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J/MNRAS/348/866   2dFGRS Percolation-Inferred Galaxy Group (2PIGG)  (Eke+, 2004)

Galaxy groups in the 2dFGRS: the group-finding algorithm and the 2PIGG catalogue. Eke V.R., Baugh C.M., Cole S., Frenk C.S., Norberg P., Peacock J.A., Baldry I.K., Bland-Hawthorn J., Bridges T., Cannon R., Colless M., Collins C., Couch W., Dalton G., De Propris R., Driver S.P., Efstathiou G., Ellis R.S., Glazebrook K., Jackson C., Lahav O., Lewis I., Lumsden S., Maddox S., Madgwick D., Peterson B.A., Sutherland W., Taylor K. <Mon. Not. R. Astron. Soc., 348, 866-878 (2004)> =2004MNRAS.348..866E
ADC_Keywords: Clusters, galaxy ; Redshifts Keywords: catalogues - galaxies: clusters: general Abstract: The construction of a catalogue of galaxy groups from the Two-degree Field Galaxy Redshift Survey (2dFGRS) is described. Groups are identified by means of a friends-of-friends percolation algorithm which has been thoroughly tested on mock versions of the 2dFGRS generated from cosmological N-body simulations. The tests suggest that the algorithm groups all galaxies that it should be grouping, with an additional 40 per cent of interlopers. About 55 per cent of the ∼190000 galaxies considered are placed into groups containing at least two members of which ∼29000 are found. Of these, ∼7000 contain at least four galaxies, and these groups have a median redshift of 0.11 and a median velocity dispersion of 260km/s. This 2dFGRS Percolation-Inferred Galaxy Group (2PIGG) catalogue represents the largest available homogeneous sample of galaxy groups. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file 2dfngpga.dat 69 78746 Galaxies used for group-finding in the NGP 2dfsgpga.dat 69 112694 Galaxies used for group-finding in the SGP 2dfngpgr.dat 77 11920 Group properties in the NGP 2dfsgpgr.dat 77 16957 Group properties in the SGP mocngpga.dat 69 73195 Mock galaxies in the NGP mocsgpga.dat 69 114189 Mock galaxies in the SGP mocngpgr.dat 77 9861 Mock group properties in the NGP mocsgpgr.dat 77 15340 Mock group properties in the SGP
See also: VII/250 : The 2dF Galaxy Redshift Survey (2dFGRS) (2dFGRS Team, 1998-2003) Byte-by-byte Description of file: 2df*ga.dat moc*ga.dat
Bytes Format Units Label Explanations
3- 10 F8.5 rad RArad Right ascension in radians (1950 coordinates) 13- 20 F8.5 rad DErad Declination in radians (1950 coordinates) 24- 29 F6.4 --- z Redshift 32- 37 F6.3 mag bJmag bJ magnitude 40- 45 F6.3 mag bJmagl limiting b_J magnitude of the survey at the position of this galaxy 48- 55 F8.6 --- n Mean number density of galaxies in the survey at the position of this galaxy 59- 62 F4.2 --- Weight [1/4.4] Weight associated with this galaxy 65- 69 I5 --- Ngroup [0/16957] Group number to which this galaxy has been assigned (0 is ungrouped) (1)
Note (1): k refers to the kth entry in the corresponding group list, i.e. "recno" of the Vizir groups files.
Byte-by-byte Description of file: 2df*gr.dat moc*gr.dat
Bytes Format Units Label Explanations
1- 7 I7 --- Nmemb [1/500] Unweighted number of members 10- 21 E12.7 rad RArad Right ascension of group centre in radians (1950 coordinates) 23- 35 E13.7 rad DErad Declination of group centre in radians (1950 coordinates) 38- 49 E12.7 --- z Group redshift 52- 63 E12.7 Mpc Sep rms projected galaxy separation in Mpc/h 66- 77 E12.7 km/s sigma Group velocity dispersion
History: Copied at http://www.mso.anu.edu.au/2dFGRS/Public/2PIGG/
(End) Patricia Vannier [CDS] 23-Apr-2012
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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