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J/A+A/420/61        X-ray clusters of galaxies               (Schuecker+, 2004)

Detection of X-ray clusters of galaxies by matching RASS photons and SDSS galaxies within GAVO. Schuecker P., Boehringer H., Voges W. <Astron. Astrophys., 420, 61-74 (2004)> =2004A&A...420...61S
ADC_Keywords: Clusters, galaxy ; X-ray sources ; Redshifts Keywords: galaxies: clusters - galaxies: general - methods: statistical - cosmology: large-scale structure of Universe Abstract: A new method for a simultaneous search for clusters of galaxies in X-ray photon maps and optical galaxy maps is described. The method appears ideally suited for the analysis of the recently proposed wide-angle X-ray missions like DUO and ROSITA. As a first application, clusters are extracted from the 3rd version of the ROSAT All-Sky Survey (IX/10) and the Early Date Release of the Sloan Digital Sky Survey (SDSS, J/AJ/123/567). The time-consuming computations are performed within the German Astrophysical Virtual Observatory (GAVO). On a test area of 140 square degrees, 75 X-ray clusters are detected down to an X-ray flux limit of 3-5*10-13erg/s/cm2 in the ROSAT energy band 0.1-2.4keV. The clusters have redshifts z<0.5. Description: Cluster parameters for 75 X-ray clusters of galaxies on a test area of 140 sq.deg. For each cluster the position, the galactic hydrogen column density, the detection likelihoods, estimated and spectroscopic redshifts, number of RASS3 photons, X-ray countrates, hardness ratios, extent likelihood and further parameters and remarks on the clusters are given. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 84 75 Cluster positions, detection significances etc. table3.dat 93 75 Cluster countrates, hardness ratios etc.
See also: J/AJ/123/567 : SDSS quasar catalog, I: Early Data Release (Schneider+, 2002) IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 4 A4 --- Seq Cluster number 6- 12 F7.4 deg RAdeg Right ascension (J2000.0) 14- 20 F7.4 deg DEdeg Declination (J2000.0) 22- 26 F5.2 10+20cm-2 NH Neutral galactic hydrogen column density 28- 33 F6.2 10-16W/m2 S Unabsorbed X-ray flux in the ROSAT energy band 0.1-2.4keV 35- 41 F7.3 --- ln(L/L0)R Detection likelihoods on RASS-3 photon maps 43- 50 F8.3 --- ln(L/L0)S Detection likelihoods on SDSS galaxy maps 53- 56 F4.2 --- zestR Estimated cluster redshift from RASS-3 59- 62 F4.2 --- zestS Estimated cluster redshift from SDSS 66- 71 F6.4 --- zspec Spectroscopic redshift 74- 75 I2 --- Nz Number of cluster galaxies used for zspec 78- 84 A7 --- Note Note whether the cluster in NOT found in a catalogue (1)
Note (1): Catalogs acronyms are: V2 = ROSAT Faint Source Catalogue, Cat. IX/29 V3 = unscreened version of V2 G = Goto et al. (2002AJ....123.1807B) B = Bahcall et al. (2003ApJS...148..243B).
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 4 A4 --- Seq Cluster number 6- 12 F7.4 deg RAdeg Right ascension (J2000.0) 14- 20 F7.4 deg DEdeg Declination (J2000.0) 22- 26 F5.1 --- Nph Number of X-ray photons 28- 32 F5.3 s-1 Gamma Maximum likelihood X-ray countrate 35- 39 F5.3 s-1 e_Gamma rms uncertainty on Gamma 41- 45 F5.3 s-1 ctr(GCA) Growth Curve Analysis (GCA) X-ray count rate 48- 52 F5.3 s-1 e_ctr(GCA) rms uncertainty on ctr(GCA) 54- 58 F5.2 --- HR(GCA) GCA hardness ratio 60- 63 F4.1 --- EXT(GCA) GCA negative logarithmic KS-probability for a point source 65- 69 F5.1 --- Rich Optical cluster richness from SDSS 71- 93 A23 --- Remarks Further remarks on the cluster (1)
Note (1): Abbreviations in the remarks: CONT = AGN within 1 arcmin from cluster position in NED CUT = cluster only partially in test area of matched filter zG = redshift in Goto et al. (2002AJ....123.1807B) teff = effective exposure time in RASS3
Acknowledgements: Peter Schuecker References: Bahcall, N.A., McKay, T.A., Annis, J., et al. 2003ApJS...148,..243B A merged catalog of clusters from the Early Sloan Digital Sky Survey Data Goto, T., et al. 2002AJ....123.1807B The Cut-and-Enhance method: Selecting clusters from the Sloan Digital Sky Survey Commissioning Data
(End) Peter Schuecker [MPE, Germany], Patricia Bauer [CDS] 18-May-2004
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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