The UV Sky: GALEX catalogs of unique sources from GR5
and of GALEXxSDSS matched sources with useful multiplicity flags

Here you can access the GR5 (data release 5) version of the GALEX catalogs of unique UV sources. These catalogs are a VO-accessible from Vizier and can be downloaded from this page (below) or from MAST

Note that an updated version (GR6/7) is now available published by Bianchi, L., Conti, A., and Shiao, B. 2014, J. Adv. Space Res., 53, 900 DOI: ; astro-ph 1312.3281 The ultraviolet sky: An overview from the GALEX surveys. ( link to ASR article or download manuscript pdf or go to astro-ph 1312.3281 )
The updated catalogs are available from MAST, and from here, and soon from from SIMBAD/Vizier

Below you will also find matched catalogs of the GALEX sources with SDSS (with useful science flags to identify multiple matches) and extracted catalogs of hot stars

go to the UVsky main page for relevant references.

Below you will find:

  1. catalogs of unique UV (GALEX) sources: from GR5 data release
  2. catalogs of matched GALEX UV sources with SDSS (GR5xDR7)
  3. catalogs of hot stars selected from GALEX-SDSS matched catalogs (GR5)
  4. catalog of matched GALEX AIS with GSC2

* PAPER DESCRIBING THE CATALOGS OF UV SOURCES available below; this is the official reference when using the catalogs:
Bianchi, L., Efremova, B., Herald, J., Girardi, L, Zabot, A., Marigo, P., Martin, C, 2011, MNRAS, 411, 2770, ( doi:10.1111/j.1365-2966.2010.17890.x) , (astro-ph: )
Catalogs of Milky Way Hot White Dwarf Candidates from GALEX's Ultraviolet Sky Surveys. Constraining Stellar Evolution.
download manuscript pdf or get the published paper: link to MNRAS paper or go to preprint in ADS ( )

* This paper discusses additional statistical properties of these catalogs and biases of sample selections:
Bianchi, L. , Herald, J., Efremova, B., Girardi, L., Zabot, A., Marigo, P., Conti, A., Shiao, B. 2011, ApSS, 335, 161, DOI: 10.1007/s10509-010-0581-x, ``GALEX Catalogs of UV sources: Statistical properties and sample science applications: Hot White Dwarfs in the Milky Way" link to paper in ADS or go to ApSS link download pdf here
The Ultraviolet Sky Surveys: Filling the Gap in our View of the Universe
download the poscript file or the pdf file or get the article from AIPC, 1135, 326
The UV sky surveys: a roadmap for future UV missions download ps file -->


Source/ reference: Note: this reference has Open Access. Catalogs can be used citing the MNRAS reference.
Bianchi, L. , Efremova, B., Herald, J., Girardi, L, Zabot, A., Marigo, P., Martin, C, 2011, MNRAS, 411, 2770 "Catalogs of Milky Way Hot White Dwarf Candidates from GALEX's Ultraviolet Sky Surveys. Constraining Stellar Evolution."
download manuscript pdf here or the link to MNRAS paper or link to preprint in ADS

Additional discussion of the statistical properties of these catalogs can be found in
Bianchi, L., Herald, J., Efremova, B., Giradi, L., Zabot, A., Marigo, P., Conti, A., Shiao, B. 2011, ApSS, DOI: 10.1007/s10509-010-0581-x, ``GALEX Catalogs of UV sources: Statistical properties and sample science applications: Hot White Dwarfs in the Milky Way" link to preprint from ADS or to paper in ApSS

Catalogs of unique GALEX sources from data release GR5, for the AIS and MIS surveys, were constructed by Bianchi et al. (2011, MNRAS) with the following criteria (see paper for more details):

1) only observations when both FOV and NUV detectors were turned on are included. This is useful for science analyses where the fraction of sources with a given FUV-NUV color is of interest, or to estimate the fraction of sources with significant detection in both FUV and NUV over the total number of sources with NUV-only detection. More observations exist in the GALEX archive taken with one detector off (mostly FUV); those can be found in the MAST page. Inclusion of observations where one detector was not exposed would bias the statistics of # FUV detections or # of sources in a given FUV-NUV color range, as the FUV magnitude may appear as a non-detection (FUV=-999) both because the FUV detector was off, or the FUV detector was on but the FUV flux of that source was actually below detection.

2) only sources within the central 0.5 degrees radius of the field-of-view are included, to avoid sources with poor photometry/astrometry near the edge, and rim artifacts. This makes the catalogs useful for statistical analysis of sources with homogeneous quality, without great loss of area coverage (also considering that overlap exist among several fields). Users interested in a particular source that happens to fall on a galex field edge, should obtain the measurements from the main catalog and examine the quality.

3) we retained sources with NUV magnitude errors less or equal 0.5mag (see column 4 of Table 2 in Bianchi et al. 2011 MNRAS paper, and Figure 4 of Bianchi et al. 2011, and Figures 2--4 of Bianchi et al. 2011 for effects of error cuts on the resulting sample statistics).

4) The general GALEX database contains all measurements for sources with repeated observations. We removed duplicate measurements to produce a unique source catalog as follows. GALEX sources within 2.5'' of each other, but from different observations, were considered duplicates. In such cases the object from the observation with the longest NUV exposure time was retained, and - in cases of equal exposure times - the object closest to the center of the field of view.

Catalogs were constructed in this way for the two GALEX surveys with the largest sky coverge (excluding the Nearby Galaxy Survey), shown below in Galactic coordinates: MIS (Medium Imaging Survey, depth about 22.7 ABmag in FUV/NUV) and AIS (All-Sky Imaging Survey, depth about 19.9/20.8 FUV/NUV ABmag). See these reviews for useful information: Bianchi, L. 2009, 320, 11, DOI: 10.1007/s10509-008-9761-3 ; Bianchi, L. 2011 ApSS, 335, 51; DOI: 10.1007/s10509-011-0612-2 )

GR5 AIS and MIS coverage

For estimating density of sources in the sky from extracted subcatalogs, it is useful to have the area coverage. Table 1 of Bianchi et al. (2011) provides the area coverage for each catalog, both total area and areas in small latitude ranges.

MIS :Catalog of unique GALEX sources from the MIS survey (12.6 million sources, 1.5GB tar file, contains 26 gzipped files, each file containing sources for a 5 degree band of Galactic latitude)

AIS :Catalogs of unique GALEX sources from the AIS survey (65.3 million sources)
The catalog is divided in 180 gzipped files, each containing sources for a 1 degree band of Galactic latitude). These are grouped in four tar files for download, covering different Galactic latitude ranges:
latitude 0 - 45 N (2.3G)
latitude 45 -90 N (1.5G)
latitude 45 - 90 S(1.6G)
latitude 0 - 45 S (2.0G)
The files within each .tar have the following naming convention, e.g.:
GR5_70_65N.ais.csv.gz, GR5_65_70S.ais.csv.gz, where

70_65N means it contains sources with b between 65 and 70 North
65_70S sources with b between -65 and -70 degrees South

Comma-separated columns contained in the catalog files are listed below. Detailed field descriptions can be found at the MAST GALEX site.

#objid, ra, dec, glon, glat, tilenum, img, subvisit, fov_radius, type, band, e_bv, istherespectrum, objtype, quality, fuv_mag, fuv_magerr, nuv_mag, nuv_magerr, fuv_mag_best, fuv_magerr_best, nuv_mag_best, nuv_magerr_best, fuv_mag_auto, fuv_magerr_auto, nuv_mag_auto, nuv_magerr_auto, fuv_mag_aper_4, fuv_magerr_aper_4, nuv_mag_aper_4, nuv_magerr_aper_4, fuv_mag_aper_6, fuv_magerr_aper_6, nuv_mag_aper_6, nuv_magerr_aper_6, fuv_artifact, nuv_artifact, fuv_flags, nuv_flags, fuv_flux, fuv_fluxerr, nuv_flux, nuv_fluxerr, fuv_x_image, fuv_y_image, nuv_x_image, nuv_y_image, fuv_fwhm_image, nuv_fwhm_image, fuv_fwhm_world, nuv_fwhm_world, photoextractid, mpstype, avaspra, avaspdec

Many of these fields will not be of interest to most users. The columns of probable interest are in bold::

1 objid: The GALEX objid
2 ra: (in degrees)
3 dec: (in degrees)
4 glon: Galactic Longitude (in degrees)
5 glat: Galactic Latitude (in degrees)
6 tilenum: tile number
7 img: image number (exposure# for _visits)
8 subvisit: sub-visit number for ais
9 fov_radius: distance from center of field-of-view in degrees
10 type: obs.type (0single,1multi)
11 band: band number (1nuv,2fuv,3both)
12 e_bv: e(B-V) Galactic reddening inferred from 100um dust emission maps
13 istherespectrum: Does this object have a (GALEX) spectrum? Yes (1), No (0)
14 objtype: 0=galaxy, 1=star, -1=unknown
15 quality: quality flag (undefined)
16 fuv_mag: same as fuv_mag_best
17 fuv_magerr
18 nuv_mag
19 nuv_magerr
20 fuv_mag_best: pipeline-chosen "best" magnitude (either mag_auto or mag_isocor)
21 fuv_magerr_best
22 nuv_mag_best
23 nuv_magerr_best
24 fuv_mag_auto: kron-like elliptical aperture magnitude
25 fuv_magerr_auto
26 nuv_mag_auto
27 nuv_magerr_auto
28 fuv_mag_aper_4: flux aperture (8.000)
29 fuv_magerr_aper_4
30 nuv_mag_aper_4
31 nuv_magerr_aper_4
32 fuv_mag_aper_6: flux aperture (17.000)
33 fuv_magerr_aper_6
34 nuv_mag_aper_6
35 nuv_magerr_aper_6
36 fuv_artifact: fuv artifact flag (logical or near source)
37 nuv_artifact
38 fuv_flags: extraction flags
39 nuv_flags
40 fuv_flux: fuv calibrated flux (micro jansky)
41 fuv_fluxerr
42 nuv_flux
43 nuv_fluxerr
44 fuv_x_image: object position along x
45 fuv_y_image: object position along y
46 nuv_x_image
47 nuv_y_image
48 fuv_fwhm_image: fwhm assuming a gaussian core
49 nuv_fwhm_image
50 fuv_fwhm_world: fwhm assuming a gaussian core
51 nuv_fwhm_world
52 photoextractid: Pointer to photoExtract Table
53 mpstype: survey type (e.g, "MIS")
54 avaspra: field center RA
55 avaspdec: field center Dec.

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We ( Bianchi et al. 2011, MNRAS, 411, 2770) matched the catalogs of unique UV sources described above, to the seventh SDSS data release (DR7)
The matched sources have up to 7 magnitudes: GALEX FUV and NUV, and SDSS u g r i z . The area coverage of the overlap between the two surveys is shown in the Figure below. Table 1 of Bianchi et al. (2011 MNRAS, 411, 2770) provides the area coverage for the matched source catalog, total and divided by latitude.
Overlap between GALEX DR5 and SDSS DR7 (AIS: yellow, MIS: green), in galactic coordinates.

GALEX-MIS - SDSS Matched Catalogs (6 million sources)
These 3 tarfiles contain 23 files, each covering a 5 degree band of Galactic latitude.

MIS GALEX magnitudes (0.4G) (GR5xDR7_*_*_gmags.mis.dat)
MIS SDSS magnitudes (0.3G) (GR5xDR7_*_*_smags.mis.dat)
MIS SDSS flags (0.2G) (GR5xDR7_*_*_sflags.mis.dat)

GALEX-AIS - SDSS Matched Catalogs (14.5 million sources)
These 3 tarfiles contain 180 files, each covering a 1 degree band of Galactic latitude.

AIS GALEX magnitudes (0.8G) (GR5xDR7_*_*_gmags.ais.dat)
AIS SDSS magnitudes (0.7G) (GR5xDR7_*_*_smags.ais.dat)
AIS SDSS flags (0.5G) (GR5xDR7_*_*_sflags.ais.dat)

These files contain the matched GALEX-SDSS objects resulting from searching the GALEX coordinates of objects in the "GALEX unique sources catalogs" described above against the SDSS PhotoPrimary table. They correpond to columns 6 and 7 of Table 2 in Bianchi et al. (2011, MNRAS, 411, 2770 ). A match radius of 3 arcsec was used in constructing final matched catalogs (see paper for details).

For each survey (MIS, AIS) the data are split among three files:
GR5xDR7_*_*_gmags.[m/a]is.dat, GR5xDR7_*_*_smags.[m/a]is.dat, and GR5xDR7_*_*_sflags.[m/a]is.dat.

There is a one-to-one correspondence between each line of all three files. For example, the 5th line of the "smags" and "sflags" files contain information on the SDSS object that matches the GALEX object listed in the 5th line of the "gmags" file.

A GALEX source may have multiple SDSS matches, due to the higher SDSS spatial resolution. Sources with multiple matches are not useful for color analyses (the GALEX magnitudes may be a composite of nearby sources), therefore we introduced a flag whereby sources with multiple optical matches can be identified.
SDSS sources are assigned a "rank" with the following meaning:

rank = 0: One (and only one) SDSS source matched the GALEX source
rank = 1: Multiple SDSS sources matched to GALEX source, with this being the closest

Space-separated columns contained in the files are listed below. Detailed descriptions for the GALEX field descriptions are given at the MAST GALEX site, and for the SDSS fields at the CAS SDSS site, under Tables, PhotoObjAll.

-- GR5xDR7_*_*_gmags.[m/a]is.dat --

Contains information on GALEX sources, plus the matched SDSS objid (listed below as "sdssid") as well as the "rank" flag. Included fields are:


-- GR5xDR7_*_*_smags.[m/a]is.dat --

Contains mainly magnitude information on SDSS sources. Included fields are:

#objid,ra,dec,dist,type, petromag_u,petromagerr_u,petromag_g,petromagerr_g,petromag_r,petromagerr_r, petromag_i,petromagerr_i,petromag_z,petromagerr_z,specobjid, propermotion,usno_blue,usno_red,rank

NOTE: "objid" here is the SDSS objid, and "ra" and "dec" are the SDSS photometric coordinates; "dist" is the distance from the corresponding GALEX source coordinates in arcmin; "rank" is described above. USNO magnitudes are from the USNO database, described at the CAS SDSS site, under Tables, USNO.

-- GR5xDR7_*_*_sflags.[m/a]is.dat --

Contains mainly photometry-flag information on SDSS sources. The individual flags (e.g, "_sat" for saturation or "_cr" for cosmic ray) for the different magnitudes (u,g,r,i,z) were extracted from SDSS "flags" field. Included fields are:

#objid,edge,u_sat,u_cr,g_sat,g_cr,r_sat,r_cr,i_sat,i_cr,z_sat,z_cr, flags,flags_u,flags_g,flags_r,flags_i,flags_z,ra,dec

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From the matched GALEX-SDSS source catalogs described above, Bianchi et al. 2011, MNRAS, 411, 2770 selected hot star candidates, by extracting the sources with GALEX UV color FUV-NUV < -0.13mag. This color cut corresponds to Effective Temperature approximately hotter than 18,000K, the exact value depending on gravity (see Sections 3 and 4 of the cited paper). While the FUV-NUV color allows one to detect the presence of a hot star, the combination of UV measurements with an additional optical band provides an approximate separation between "single" hot stars, and hot stars with a cooler companion (see Fig.1 of Bianchi 2009, ApSS, 320, 11). Bianchi et al. (2011, MNRAS, 411, 2770) adopted a color cut of NUV-r >0.1mag to separate candidate binaries among this sample. Note that the binaries locus is contaminated by some QSOs with non-canonical UV colors (Bianchi et al. 2009, AJ, 137, 3761), the relative number of extragalactic sources increases towards fainter magnitudes (Bianchi et al. 2011, ApSS, DOI: 10.1007/s10509-010-0581-x). The hot-star candidates with NUV-r <0.1mag are mostly single stars, although some types of binaries are also included in this color locus ; most importantly, serendipitous spectroscopic follow-up of a subsample indicates the QSO contamination to be negligible in this selection. Therefore, the purity of the "single hot-star" sample is much higher than for hot stars in the binary locus , and the latter are flagged in the catalogs.
The catalog header includes a byte-by-byte description of the columns. Most fields are described in the general catalog documentation, given above.
The source paper Bianchi et al. (2011, MNRAS, 411, 2770) includes an analysis of these hot-star candidates catalogs with Milky way models, which provides some constraints on the Initial-Final mass relation (IFMR).

Note that:

  1. only "rank0" sources are included in these files (see paper). These are GALEX sources with only one SDSS match. There are more GALEX sources in this color range, with multiple SDSS matches; these are included in the general catalogs (above) but not in these extracted catalogs.
  2. sources with NUV-r >0.1 are flagged: these are candidate stellar binaries with a hot star, but some QSOs may intrude the sample (see Bianchi et al. 2009, AJ, 137, 3761).
  3. Only sources with 1-sigma error less than 0.3mag in both FUV and NUV are included.
  4. The large majority of sources are hot white dwarfs, however no gravity selection has been applied, to make the catalogs more inclusive and more generally useful.

GALEX-MIS---SDSS hot star candidate catalog (9032 sources)

GALEX-AIS---SDSS hot star candidate catalog (28333 sources)

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from Bianchi, L. et al. 2011, ApSS, 335, 161, DOI: 10.1007/s10509-010-0581-x
will be posted with the newer version
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