Software Zeropoint and Collimation Error: 2-star SNAFU

  To be done at the beginning of a run, but definitely after an instrument change.

1. At the Telescope Computer System Terminal, enter INPSCF and set HATERM 1 (section ).
2. Select slit view mode and enable the TV crosswires.
3. Select a star with Hour Angle < 3 hours and Declination > 85.
4. Slew to that object.
5. Type SNAFU at the User Interface.
6. Move the object to the SNAFU reference position (see end of Section ) using the handset.
7. Press the ACK button on the Control Desk until it goes out.
8. Select a new star at 30< Dec < 40and |HA| < 3.
9. Slew to that object.
10. On Telescope Computer System Terminal change HATERM to 2.
11. Type SNAFU again on the User Interface.
12. Position the object as before on the TV monitor.
13. Press ACK button until extinguished.
14. If, in action (6) and (12), the corrections to the telescope positions were large (> 10 arcsecs) then repeat the process from (1) (INPSCF will already be running).
15. Record the values of the variables PCIH, PCID and PCCH on the form provided. (Get their values by typing @PCIH etc. within INPSCF).
16. Type END at the Telescope Control System Console to exit from INPSCF.