The Galaxy Evolution Explorer (GALEX). Its legacy of UV surveys, and science highlights

Abstract

The Galaxy Evolution Explorer (GALEX) imaged the sky in the Ultraviolet (UV) for almost a decade, delivering the first sky surveys at these wavelengths. Its database contains far-UV (FUV, λ _eff∼1528 Å) and near-UV (NUV, λ _eff∼2310 Å) images of most of the sky, including deep UV-mapping of extended galaxies, over 200 million source measurements, and more than 100,000 low-resolution UV spectra. The GALEX archive will remain a long-lasting resource for statistical studies of hot stellar objects, QSOs, star-forming galaxies, nebulae and the interstellar medium. It provides an unprecedented road-map for planning future UV instrumentation and follow-up observing programs in the UV and at other wavelengths.

We review the characteristics of the GALEX data, and describe final catalogs and available tools, that facilitate future exploitation of this database. We also recall highlights from the science results uniquely enabled by GALEX data so far.

Appendix: Where to find information, catalogs, and tools

Documentation on GALEX archive data and pipeline products can be found on the MAST site;² some relevant papers, science-ready catalogs and source classification can be found on the author’s “UVsky” project web site.³

The BCS catalogs of GALEX unique sources are publicly available from the author’s website,⁴ from MAST⁵ as part of the “High-Level Science Product” collection, and with SQL access from MAST casjobs (http://galex.stsci.edu/casjobs/, in the context GALEXcatalogs: “bcscat_ais” and “bcscat_mis”); they will soon be also available in CDS’s Vizier. Matched catalogs (GALEX BCScat’s matched with SDSS, GSC2, Pan-STARRS, 2MASS, etc.), with useful added flags, are being added on the http://dolomiti.pha.jhu.edu/uvsky web site, together with science catalogs of selected samples with derived physical parameters for the sources.

The first version of the BCS catalogs (Bianchi et al. 2011a), and matched GALEX-optical catalogs are also available from http://dolomiti.pha.jhu.edu/uvsky, as well as from MAST⁶ and Vizier.⁷

Other GALEX catalogs available from MAST include GCAT (catalog of GALEX unique sources, not updated beyond data release GR6; it differs from BCS unique-source catalog in that it also includes NUV observations (up to GR6) with the FUV detector turned off, and rim/edge sources are not eliminated, but flags are provided), and GALEX catalogs of the Kepler field.

Among the useful tools for exploring GALEX data at MAST, we recall “galexview” (http://galex.stsci.edu/GalexView); since January 2014, GALEX data can also be explored within a broader context from MAST’s portal: http://mast.stsci.edu/explore.

Finally, gPhoton (Million, Fleming, Shiao, 2014, in preparation) is accessible at https://github.com/cmillion/gPhoton.