Purpose

This page is meant for support astronomers only

This document describes the procedure for recovering use of a NIRSPEC filter wheel which refuses to home. The symptom is that when the filters are commanded to home via the NIRSPEC startup script or from the XNIRSPEC/Engineer/Motors/Init menu, XNIRSPEC returns an error message indicating that one of the filter wheels failed to home.

Procedure

  1. Attempt to initialize the stage one more time only using the XNIRSPEC/Engineer/Motors/Init menu item.
  2. Check the status of the switches using the XNIRSPEC/Engineer/Motors/Read Switches menu item.
  3. If no switches are set for the filter wheel in question, this indicates that the stage is not centered on a filter. Follow these steps to recenter:
  4. On the Read Switches menu, check whether the Pri Init or Sec Init light is 'on':
  5. Once you've located a primary or secondary initialization switch and used the filMinitloc keyword to define position, the XNIRSPEC window should properly reflect the current position. This means that you can use the Echelle Format Simulator window to manipulate the instrument as long as you set the requested filter to whatever is currently in the flaky wheel.
  6. If you are brave, you can try moving to an adjacent filter using the filter selector buttons on XNIRSPEC. But beware --- if the move fails, you'll need to start again looking for position switches and initialization switches!