GALEX UV Unique Source Catalogs ("GUVcat") and Cross-Matches With Gaia and SDSS ("GUVmatch")
Primary Investigator: Luciana Bianchi
HLSP Authors: Luciana Bianchi, Bernie Shiao, David Thilker
Citations: See ADS Statistics
The GALEX database contains almost 600 million source measurements in far-UV and near-UV. Some sources have repeated measurements (useful to search for variability, for example), due to repeated observations of the same field or overlap between fields. Bianchi, Shiao, and Thilker 2017 constructed catalogs of clean, unique (i.e. only one entry for each object) UV sources, useful to estimate density of sources across the sky or the number of sources with given magnitude or color ranges, or to match UV sources with other catalogs (revised version 2020). Flags are included to check for artifacts, as well as for existing multiple observations, and flags indicating whether a source is within the footprint of a large galaxy or stellar cluster (see Figure 5 in Bianchi et al. 2017) where source identification and photometry may be unreliable or inconsistent across the bands. GUVcat is composed using tiles from the AIS (All-Sky Imaging Survey), with a depth of about 19.9/20.8 in FUV/NUV ABmag. Additional tables and images of UV sources over extended objects (galaxies and stellar clusters) can be found at the author's website: http://dolomiti.pha.jhu.edu/uvsky
Bianchi & Shiao 2020 matched the GUVcat_AIS with SDSS DR14 and Gaia DR2 databases (GUVmatch). Tags are included to identify and track multiple optical matches to UV sources. For details about the matching parameters, and catalogs content in terms of astrophysical classes of objects, see Bianchi & Shiao 2020. For sky coverage of GUVcat and GUVmatched catalogs, see Bianchi et al. 2019, ApJS 241, 14 and the AREAcat tool at: http://dolomiti.pha.jhu.edu/uvsky/area/AREAcat.php
There are four total tables available at MAST:
- AIS ("GUVcat_AISfov055") = catalog of sources with duplicate entries removed
- AISPlus ("GUVcat_AISfov055plus") = catalog of sources where duplicate entries are tagged but not removed
- AISxGaiaDR2 ("GUVmatch_AISxGaiaDR2") = AIS GUVcat cross-matched with Gaia DR2
- AISxSDSSDR14 ("GUVmatch_AISxSDSSdr14") = AIS GUVcat cross-matched with SDSS DR14
For additional information, see the team's page (outside MAST) at http://dolomiti.pha.jhu.edu/uvsky/, for additional information and ways to access the catalogs.
Relationship To Other GALEX Unique Source Catalogs
This catalog supersedes the previously released BCSCat entirely, by patching some fields that had been incorrectly merged by the pipeline (a bug that had introduced some flawed sources and artifacts in the database and in previous catalogs), and by adding useful tags for science analysis. Compared to GCAT, GUVcat includes tiles released as part of the final GALEX data release (GR7) and thus uses the most amount of available AIS tiles between the other unique source catalogs. In addition, GUVcat patches the incorrect co-adds and adds tags useful for science analysis and sample cleaning.
Data file naming convention:
- <catalog_name> = Name of the catalog, one of "ais", "aisplus", "aisxgaiadr2", "aisxsdssdr14"
- <lat1> = Lower Galactic boundary, in degrees, for this slice. Example: "15s" corresponds to -15 degrees or "45n" corresponds to +45 degrees
- <lat2> = Upper Galactic boundary, in degrees, for this slice. Example: "15s" corresponds to -15 degrees or "45n" corresponds to +45 degrees
Data file types:
|_cat.csv||Full catalog exported as a .csv file.|
The catalogs are availalbe in CasJobs for searching and cross-matching with SQL access, and as CSV files for bulk downloads. Each of the four GUVcat catalogs and cross-match catalogs are stored in separate tables under the "GALEX_Catalogs" Context. The four table names are "GUVcat_AIS_FOV055" ("AIS"), "GUVcat_AIS_FOV055Plus" ("AISPlus"), "GUVmatch_AISxGaiaDR2" ("AISxGaiaDR2"), and "GUVmatch_AISxSDSSdr14" ("AISxSDSSDR14").
The catalogs are available for direct download from the table below. Each .csv file is typically between 1 and 10 GB in size. You can also download the catalogs in various formats from the author's webpage: http://dolomiti.pha.jhu.edu/uvsky
|GLAT Lower||GLAT Upper||AIS||AISPlus||AISxGaiaDR2||AISxSDSSDR14|