Zurich Structure & Morphology Catalog v1.0 Definitions

COSMOS Overview

The COSMOS Archive serves data taken for the Cosmic Evolution Survey (COSMOS) project. COSMOS is an astronomical survey designed to probe the formation and evolution of galaxies as a function of cosmic time (redshift) and large scale structural environment. The survey covers a 2 square degree equatorial field with imaging by most of the major space-based telescopes (Hubble, Spitzer, GALEX, XMM, Chandra) and a number of large ground based telescopes (Subaru, VLA, ESO-VLT, UKIRT, NOAO, CFHT, and others).

IRSA serves the COSMOS archive using the following search methods:

Zurich Structure & Morphology Catalog v1.0 Overview

This catalog contains the measurements presented in:

  1. 1. Scarlata, Carollo, Lilly et al 2007, ApJS, 172, 406 (i.e., the Zurich Estimator of Structural Type [ZEST] catalog; measurements down to a limiting magnitude of I_AB=24. ZEST measurements for galaxies with half-light radii < 0 .17" are unreliable, especially for galaxies with a steep light profile)
  2. 2. Sargent, Carollo, Lilly et al 2007, ApJS, 172, 434 (i.e., Single-Sersic GIM2D fits; measurements down to a limiting magnitude of I_AB=22.5;formal GIM2D fits are also listed for approx. 2650 compulsory zCOSMOS-Bright x-ray, radio, etc. sources with I_AB > 22.5 - however, the quality of the fits deteriorates for sources substantially fainter than ~I_AB~23)

This v1.0 catalog is based on the May 2006 release % of Alexie Leauthaud's ACS catalog (cut at the limits mentioned above)

Notes:

(a) All ACS_"parameter" columns are copied from the original May 2006 Leauthaud catalog

(b) The catalog has been cross-correlated with the January 2006 Capak catalog.

All "Capak IDs, RAs, and Decs" refer to this version of the ground-based photometric catalog, and provide the closest ground-based match to the ACS source within a radius of 0.6 arcseconds.

(c) The catalog contains 71 colums and 131532 lines. Each line is written in fortran format: "format(i9,1x,2d23.12,1x,a37,1x,67d23.12)"

(d) An entry of -999999 indicates "no measurement" (including in the ACS and Capak catalogs).

(e) The pixel scale for the quantities in pixels is 0.03".

Zurich Structure & Morphology Catalog v1.0 Column Definitions

Gator serves the Zurich Structure & Morphology Catalog v1.0 (76 columns [71 delivered + 5 IRSA-created], 131,532 data rows). The column descriptions can be found below.

Column Name Data Type Units Description
SequentialID int   Identification number
RA float degrees Right ascension
DEC float degrees Declination
CAPAK_ID float   ID based on ground-based photometric catalog of Capak 2006
CAPAK_RA float degrees Closest matched right ascension to ground-based catalog within 0.6"
CAPAK_DEC float degrees Closest matched declination to ground-based catalog within 0.6"
ACS_MAG_AUTO float   Total magnitude of object- used for catalog selection
ACS_MAGERR_AUTO float magnitude Magnitude error
ACS_X_IMAGE float pixel X-pixel position on ACS-tile
ACS_Y_IMAGE float pixel Y-pixel position on ACS-tile
ACS_XPEAK_IMAGE float pixel X-pixel position of object peak flux on ACS tile
ACS_YPEAK_IMAGE float pixel Y-pixel position of object peak flux on ACS tile
ACS_ALPHAPEAK_ float degrees RA of object peak flux
ACS_DELTAPEAK_ float degrees Dec of object peak flux
ACS_A_IMAGE float   SExtractor semi-major axis
ACS_B_IMAGE float   SExtractor semi-minor axis
ACS_THETA_IMAGE float   SExtractor position angle
ACS_ELONGATION float   SExtractor a/b [semi-major axis / semi minor axis]
ACS_CLASS_STAR float   SExtractor stellarity parameter
ACS_IDENT float   Unique number that identifies object
ACS_SE float   1 = Detection from 'hot' pass of SExtractor.

0 = Detection from 'cold' pass of SExtractor.
ACS_MU_CLASS float   Type of object.

1 = galaxy
2 = star

3 = spurious
ACS_OVERLAP float   Object overlap flag. All objects here have overlap =1 i.e. no overlap.
ACS_NEARSTAR float   Object in star mask flag. All the objects in this morphological catalog have "nearstar = 1" which means they are not in a star mask.
ACS_MASK float   Object in automatic mask flag.

2 = star used to make automatic mask
ACS_MASKED float   Object in manual mask flag.

-1 = manual mask (astrophysical obj)

0 = manual mask (artifact or image defect)

1 = not in manual mask
ACS_CLEAN float   Object useable flag.

0 = do not use this object

1 = use this object
ACS_UNIQUE float   Object unique flag. All the objects in this morphological catalog have "unique = 1" which means they are all "unique" in the original ACS catalog.
GG float   ZEST Gini coefficient
M20 float   ZEST second order moment of the 20% brightest pixels
CC float   ZEST concentration
AA float   ZEST asymmetry
R20 float pixels ZEST semi-major axis length of ellipse encompassing 20% of total light
R50 float pixels ZEST semi-major axis length of ellipse encompassing 50% of total light
R80 float pixels ZEST semi-major axis length of ellipse encompassing 80% of total light
RPET float pixels Zest semi-major axis length for Petrosian Radius ellipse
FLAGRPET float   Petrosian radius flag.

0 = single Petrosian radius measured

2 = multiple radii measured (noisy SB profile)

5 = SB profile was corrected for diffuse light contribution from neighboring object(s)
FLUX_GIM2D float counts GIM2D total flux
LE_FLUX_GIM2D float   LE_FLUX_GIM2D (99% conf. lower error on R_GIM2D)
UE_FLUX_GIM2D float   UE_FLUX_GIM2D (99% conf. lower error on R_GIM2D)
R_GIM2D float arcseconds GIM2D psf-convolved half-light radius of object
LE_R_GIM2D float   99% conf. lower error on R_GIM2D
UE_R_GIM2D float   99% conf. upper error on R_GIM2D
ELL_GIM2D float   GIM2D ellipticity = 1-b/a of object
LE_ELL_GIM2D float   99% conf. lower error on ELL_GIM2D
UE_ELL_GIM2D float   99% conf. upper error on ELL_GIM2D
PA_GIM2D float degrees GIM2D position angle of object - cw from +y-axis
LE_PA_GIM2D float   99% conf. lower error on PA_GIM2D
UE_PA_GIM2D float   99% conf. upper error on PA_GIM2D
DX_GIM2D float arcseconds x-offset of GIM2D-model center from ACS-coordinate center
LE_DX_GIM2D float   99% conf. lower error on DX_GIM2D
UE_DX_GIM2D float   99% conf. upper error on DX_GIM2D
DY_GIM2D float arcseconds y-offset of GIM2D-model center from ACS-coordinate center
LE_DY_GIM2D float   99% conf. lower error on DY_GIM2D
UE_DY_GIM2D float   99% conf. upper error on DY_GIM2D
SERSIC_N_GIM2D float   GIM2D Sersic index
LE_N_GIM2D float   99% conf. lower error on SERSIC_N_GIM2D
UE_N_GIM2D float   99% conf. upper error on SERSIC_N_GIM2D
R_0P5_GIM2D float arcseconds GIM2D half-light radius of object without PSF convolution
CHI_GIM2D float   reduced CHI2 of the best GIM2D model fit
ITER_GIM2D float   no. of iterations required for GIM2D fit to converge
PC_1 float   ZEST first principal component
PC_2 float   ZEST second principal component
PC_3 float   ZEST third principal component
TYPE float   ZEST Type CLASS

1 = Early type

2 = Disk

3 = Irregular Galaxy

9 = no classification
BULG float   ZEST "Bulgeness" CLASS - only for Type 2 (disk) galaxies.

0 = bulge dominated galaxy

1,2 = intermediate-bulge galaxies

3 = pure disk galaxy

9 = no classification
IRRE float   ZEST Irregularity CLASS - only for Type 1 (elliptical) galaxies

0 = regular

1 = irregular

9 = no value
ELLI float   ZEST Ellipticity CLASS, 0 = fac-on, 1,2 = increasingly higher elongation, 3 = edge-on, 9 = no classification of elongation
STELLARITY float   Visual Stellarity flag.

0 if ACS_CLASS_STAR<0.6 (object is ASSUMED to be a galaxy; no visual inspection)

0 if ACS_CLASS_STAR>=0.6 AND object visually identified as a galaxy.

1 if ACS_CLASS_STAR>=0.6 AND visually identified as a star.

2 if ACS_CLASS_STAR>=0.8 (object is assumed to be a star and was not visually inspected)

3 if ACS_CLASS_STAR<0.6 but object is visually identified as a star (e.g. saturated star, etc)
JUNKFLAG float   0 = good object

1 = spurious
ACSTile char   ACS TILE number from which the object is extracted