2009-10-01T13:30:00
1000
UCAC3 nocross
The Third US Naval Observatory CCD
Astrograph catalogue (UCAC3) is an all-sky catalgoue containing just over 100
million objects covering about R = 8-16 mag. This table contains
the original data content of UCAC3 but leaves out the data objetained
by crossmatching to other catalogs.
2010AJ....139.2184Z
stars
surveys
astrometry
proper-motions
The UCAC3 all-sky CCD astrograph catalogue, minus
the fields from 2MASS and SuperCosmos and matching/object flags (which
can be recovered with a local crossmatch).
Positions are on the International Celestial Reference
System (ICRS) as represented by the Hipparcos / Tycho-2 catalogs.
The epoch for the positions of all stars is J2000.0; the weighted
mean catalog position was updated using the provided proper
motions. The observational UCAC position is but one of several
going into these values and is not given in the UCAC3, thus the
original UCAC observation cannot be recovered from these data.
Systematic errors are expected to be below 0.1 mag for im1, im2
photometric results obtained from the UCAC CCD pixel data. The aperture
photometry is considered more robust, particularly for "odd" cases, while
the model fit magnitude is expected to be more accurate for "well
behaved" stars.
For many stars a photometric error based on the scatter from
individual observations of that star on different CCD frames
could be obtained. A model error was also attempted to be
assigned, based on the S/N ratio. The error quoted here is
the larger of the 2. If that error exceeds 0.9 mag the error
was set to 0.9 mag.
The object type flag is used to identify possible problems
with a star and has the following meaning:
====== ===============================================
S warning: object could be from possible streak
N warning: object is near overexposed star
blank good star
c good star (data copied from another entry)
o warning: contains at least 1 overexposed image
O warning: all images are overexposed or "bad"
====== ===============================================
The dsf flag is a double star flag used to indicate the
type/quality of double star fit with the following meaning:
= ============================================================
0 single star
1 primary of pair with unreal secondary = single
2 forced separation, on same frame
3 blended image, some CCD frames show single star, some double
4 forced separation, 2 objects on same frame number
5 primary component of real double
6 secondary component of real double
7 other "odd" case
= ============================================================
A zero for the number of used images indicates that all images
have some "problem" (such as overexposure). In that case an unweighted
mean over all available images (na) is taken to derive the mean
position, while normally a weighted mean was calculated based on
the "good" images, excluding possible problem images (nu <= na).
0/0-11
2.649e-19 4.414e-19
A crossmatch between UCAC3 and PPMXL,
created solely based on positions with a window of 1.5 arcsec radius.
//scs#pgs-pos-index
Corrections between UCAC3
and the ICRS as represented by PPMXL on a grid of degrees,
obtained by substracting
UCAC3 from PPMXL in cones of radius sqrt(2)/2 degrees around
the given center position.
Optical
1
=90:
inPars["DEC"] = 89.5*inPars["DEC"]/abs(inPars["DEC"])
return ("alpha=floor(%%(%s)s)+0.5 "
" and delta=floor(%%(%s)s)+0.5")%(
base.getSQLKey("RA", inPars["RA"], outPars),
base.getSQLKey("DEC", inPars["DEC"], outPars))
]]>
0.1
static
UCAC3 ICRS corr
Corrections between UCAC3 and PPMXL
/ppmxl/q/cone/form
`_.
]]>
Optical
1
`_ or
`plain text `_.
Here are maps of the corrections over the entire sky for
RA, Declination and the proper motions:
.. image:: ./static/icrscorrplots.png
]]>