20170330

Twilight Tests

Note: Twilight exposures are critical science calibrations for LRS and VIRUS and if possible should be done every night that science data is taken.

twilights with VIRUS with different tracker positions

Purpose: There is some interest in seeing what the long term illumination correction changes look like including what different track positions do to them. The script is "specialtwilight" in /home/mcs/astronomer/bin/. It takes a single argument which is the Observation number.

Procedure:

• Despite of pressures at the start of the night try to get the twilights.
• Setup the guide camera for sky twilight (GC2, 0.1 sec, B filter)
• When you hit the correct flux level (biased to a slight higher value, perhaps 5k) execute the specialtwilight script

On-sky science:

We have a few changes in procedure that are important to note:

1) Use shuffle_config to setup the files with the latest values.

2) For LRS2 and LRS2+parallelVIRUS use vlexp code as per normal.

3) For VIRUS hetdex fields please use the $HET_SRC_ROOT/integration/hetdex-dither.py script which has the new guider dither method built into it. Note you will have to put in the actual observation number. We hope to update vlexp in the near future. You should look at the help pages to remind you how to specify observations. Here it is repeated for your reading:

$HET_SRC_ROOT/integration/hetdex-dither.py --help
usage: hetdex-dither.py [-h] [-e EXPTIME] [--dry-run] [--no-gp-dither] [-s]
                        obs object

Execute a 3-dither HETDEX observation.

positional arguments:
  obs                   Observation number.
  object                Object descriptor.

optional arguments:
  -h, --help            show this help message and exit
  -e EXPTIME, --exptime EXPTIME
                        Exposure time per dither in s. Defaults to 360s.
  --dry-run             Print actions without executing commands on the
                        hardware
  --no-gp-dither        Run the 3 dithers using the dither mechanism instead
                        of offsetting the fiducial in the guide probes
  -s, --skip-last-write
                        Skip the last ``wait_for_write``

Watch out for the moon brightness at the start of the night. I am not sure that the automatic moon brightness works in htopx so you should set this manually to make sure you don't hit inappropriate targets or miss targets. After the moon sets just turn off the moon brightness.

At the start of the night please try to hit any P4 targets in the West.

During any thin parts of the night (few targets) please try to get your standards or the engineering test list below.

Watch out for the request telluric standards needed just before or after UT17-2-004!

For PSU17-2-003 you must first setup on the bright star at the very start of the track, then offset by the value given in the comments for the A object using offset_trajectory. Take an acam image and observe the A position. Then when the 1st exposure is complete use offset_trajectory and the values in the B comments to get to the B position. Save an acam image and observe the B position. Then when the 2nd exposure is complete use offset_trajectory and the values in the C comments to get to the C position. Take an acam image and observe the C position. It would be a good idea to save the RA and DEC of the guide star that was used if it works all the way through the sequence.

Here is a rough outline for the PSU17-2-003 observing:

• Setup on the bright star indicated
• Start guiding on a guide probe (hopefully one in the center of the range)
• syscmd -T 'offset_trajectory(dra=-12, ddec=30, adjust_probes="true")' to get to position A from the setup star
• Save an ACAM image
• observation in index 396
• syscmd -T 'offset_trajectory(dra=-28, ddec=0, adjust_probes="true")' to get to position B from position A
• Save an ACAM image
• observation in index 397
• syscmd -T 'offset_trajectory(dra=12, ddec=12, adjust_probes="true")' to get to position C from position B
• Save an ACAM image
• observation in index 398

On-sky engineering:

This should be the lowest priority but could be done when the moon rises or during a hole in the queue (after standards have been taken). The priority of the tests is in the order given below.

Relative Plate scale test with ACAM, GC1 and GC2

Purpose: There is some indication that the plate scale on the GC1 and GC2 is different than the theoretical values. We would like to collect a different type of data set to test this.

Procedure:

• Use do_shuffle to set up on a moderately brightness star, one that will not saturate on the ACAM in 5 seconds, perhaps 14th mag.
• Center up the GC1 and GC2 on their target stars.
• Guide on the ACAM with a very large guide box.
• Start the metrology loops for GC1 and GC2 make sure their boxes cover most of the field of view.
• Start saving 10 images on ACAM, GC1 and GC2.
• Do a fiducial offset but not so large that the GC1 and GC2 loose their stars. Perhaps 6" in X. I think the command is syscmd -v -T 'ACQ_offset_fiducial(dx_asec=6, dy_asec=0)'
• Wait for the ACAM guide star to settle down at the new location.
• Start saving 10 images on ACAM, GC1 and GC2.

• start test over but do the offset in Y instead of X.

If you want to do this test with one of the guiders as the controlling then use syscmd -v -T 'Guider1_offset_fiducial(dx_asec=6, dy_asec=0)' or syscmd -v -T 'Guider2_offset_fiducial(dx_asec=6, dy_asec=0)' but be sure to allow the guider enough time to settle down given the problems with the orientation angle.

Also try offsets like the hetdex dither. start at initial position, then offset by dx_asec=-1.27, dy_asec=0.73, save some data then move to the last position dx_asec=0.0, dy_asec=-1.46.

Closed dome:

At the present time I don't think there are any long cals that need to be done but please have a look at:

​https://hettrac:8001/trac/WFUCommissioning/wiki/NightOperations/SciencePlans/longcals