------------------------------------------------------------ COSMOS ACS GALAXY CATALOG - cosmos_xgroup_galaxies_20110914a_public.fits 2011 September 14, updated 2011 November 15 (v20110914a) Matt George and Alexie Leauthaud mgeorge@astro.berkeley.edu, asleauthaud@lbl.gov ------------------------------------------------------------ This is a COSMOS ACS based catalog, similar to the one presented in Leauthaud et al 2007. The main difference between this catalog and the Leauthaud et al 2007 one is that the raw ACS images have now been corrected for the effects of charge transfer inefficiency (CTI, see Massey et al. 2010 for further details). Since the CTI correction scheme slightly changes the noise properties of the raw images, the detections have also changed. For this reason, the GAL_ID field in this catalog can not be used to match to objects in the 2007 catalog. The pixel scale for this catalog is 0.03". To reference this ACS catalog please reference Leauthaud 2007 with updates presented in Leauthaud et al (in prep). This catalog does not contain all the SExtractor fields nor all the fields from the COSMOS photoz catalog. Instead, this catalog has been trimmed to keep what we consider to be the most useful fields to keep the file size more manegeable. This catalog is truncated at F814W (MAG_AUTO) < 24.2 due to the K-band completeness limit for stellar masses and because photoz uncertainties rise near this limit. Objects within ACS masks have also been removed (these are the same masks as in Leauthaud et al. 2007) and a variety of bad detections have been removed ("clean"=1 and "mu_class"=1) as well as galaxies without stellar masses. We expect that this is the version of the catalog that will be made publicly available. Please let us know if you find problems or have suggested changes to be made. ----------SEXTRACTOR FIELDS---------- GAL_ID - unique number that identifies object for the Leauthaud 2010 catalog MAG_AUTO - F814W total magnitude from Sextractor RA - from Sextractor DEC - from Sextractor ----------STELLAR MASS---------- Stellar mass calculated by Kevin Bundy (details can be found in section 2.3 of Leauthaud et al. 2010, http://adsabs.harvard.edu/abs/2010ApJ...709...97L). A Chabrier IMF is assumed. SM - log of stellar mass SM_ERR - error on stellar mass ----------GROUP PARAMETERS---------- Group parameters are described in George et al. 2011 (ApJ 742, 125. arxiv:1109.6040). Galaxies are associated with groups based on their redshift and proximity to X-ray group positions, and assigned probabilities for membership. Mock catalogs and spectroscopic tests suggest that a membership cut of P>0.5 maximizes the purity and completeness of the sample. One can also weight measured properties by the probability that a galaxy belongs to a group. See group catalog file for a description of group quality flags (group_flag = 1 is good). GROUP_ID - ID of group to which galaxy has maximum membership probability GROUP_FLAG - FLAG_INCLUDE value for GROUP_ID from group catalog P_MEM - probability that this galaxy is a member of GROUP_ID MMGGs - flag for "BCGs" (1 if galaxy is MMGGs of GROUP_ID) DIST_MMGGs - projected distance of object from MMGGs for GROUP_ID as a fraction of R200c See group catalog for description of group center. From the lensing signals stacked around different centers, MMGGs appears to be the best tracer of the center of mass. The above fields are for member galaxies selected by photozs only. We also select members using the best available redshift (replacing photozs with speczs when available). Each of the above group membership fields has a corresponding entry for this photoz+specz selection, just append _ZBEST, e.g. GROUP_ID_ZBEST GROUP_FLAG_ZBEST ... ----------PHOTOZ CATALOG FROM OLIVIER---------- Fields from Olivier Ilbert's photoz catalog v1.7 (photoz_vers1.7_010809). A matching radius of 1 arcsecond has been used to match the catalogs. ZPHOT - photo-z measured using the galaxy templates. Median of the maximum likelihood distribution ("zPDF" in oliviers catalog) ZPHOT_ERRLO - lower limit, 68% confidence level for zMinChi2 ZPHOT_ERRHI - upper limit, 68% confidence level for zMinChi2 MNUV_MR - Dust corrected color, M(NUV)-M(R) corrected from dust-extinction. Classification used in mass function paper: <1.2 for highly star-forming and >3.5 for quiescent ----------COSMOLOGICAL PARAMETERS (WMAP5)---------- Omega b 0.0438000 Omega m 0.258000 Omega l 0.742000 H0 72.0000 Sigma_8 0.796000 ----------EXTERNAL FILES USED---------- X-ray catalog - Xmass_chaxmm10_mie_ext6_id_update1010_zupdate.cat X-ray SExtractor coords - cosmos_m46finalmie_ext5.txt Photoz catalog - photoz_vers1.7_010809 Photoz PDFs - pdzBay_v1.7_010809.out.gz Image mask (FLAG_MASK) - COSMOS_borders_F814W_mask.fits Spectroscopic catalog - observed_targets_20110513.dat ----------VERSION HISTORY---------- 20101006 - initial release (beta version) 20110209 - fixed bug in field density estimate, shifting membership threshold from P>0.7 to 0.5. Minor fix replacing a small number of missing photozs for bright sources with speczs. Replaced X-ray catalog Xmass_cha54xmm_mie_ext5_zupdate0510_zerr.cat with Xmass_chaxmm10_mie_ext6_id_update1010_zupdate.cat 20110914 - modified field names and null values. updated spectroscopic catalog to include zCOSMOS 20k and exclude IMACS spectra. Trimmed catalogs to groups with XFLAG<=3, and galaxies with a stellar mass. Removed some fields for streamlining. 20110914a - modified field names again to follow IRSA guidelines. Added MMGGS_ZBEST column to galaxy catalog. The data should be unchanged from 20110914.