J/AJ/127/1811 Catalog of SDSS compact groups of galaxies (Lee+, 2004)
A catalog of compact groups of galaxies in the SDSS commissioning data.
Lee B.C., Allam S.S., Tucker D.L., Annis J., Johnston D.E., Scranton R.,
Acebo Y., Bahcall N.A., Bartelmann M., Bohringer H., Ellman N.,
Grebel E.K., Infante L., Loveday J., Mckay T.A., Prada F., Schneider D.P.,
Stoughton C., Szalay A.S., Vogeley M.S., Voges W., Yanny B.
<Astron. J., 127, 1811-1859 (2004)>
=2004AJ....127.1811L 2004AJ....127.1811L
ADC_Keywords: Surveys ; Galaxy catalogs ; Photometry, SDSS
Keywords: atlases - catalogs - surveys
Abstract:
Compact groups (CGs) of galaxies - relatively poor groups of galaxies
in which the typical separations between members is of the order of a
galaxy diameter - offer an exceptional laboratory for the study of
dense galactic environments with short (<1Gyr) dynamical timescales.
We present an objectively defined catalog of CGs in 153deg2 of the
Sloan Digital Sky Survey (SDSS) Early Data Release (J/AJ/123/567).
To identify CGs, we applied a modified version of Hickson's criteria
of 1982 aimed at finding the highest-density CGs and thus reducing the
number of chance alignments. Our catalog contains 175 CGs down to a
limiting galaxy magnitude of r*=21. The resulting catalog has a median
depth of zmed∼0.13, substantially deeper than previous CG catalogs.
Since the SDSS will eventually image up to one-quarter of the
celestial sphere, we expect our final catalog, based on the completed
SDSS, will contain on the order of 5000-10000CGs. This catalog will
be useful for conducting studies of the general characteristics of
CGs, their environments, and their component galaxies.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 86 177 The SDSS Compact Group Properties
table2.dat 148 752 The SDSS Compact Group Members
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See also:
J/AJ/123/567 : SDSS quasar catalog, I: Early Data Release (Schneider+, 2002)
J/AJ/126/2579 : SDSS quasar catalog. II. First data release (Schneider+, 2003)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- SDSSCG Compact group identification
6- 7 I2 h RAh Hour of right ascension (J2000) (1)
9- 10 I2 min RAm Minute of right ascension (J2000) (1)
12- 16 F5.2 s RAs Second of right ascension (J2000) (1)
18 A1 --- DE- Sign of the declination (J2000) (1)
19- 20 I2 deg DEd Degree of declination (J2000) (1)
22- 23 I2 arcmin DEm Arcminute of declination (J2000) (1)
25- 29 F5.2 arcsec DEs Arcsecond of declination (J2000) (1)
31- 34 F4.1 arcsec thetaG Angular diameter of the smallest circle
36- 40 F5.2 mag/arcsec2 muG Total r* magnitude of the Ntot group
members averaged over theta
42 I1 --- Ntot Total number of galaxies in the group
within 3mag of the brightest group member
44- 48 F5.3 mag Dr*mag The r* magnitude difference between
brightest and faintest group members
50- 54 F5.2 --- N/G Ratio of diameters, thetaN/thetaG (2)
56- 61 F6.4 --- zph ? Brightest group member's photometric
redshift
63- 68 F6.4 --- zsp ? Group spectroscopic redshift (3)
70 I1 --- n_zsp ? Number of group members in zsp
72- 86 A15 --- Comm Additional comments (4)
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Note (1): Of the center of the smallest circle containing all group members
within 3mag of the brightest group member.
Note (2): Ratio of thetaN, the angular diameter of the largest concentric
circle that contains no other (external) galaxies within 3mag of the
brightest group member, to thetaG, the angular diameter of the
smallest circle containing all group members within this magnitude
range.
Note (3): Based upon the median of the spectroscopic redshifts of its
member galaxies. If available, a group member's SDSS spectroscopic
redshift was used; otherwise, if available, its spectroscopic redshift
from NED (the NASA/IPAC Extragalactic Database) was used.
Note (4): Additional comments use the symbols:
+1 = A faint background galaxy is visible that could be a member of
the group
+2 = Two faint background galaxies are visible that could be members
of the group
M(ab) = Galaxies a and b appear to be merging
I(ab) = Galaxies a and b appear to be interacting
T(a) = Galaxy a shows a tidal tail
h(abc) = Galaxies a, b, and c appear to be embedded within a common halo
QSO(a) = Galaxy a is classified as a QSO in NED
isolated? = Faint background galaxies are visible that could be members
of the group
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- SDSSCG Name of the group member (1)
5 A1 --- Galaxy [a-g] Galaxy identification in the group (1)
7- 8 I2 h RAh Hour of right ascension (J2000)
10- 11 I2 min RAm Minute of right ascension (J2000)
13- 17 F5.2 s RAs Second of right ascension (J2000)
19 A1 --- DE- Sign of the declination (J2000)
20- 21 I2 deg DEd Degree of declination (J2000)
23- 24 I2 arcmin DEm Arcminute of declination (J2000)
26- 30 F5.2 arcsec DEs Arcsecond of declination (J2000)
32- 37 F6.3 mag r*mag SDSS non-dereddened r-band model magnitude
39- 43 F5.3 mag e_r*mag Estimated rms error in r*mag
45- 49 F5.3 mag A(r*) Reddening in r*mag (2)
51- 56 F6.3 mag u*-g* SDSS non-dereddened (u*-g*) model color
58- 62 F5.3 mag e_u*-g* Estimated rms error in u*-g* (3)
64- 69 F6.3 mag g*-r* SDSS non-dereddened (g*-r*) model color
71- 75 F5.3 mag e_g*-r* Estimated rms error in g*-r* (3)
77- 82 F6.3 mag r*-i* SDSS non-dereddened (r*-i*) model color
84- 88 F5.3 mag e_r*-i* Estimated rms error in r*-i* (3)
90- 95 F6.3 mag i*-z* SDSS non-dereddened (i*-z*) model color
97-101 F5.3 mag e_i*-z* Estimated rms error in i*-z* (3)
103-110 F8.6 --- zsp ? SDSS spectroscopic redshift (4)
112-117 F6.4 --- zNED ? NED spectroscopic redshift (5)
119-148 A30 --- Note Source name of NED-derived spectroscopic
redshift
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Note (1): The galaxy identification is composed of the CG identification
number (from col. [1] of Table 1) and an identification letter for
galaxy (where "a" is the brightest group member, "b" the second
brightest, ...).
Note (2): Where A(r*)=2.751*E(B-V) as estimated from the Schlegel et al.,
(1998ApJ...500..525S 1998ApJ...500..525S) reddening maps.
Note (3): Estimated by adding the rms errors in quadrature.
Note (4): Of the 744 CG members, 135 have SDSS spectroscopic redshifts.
Note (5): Of the 744 CG members, 49 have spectroscopic redshifts from NED.
Of these 49, 23 have no corresponding spectroscopic redshift from
the SDSS.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 06-Jul-2004