20170617

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 and allows the use of the WFS. please setup a WFS for HETDEX observations. Note you will have to put in the actual observation number. 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``
  -i {lrs2,virus}, --instrument {lrs2,virus}
                        Use the specified instrument. Defaults to virus.

Watch out for the moon brightness at the end of the night particularly for the HETDEX observations.

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

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

Watch out for saving ACM images before and after each exposure for the PSU17-2-003!

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

For PSU17-2-003 you must first setup on the bright star (use the i filter in ACAM), save an ACAM image. Then take your first observation. Then save an ACAM image. After the observation is over offset by the value given in the comments for the A object using offset_trajectory. Take an acam image and observe the A position. Save an acam image after the 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. When complete save a final ACAM image.

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.

Standards in each IFU

Purpose: We wish to get spectrophotometric standards in each of the IFU. Just give the IFU number to shuffle and then setup like a normal HETDEX observation. Please use the dither script. The exposure time will vary but will likely be less than 1 minute. Please check for saturation.

Testing of the ACAM position

Purpose: We want to see if the ACAM position changes with respect to the IHMP over time. We want this data about 2 times per week and when ever we get an unusually high or low temperature.

Determine the Center of the BIB:

• Select a 14th mag star in a reasonably rich field with shuffle for the BIB
• Setup on the very center of the BIB field of view (79, 98) and save an image.
• Guide on one of the guide probes
• Put in the ACAM and save an shallow image with the target star not saturated.
• Report on the position of the BIB in the night report and on NightOperations/Commissioning/Results
• Save a deeper image which should show more than a dozen stars.

Determine the Center of LRS2-B

• Select a 14th mag star in a reasonably rich field with shuffle for the LRS2-B
• Setup on LRS2-B and start guiding on one of the guiders
• Take LRS2-B spectrum, probably 60 seconds.
• Adjust the position so that the star is at the center of LRS2-B IFU using lmap note there might be sign flips
• Confirm the star is at the center of the IFU by taking a spectrum.
• Once it is as the center of the IFU put in the ACAM and take a shallow image so that the star is not saturated.
• Report on the position of the LRS2-B in the night report and on NightOperations/Commissioning/Results
• Take a deeper image so that there are large number of stars.

Determine the Center of LRS2-R

• Select a 14th mag star in a reasonably rich field with shuffle for the LRS2-R
• Setup on LRS2-R and start guiding on one of the guiders
• Take LRS2-R spectrum, probably 60 seconds.
• Adjust the position so that the star is at the center of LRS2-R IFU using lmap
• Confirm the star is at the center of the IFU by taking a spectrum.
• Once it is as the center of the IFU put in the ACAM and take a shallow image so that the star is not saturated.
• Report on the position of the LRS2-R in the night report and on NightOperations/Commissioning/Results
• Take a deeper image so that there are large number of stars.

Repeat the above tests a few times at different Az to confirm that the positions are good.

Testing Probe offsets

Purpose: We want to see how accurately we offset using probe offsets with the same tools that we used for the guide probe measurements.

Procedure:

• Setup on For VIRUS on IFU 095 for Globular cluster ngc6205 in the east early in the track.
• Setup on GC1 (You can also run a WFS to keep good IQ).
• Expose VIRUS for 180 seconds syscmd -v -V 'expose( seconds=180, x_binning=2, y_binning=1, type="sci", object="ngc6205_095_E", observation=2, exposure=1 )'
• Wait for the shutter to close syscmd -V 'wait_for_shutter_close(observation=2, exposure=1 )'
• Move to 2nd dither position with a probe offset move mgp -toff=-1.27,0.73
• Expose VIRUS for 180 seconds syscmd -v -V 'expose( seconds=180, x_binning=2, y_binning=1, type="sci", object="ngc6205_095_E", observation=2, exposure=2 )'
• Wait for the shutter to close syscmd -V 'wait_for_shutter_close(observation=2, exposure=1 )'
• Move to 3rd dither position with a probe offset move mgp -toff=0.0,-1.46
• Expose VIRUS for 180 seconds syscmd -v -V 'expose( seconds=180, x_binning=2, y_binning=1, type="sci", object="ngc6205_095_E", observation=2, exposure=3 )'
• Wait for the shutter to close syscmd -V 'wait_for_shutter_close(observation=2, exposure=3 )'
• Move back to the start with a probe offset move mgp -toff=1.27,0.73

• Repeat the test but guiding on GC2 Be sure to change the observation number to 3
• Repeat the test but guiding on GC1 Be sure to change the observation number to 4
• Repeat the test but guiding on GC2 Be sure to change the observation number to 5

Closed dome:

Please do the following if you are closed:

• 10 VIRUS darks of 360 seconds
• 200 ldls flats for VIRUS
• dark 1800s x3 for LRS2
• FeAr 1800s red x4
• FeAr 1800s blue x4

See the long cals page for more information:

​https://het.as.utexas.edu:8001/trac/WFUCommissioning/wiki/NightOperations/SciencePlans/longcals