III/268 DEEP2 Redshift Survey, Data Release 4 (Matthews+ 2013)
The DEEP2 Redshift Survey (Data Release 4)
Matthews D.J., Newman J.A., Coil A.L., Cooper M.C., Gwyn S.D.J.
<Astrophys. J. Suppl. Ser. 204, 21 (2013)>
=2013ApJS..204...21M 2013ApJS..204...21M
=2013yCat.3268....0M 2013yCat.3268....0M
ADC_Keywords: Galaxy catalogs ; Redshifts ; Velocity dispersion
Keywords: astrometry ; catalogs ; galaxies: distances and redshifts ;
galaxies: photometry ; surveys ; techniques: photometric
Abstract:
This paper describes a new catalog that supplements the existing DEEP2
Galaxy Redshift Survey photometric and spectroscopic catalogs with
ugriz photometry from two other surveys: the Canada-France-Hawaii
Legacy Survey (CFHTLS) and the Sloan Digital Sky Survey (SDSS). Each
catalog is cross-matched by position on the sky in order to assign
ugriz photometry to objects in the DEEP2 catalogs. We have
recalibrated the CFHTLS photometry where it overlaps DEEP2 in order to
provide a more uniform data set. We have also used this improved
photometry to predict DEEP2 BRI photometry in regions where only
poorer measurements were available previously. In addition, we have
included improved astrometry tied to SDSS rather than USNO-A2.0 for
all DEEP2 objects. In total this catalog contains ∼27, 000 objects
with full ugriz photometry as well as robust spectroscopic redshift
measurements, 64% of which have r > 23. By combining the secure and
accurate redshifts of the DEEP2 Galaxy Redshift Survey with ugriz
photometry, we have created a catalog that can be used as an excellent
testbed for future photo-z studies, including tests of algorithms for
surveys such as LSST and DES.
Description:
The DEEP2 redshift survey was achieved with the DEIMOS multi-object
spectrograph on the Keck II 10m telescope in 2002-2008; it used a
total of 411 slitmasks covering approximately 3 square degrees over
4 separate fields. As detailed in Newman et al. (2013ApJS..208....5N 2013ApJS..208....5N),
targets were selected from the BRI photometric catalogs of Coil et al.
(2004ApJ...617..765C 2004ApJ...617..765C, Cat. II/301), reaching a limiting magnitude of
RAB=24.1mag. The 1200 line/mm grating was employed with a central
wavelength of 780nm, yielding a resolution of R∼5000 and typically
covering a wavelength range of 650-910nm (depending on slit placement
on the mask). The OG550 order-blocking filter was used to limit flux
blueward of 555nm, and each slitmask was observed for approximately
one hour, depending on the observing conditions (i.e. transparency
and/or seeing). Typical slitlengths are around 6arcsec, with a
standard 1arcsec slitwidth.
The DEEP2-DR4 Redshift Survey includes 52,989 entries, corresponding
to all spectroscopic targets regardless of whether an accurate
redshift was measured; only galaxies with redshift quality q_z≥3
should be treated as having a reliable redshift measurement (objects
identified as stars are given q_z=-1). Also, be sure to note that
while there are 52,989 entries in the redshift catalog, some objects
were observed multiple times (to test redshift accuracy, etc.) and the
redshift catalog contains 50,319 unique objects. In addition to the
full catalog, here we provide a trimmed, unique redshift catalog which
removes duplicated objects (keeping entries with higher redshift
quality where appropriate):
Acknowledging DEEP2:
Scientific and technical publications using DEEP2 data should
acknowledge (http://deep.ps.uci.edu/DR4/credit.html)
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
deep2dr4.dat 338 50319 Unique sources of the DEEP2 Redshift Survey
deep2all.dat 338 52989 All observations (is a superset of deep2dr4)
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See also:
http://deep.ps.uci.edu/DR4/zcatalog.html : DEEP2-DR4 Home Page
II/301 : The DEEP2-DR1 Photometric Catalog (Coil+ 2004)
J/ApJ/625/6 : Galaxy groups in the DEEP2 Galaxy Redshift Survey (Gerke+, 2005)
J/ApJ/654/115 : DEEP2 Galaxy Redshift Survey: SDSS QSOs (Coil+, 2007)
J/ApJS/202/6 : XDEEP2 survey catalog (Goulding+, 2012)
J/MNRAS/377/806 : Tully-Fisher relation of DEEP2 galaxies (Chiu+, 2007)
Byte-by-byte Description of file: deep2dr4.dat deep2all.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- ObjNo Unique object identifier from pcat (see II/301)
11- 19 F9.5 deg RAdeg Right ascension (J2000)
21- 29 F9.5 deg DEdeg Declination (J2000)
31- 38 F8.3 mag Bmag CFHT B-band AB magnitude (1)
42- 47 F6.3 mag Rmag CFHT R-band AB magnitude (1)
49- 56 F8.3 mag Imag CFHT I-band AB magnitude (1)
58- 65 F8.3 mag e_Bmag mean error on Bmag
69- 74 F6.3 mag e_Rmag mean error on Rmag
76- 83 F8.3 mag e_Imag mean error on Imag
87- 91 F5.2 pix RG Source radius (2)
94- 98 F5.3 --- Ell [0/2] Ellipticity (1-b/a)
101-105 F5.1 deg PA [-90/90] Position angle of source ellipse
107-112 F6.3 --- Pgal [-2/3] Probability of source being a galaxy (3)
115-120 F6.3 mag EBV Galactic reddening E(B-V) from Schlegel
123-130 F8.3 mag BMag ?=-999 Absolute B-band magnitude
(Willmer et al. 2006ApJ...647..853W 2006ApJ...647..853W)
132-139 F8.3 mag U-B ?=-999 Rest-frame U-B color (AB)
143-150 I8 --- ObjName Observed ID (4)
152-155 I4 --- Mask [1100/4345] Slitmask number of the observation
157-159 I3 --- Slit [0/171] Slitlet number of the observation
161-170 A10 "date" Date Observation date (YYYY-MM-DD)
172-178 F7.1 d MJD [52499/54537] Modified JD of observation
180-187 F8.4 deg slitRA Right ascension of slit center
189-196 F8.4 deg slitDE Declination of slit center
199-203 F5.2 arcsec slitLen [1.9/91] Slit length
206-210 F5.1 deg slitPA [-93/270] Position angle of slit
213-220 F8.5 --- z [-1/3.5] Observed best-fitting redshift
222-229 F8.5 --- zBest [-1/3.5] Best redshift
(corrected for heliocentric motion)
231-240 F10.5 --- e_z [-6/] Redshift error (<0 for problematic fit)
242-243 I2 --- q_z [-1/4]?=-2 Redshift quality code, 4=best (5)
245-250 A6 --- Cl [AGN GALAXY STAR] Type of best-fitting template
252-257 A6 --- sCl Coarse classification for stellar templates
259-270 E12.6 --- Rchi2 reduced χ2 value for the redshift fit
276-280 I5 --- dof [0/17747] Degrees of freedom for redshift fit
283-287 F5.1 km/s sigV ?=999.9 velocity dispersion
289-294 F6.1 km/s e_sigV ?=9999 Error on sigV
296-343 A48 --- Comment Comments (6)
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Note (1): magnitudes from pcat (II/301), corrected from galactic extinction
Note (2): Gaussian radius of a circular 2-D Gaussian fit to the R-band
image, in pixels (1pix=0.207arcsec)
Note (3): The value '3' indicates a resolved galaxy; values between 0 and 1
gives the probability that the source is an unresolved galaxy.
Note (4): The CFHT 12K BRI catalogs are created on a pointing-by-pointing
bases and not at a field-by-field level (for more info regarding the
DEEP2 fields and pointings, refer to the description of the
photometric catalogs). For objects that fall in the regions of overlap
between the various photometric pointings within a given field, the
objects can appear in multiple photometric catalogs, being assigned
different 8-digit DEEP2 identification numbers in each catalog. These
duplications have been resolved such that a unique identifier is
assigned ("ObjNo" field). However, the slitmasks are designed on a
pointing-by-pointing basis, so objects are actually targeted based on
their id numbers in a particular pointing. Most importantly, since the
spec2d data reduction pipeline draws the object id information from
the slitmask design files, the object id in the "spec1d" files is this
pointing-specific number. In order to facilitate matching of entries
in the redshift catalog to 1-d spectral files, the "ObjName" field is
included, which gives the pointing-specific id number.
Note (5): Values ≥3 indicate reliable redshifts. Qualities codes are:
-2 = Object was effectively unobserved
-1 = Object is identified as a star (i.e., z∼0)
0 = Object has yet to be inspected; quality still to be assigned.
1 = Redshift unlikely to be recovered for this source;
redshift value in catalog is not meaningful.
2 = Redshift may yet to be recovered for this source;
redshift value in catalog is not meaningful.
3 = Secure redshift
4 = Very secure redshift.
Note (6): abbreviations used in comments:
bsky = bad sky subtraction
bcol = bad column(s) (parallel to the dispersion direction)
bcont = bad continuum shape
bext = bad extraction window (displaced, too wide/narrow, or contamination)
edge = object too near the end of the slitlet
disc = discontinuity (non-physical jump in the continuum)
marg = marginal extraction (S/N is low)
sngl = single (only one spectral feature is visible; note that the
resolved [OII] double represent 2 features).
supser = superimposed serendipitous object (two redshifts measurable from
the spectrum)
fix = fixed the element of the reduction which went wrong
iffy = something wrong that makes the observation unreliable as an
integrated spectrum. May be further qualified by adding bsky,
bcont, bcol, bext, disc or edge to explain the problem.
offser = offset serendip (a second spectrum is present in the slitlet
but is well enough separated or dim enough that the extraction
is not seriously affected). Note that the redshift of the
serendip is not necessarily recorded.
fill-gap failed = a robust 1-D spectrum could not be constructed
ZREVISED = the redshift was "fixed"
ZREVISED: zfix failed = a redshift revision was attempted, but failed.
ZMATCH-FAIL = cases where a redshift was previously identified with a
quality 3 or 4, but the spec1d pipeline failed to yield
a good fit that matches the previous redshift value.
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History:
from http://deep.ps.uci.edu/DR4/home.html
(End) Francois Ochsenbein [CDS] 13-Mar-2013