DEIMOS user script align

Name

align_check -- check slitmask alignment between spectral exposures

Purpose

Tilt the grating to the zeroth-order imaging position and
acquire a direct image with the current filter to check
slitmask alignment in between spectral exposures. If
started while an exposure is in progress, the script will
wait for the current exposure to finish before reconfiguring
the grating. The observer must run xbox in and IRAF session
on the resulting image to correct pointing.

The script reconfigures DEIMOS for spectroscopy immediately
after the image starts reading out on the assumption that only
a small shift will be required to fix the alignment. If a
significant shift or a significant rotation is recommended by
xbox, then the script should be re-run to verify alignment
following the move.

Usage

align_check [-n] [ttime]

Arguments

ttime = exposure time for alignment check

Flags

-n = noquery mode

Restrictions

- Can only be used when slider 3 or 4 is in use

Procedure

- Wait for any ongoing image to complete
- Configure DEIMOS for zeroth order imaging on the current slider
- Acquire a direct image of the specified integration time
to check slitmask alignment and wait for readout to commence
- Reconfigure spectrograph to spectroscopy mode settings
- Verify proper reconfiguration
- Pause until observer has sent moves
- Wait for FCS to begin tracking
- Launch a new exposure

Time requirements

- completes in 2:05, assuming 20 second exposure time

Exit values

0 = normal completion
1 = wrong number of arguments

Example

1) Make an alignment check using default exposure time:
align_check

2) Make an alignment check using longer exposure time:
align_check 40