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1999ApJS..12x..yyyCotton+
Cotton, Condon & Arbizzani:
Arcsecond Positions of UGC Galaxies
ctsy. W. Cotton, TeX->ASCII and reformatting by H.Andernach 7/99
Abstract
We present accurate B1950 and J2000 positions for all confirmed
galaxies in the Uppsala General Catalog (UGC). The positions were
measured visually from Digitized Sky Survey images with rms
uncertainties sigma >= [ (1\farcs2)^2 + (\theta/100)^2]^{1/2}$,
where \theta is the major-axis diameter. We compared each
galaxy measured with the original UGC description to ensure high
reliability. The full position list is available in the electronic
version only.
POSITION MEASUREMENTS
Galaxy positions were measured from 6' x 6' FITS-format DSS
postage-stamp images obtained from the Space Telescope Science
Institute's WWW server
URL {http://stdatu.stsci.edu/cgi-bin/dss\_form}. We obtained their
POSS~II images if available and POSS~I images otherwise. Some entries
in the UGC are multiple systems containing two or more galaxies having
individual angular diameters <1'. We measured these galaxies
individually, and they are distinguished in our list by the suffixes
a, b, c,... in order of increasing J2000 right ascension.
A sample of the UGC galaxy position list is given in Table 1.
The first column contains the UGC catalog number, to
which we have added lower-case suffixes a, b, c,\dots in order of
increasing J2000 right ascension to distinguish individual galaxies in
groups. Our suffixes usually agree with the lower-case suffixes found
in the UGC notes, but not always. The second column contains the
hours, minutes, and seconds of right ascension precessed to equinox
J2000 plus the rms uncertainty in in seconds. The third column lists
the degrees, arcminutes, and arcseconds of J2000 declination plus the
rms uncertainty in arcseconds. Columns 4 and 5 give the corresponding
B1950 right ascension and declination. The full list appears in the
electronic version only.
Table 1. Optical Positions of UGC Galaxies
(N=13391 entries for 12910 unique UGC numbers)
#UGC Aa RADEC_B1950 RADEC_J2000 +-s +-"
----+----1----+----2----+----3----+----4----+----5----+
00001a 000003.96+162224.8 000237.85+163906.8 .10 1.5
00001b 000004.06+162155.4 000237.95+163837.4 .10 1.5
00002 235952.03+443832.5 000226.14+445514.3 .13 1.4
bcotton@nrao.edu,
jcondon@nrao.edu