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

Summary

Initial afternoon setup
Taking an FCS reference image for each configuration
FCS Setup sub-panel

Initial afternoon setup

Follow the afternoon checklist up through Determine instrument focus.
cdfcs. In a polo window, set your current default directory to the FCS output directory by typing cdfcs.
Verify FCSTRACK. Check that the indicator for fcstrack is colored blue on the intrcon on your leftmost display. If it is not running, then start it as follows:
- From the OpenWindows pulldown menu, select the item DEIMOS Control Menu > Subcomponents... > Start FCSTRACK.
- If the intercon indicator does not turn blue and no window running fcstrack appears, check the console window for error messages; if another user has left fcstrack running, your support astronomer must terminate that version before you can run a new one.

Taking an FCS reference image for each configuration

All of the calibrations for a given instrument configuration (i.e., a specific selection of grating or mirror, grating tilt, filter, etc.) should be taken at a fixed position angle of the instrument and without any intervening rotations of the instrument. Accordingly, you should coordinate with summit staff to determine at what hour they are planning to fill the dewar, since they may need to rotate DEIMOS (to PA = -25) in order to have access to the LN2 fill port.

Prepare DEIMOS for FCS setup:

Configure spectrograph. Configure the instrument with the desired grating, tilt wavelength, and filter for that configuration.
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, it is recommended that you 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. Configure the DEIMOS instrument for remote control of rotation:
- 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. If other conditions are indicated by the red lamp icons on the right side of the display (e.g., "Band Brake Applied", "Manual Hand Paddle Control", etc.), consult with summit personnel to correct these conditions so that DEIMOS can be rotated remotely.
- In the lower-left corner of the rotation sub-panel on the DEIMOS GUI, check that it reports "DCS control denied". If it indicates that DCS control is allowed, then click on the Allow DCS Control? button and select the no entry from the pop-up menu.

FCS Setup sub-panel

A note about reference frames: For each instrument configuration that you plan to use during observing, you should first obtain an FCS reference frame during the afternoon. Most observers will take a new reference frame for each instrument configuration each night. However, if you are re-observing a slitmask that was observed on a previous night, you will want to use the existing reference frame.

Setup

On the main panel of the DEIMOS FCS GUI, click the Setup button. This will bring up the "FCS SETUP" sub-panel.

The FCS spectral spots should have at least 2000 DN (counts). By default, FCS takes a 1 second exposure which works for most setups (7000 to 8500 A). At other wavelengths, a longer exposure time may be necessary. FCS exposure time is adjustable from the FCS Setup sub-panel.

Case 1: Take a new reference frame:
- Near the bottom of the FCS SETUP sub-panel, select "New" for "Choose reference frame type:"
- Click on Prepare for new reference frame.
- When the FCS system is ready, click on Take new reference frame and select Spectrographic when prompted.
Case 2: Match a previous reference frame:
- Near the bottom of the FCS SETUP sub-panel, select "Match previous" for "Choose reference frame type:"
- Click on Prepare for matching reference frame.
- When the FCS system is ready, click on Take matching reference frame and select Spectrographic when prompted.
  - Matching a previous reference frame will slightly adjust the instrument focus (if necessary).
  - FCS will automatically start to check that it can match the previous reference frame. It will automatically stop when it is finished.

There is also a choice for taking a "Direct" reference frame. This uses an LED instead of the CuAr lamps. The LED shines in the R band. Therefore, if taking direct images of the sky in the B, V, I, or Z filters, please select "Spectrographic" for your FCS reference frame.

Display

Once this image reads out, it should appear on the FIGDISP image display on your screen. For the first image read out, you should:

resize the FIGDISP window to be as wide as the screen allows and only about half its initial height.
On the blue 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.
check the count level of the FCS spectral spots. If less than 2000 DN, adjust the FCS exposure time and re-take the reference frames.

The FIGDISP display parameters should be set correctly for each additional setup.

Verify Tracking

If you have taken a new reference image, you need to verify that FCS can track. The Match Previous option will automatically test wheter FCS can track. Once you have the reference image, 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". 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 instrument configuration you plan to use during the night.

Note: if you'll be using the grating in zeroth order to acquire slitmask alignment images, you do NOT need to create a separate FCS setup. Typically, there is not enough flexure in the 30-60 second alignment images to pose a problem to xbox.