星系形态星表数据描述.doc

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:
· Spatial search on all images and small catalogs, using Atlas
· Advanced search on only the larger catalogs, using Gator
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