imact is a link to the
utility which finds all of the
U.S. Naval Observatory ACT Reference
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 ACT number is the zone (right ascension as hhmm from 0000 to 2330)
followed by the sequence number of the star within the RA-sorted zone.
This number may change with each release of the ACT catalog.
Find ACT Catalog Stars in Image Region
Set the environment variable ACT_PATH to the directory where the root
directory of the CDROM is located. If the environment variable is not set,
the default is to look at /data/act.
The minimum command line is
imact FITS or IRAF filename
The same effect can be obtained by running
imcat -c act FITS or IRAF filename
- List the 10 brightest ACT Reference Catalog stars in a FITS image
- List the ACT Reference Catalog stars in a FITS image to a file
- Plot ACT Reference Catalog stars onto a FITS image