Plotting the USNO-SA2.0 Catalog on a Telescope Image
Using SAOimage and imusa2

This SAOimage display shows the alignment of USNO-SA2.0 Stars with a test image after a world coordinate system has been fit. The coordinates plotted are based on header keywords describing a plane-tangent system fit by matching HST Guide stars and sources found in the image. This image was produced by a one-line Unix shell script for this task, saoua2: saoimage -reg `imusa2 -r 10 $1` -wcscom susa2_-ha_%s $1 where the argument to the task is the name of the file to be displayed. The immatch program will provide a list of the stars in the image which match catalog stars.

Click on the image for full-screen view

imusa2 finds all of the USNO-SA2.0 Stars in the image based on the world coordinate system parameters in its header and writes them to the region file testx90mw.fits.usa2, seen on the right. The name of this file is sent to standard output which the backquotes give to SAOimage as a command line argument following the -reg command.

# USNO SA-2.0 Catalog Stars (10" radius) CIRCLE(283,620,16) # usa2 1200.01930685 CIRCLE(33,921,16) # usa2 1200.01931122 CIRCLE(607,773,16) # usa2 1200.01930106 CIRCLE(178,796,16) # usa2 1200.01930862 CIRCLE(132,860,16) # usa2 1200.01930953 . . . CIRCLE(52,202,16) # usa2 1200.01931097 CIRCLE(635,672,16) # usa2 1200.01930054 CIRCLE(299,207,16) # usa2 1200.01930648 CIRCLE(853,931,16) # usa2 1200.01929679 CIRCLE(394,701,16) # usa2 1200.01930487

If the w key is struck when the SAOimage cursor is centered on the galaxy in the middle of this picture, the following appears on the user's terminal:

susa2 2.9.4, 29 June 2001, Doug Mink SAO  Find closest star
USNO SA-2.0    51.21479  45.59067 galactic r= 900.00 at epoch 2000.00
USNO SA2 numberGal Lon    Gal Lat    MagB  MagR Plate  Arcsec
1200.01930422  51.22835  45.57507  16.8  16.4  330    65.73