DEIMOS FCS Setup Checklist

Purpose

This checklist leads you through the set procedure for the DEIMOS Flexure Compensation System (FCS).

Preparing DEIMOS for FCS setup

Configure spectrograph. Configure the instrument with the desired grating, tilt wavelength, and filter for acquiring spectra.
Close hatch. Make certain that the remotely-controlled hatch at the front of DEIMOS is closed.
Extinguish lamps. Make certain that all of the internal calibration lamps are turned off.
Insert slitmask. To reduce the amount of stray light that reaches the dewar, insert a slitmask. Any slitmask will do, even the focus holes mask or the longslit.
Idle tracking. Make sure that the FCS tracking loop is in the idle state. Check the FCS MODE status on the left side of the main panel of the DEIMOS FCS GUI; it should indicate Off and the FCS STATUS display on the right side of this panel should indicate idle. If not, then click on the Stop button, and wait until the FCS STATUS displays idle.
Enable rotator. Bring up the Rotation sub-panel from the the main DEIMOS Dashboard GUI. If the rotation status indicates that rotation is locked, press the UNLOCK button.

Taking the Reference Frame

The first set of instructions below pertain to the normal case of observing a slitmask without regard to previous observations. If you are re-observing a slitmask that was observed on a previous night of your run, then follow the matching procedure below. If you are re-observing a slitmask that was observed on a previous run, then follow the archival matching procedure below.

Normal (Non-Matching) Case

Launch Setup panel. On the main panel of the DEIMOS FCS GUI, click the Setup button. This will bring up the FCS Setup sub-panel.
Reset exposure time. On the right-hand side of the Setup subpanel, click the Exposure Time button and select 1.
Select mode. Near the bottom of the FCS SETUP sub-panel, select New for Choose reference frame type.
Home FCS Stages. On the Setup Subpanel, click the button in the lower left corner reading Prepare for new reference frame. Wait for the message box at the bottom of that subpanel to show
```
fcszero new successful. You are now ready to take reference images
```
Acquire reference image. When the FCS system is ready, click on Take new reference frame and select Spectrographic when prompted. The system will acquire an FCS exposure.
Adjust FIGDISP. The newly-acquired reference image should appear on the FIGDISP image display on your screen. For the first image read out, you should do the following on the tk control window:
- Click the NORMAL and CENTER buttons to restore normal zoom and pan factors.
- Click HISTEQ to select the histogram-equalized colormap.
- Click IN to zoom in until the window is filled.
- Click the green Stats Box button to put the mouse into statistics mode.
Measure peak flux. Draw a statistics box around the 2 spectra on the left half of the FIGDISP display by clicking and dragging with the left mouse button. In the resulting popup window, note the max value. Draw another statistics box around the 2 spectra on the right-hand side and again note the max value.
Adjust exposure time. If the peak flux in each statistics box is at least 2000, the reference frame is acceptable; proceed to the next step. If not, then select a longer expoxure time by clicking the Exposure Time button on the Setup subpanel and choosing a longer exposure time. Click on Take new reference frame and select Spectrographic when prompted. The system will acquire an new FCS exposure. Repeat the previous step to measure the peak flux and continue to lengthen the exposure time until both sides have a peak flux over 2000.
Verify Tracking. Click Start on the main FCS GUI to enable FCS. The FCS Status should report OK immediately. Within a minute, FCS should lock on with messages of Tracking and On Target, as shown here. If FCS Status reports Lockout, ensure the shutter is open. If FCS Status still does not report OK, please contact your support astronomer.
Repeat as needed. Repeat all steps in this section for each unique combination of grating, central wavelength, and filter you plan to use during the night.

Matching Against a Previous Night

Follow this procedure if you are re-observing a slitmask that was observed on a previous night of your run. Note: if you want to match against observations made on a previous observing run, please see the procedure below.

Launch Setup panel. On the main panel of the DEIMOS FCS GUI, click the Setup button. This will bring up the FCS Setup subpanel.
Verify match. On the FCS Setup subpanel, ensure that the Current Reference File, Current Image File, and CurrentLog File are all defined. If they are not, then either the reference file from the previous night needs to be copied into the FCS directory, or the instrument is not configured with exactly the right grating, wavelength, and filter to match the previous setup.
Select mode. Near the bottom of the Setup sub-panel, select Matching for Choose reference frame type.
Home FCS Stages. On the Setup subpanel, click the button in the lower left corner reading Prepare for matching reference frame. Wait for the message box at the bottom of that subpanel to show
```
fcszero match successful. You are now ready to take reference images
```
Acquire reference image. When the FCS system is ready, click on Take matching reference frame and select Spectrographic when prompted. The system will take several minutes to reset the focus to the value employed in the old FCS setup, run FCS to achieve FCS lock against the old FCS reference image, restore the focus value, and acquire a new FCS reference exposure. Your indication that the procedure is done will be when the Current Image File shown on the FCS Setup panel changes.
Adjust FIGDISP. The newly-acquired reference image should appear on the FIGDISP image display on your screen. For the first image read out, you should do the following on the tk control window:
- Click the NORMAL and CENTER buttons to restore normal zoom and pan factors.
- Click HISTEQ to select the histogram-equalized colormap.
- Click IN to zoom in until the window is filled.
- Click the green Stats Box button to put the mouse into statistics mode.
Measure peak flux. Draw a statistics box around the 2 spectra on the left half of the FIGDISP display by clicking and dragging with the left mouse button. In the resulting popup window, note the max value. Draw another statistics box around the 2 spectra on the right-hand side and again note the max value.
Adjust exposure time. If the peak flux in each statistics box is at least 2000, the reference frame is acceptable; proceed to the next step. If not, then select a longer expoxure time by clicking the Exposure Time button on the Setup subpanel and choosing a longer exposure time. Click on Take new reference frame and select Spectrographic when prompted. The system will acquire an new FCS exposure. Repeat the previous step to measure the peak flux and continue to lengthen the exposure time until both sides have a peak flux over 2000.
Verify Tracking. Click Start on the main FCS GUI to enable FCS. The FCS Status should report "OK" immediately. Within a minute, FCS should lock on with messages of "Tracking" and "On Target", as shown here. If FCS Status reports "Lockout", ensure the shutter is open. If FCS Status still does not report "OK", please contact your support astronomer.
Repeat as needed. Repeat all steps in this section for each unique combination of grating, central wavelength, and filter you plan to use during the night.

Matching Against a Previous Run

Follow these steps to set up FCS to match against a reference image acquired on a previous run.

Determine the UT date of the original observation.
Locate the corresponding subdirectory for that UT date in /home/dmoseng/fcs_reference (on deimosserver). For example, FCS reference files for 2009-Oct-01 may be found in the directory /home/dmoseng/fcs_reference/2009oct01.
Copy the old reference files into the new FCS directory by issuing these commands on deimosserver:
```
cdfcs
retrieve_fcsref date
```
Continue with the procedure for matching described above.