Calculating a Two-Star Matrix

The steps here are very similar to those in Section 5.2.2, where the individual steps are detailed. We assume that the operator has already logged the first star from Section 5.2.2.

1. Identify a bright star far from any previously logged stars.
2. Move the telescope using rshift -t to point the TelRad at the star.
3. Take a short exposure of the star with rexpose.
4. Repeat until the star is centered on the CCD.
5. Record the star with rstarlog.
6. When two stars have been recorded, output the file with rstarwrite.
7. Run the interactive idl program twostartp.pro.

   This program calculates a two-star matrix using a file written by rstarwrite. It can also calculate the telescope pole location. The syntax is as follows.
   

   IDL> twostartp

   syntax - twostartp,starfile,rconv=rconv,dconv=dconv,lon=lon,the_offset=the_offset

      Reads in tpoint formatted files

   The lon option is the telescope longitude, in degrees. The default is LANL. The the_offset option is the telescope polar offset as determined in Section 5.2.3. The default is -3.8${^\circ}$, for the 3a telescope. After starting, the program presents a menu of options.

8. Chose option `c' to find the telescope pole.

   This is where some experimentation needs to be done to figure out whether the numbers mean the telescope should be moved up, down, east or west. This will be added to later revisions of this chapter.

9. Chose option `f' to save the matrix file to disk.