Domnius at Kraj, were painted by the well-known Venetian Renaissance miniaturist Maestro di Pico. Regardless of the possible input of his workshop and assistants during the painting process of the decorative frame and initials, these illuminations help expand the catalogue of Maestro di Pico’s works and represent valuable contribution to the painting in Renaissance Dalmatia.
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Kunsági-Máté, Sándor, Róbert Beck, István Szapudi, and István Csabai. "Photometric redshifts for quasars from WISE-PS1-STRM." Monthly Notices of the Royal Astronomical Society, August 26, 2022. http://dx.doi.org/10.1093/mnras/stac2411.
Full textAbstract:
Abstract Three-dimensional wide-field galaxy surveys are fundamental for cosmological studies. For higher redshifts (z ≳ 1.0), where galaxies are too faint, quasars still trace the large-scale structure of the Universe. Since available telescope time limits spectroscopic surveys, photometric methods are efficient for estimating redshifts for many quasars. Recently, machine learning methods are increasingly successful for quasar photometric redshifts, however, they hinge on the distribution of the training set. Therefore a rigorous estimation of reliability is critical. We extracted optical and infrared photometric data from the cross-matched catalogue of the WISE All-Sky and PS1 3π DR2 sky surveys. We trained an XGBoost regressor and an artificial neural network on the relation between color indices and spectroscopic redshift. We approximated the effective training set coverage with the K nearest neighbors algorithm. We estimated reliable photometric redshifts of 2,562,878 quasars which overlap with the training set in feature space. We validated the derived redshifts with an independent, clustering-based redshift estimation technique. The final catalog is publicly available.
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Ryczanowski, Dan, Graham P. Smith, Matteo Bianconi, Sean McGee, Andrew Robertson, Richard Massey, and Mathilde Jauzac. "Enabling discovery of gravitationally lensed explosive transients: a new method to build an all-sky watch-list of groups and clusters of galaxies." Monthly Notices of the Royal Astronomical Society, January 25, 2023. http://dx.doi.org/10.1093/mnras/stad231.
Full textAbstract:
Abstract Cross-referencing a watchlist of galaxy groups and clusters with transient detections from real-time streams of wide-field survey data is a promising method for discovering gravitationally lensed explosive transients including supernovae, kilonovae, gravitational waves and gamma-ray bursts in the next ten years. However, currently there exists no catalogue of objects with both sufficient angular extent and depth to adequately perform such a search. In this study, we develop a cluster-finding method capable of creating an all-sky list of galaxy group- and cluster-scale objects out to z ≃ 1 based on their lens-plane properties and using only existing data from wide-field infrared surveys such as VHS and UHS, and all-sky WISE data. In testing this method, we recover 91 per cent of a sample containing known and candidate lensing objects with Einstein radii of θE ≥ 5″. We also search the surrounding regions of this test sample for other groups and clusters using our method and verify the existence of any significant findings by visual inspection, deriving estimates of the false positive rate that are as low as 6 per cent. The method is also tested on simulated Rubin data from their DP0 programme, which yields complementary results of a good recovery rate of ≳ 80 per cent for M200 ≥ 7 × 1013M⊙ clusters and with no false positives produced in our test region. Importantly, our method is positioned to create a watchlist in advance of Rubin’s LSST, as it utilises only existing data, therefore enabling the discovery of lensed transients early within the survey’s lifetime.
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Nagoshi, Shumpei, Fumihide Iwamuro, Kazuma Wada, and Tomoki Saito. "Discovery of a new extreme changing-state quasar with 4 mag variation, SDSS J125809.31+351943.0." Publications of the Astronomical Society of Japan, November 24, 2020. http://dx.doi.org/10.1093/pasj/psaa108.
Full textAbstract:
Abstract We report the discovery of a quasar, SDSS J125809.31+351943.0 (J1258), which brightened in optical wavelengths for 4 mag from 1983 to 2015: one of the largest quasar brightening events so far. The history of optical photometry data of this quasar from the Catalina Real-time Transient Survey and All Sky Automated Survey for Super Novae (ASAS-SN), mid-infrared photometry data from the WISE satellite, and the broad emission line (BEL) flux obtained by spectroscopy of the Sloan Digital Sky Survey shows significant increases between 2003 and 2015. Investigating the Canada–France–Hawaii Telescope photometric observations in 1983 and the United States Naval Observatory B catalogue, which contains data from 1975 and 1969, we found that the source was 4 mag fainter before than at the peak of the recent ASAS-SN photometry. From the history of these data, we identified J1258 as a new changing-state quasar (CSQ). We also performed follow-up spectroscopic observations in 2018 December and 2019 May using the 2 m telescope at the Nishi-Harima Astronomical Observatory. The results show that the continuum flux and the BEL flux decreased to about 50% of their peak. This indicates that J1258 present two changing states for the BEL flux and continuum flux. We argue that J1258’s variability, especially its brightening event, can be explained by the propagation of the heating front and the accretion disk state transitions based on the timescale and Eddington ratio variations. The estimated mass of the black hole of J1258 is about an order of magnitude larger than the CSQs found so far. Since both the changing timescale and the size of the accretion disk depend on the black hole mass, the J1258 brightening event can be interpreted as a scaled version of the variability in other CSQs. This suggests that samples of distant quasars with larger black hole masses may contain objects with longer and more severe variations.
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Gigoyan, K. S., A. M. Mickaelian, and G. R. Kostandyan. "Revised and Updated Catalogue of the First Byurakan Survey Late-Type Stars. 2nd Edition." Communications of the Byurakan Astrophysical Observatory, 2018, 262–67. http://dx.doi.org/10.52526/25792776-2018.2.2-262.
Full textAbstract:
Eighteen lists of late-type stars (LTSs) have been published between 1990 and 2016. These LTSs have been found in the low-dispersion spectroscopic plates of the First Byurakan Survey (FBS). The systematic search and selection was carried out on a surface _16000 deg2 on almost the whole area of the FBS. As a result, \Revised And Updated Catalogue Of The First Byurakan Survey Of Late-Type Stars" was generated (LTSs, _rst version). Since 2007, all FBS low-resolution spectral plates are digitized, and Digitized First Byurakan Survey (DFBS) database and second catalog of objects has been assembled. All DFBS spectral plates are analysed with the help of standard image analysis softwares (FITSView and SAO Image ds9) and numerous of comparatively faint LTSs were discovered. We present the 2nd version of the FBS catalogue of LTSs with new data. We have made cross-correlation with the Digitized First Byurakan Survey (DFBS), the United State Naval Observatory-B1.0 Catalogue, the Two Micron All-Sky Survey (2MASS), the Wide-Field Infrared Survey Explorer (new version-ALLWISE) catalogue, the Infrared Astronomical Satellite Point Source Catalogue/Faint Source Catalogue, the AKARI catalogue, the ROSAT Bright Source Catalogue/Faint Source Catalogue, the General Catalogue of Variable Stars, Sloan Digital Sky Survey (SDSS) photometric catalogue. We have added updated IMBAD data for the objects. For numerous of the new detected objects we present accurate Digitized Sky Survey 2 positions, approximate spectral subtypes refined from the DFBS low-dispersion spectra, luminosity classes estimated from 2MASS colours, and available proper motions for 1471 FBS LTSs. 2nd Version of the Revised and Updated Catalogue lists a large number of completely new objects, which promise to extend very significantly the census of M giants, faint N-type Asymptotic Giant Branch (AGB) carbon stars, CH {type carbon giants at high Galactic latitudes, also M dwarfs in the vicinity of the Sun up to 16.0-17.0 mag. in visual. We present also some important data from the Gaia DR2 data base for FBS LTSs. Some supplementary spectra obtained with the Byurakan Observatory 2.6 m telescope and LAMOST telescope are shown.
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"The ROSAT Wide Field Camera all-sky survey of extreme-ultraviolet sources - II. The 2RE Source Catalogue." Monthly Notices of the Royal Astronomical Society, June 15, 1995. http://dx.doi.org/10.1093/mnras/274.4.1165.
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Mickaelian, Areg M. "Astronomical Surveys and Big Data." Open Astronomy 25, no. 1 (January 1, 2016). http://dx.doi.org/10.1515/astro-2017-0113.
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AbstractRecent all-sky and large-area astronomical surveys and their catalogued data over the whole range of electromagnetic spectrum, from γ-rays to radio waves, are reviewed, including such as Fermi-GLAST and INTEGRAL in γ-ray, ROSAT, XMM and Chandra in X-ray, GALEX in UV, SDSS and several POSS I and POSS II-based catalogues (APM, MAPS, USNO, GSC) in the optical range, 2MASS in NIR, WISE and AKARI IRC in MIR, IRAS and AKARI FIS in FIR, NVSS and FIRST in radio range, and many others, as well as the most important surveys giving optical images (DSS I and II, SDSS, etc.), proper motions (Tycho, USNO, Gaia), variability (GCVS, NSVS, ASAS, Catalina, Pan-STARRS), and spectroscopic data (FBS, SBS, Case, HQS, HES, SDSS, CALIFA, GAMA). An overall understanding of the coverage along the whole wavelength range and comparisons between various surveys are given: galaxy redshift surveys, QSO/AGN, radio, Galactic structure, and Dark Energy surveys. Astronomy has entered the Big Data era, with Astrophysical Virtual Observatories and Computational Astrophysics playing an important role in using and analyzing big data for new discoveries.
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Mickaelian, A. M., H. V. Abrahamyan, G. M. Paronyan, and G. A. Mikayelyan. "Astronomical Surveys, Catalogues, Archives, Databases and Virtual Observatories." Communications of the Byurakan Astrophysical Observatory, December 29, 2022, 179–86. http://dx.doi.org/10.52526/25792776-22.69.2-179.
Full textAbstract:
Astronomical surveys and catalogs are the main sources for the discovery of new objects, both Galactic and extragalactic. Archives and Databases maintain billions of astronomical objects; planets, comets, stars, exoplanets, nebulae, galaxies, and quasars. We will review the current background in astronomy for further all-sky or large-area studies. Modern astronomy is characterized by multiwavelength (MW) studies (from gamma-ray to radio) and Big Data (data acquisition, storage, mining and analysis). Present astronomical databases and archives contain billions of objects observed at various wavelengths, and the vast amount of data on them allows new studies and discoveries. Surveys are the main source also for accumulation of observational data for further analysis, interpretation, and achieving scientific results. We review the main characteristics of astronomical surveys (homogeneity, completeness, sensitivity, etc.), compare photographic and digital eras of astronomical studies (including the development of wide-field observations), and describe the present state of MW surveys. Among others, Fermi-GLAST, INTEGRAL (gamma-ray), ROSAT, Chandra, XMM (X-ray), GALEX (UV), DSS1/2, SDSS, Hubble, Gaia (optical), 2MASS, IRAS, AKARI, WISE, Herschel (IR), NVSS and FIRST (radio) surveys and major astronomical archives and databases will be presented and discussed, as well as surveys and databases for variable and transit objects.
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Kelvin, Lee S., Imran Hasan, and J. Anthony Tyson. "Sky subtraction in an era of Low Surface Brightness astronomy." Monthly Notices of the Royal Astronomical Society, January 18, 2023. http://dx.doi.org/10.1093/mnras/stad180.
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Abstract The Vera C. Rubin Observatory Wide-Fast Deep (WFD) sky survey will reach unprecedented surface brightness depths over tens of thousands of square degrees. Surface brightness photometry has traditionally been a challenge. Current algorithms which combine object detection with sky estimation systematically over-subtract the sky, biasing surface brightness measurements at the faint end and destroying or severely compromising low surface brightness light. While it has recently been shown that properly accounting for undetected faint galaxies and the wings of brighter objects can in principle recover a more accurate sky estimate, this has not yet been demonstrated in practice. Obtaining a consistent spatially smooth underlying sky estimate is particularly challenging in the presence of representative distributions of bright and faint objects. In this paper we use simulations of crowded and uncrowded fields designed to mimic Hyper Suprime-Cam data to perform a series of tests on the accuracy of the recovered sky. Dependence on field density, galaxy type and limiting flux for detection are all considered. Several photometry packages are utilised: Source Extractor, Gnuastro, and the LSST Science Pipelines. Each is configured in various modes, and their performance at extreme low surface brightness analysed. We find that the combination of the Source Extractor software package with novel source model masking techniques consistently produce extremely faint output sky estimates, by up to an order of magnitude, as well as returning high fidelity output science catalogues.