Purpose

This checklist describes the procedure for aligning multiobject slitmasks on DEIMOS, assuming you are:

using slitmasks which have alignment boxes
using the xbox software for slitmask alignment

Procedure: Synopsis

This is a brief version for use by experienced DEIMOS observers. Novices should read the detailed procedure below.

Complete preliminary steps
- Focus telescope
- Insert correct slitmask
- Send grating to science wavelength
- Get out finder charts
- Verify target name and coordinates are correct
- Verify position angle
- Verify pointing origin is DEIMOS
Complete coarse acquisition
- Identify fiducial star on MAGIC display
- Get current coordinates (x1,y1) off MAGIQ
- Get corresponding desired coordinates (x2,y2) off finder
- Offset telescope with gmov x1 y2 x2 y2
Complete fine alignment
- Wait for FCS to track
- Click GO ZERO to tilt grating to zeroth order
- Set CCD readout mode to Direct
- Set exposure time to 20 sec
- Click Expose to acquire exposure
- When exposure begins, type do_xbox in IRAF
- When exposure ends, run xbox
- Repeat fine alignment if either:
  - A rotation was required
  - A move greater than 0.5 arcsec was required
Acquire science image
- Click GO BACK to tilt grating to science wavelength
- Select Spectral readout
- Set exposure time (typically 900-1800 sec)
- Execute wffcs ; goi
- Verify that exposure starts

Procedure: Detail

Complete preliminary steps

Focus telescope.
- In the MAGIQ UI, middle click on your next target.
- Ask to OA to run Mira in the neighborhood of your target. If you'll be on the field for several hours, then have the OA focus 1-2 hours west of the field.
- Wait about 10 minutes for the OA to acquire an appropriate star and run Mira.
Insert correct slitmask. You can do this while the telescope slews.
Send grating to science wavelength. Allow the flexure compensation system (FCS) to correct flexure resulting from changing the DEIMOS rotator position by setting the instrument up in your next spectroscopy configuration. Verify that the flexure compensation system starts sending corrections (i.e., confirm that the FCS GUI does not indicate Lockout).
Get out finder charts. Have it handy for use when you get to the field.
Acquire target.
When the OA tells you that your target is on DEIMOS, check the following information on FACSUM to verify that your position is correct:
- Verify target name and coordinates are correct
- Verify position angle (skypa field on FACSUM)
- Verify pointing origin (shown in lower right corner of FACSUM) is DEIMOS

Complete coarse acquisition

The goal of this step is to put the alignment stars into their boxes by placing a fiducial star onto a specified guider pixel.

Identify fiducial star. By comparing your finder chart to the ijmage on the MAGIQ user interface, identify the fiducial star.
Get current coordinates. On the MAGIQ UI, place the cursor on the fiducial star and note the current pixel location (x1,y1).
Get desired coordinates. On the finder chart, note the desired location of this star when the mask is aligned (x2,y2).
Offset telescope. At a polo prompt, use the gmov command to perform a telescope offset from the current coordinates (x1,y1) to the desired coordinates (x2,y2):
```
	gmov x1 y1 x2 y2
```

Note: If you are unable to complete this step, then you may need to resort to the alternative method of completing the coarse alignment.

Complete fine alignment

In this step, you will refine the positions of the stars within their respective alignment boxes to achieve optimal centering of the slitmask.

Wait for FCS to track. It's important to allow the flexure compenstion system to remove any residual flexure before your acquire your fine alignment images; otherwise, the xbox software won't be able to locate your alignment boxes. Wait for the FCSGUI to indicate that the system is Tracking.
Click GO ZERO. On the Dashboard's gratings subpanel, click the GO ZERO button to tilt the grating to the zeroth order position for direct imaging.
Set CCD readout mode to Direct. On the Dashboard, change the CCD readout mode to Direct.
Set exposure time to 20 sec. On the Dashboard, change the exposure time to 20 sec. Note: If conditions are poor or stars are faint, a longer time may be required to obtain adequate S/N for centroiding.
Click Expose. On the Dashboard, click the Expose to start the exposure.
Run do_xbox. In the IRAF window, type do_xbox once the exposure begins. The script will wait for the current image to be written, will determine the name of the image, and then will beep to indicate that it's time for you to wake up and run xbox.
Run xbox.
- For each alignment box, xbox will plot row and column cuts through the box to show the quality of the centering. Press:
  - q if the centering is acceptable
  - i to ignore the current box if the star is not seen or the object is inappropriate (bad coordinates, galaxy, double-star, etc.)
  - spacebar to reset the sky level if it was incorrectly measured by the program (sky will be reset to the current y-position of the cursor)
- When done reviewing all boxes, xbox will plot a residual map. If any discrepant points are noted, press d to delete the offending point and f to re-do the fit. Press q when the fit is acceptable.
- The program will report the suggested moves in rotation and position, as well as the uncertainties (in parenthesis).
- Answer y to the prompt:
```
     [CONFIRM]  Send DCS commands? (y/n) [y]:
```
- Accept the suggested rotator move if it is significant compared to the uncertainty.
- Perform another alignment iteration if:
  - a rotator move was required, or
  - a move > 0.5 arcsec was required
Acquire science image.
- Click GO BACK. On the Dashboard's gratings subpanel, click the GO BACK button to tilt the grating back to the science wavelength position for spectroscopy.
- Select Spectral readout. On the Dashboard, change the CCD readout mode to Spectral.
- Set exposure time. On the Dashboard, set the exposure time to the appropriate length (typically 900-1800 sec).
- Execute wffcs ; goi. Type this command into a polo xterm window. This will wait for the FCS to track and then will start a spectral exposure.
- Verify exposure. Make sure that the exposure begins. It may take a couple of minutes for the FCS to lock.

Alternative Coarse Alignment Procedure

If the Easy Way fails to work (for example, predicted TV guider pixel positions are not available), you can try this alternative method:

Point telescope to slitmask center. As above, verify:
- RA/Dec coordinates are same as mask design
- Sky PA are same as mask design
- Pointing origin is DEIMOS
Configure the instrument for imaging:
- set slider to zeroth order imaging position, or insert mirror
- set desired slitmask
- set CCD readout mode to Direct
- set exposure time to 20 sec
Acquire first direct image exposure through mask.
Generate box coordinate file in IRAF via get_boxes filename, where filename is the name of the image you just acquired. This will create a file called box.maskname in the current directory.
Remove the slitmask (i.e., set slitmask to None)
Acquire second exposure.
In IRAF, display this second (no mask) direct image with the predicted box positions overlaid by executing this command in IRAF:
```
	check_boxes last box.maskname
```
Inspect the image display and compare the overplotted guide box positions to the stars in the field. Identofy at least one of the alignment stars and measure the PANE pixel coordinates. Call these x1 and y1.
Display the first image of the field (with mask in place) in IRAF via
```
	dmosdisplay filename
```
Identify the corresponding alignment box for the alignment star and note the PANE coordinates of the box center. Call these x2 and y2.
Move the telescope by typing the following command into a polo window:
```
	mov x1 y1 x2 y2
```
The alignment stars should now be in their boxes; proceed with fine alignment.