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J/AJ/121/2331 SDSS redshifts in the Coma cluster (Castander+, 2001)
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The First Hour of Extra-galactic Data of the Sloan Digital Sky Survey
Spectroscopic Commissioning: The Coma Cluster.
Castander F.J., Nichol R.C., Merrelli A., Burles S., Pope A.,
Connolly A.J., Uomoto A., Gunn J.E., Anderson J.E., Annis J.,
Bahcall N.A., Boroski W.N., Brinkmann J., Carey L., Crocker J.H.,
Csabai I., Doi M., Frieman J.A., Fukugita M., Friedman S.D.,
Hilton E.J., Hindsley R.B., Ivezi Z., Kent S., Lamb D.Q., Leger R.F.,
Long D.C., Loveday J., Lupton R.H., MacGillivray H., Meiksin A.,
Munn J.A., Newcomb M., Okamura S., Owen R., Pier J.R., Rockosi C.M.,
Schlegel D.J., Schneider D.P., Seigmund W., Smee S., Snir Y.,
Starkman L., Stoughton C., Szokoly G.P., Stubbs C., SubbaRao M.,
Szalay A., Thakar A.R., Tremonti C., Waddell P., Yanny B., York D.G.
<Astron. J. 121, 2331 (2001)>
=2001AJ....121.2331C
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ADC_Keywords: Clusters, galaxy ; Photometry ; Redshifts
Keywords: Catalogs - cosmology: observations -
galaxies: clusters: individual (Coma) -
galaxies: fundamental parameters - methods: data analysis
Abstract:
On 1999 May 26, one of the Sloan Digital Sky Survey (SDSS) fiber-fed
spectrographs saw astronomical first light. This was followed by the
first spectroscopic commissioning run during the dark period of 1999
June. We present here the first hour of extragalactic spectroscopy
taken during these early commissioning stages: an observation of the
Coma cluster of galaxies. Our data samples the southern part of this
cluster, out to a radius of 15{deg} (1.8h^-1^Mpc, approximately to the
virial radius) and thus fully covers the NGC 4839 group. We provide
redshifts and spectral classifications for 196 Coma galaxies, of which
45 redshifts are new. For the 151 galaxies in common with the
literature, we find excellent agreement between our redshift
determinations and the published values, e.g., for the largest
homogeneous sample of galaxies in common (63 galaxies observed by
Colless & Dunn, 1996ApJ...458..435C) we find a mean offset of 3km/s
and an rms scatter of only 24km/s.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 54 196 Galaxy Redshifts
table2.dat 93 196 Galaxy Classifications
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [CNM2001] Fiber extraction ID number
5- 8 I4 --- GMP ? The Godwin, Metcalfe & Peach (1983,
Cat. <VII/42>) number
10- 11 I2 h RAh Right Ascension (J2000) (1)
13- 14 I2 min RAm Right Ascension (J2000) (1)
16- 19 F4.1 s RAs Right Ascension (J2000) (1)
20 A1 --- DE- Declination sign (J2000)
21- 22 I2 deg DEd Declination (J2000) (1)
24- 25 I2 arcmin DEm Declination (J2000) (1)
27- 28 I2 arcsec DEs Declination (J2000) (1)
30- 33 I4 km/s cz The cross-correlation redshift (2)
35- 36 I2 km/s e_cz Uncertainty in cz (3)
38- 41 F4.1 --- RCoeff The cross-correlation coefficient
43- 47 F5.2 mag bmag The b band magnitude from the
SuperCOSMOS catalog (4)
49- 53 F5.2 mag rmag The r band magnitude from the
SuperCOSMOS catalog (4)
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Note (1): Fiber position. For some objects this is a bit off of the galaxy.
Note (2): Corrected to the heliocentric reference frame.
Note (3): Includes the error in the wavelength calibration combined in
quadrature with the error resulting from the cross-correlation
technique.
Note (4): Calibrated to the Godwin, Metcalfe & Peach (1983, Cat. <VII/42>)
system.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [CNM2001] Fiber extraction ID number
5- 9 A5 --- LClass Line strength classification (1)
11- 15 A5 --- PCA The Principal Component Analysis
classification (1)
17- 18 A2 --- Wavelet The Wavelet classification
20- 24 F5.2 Gyr S1Age The best fit age of the first star formation
model (2)
26 I1 --- S1SF The best SFR prescription of the first star
formation model (3)
28- 32 F5.2 --- S1Chi The first star formation model reduced
{chi}^2^ value
34- 38 F5.2 Gyr S2Age The best age of the second star formation
model (4)
40- 45 F6.3 Gyr S2Tau The best time scale of the second star
formation model
47- 51 F5.2 --- S2Chi The second star formation model reduced
{chi}^2^ value
53- 58 F6.3 --- C1 The PCA eigencoefficient coefficient c_1_
60- 65 F6.3 --- C2 The PCA eigencoefficient coefficient c_2_
67- 72 F6.3 --- C3 The PCA eigencoefficient coefficient c_3_
74- 79 F6.2 --- Theta The PCA {theta} angle coefficient
81- 86 F6.2 --- Phi The PCA {phi} angle coefficient
88- 92 F5.3 --- Rad2 The PCA square of the radius coefficient
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Note (1): Classification:
AB: absorption-line galaxies
EM: emission-line-dominated spectra
AB+EM: absorption-line-dominated galaxies
EM+AB: emission- and absorption-line galaxies
PS: post-starburst galaxies
Note (2): Model 1: The star formation rate (SFR) depends on the galaxy gas
fraction as {Phi}(t)={nu}f_g_(t). The best fit model spectrum is
computed minimizing with respect to the age and the astration rate
{nu}. In fact, we minimized this astration rate parameter using 8
discrete values. Following Fioc & Rocca-Volmerange, we used the Rana &
Basu (1992A&A...265..499R) IMF and values of the astration parameter
that reproduce the colors of the different spectral type galaxies
observed locally. We also added a one Gigayear starburst model.
Note (3): 1 corresponds to a one Gigayear starburst model;
numbers from 2 to 9 correspond to decreasing values of the astration
rate parameter {nu} where large {nu} values resemble star formation
histories typical of early-type galaxies and small {nu} values,
typical of late-type galaxies.
Note (4): Model 2: An exponential SFR law {Phi}(t)={tau}^{-1}exp(-t/{tau})
and minimizing with respect to the age and the time scale {tau}. In
this case, we used a standard Salpeter IMF with lower and upper mass
limits of 0.1 and 120 times solar, respectively.
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History:
From electronic version of the journal
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(End) Greg Schwarz [AAS], Francois Ochsenbein [CDS] 04-Sep-2001