Find USNO UCAC3 Stars in Image Region

WCSTools programs
imucac3 is a link to the WCSTools imcat utility which finds all of the U.S. Naval Observatory UCAC3 Catalog objects in a FITS or IRAF image and lists their sky and image positions. World coordinate system (WCS) information must be present in the image header to describe, in a standard way, the relationship between sky coordinates and image pixels. This information is used by the program to find the region in the sky to search and to transform right ascension and declination sky coordinate pairs to image coordinate (X,Y) pairs. Output is sent to a file called filename.uac and to standard output if the -v flag is set. The UCAC3 number is the zone ((180 + 2 * declination in degrees) followed by the sequence number of the star within the RA-sorted zone. This number will change with each release of the USNO UCAC catalog.

Before you can use this program, the path to the directory containing the region files must be set. The default is to use the value of the variable ucac3path in the source code file libwcs/ucacread.c, which is initially set to /data/astrocat/ucac3, which is where the catalog resides at the Center for Astrophysics. If you do not have access to the source code and need to change the path, you can set the environment variable UCAC3_PATH to the directory containing the region files, and that will override the file setting.

The minimum command line is imucac3 FITS or IRAF filename

The same effect can be obtained by running imcat -c ucac3 FITS or IRAF filename

Command Line Arguments


List the 10 brightest UCAC3 stars in a FITS image from a CDROM
List the UCAC3 stars in a FITS image to a file
Plot UCAC3 stars onto a FITS image

Last updated 18 November 2009 by Doug Mink

Telescope Data Center