Plotting the USNO-B1.0 Catalog on a Telescope Image
Using SAOimage and imub1

This SAOimage display shows the alignment of USNO-B1.0 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, saoub1: saoimage -reg `imub1 -q o -r 10 $1` -wcscom sub1_-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

imub1 finds all of the USNO-B1.0 Stars in the image based on the world coordinate system parameters in its header and writes them to the region file testx90mw.fits.ub1, 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-B1.0 Catalog (10" radius) CIRCLE(527,446,16) # ub1 1214.0243793 CIRCLE(661,661,16) # ub1 1214.0243761 CIRCLE(960,978,16) # ub1 1215.0243433 CIRCLE(529,33,16) # ub1 1213.0243493 CIRCLE(738,763,16) # ub1 1214.0243749 . . . CIRCLE(991,539,16) # ub1 1214.0243704 CIRCLE(290,966,16) # ub1 1214.0243846 CIRCLE(562,450,16) # ub1 1214.0243777 CIRCLE(555,448,16) # ub1 1214.0243781 CIRCLE(541,444,16) # ub1 1214.0243788

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:

sub1 3.3.0, 28 January 2003, Doug Mink SAO  Find closest star
      ub1  16:15:56.357 +31:24:24.82 J2000 r= 120.00 at epoch 2000.00
USNO_B1_number  RA2000       Dec2000     MagB1  MagR1  MagB2  MagR2  MagN  PM  NI  Arcsec
1214.0243793 16:15:56.126 +31:24:24.15   11.71  10.79  10.76  10.53  10.49  0  5    3.03