Find Stars in FITS and IRAF Image Region

WCSTools programs
imstar is a utility for finding all of the stars in a FITS or IRAF image and listing their sky positions if a world coordinate system is present. World coordinate system (WCS) information in the image header describes, in a standard way, the relationship between sky coordinates and image pixels. This information is used by the program to transform image coordinate (X,Y) pairs to right ascension and declination sky coordinate pairs.

Output is sent to a file called filename.stars and to standard output if the -v flag is set. The output includes the right ascension and declination if the a world coordinate system is defined in the image header or on the command line, the instrumental magnitude of the star, with the brightest star in the image set to 0.0, the image and and y coordinates of the center of the star, the integrated brightness of the star in counts, and the peak brightness of the star in counts. If the -q option is used to set a region character, output is to filename.reg.

Before version 2.6.18, the output file defaulted to tab table format; in version 2.6.18 and later, this format is written if the -tw flags are used. This file can be used as a reference catalog by imwcs, immatch, imcat, or scat.

If the -w flag is used in versions 2.3 to 2.6.17, or the -ow flags are used in versions 2.6.18 or later, the output file, named filename.dao, is in the DAOFIND format (x y magnitude on each line) and can be used by imwcs or immatch instead of searching an image.

Command Line Arguments

Search Parameters


1. Make a reference catalog from an image with a WCS
2. List stars in an image with a WCS
3. List stars in an image with no WCS
4. Plot stars found in an image

Last updated 30 July 2002 by Jessica Mink

Telescope Data Center