J/ApJS/172/70 zCOSMOS-bright catalog, DR3 (Lilly+, 2007)
zCOSMOS: a large VLT/VIMOS redshift survey covering 0<z<3 in the COSMOS field.
Lilly S.J., Fevre O.L., Renzini A., Zamorani G., Scodeggio M., Contini T.,
Carollo C.M., Hasinger G., Kneib J.-P., Iovino A., Le Brun V., Maier C.,
Mainieri V., Mignoli M., Silverman J., Tasca L.A.M., Bolzonella M.,
Bongiorno A., Bottini D., Capak P., Caputi K., Cimatti A., Cucciati O.,
Daddi E., Feldmann R., Franzetti P., Garilli B., Guzzo L., Ilbert O.,
Kampczyk P., Kovac K., Lamareille F., Leauthaud A., Le Borgne J.-F.,
Mccracken H.J., Marinoni C., Pello R., Ricciardelli E., Scarlata C.,
Vergani D., Sanders D.B., Schinnerer E., Scoville N., Taniguchi Y.,
Arnouts S., Aussel H., Bardelli S., Brusa M., Cappi A., Ciliegi P.,
Finoguenov A., Foucaud S., Franceschini R., Halliday C., Impey C.,
Knobel C., Koekemoer A., Kurk J., Maccagni D., Maddox S., Marano B.,
Marconi G., Meneux B., Mobasher B., Moreau C., Peacock J.A., Porciani C.,
Pozzetti L., Scaramella R., Schiminovich D., Shopbell P., Smail I.,
Thompson D., Tresse L., Vettolani G., Zanichelli A., Zucca E.
<Astrophys. J. Suppl. Ser., 172, 70-85 (2007)>
=2007ApJS..172...70L 2007ApJS..172...70L
ADC_Keywords: Surveys ; Redshifts
Keywords: cosmology: observations - galaxies: active -
galaxies: distances and redshifts - galaxies: evolution -
large-scale structure of universe - quasars: general - surveys
Abstract:
zCOSMOS is a large-redshift survey that is being undertaken in the
COSMOS field using 600hr of observation with the VIMOS spectrograph
on the 8m VLT. The survey is designed to characterize the
environments of COSMOS galaxies from the 100kpc scales of galaxy
groups up to the 100Mpc scale of the cosmic web and to produce
diagnostic information on galaxies and active galactic nuclei. The
zCOSMOS survey consists of two parts:
(1) zCOSMOS-bright, a magnitude-limited I-band IAB<22.5 sample of
about 20000 galaxies with 0.1<z<1.2 covering the whole 1.7deg2
COSMOS ACS field, for which the survey parameters at z∼0.7 are
designed to be directly comparable to those of the 2dFGRS at z∼0.1;
and (2) zCOSMOS-deep, a survey of approximately 10000 galaxies
selected through color-selection criteria to have 1.4<z<3.0, within
the central 1deg2.
This paper describes the survey design and the construction of the
target catalogs and briefly outlines the observational program and the
data pipeline. In the first observing season, spectra of 1303
zCOSMOS-bright targets and 977 zCOSMOS-deep targets have been
obtained.
Description:
zCOSMOS (P.I. Simon Lilly) is a large redshift survey undertaken in
the COSMOS field using the VIMOS spectrograph mounted at the Melipal
Unit Telescope of the VLT at ESO's Cerro Paranal Observatory, Chile.
zCOSMOS (ESO Large Programme LP175.A-0839) was awarded about 600
hours of Service Mode observing time on the ESO VLT, which was
executed between 2005-2010.
The zCOSMOS redshift survey has been designed to efficiently utilize
VIMOS by splitting the survey into two parts. The first,
zCOSMOS-bright, which is the subject of DR3, aims to produce a
redshift survey of approximately 20000 I-band selected galaxies at
redshifts z<1.2. Covering the approximately 1.7deg2 of the COSMOS
field (essentially the full ACS-covered area), the transverse
dimension at z∼1 is 75Mpc. The second part, zCOSMOS-deep, observed a
smaller number of galaxies selected to mostly lie at higher redshifts,
1.5<z<3.0.
This DR3 release is expected to be the final release of the
zCOSMOS-bright spectroscopic catalogue. The full set of extracted
1-dimensional spectra are being released, plus a catalogue in which we
give for each target the 1-D spectra filenames, the I-band magnitude
used for the selection, as well as the measured redshift and
confidence class. A full description of the survey can be found in
Lilly et al., 2007ApJS..172...70L 2007ApJS..172...70L, and Lilly et al.,
2009ApJS..184..218L 2009ApJS..184..218L, and a future paper to be submitted.
Observations for the DR3 sample were carried out with the VIMOS
spectrograph mounted on the 8m VLT/UT3 telescope during extensive
Service Mode runs from 2005 to 2009. Observations used the MR grism
with 1.0 arcsec slits, yielding a spectral resolution R∼600 at
2.5Å/pixel and a spectral range 5550-9450Å. All masks are
observed with the slits oriented N-S. The pattern of pointings is
such that every target in the central region have had eight
opportunities to be selected for observation.
Spectra for 20689 objects could be extracted from the VIMOS
observations and are presented in this DR3 release. The targets are
selected across the whole 1.7deg2 COSMOS field centred at
RAJ2000=10:00:2s and DEJ2000=02:13:37 extending over 1.30x1.24deg in
the right ascension-declination plane.
The primary input catalogue for slit-mask design was generated using
SExtractor (Bertin & Arnouts, 1996A&AS..117..393B 1996A&AS..117..393B) applied to the
COSMOS F814W HST/ACS images sampled at 0.03arcsec/pixel (Koekemoer et
al., 2007ApJS..172..196K 2007ApJS..172..196K, Leauthaud et al., 2007ApJS..172..219L 2007ApJS..172..219L) in a
"hot and cold" two-pass process to first identify bright objects.
This substantially reduced the tendency of the HST-based catalogue to
"over-resolve" extended galaxies into multiple components. This
initial SExtractor catalogue was then "cleaned" by carrying out a
detailed comparison with one extracted from a stack of i* images
obtained with MEGACAM on the 3.6m Canada-France-Hawaii telescope and
processed at the TERAPIX data reduction center in Paris. This
catalogue was also used to supplement the ACS catalogue for regions
where the ACS images were either unavailable or unusable. The
zCOSMOS-bright target catalogue is intended to be simply defined as
having an ACS/HST SExtractor "magauto" brightness in the range
15.00<IAB(814)<22.50.
Generally, objects to be inserted into the slit mask were chosen
randomly from the target catalogue. However, a few percent of targets
(generally X-ray sources) were designated as "compulsory". These were
inserted into the masks with first priority and, as a result, they are
about 1.5 times over-represented in the spectroscopic catalogue.
Objects strongly suspected of being stars on the basis of morphology
and spectral energy distribution were classified as "forbidden" and
not included in the mask designs. These comprise about 15% of the
IAB<22.5 sample. The criteria for this exclusion were deliberately
quite conservative and as a result about 4% of the spectroscopic
targets turn out to be stars.
For each slit there was a primary target. Naturally, sometimes other
objects in the target catalogue happened to fall in the same
slit. These "secondary targets" were reduced in the same way. If these
secondary objects were forbidden, their spectra were anyway reduced
and included in the catalogue.
This release DR3 is expected to be the final release of the
zCOSMOS-bright dataset. It supersedes, revises and significantly
extends the previous releases. The first data release DR1 from October
2007 contained 1264 spectra and a corresponding catalogue. The
superseding second data release DR2 from October 2008 contained 10643
spectra and a corresponding catalogue. The ESO Archive Science Group
migrated the DR2 release to the Phase 3 infrastructure in February
2014 under Release Number 1. This makes this third DR3 zCOSMOS-bright
data release archived under Release Number 2 in the Phase 3
infrastructure.
Acknowledgements:
All publications based on ESO archive data should carry the
following acknowledgement:
"Based on observations made with the European Southern Observatory
telescopes obtained from the ESO/ST-ECF Science Archive Facility."
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
zcosmos3.dat 107 20689 zCOSMOS Spectroscopic Redshift Survey, DR3
sp/* . 20689 Individual fits spectra
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See also:
III/250 : The VIMOS VLT deep survey (VVDS-DEEP) (Le Fevre+ 2005)
J/A+A/428/1043 : Redshifts from VIMOS VLT Deep Survey (Le Fevre+, 2004)
II/284 : COSMOS Multi-Wavelength Photometry Catalog (Capak+, 2007)
J/ApJS/172/46 : VLA-COSMOS survey. II. (Schinnerer+, 2007)
Byte-by-byte Description of file: zcosmos3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- zCOSMOS [700137/960004] zCOSMOS identification number
(OBJECT_ID)
8- 17 F10.6 deg RAdeg Right ascension (J2000) (RAJ2000)
19- 26 F8.6 deg DEdeg Declination (J2000) (DEJ2000)
28- 33 F6.4 --- z ?=- Redshift (REDSHIFT)
35- 39 F5.1 --- CC Confidence class (CC) (1)
41- 45 F5.2 mag Imag Selection mag F814W AB (IMAG_AB)
47- 48 I2 --- FlagS [-1/1] Flag for satisfying bright sample
selection (FLAG_S)
50 I1 --- FlagX [0/2] Flag for X-ray selection (FLAG_X)
52 I1 --- FlagR [0/2] Flag for radio selection (FLAG_R)
54 I1 --- FlagUV [0/2] Flag for UV selection (FLAG_UV)
56-107 A52 --- FileName Name of the spectrum fits file in
subdirectory sp (FILENAME)
--------------------------------------------------------------------------------
Note (1): Confidence Class (CC) defined as 3 digits (ab.c).
* Unit digit (b in ab.c) represents the confidence class:
--------------------------------------------------------------------
CC Description Spectroscopic Photo-z consistency
verification within dz=0.08(1+z)
--------------------------------------------------------------------
4 Very secure redshift,
beautiful redshift >99.5% 97%
3 Secure redshift >99.5% 97%
9 One line redshift 95% 84%-95% (after
(best guess) (after correction) correction with photo-z)
2 Probable redshift 92% 93%
1 Insecure redshift 70% 72%
0 Unidentified spectrum
--------------------------------------------------------------------
* the decimal (.c) represents the Spectroscopic/photometric consistency:
--------------------------------------------------------------------
.5 Spectroscopic redshift consistent within 0.08(1+z) of the
photometric redshift, both for galaxies, stars and AGN.
.4 No photometric redshift available, includes all spectroscopic
AGN and stars
.3 Special case for Class 18 and 9: Consistent with photo-z only
after the redshift changed to the alternate redshift,
a switch which is then applied
.1 Spectroscopic and photometric redshifts are not consistent at
the level of 0.08(1+z)
--------------------------------------------------------------------
* the tens (a in ab.c) is
---------------------------
0 = Galaxies and stars
1 (+10) = Broad line AGN
2 (+20) = Secondary targets
---------------------------
History: Data copied at
https://irsa.ipac.caltech.edu/data/COSMOS/spectra/z-cosmos/DR3/
(End) Patricia Vannier [CDS] 13-Jun-2023