Background

The FCS fix GUI is intended to help restore the ability of the DEIMOS Flexure Compensation System to track when the spatial or spectral offsets are too large for it to recover on its own.

Invocation

It can be invoked from the actions pulldown menu on the DEIMOS instrument control GUI.

Procedure

Follow these steps to recover when FCS gets stuck on a state other than Tracking:

1. Step 1: Grab FCS images. Click on the button labeled Get FCS images. Thi will display:
   • the FCS reference image for the current configuration;
   • the latest FCS image.
2. Step 2: Capture spot coordinates. Identify a CuAr spot that is visible in both the top and bottom images, and right-click on the feature center for both images. This will automatically update the pixel coordinates of the spot on the reference image (x_ref, y_ref) on the current image (x_cur, y_cur).
3. Step 3: Send FCS Moves. Click on the the Send FCS moves button to shift the DEIMOS optics to return the spot on the current image as close as possible to the corresponding spot on the reference image. This invokes the fcsmov script, which will execute the following sequence:
   • Disable FCS tracking.
   • Invoke fcsmove to shift the spots.
   • Enable FCS tracking.
   • Wait for FCS to enter Tracking mode, or for 5 FCS iterations to complete.

• If FCS successfully starts tracking, the script will indicate so by printing the message:

   SUCCESS! FCS is tracking; please proceed with observing.

  In this case, you can Close the GUI and resume observations.
• If FCS is unable to track, then the script will print:

  	ERROR! FCS is NOT tracking; please click 'Unstick Grating' button.

  In this case, click on the Unstick Grating button to recover. This will:
  • Remember the current wavelength.
  • Disable FCS tracking.
  • Run the unstick_grating procedure to home the grating tilt.
  • Return the grating to the original central wavelength.
  • Enable FCS tracking.
  • Wait for FCS to enter Tracking mode, or for 5 FCS iterations to complete.
  If FCS successful starts tracking, the script will indicate so by printing the message:

  	SUCCESS! FCS is tracking; please proceed with observing.

  In this case, you can quit the tool and resume observations.
  If FCS is unable to track, then the script will print:

  	ERROR! FCS is NOT tracking; please contact Staff Astronomer.

  In this case, you will need to consult your Staff Astronomer to diagnose the problems with the system.
• Close. When you are done with the GUI, click Close to terminmate the GUI and the associated ds9 window.