The catalogs can also be donwloaded from MAST
More than 200 million UV sources have been measured
in two UV bands: far-UV (1344-1786Ang) and near-UV (1771-2831Ang) by GALEX,
the first mission to perform sky surveys at these wavelengths.
What are these sources? How many are Milky Way stars, and how many are extragalactic objects?
How are they distributed in colors, magnitudes, luminosity? How do we extract samples of sources
by astrophysical class? Which classes of objects are best selected and characterized from UV surveys?
Are there peculiar classes of objects discovered from the GALEX data?
The series of papers below answers these questions.
We analyzed the content of the "UV sky",
and provide 'clean' catalogs
of UV sources from the two major GALEX surveys, AIS (depth about 21 ABmag in UV), and MIS (depth about 23 ABmag in UV)
Below you will find:
Bianchi, L. , 2011, ApSS, 335, 51; DOI: 10.1007/s10509-011-0612-2 ( download pdf )
Bianchi, L. , Efremova, B., Herald, J., Girardi, L, Zabot, A., Marigo, P., Martin, C, 2011,
MNRAS, 411, 2770
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
Hutchings, J.B., and Bianchi, L. , 2010, AJ, 140, 1987
Bianchi, L. 2009,
in "Space Astronomy: The UV Window to the Universe", APSS, 320, 11 ( DOI: 10.1007/s10509-008-9761-3 )
Bianchi, L., Hutchings, J.B., Efremova, B. et al. 2009, AJ, 137, 3761 ( astro-ph arXiv:0901.1896 )
Bianchi, L., Efremova, B., Herald, J. et al. 2009, in "Future Directions in Ultraviolet Spectroscopy",
eds.Van Steenberg et al AIPC, 1135, 326
this is an invited review in "The UV Universe 2010"
(St. Petersburg June 2010), editors B. Shustov, A.I. Gomez de Castro, and M. Sachkov
"GALEX and star formation"
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 (http://arxiv.org/abs/1011.1733 )
THIS IS THE PAPER DESCRIBING THE CATALOGS OF UV SOURCES available below
The catalogs can also be dowloaded from the MAST database
(click here)
and are online from
Vizier
this paper discusses additional statistical properties of these catalogs and biases of sample selections
A sample of 19000 QSO Caldidates with redshift 0.5 to 2.0
download pdf or link to the
AJ catalog
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 www.spirngerlink.com
Ultraviolet Quasi Stellar Objects
download pdf file
The UV sky surveys: a roadmap for future UV missions
download ps file
Source/ 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
Note: this reference has Open Access. Catalogs can be used citing the MNRAS reference.
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 galex.stsci.edu 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 )
 |
Catalogs:
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.
 |
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:
#objid,ra,dec,glon,glat,e_bv,fuv_mag,fuv_magerr,nuv_mag,nuv_magerr,fuv_artifact,nuv_artifact,
fuv_flags,nuv_flags,sdssid,rank,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,istherespectrum
-- 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
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:
GALEX-MIS---SDSS hot star candidate catalog (9032 sources)
GALEX-AIS---SDSS hot star candidate catalog (28333 sources)