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J/AJ/121/2331   SDSS redshifts in the Coma cluster            (Castander+, 2001)

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
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° (1.8h-1Mpc, 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:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 54 196 Galaxy Redshifts table2.dat 93 196 Galaxy Classifications
Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
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)
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.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
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 χ2 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 χ2 value 53- 58 F6.3 --- C1 The PCA eigencoefficient coefficient c1 60- 65 F6.3 --- C2 The PCA eigencoefficient coefficient c2 67- 72 F6.3 --- C3 The PCA eigencoefficient coefficient c3 74- 79 F6.2 --- Theta The PCA θ angle coefficient 81- 86 F6.2 --- Phi The PCA φ angle coefficient 88- 92 F5.3 --- Rad2 The PCA square of the radius coefficient
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 Φ(t)=νfg(t). The best fit model spectrum is computed minimizing with respect to the age and the astration rate ν. 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 ν where large ν values resemble star formation histories typical of early-type galaxies and small ν values, typical of late-type galaxies. Note (4): Model 2: An exponential SFR law Φ(t)=τ^{-1}exp(-t/τ) and minimizing with respect to the age and the time scale τ. In this case, we used a standard Salpeter IMF with lower and upper mass limits of 0.1 and 120 times solar, respectively.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Francois Ochsenbein [CDS] 04-Sep-2001
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