Gaia Early Data Release 3. Building the Gaia DR3 source list -- Cross-match of Gaia observations
F. Torra, J. Castañeda, C. Fabricius, L. Lindegren, M. Clotet, J. J. González-Vidal, S. Bartolomé, U. Bastian, M. Bernet, M. Biermann, N. Garralda, A. Gúrpide, … 展开作者
F. Torra, J. Castañeda, C. Fabricius, L. Lindegren, M. Clotet, J. J. González-Vidal, S. Bartolomé, U. Bastian, M. Bernet, M. Biermann, N. Garralda, A. Gúrpide, U. Lammers, J. Portell, J. Torra
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19 pages, 18 figures. Accepted for publication in Astronomy & Astrophysics
The Gaia Early Data Release 3 (Gaia EDR3) contains results derived from 78 billion individual field-of-view transits of 2.5 billion sources collected by the European Space Agency's Gaia mission during its first 34 months of continuous scanning of the sky. We describe the input data, which have the form of onboard detections, and the modeling and processing that is involved in cross-matching these detections to sources. For the cross-match, we formed clusters of detections that were all linked to the same physical light source on the sky. As a first step, onboard detections that were deemed spurious were discarded. The remaining detections were then preliminarily associated with one or more sources in the existing source list in an observation-to-source match. All candidate matches that directly or indirectly were associated with the same source form a match candidate group. The detections from the same group were then subject to a cluster analysis. Each cluster was assigned a source identifier that normally was the same as the identifiers from Gaia DR2. Because the number of individual detections is very high, we also describe the efficient organising of the processing. We present results and statistics for the final cross-match with particular emphasis on the more complicated cases that are relevant for the users of the Gaia catalogue. We describe the improvements over the earlier Gaia data releases, in particular for stars of high proper motion, for the brightest sources, for variable sources, and for close source pairs.
The first data release from the Gaia mission contains accurate positions and magnitudes for more than a billion sources, and proper motions and parallaxes for the majority of the 2.5~million Hipparcos and Tycho-2 stars. We describe three essential elements of the initial data treatment leading to this catalogue: the image analysis, the construction of a source list, and the near real-time monitoring of the payload health. We also discuss some weak points that set limitations for the attainable precision at the present stage of the mission. Image parameters for point sources are derived from on…
The Gaia mission is a magnitude-limited whole-sky survey that collects an impressive quantity of astrometric, spectro-photometric and spectroscopic data. Among all the on-board instruments, the Radial Velocity Spectrometer (RVS) produces millions of spectra up to a magnitude of G$_{RVS} \sim 16$. For the brightest RVS targets, stellar atmospheric parameters and individual chemical abundances are automatically estimated by the Generalized Stellar Parametriser - spectroscopy group (GSP-Spec). These data will be published with the third Gaia Data Release. Some major ingredients of the determinati…
Thanks to its spatial resolution the ESA/Gaia space mission offers a unique opportunity to discover new multiply-imaged quasars and to study the already known lensed systems at sub-milliarcsecond astrometric precisions. In this paper, we address the detection of the known multiply-imaged quasars from the Gaia Data Release 2 and determine the astrometric and photometric properties of the individually detected images found in the Gaia DR2 catalogue. We have compiled an exhaustive list of quasar gravitational lenses from the literature to search for counterparts in the Gaia Data Release 2. We the…
We describe two ground based observing campaigns aimed at building a grid of approximately 200 spectrophotometric standard stars (SPSS), with an internal ~1% precision and tied to Vega within ~3%, for the absolute flux calibration of data gathered by Gaia, the ESA astrometric mission. The criteria for the selection and a list of candidates are presented, together with a description of the survey strategy and the adopted data analysis methods. We also discuss a short list of notable rejected SPSS candidates and difficult cases, based on identification problems, literature discordant data, visua…
Although the Gaia catalogue on its own will be a very powerful tool, it is the combination of this highly accurate archive with other archives that will truly open up amazing possibilities for astronomical research. The advanced interoperation of archives is based on cross-matching, leaving the user with the feeling of working with one single data archive. The data retrieval should work not only across data archives, but also across wavelength domains. The first step for seamless data access is the computation of the cross-match between Gaia and external surveys. The matching of astronomical c…
Gaia's Early Third Data Release (EDR3) does not contain new radial velocities because these will be published in Gaia's full third data release (DR3), expected in the first half of 2022. To maximise the usefulness of EDR3, Gaia's second data release (DR2) sources (with radial velocities) are matched to EDR3 sources to allow their DR2 radial velocities to also be included in EDR3. This presents two considerations: (i) arXiv:1901.10460 (hereafter B19) published a list of 70,365 sources with potentially contaminated DR2 radial velocities; and (ii) EDR3 is based on a new astrometric solution and a…
The Gaia Archive provides access to observations of around a billion sky sources. The primary access to this archive is via TAP services such as GACS and ARI-Gaia, which allow execution of SQL-like queries against a large remote database returning a result set of manageable size for client-side use. Such services are generally used for extracting relatively small source lists according to potentially complex selection criteria. But they can also be used to obtain statistical information about all, or a large fraction of, the observed sources by building histogram-like results. We examine here …
We present the Gaia-Groundbased Observational Service for Asteroids (GOSA). Gaia-GOSA is an interactive tool which supports observers in planning photometric observations of asteroids. Each user is able to personalise the observation plan taking into account the equipment used and the observation site. The list of targets has been previously selected among the most relevant and scientifically remarkable objects, while the prediction of the transits in the Gaia's field of view have been calculated at the Observatoire de la Côte d'Azur. The data collected by the GOSA community will be exploited …
The Chandra-Gaia Catalog of Counterparts: Resolving ambiguous Gaia matches to X-ray sources in the Chandra Source Catalog using Machine Learning
Center for Astrophysics Harvard \& Smithsonian, 60 Garden St, Cambridge MA 02138, USA；Harvard John A. Paulson School of Engineering；Universidad del Rosario, School of Engineering, Science；The NSF AI Institute for Artificial Intelligence；New York University, Courant Institute, 60 5th Avenue, New York NY, USA；Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213；New College of Florida, 5800 Bayshore Road, Sarasota, FL 34243, USA；Astrophysics Laboratory, 3251 Hanover St, Palo Alto, CA 94304, USA
Context. Although the Gaia catalogue on its own is a very powerful tool, it is the combination of this high-accuracy archive with other archives that will truly open up amazing possibilities for astronomical research. The advanced interoperation of archives is based on cross-matching, leaving the user with the feeling of working with one single data archive. The data retrieval should work not only across data archives but also across wavelength domains. The first step for a seamless access to the data is the computation of the cross-match between Gaia and external surveys. Aims. We describe th…
The Gaia Data Release 2 provides precise astrometry for nearly 1.5 billion sources across the entire sky, including several thousand asteroids. In this work, we provide evidence that reasonably large asteroids (diameter $>$ 20 km) have high correlations with Gaia relative flux uncertainties and systematic right ascension errors. We further capture these correlations using a logistic Bayesian additive regression tree model. We compile a small list of probable large asteroids that can be targeted for direct diameter measurements and shape reconstruction.
In this work, we use $13$ microlensing candidates with dark lenses from OGLE III catalogue \cite{2016MNRAS.458.3012W} and cross-match them with the GAIA catalogue. We identify the microlensing source stars in the GAIA catalogue by comparing the coordinate and the magnitude of stars and using the proper motion and the parallax parameters of the source stars. Combining with the microlensing light curves as well as the microlensing parallax effect, we determine the mass and the distance of lenses from Earth. We conclude that the lens for this set of microlensing events for the massive lenses are …
We present the second Gaia data release, Gaia DR2, consisting of astrometry, photometry, radial velocities, and information on astrophysical parameters and variability, for sources brighter than magnitude 21. In addition epoch astrometry and photometry are provided for a modest sample of minor planets in the solar system. A summary of the contents of Gaia DR2 is presented, accompanied by a discussion on the differences with respect to Gaia DR1 and an overview of the main limitations which are still present in the survey. Recommendations are made on the responsible use of Gaia DR2 results. Gaia…
We present a Bayesian method to cross-match 5,827,988 high proper motion Gaia sources ($μ>40 \ mas \ yr^{-1}$) to various photometric surveys: 2MASS, AllWISE, GALEX, RAVE, SDSS and Pan-STARRS. To efficiently associate these objects across catalogs, we develop a technique that compares the multidimensional distribution of all sources in the vicinity of each Gaia star to a reference distribution of random field stars obtained by extracting all sources in a region on the sky displaced 2$^\prime$. This offset preserves the local field stellar density and magnitude distribution allowing us to chara…
The Gaia DR2 sample of short-timescale variable candidates results from the investigation of the first 22 months of Gaia photometry for a subsample of sources at the Gaia faint end. For this exercise, we limited ourselves to the case of suspected rapid periodic variability. Our study combines fast-variability detection through variogram analysis, high-frequency search by means of least-squares periodograms, and empirical selection based on the investigation of specific sources seen through the Gaia eyes (e.g. known variables or visually identified objects with peculiar features in their light …
We describe the preliminary results of a ground-based observing campaign aimed at building a grid of approximately 200 spectro-photometric standard stars (SPSS), with an internal $\simeq 1$\% accuracy (and sub-percent precision), tied to CALSPEC Vega and Sirius systems within $\simeq 1$\%, for the absolute flux calibration of data gathered by {\it Gaia}, the European Space Agency (ESA) astrometric mission. The criteria for the selection and a list of candidates are presented, together with a description of the survey's strategy and the adopted data analysis methods. All candidates were also mo…
The VLBI USNO 2016A (U16A) solution is part of a work-in-progress effort by USNO towards the preparation of the ICRF3. Most of the astrometric improvement with respect to the ICRF2 is due to the re-observation of the VCS sources. Our objective in this paper is to assess U16A's astrometry. A comparison with ICRF2 shows statistically significant offsets of size 0.1 mas between the two solutions. While Gaia DR1 positions are not precise enough to resolve these offsets, they are found to be significantly closer to U16A than ICRF2. In particular, the trend for typically larger errors for Southern s…
The precision of the parallax measurements by Gaia is unprecedented. As of Gaia Data Release 2, the number of known nearby open clusters has increased. Some of the clusters appear to be relatively close to each other and form aggregates, which makes them interesting objects to study. We study the aggregates of clusters which share several of the assigned member stars in relatively narrow volumes of the phase space. Using the most recent list of open clusters, we compare the cited central parallaxes with the histograms of parallax distributions of cluster aggregates. The aggregates were chosen …
ExoDNN: Boosting exoplanet detection with artificial intelligence. Application to Gaia Data Release 3
ATG Science & Engineering for the European Space Agency (ESA)（欧洲航天局工程与技术科学部）；Universidad Complutense de Madrid（马德里康普顿斯大学）；Centro de Astrobiología (CAB, CSIC-INTA)（天体生物学中心（CSIC-INTA））；ISDEFE；European Space Agency (ESA), European Space Astronomy Centre (ESAC)（欧洲航天局欧洲空间天文中心）；European Space Agency (ESA), European Space Research and Technology Centre (ESTEC)（欧洲航天局欧洲空间研究与技术中心）
The second release of Gaia data (Gaia DR2) contains the astrometric parameters for more than half a million quasars. This set defines a kinematically non-rotating reference frame in the optical domain referred to as the Gaia-CRF2. The Gaia-CRF2 is the first realisation of a non-rotating global optical reference frame that meets the ICRS prescriptions, meaning that it is built only on extragalactic sources. It consists of the positions of a sample of 556 869 sources in Gaia DR2, obtained from a positional cross-match with the ICRF3-prototype and AllWISE AGN catalogues. The sample constitutes a …
The recently published Gaia DR3 catalog of 181327 spectroscopic binaries (SB) includes the Keplerian elements of each orbit but not the measured radial velocities (RVs) and their epochs. Instead, the catalog lists a few parameters that characterize the robustness of each solution. In this work, we use two external sources to validate the orbits - 17563 LAMOST DR6 and 6018 GALAH DR3 stars with measured RVs that have Gaia-SB orbits. We compare the expected RVs, based on the Gaia orbits, with the LAMOST and GALAH measurements. Finding some orbits that are inconsistent with these measurements, we …
We present a sub-arcsecond cross-match of Gaia Data Release 3 (DR3) against the INT Galactic Plane Surveys (IGAPS) and the United Kingdom Infrared Deep Sky Survey (UKIDSS). The resulting cross-match of Galactic Plane Surveys (XGAPS) provides additional precise photometry ($U_{RGO}$, $g$, $r$, $i$, H$α$, $J$, $H$ and $K$) to the Gaia photometry. In building the catalogue, proper motions given in Gaia DR3 are wound back to match the epochs of the IGAPS constituent surveys (INT Photometric \ha Survey of the Northern Galactic Plane, IPHAS, and the UV-Excess Survey of the northern Galactic plane, U…
We extend the SDSS Stripe 82 Standard Stars Catalog with post-2007 SDSS imaging data. This improved version lists averaged SDSS ugriz photometry for nearly a million stars brighter than r~22 mag. With 2-3x more measurements per star, random errors are 1.4-1.7x smaller than in the original catalog, and about 3x smaller than for individual SDSS runs. Random errors in the new catalog are ~< 0.01 mag for stars brighter than 20.0, 21.0, 21.0, 20.5, and 19.0 mag in u, g, r, i, and z-bands, respectively. We achieve this error threshold by using the Gaia Early Data Release 3 (EDR3) Gmag photometry to …
Interpreting and modelling astronomical catalogues requires an understanding of the catalogues' completeness or selection function: objects of what properties had a chance to end up in the catalogue. Here we set out to empirically quantify the completeness of the overall Gaia DR3 catalogue. This task is not straightforward because Gaia is the all-sky optical survey with the highest angular resolution to date and no consistent ``ground truth'' exists to allow direct comparisons. However, well-characterised deeper imaging enables an empirical assessment of Gaia's $G$-band completeness across par…
Machine learning has increasingly gained more popularity with its incredibly powerful ability to make predictions or calculated suggestions for large amounts of data. We apply the machine learning classification to 85,613,922 objects in the $Gaia$ data release 2, based on the combination of the Pan-STARRS 1 and AllWISE data. The classification results are cross-matched with Simbad database, and the total accuracy is 91.9%. Our sample is dominated by stars, $\sim$ 98%, and galaxies makes up 2%. For the objects with negative parallaxes, about 2.5\% are galaxies and QSOs, while about 99.9% are st…
We present a mock catalog of Milky Way stars, matching in volume and depth the content of the Gaia data release 2 (GDR2). We generated our catalog using Galaxia, a tool to sample stars from a Besancon Galactic model, together with a realistic 3D dust extinction map. The catalog mimicks the complete GDR2 data model and contains most of the entries in the Gaia source catalog: 5-parameter astrometry, 3-band photometry, radial velocities, stellar parameters, and associated scaled nominal uncertainty estimates. In addition, we supplemented the catalog with extinctions and photometry for non-Gaia ba…
