J/A+A/609/A84 VIPERS spectroscopic redshifts (PDR-2) (Scodeggio+, 2018)
The VIMOS Public Extragalactic Redshift Survey (VIPERS).
Full spectroscopic data and auxiliary information release (PDR-2).
Scodeggio M., Guzzo L., Garilli B., Granett B.R., Bolzonella M.,
De La Torre S., Abbas U., Adami C., Arnouts S., Bottini D., Cappi A.,
Coupon J., Cucciati O., Davidzon I., Franzetti P., Fritz A., Iovino A.,
Krywult J., Le Brun V., Le Fevre O., Maccagni D., Malek K., Marchetti A.,
Marulli F., Polletta M., Pollo A., Tasca L.A.M., Tojeiro R., Vergani D.,
Zanichelli A., Bel J., Branchini E., De Lucia G., Ilbert O.,
Mccracken H.J., Moutard T., Peacock J.A., Zamorani G., Burden A.,
Fumana M., Jullo E., Marinoni C., Mellier Y., Moscardini L., Percival W.J.
<Astron. Astrophys., 609, A84 (2018)>
=2018A&A...609A..84S 2018A&A...609A..84S (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Redshifts ; Optical
Keywords: cosmology: observations - large-scale structure of Universe -
galaxies: distances and redshifts - galaxies: statistics - surveys
Abstract:
We present the full public data release (PDR-2) of the VIMOS Public
Extragalactic Redshift Survey (VIPERS), performed at the ESO VLT. We
release redshifts, spectra, CFHTLS magnitudes and ancillary
information (as masks and weights) for a complete sample of 86 775
galaxies (plus 4732 other objects, including stars and serendipitous
galaxies); we also include their full photometrically-selected parent
catalogue. The sample is magnitude limited to iAB≤22.5, with an
additional colour-colour pre-selection devised as to exclude galaxies
at z<0.5. This practically doubles the effective sampling of the VIMOS
spectrograph over the range 0.5<z<1.2 (reaching 47% on average),
yielding a final median local galaxy density close to
5x10-3h3/Mpc3. The total area spanned by the final data set is
~=23.5deg2, corresponding to 288 VIMOS fields with marginal
overlaps, split over two regions within the CFHTLS-Wide W1 and W4
equatorial fields (at RA~=2 and ~=22h, respectively). Spectra were
observed at a resolution R=220, covering a wavelength range
5500-9500Å. Data reduction and redshift measurements were performed
through a fully automated pipeline; all redshift determinations were
then visually validated and assigned a quality flag. Measurements with
a quality flag ≥2 are shown to have a confidence level of 96% or
larger and make up 88% of all measured galaxy redshifts (76552 out of
86775), constituting the VIPERS prime catalogue for statistical
investigations. For this sample the rms redshift error, estimated
using repeated measurements of about 3000 galaxies, is found to be
σz=0.00054(1+z). All data are available at
http://vipers.inaf.it and on the ESO Archive.
Description:
Final public release of complete VIPERS galaxy catalogue of ∼90,000
redshifts (PDR-2)
The "VIMOS Public Extragalactic Redshift Survey" (VIPERS) is a
completed ESO Large Program that has mapped in detail the spatial
distribution of normal galaxies over an unprecedented volume of the
z∼1 Universe. It used the VIMOS spectrograph at the 8∼m Very Large
Telescope to measured spectra for more than 90,000 galaxies with red
magnitude I(AB) brighter than 22.5 over an overall area of nearly 24
square degrees. At this redshift, VIPERS fills a unique niche in
galaxy surveys, optimizing the combination of multi-band accurate
photometry (5 bands from the CFHT-LS, plus Galex-NUV and NIR from
WIRCAM and other facilities over most of the area) with the
multiplexing capability of VIMOS. A robust color-color pre-selection
allowed the survey to focus on the 0.5<z<1.2 redshift range,
yielding an optimal combination of large volume (5x107h-3Mpc3)
and high effective spectroscopic sampling (46% on average). VIPERS has
produced a data set that in many respects represents for the first
time the equivalent at z∼1 of the large surveys of the "local" (z<0.2)
Universe built at the beginning of this century (SDSS and 2dFGRS).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
vipersw1.dat 124 60528 PDR-2 spectroscopic catalogue, VIPERS field W1
vipersw4.dat 124 30979 PDR-2 spectroscopic catalogue, VIPERS field W4
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See also:
http://vipers.inaf.it/rel-pdr2.html : VIPERS PDR2 Home Page
Byte-by-byte Description of file: vipersw1.dat vipersw4.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- VIPERS VIPERS object name, according to IAU
standards, VIPER NNNNNNNNN
18- 26 I9 --- ID VIPERS identification number
28- 38 F11.7 deg RAdeg Right ascension (J2000)
40- 49 F10.7 deg DEdeg Declination (J2000)
51- 57 F7.4 mag imag CFHTLS T0005 i magnitude (AB)
59- 64 E6.4 mag e_imag CFHTLS T0005 i magnitude error (AB)
66- 71 A6 --- Pointing Pointing
73 I1 --- Quadrant [1/4] Quadrant
75- 80 F6.4 --- zsp Spectroscopic redshift
82- 86 F5.1 --- zflg Spectrosocpic flag (1)
88- 96 F9.4 --- norm ?=-99 Normalization factor. The spectrum has
been multiplied by this value to be
normalized to the i value
98 I1 --- epoch [1/2] Observing epoch (2)
100 I1 --- photoMask [0/1] Flag indicating whether the object falls
within the photometric mask (3)
102-110 F9.7 --- TSR Target Sampling Rate (4)
112-120 F9.7 --- SSR Spectroscopic Success Rate (5)
122-124 I3 --- classFlag The VIPERS galaxy target selection flag (6)
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Note (1): Redshift measurement quality flag.
The integer part of the flag has the following meaning:
4 = a high-confidence, highly secure redshift, based on a high SNR spectrum
and supported by obvious and consistent spectral features. The
confidence level of Flag 4 measurements is estimated to be 99% secure.
3 = also a very secure redshift, comparable in confidence with Flag 4,
supported by clear spectral features in the spectrum, but not
necessarily with high SNR.
2 = a fairly secure, ∼90% confidence redshift measurement, supported by
cross-correlation results, continuum shape and some spectral features.
9 = a redshift based on only one single clear spectral emission feature.
1 = a reasonable redshift measurement, based on weak spectral features
and/or continuum shape, for which there is roughly a 50% chance that
the redshift is actually wrong.
In case of broad emission lines typical of broad line AGN,
a prefix of 1 is added to zflag, i.e.
14 = secure AGN with a >95% secure redshift, at least 2 broad lines;
13 = secure AGN with good confidence redshift, based on one broad line and
some faint additional feature;
12 = a >95% secure redshift measurement, but lines are not significantly
broad, might not be an AGN;
19 = secure AGN with one single secure emission line feature, redshift based
on this line only;
11 = a tentative redshift measurement, with spectral features not
significantly broad.
Second objects in slit get a 2 as prefix to the flag, i.e.
24 = a second object with flag 4
23 = a second object with flag 3
22 = a second object with flag 2
29 = a second object with flag 9
21 = a second object with flag 1
And similarly for BLAGN (214, 213, 212, ...).
Suffix in form of decimal digit has the following meaning:
.5 = the spectroscopic redshift is compatible within 1σ with
photometric redshift, i.e zphotmin < zspec < zphotmax
.4 = the spectroscopic redshift is compatible with photometric redshift at
the 2σ level, i.e. minvalue < zspec < maxvalue
where
minvalue=min[ zphot-(1+zphot)*0.05, zphotmin ]
maxvalue=max[ zphot+(1+zphot)*0.05, zphotmax ]
and 0.05 is twice the median scatter of the comparison between
spectroscopic and photometric redshifts.
.2 = spectroscopic redshift is NOT compatible with photometric redshift
.1 = no photometric redshift available
Note (2): Observing epoch as follows:
1 = objects have been observed before VIMOS refurbishing in summer 2010
2 = objects have been observed after summer 2010
Note (3): Flag as follows:
1 = if the object is inside the mask
0 = if it is outside.
Objects outside the photometric mask have a less reliable photometry
Note (4): The Target Sampling Rate (TSR) is defined as the ratio of the observed
objects over the number of possible targets: TSR=Nspec/Nparent, where Nspec
is the number of detected targets and Nparent is the number of all the
possible random targets.
TSR has been computed in small rectangular apertures to take into account
the shadowing effect of MOS slits in the sampling of the galaxy
distribution. TSR and is needed to take into account the fact that not all
the possible targets can be observed in the single pass strategy adopted in
VIPERS. See Scodeggio et al. 2016 for details
Note (5): The Spectroscopic Success Rate (SSR) is defined as the ratio of the
galaxies with a successfully measured redshift (flag = 2.*,3.*,4.*,9.*) over
the total sample of detected galaxies.
SSR is a function of the apparent magnitude (since to bright objects
correspond spectra with high signal-to-noise, from which the redshift can be
more easily measured), of the galaxy luminosity and rest-frame color and of
the overall quadrant quality, quantified via the mean SSR for all galaxies
in that quadrant. See Scodeggio et al. 2016 for detail
Note (6): The VIPERS galaxy target selection flag, based on the CFHTLS T005
catalogue as follows:
1 = VIPERS main galaxy target, i.e. galaxy with colors compatible with
z>0.5, according to the color criteria described in Guzzo et al.
(2014A&A...566A.108G 2014A&A...566A.108G)
0 = galaxy with colors compatible with z<0.5, according to the color
criteria described in Guzzo et al. (2014A&A...566A.108G 2014A&A...566A.108G)
-1 = stellar like object according to the VIPERS star/galaxy separation
criteria
-2 = magnitude i >22.5
-3 = magnitude i <17.5
-88 = problematic object, possibly saturated image
-99 = problematic object, missing photometric data
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History:
Copied at http://vipers.inaf.it/rel-pdr2.html
(End) Patricia Vannier [CDS] 04-Nov-2022