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NOTE: Most of the High Level Science Products are unavailable while unscheduled maintenance is being performed. They will be incrementally restored over the course of this week. We apologize for any inconvenience.

The GALEX-SDSS-WISE Legacy Catalog (GSWLC)

Salim et al. 2016, ApJS, 227, 2
See also: Salim et al. 2007, ApJS, 173, 267

Introduction

Data Products

Data Access

README (TXT)

Introduction

Distribution on the sky of galaxies included in GSWLC. Each panel shows SDSS target galaxies as shaded areas, covering ~9000 sq. deg.
GSWLC is a catalog of physical properties for 700,000 galaxies with SDSS redshifts z<0.3, using data from GALEX, SDSS, and WISE. The galaxy properties (stellar mass, dust attenuation, star formation rates) are obtained via UV/optical SED fitting using a Bayesian framework. The catalog contains galaxies within GALEX footprints regardless of a UV detection. Mid-IR star formation rates are derived from WISE 22μm data. Additional details are available in the publications listed above, and in the README file.

Data Products

There are four different catalogs, in both ASCII and FITS format. They are summarized in the table below, and are available for download. You can also query the catalogs (without downloading all of them) using STScI's CasJobs. See the Data Access section below for instructions. The column names are defined in Table 1 of Salim et al. 2016, and are also included below and in the table notes section in CasJobs.

MAST Name Name in
Salim (2016)
Size (MB)
TXT/FITS
Download
hlsp_gswlc_galex-sdss-wise_multi_d1_multi_v1_cat.txt GSWLC-D1 9.2 / 4.6 TXT FITS
hlsp_gswlc_galex-sdss-wise_multi_m1_multi_v1_cat.txt GSWLC-M1 69 / 34 TXT FITS
hlsp_gswlc_galex-sdss-wise_multi_a1_multi_v1_cat.txt GSWLC-A1 122 / 60 TXT FITS
hlsp_gswlc_galex-sdss-wise_multi_x1_multi_v1_cat.txt GSWLC-X1 126 / 62 TXT FITS
Column Description
OBJID SDSS photometric identification number
GLXID GALEX photometric identification number
PLATE SDSS spectroscopic plate number
MJD SDSS spectroscopic plate date
FIBER_ID SDSS spectroscopic fiber identification number
RA Right Ascension from SDSS [deg]
DECL Declination from SDSS [deg]
Z Redshift from SDSS
REDCHISQ Reduced goodness-of-fit value for the SED fitting
LOGMSTAR Stellar mass [solar masses]
LOGMSTARERR Error of the stellar mass [solar masses]
LOGSFRSED UV/optical (SED) star formation rate [solar masses / year]
LOGSFRSEDERR Error of the SFR [solar masses / year]
AFUV Dust attenuation in rest-frame FUV [mag]
AFUVERR Error of dust attenuation in FUV [mag]
AB Dust attenuation in rest-frame B [mag]
ABERR Error of dust attenuation in B [mag]
AV Dust attenuation in rest-frame V [mag]
AVERR Error of dust attenuation in V [mag]
FLAG_SED SED fitting flag (0=OK, 1=broad-line spectrum, 2=χr2>30, 5=missing SDSS photometry
UV_SURVEY 1=GSWLC-1, 2=GSWLC-m, 3=GSWLC-D
LOGSFRAW Mid-IR star formation rate from WISE (AllWISE catalog) [solar masses / year]
FLAG_WISE Mid-IR SFR (AllWISE) flag (0=OK, 1=no mid-IR SFR (low SSFR), 5=no 22 μm detection)
LOGSFRUW Mid-IR star formation rate from WISE (unWISE catalog) [solar masses / year]
FLAG_UNWISE Mid-IR SFR (unWISE) flag (0=OK, 1=no mid-IR SFR (low SSFR), 5=no 22 μm detection)
FLAG_MGS 0=not in SDSS Main Galaxy Sample (MGS), 1=in MGS

Data Access

In addition to downloading the data files above, you may also conduct SQL queries using STScI's CasJobs and download the results as csv or FITS tables. First, sign-up for an STScI CasJobs account. Note that this is NOT the same as any general STScI account you may have registered: CasJobs accounts are self-contained within STScI. Some example screenshots and simple queries are provided below.

Example Screenshots (click for larger versions)
You'll see this screen when you visit the CasJobs page, if not signed in. The login button is at the top.
The "Query" tab is where you execute your SQL queries. You select a Context with the drop-down at the top left. In the case of GSWLC, you select "HLSP_GSWLC" to query the four tables.
The "MyDB" tab is where you can examine output tables you create, or output tables stored by STScI. Be sure to change the Context to the appropriate area (your output tables are always under "MyDB").

Example SQL Scripts

Example 1: Select star-forming galaxies in the Coma Cluster.
This example selects sources from the GSWLC-M catalog that satisfiy RA, DEC, redshift, and star formation rate cuts. The "select *" component selects all rows from the GSWLC-M table.
Example 2: Select galaxies including data from SDSS tables in MAST CasJobs.
This example selects galaxies based on columns from both GSWLC and SDSS. It uses a SQL join to cross-identify objects in the GSWLC with SDSS DR12. You can use SQL joins to match objects in one table within MAST CasJobs with another table, as long as they share at least one column of unique values in common, referred to as a "primary key". In this case, the SDSS identifier is in both tables and can be used to do matching between objects.
[1 ]  select h.*, mc.NUV_A_WORLD, mc.NUV_B_WORLD from gswlc_galex_sdss_wise_multi_a1 as h
[2 ]  into mydb.GSWLC_galaxies
[3 ]  inner join GALEX_GR6Plus7.photoobjall as mc on glxid = mc.objid
[4 ]  where
[5 ]  logsfrsed - logmstar > -10.9 and logsfrsed - logmstar < -10.3
[6 ]  and logmstar > 10.5 and logmstar < 11.1
[7 ]  and mc.NUV_B_WORLD / mc.NUV_A_WORLD > 0.8
[8 ]  and NUV_A_WORLD > 0.002
[9 ]  and NUV_A_WORLD > 0.
[10]  and NUV_B_WORLD > 0.
  

Explanation of SQL:

Line 1: Selects all columns in GSWLC A1 table, and the NUV_A_WORLD and NUV_B_WORLD columns from the GALEX PhotoObjAll table. Note that "h" and "mc" are aliases for these tables defined later in the script.

Line 2: The output table of results in put into a new table called "GSWLC_galaxies" inside the MyDB Context. Note that the name of your output table must not exist, since result tables will not be overwritten. You must either drop a table in the MyDB tab or choose a new output table name if a table already exists with your output name.

Line 3: This uses SQL "inner join" to match the "glxid" column in GSWLC A1 table with the "objid" column in the GALEX PhotoObjAll table. So this uses the GALEX ID in both tables to allow cross-identification between the two tables.

Lines 4-10: These are the constraints on which rows to keep, applying cuts on star formation rate and object shape/size.