4.8 If the Servo Should Unlock

  1. An obnoxious sounding buzzer will go off. Don't panic - compose yourself.

  2. Stop or Abort the scan in progress. If the scan is in the reverse direction and has not yet passed through ZPD then it is useless and should be aborted. However, if the scan is in the forward direction it may be worth saving, depending on the resolution which has been achieved up to the point of the servo unlock.

  3. Once the scan has been terminated, push the ZPD servo button on the main control panel. The carriage will return to mechanical ZPD, and the buzzer will eventually go off.

  4. Reenter fringe mode.

  5. Refind optical ZPD, and resume observations.

Please send comments and suggestions to: veillet@cfht.hawaii.edu