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Observing Plan for the September 18-2030 Engineering Nights

Proposal Id: 2013A-9999
Exposure Scripts: Most of the exposure script for this night are available in ~DECamObserver/ExposureScripts/engineering_20130918
(from the Observer Console GUI select Exposure Control --> Load Exposure Script --> Choose File)

(Late) Afternoon

Full set of zeros and dome flats
Script: prenight_calibration.json (note that this is a (standard) DES script. From the the Observer Console GUI select Exposure Control --> Load Exposure Script --> Select DECam Script then choose DES/prenight_calibration.json in the dialog window)

PTC (Afternoon)

On one of the three afternoons we need to run the photon transfer curve script PTC_r.json.
This is a standard DES script so it can be loaded from the Observer Console GUI in the same way as the prenight_calibration script.

Starflats

Instructions from Gary:

We need more depth on the u-band flats. For u band this has to be done as early as possible before the moon rises too high on these bright nights. The only real chance at this will be just at the start of the third engineering night.

We also want the lowest possible Galactic latitude. This location is just about the lowest-latitude location available at low airmass at this time:

RA=19:00:00  DEC=-50:00:00 (sets at about 01:00 local time)

Starting from this location we'll run the script Starflats_u.json that takes 22 offset exposures.
There are 22 exposures in the sequence, so 22 x (200+30)s -> about 1.4 hours.

The pointing is not critical (1 arcmin accuracy is fine). Poor seeing can be tolerated. But do not bother with this if there are any visible clouds.

SISPI Studies

The SISPI teams plans to perform a few tests related to some of the problems we had in past weeks with the shutter. We'll schedule this as the first thing Wednesday or Friday night. Klaus will be online and work with the observers remotely.

obstac

Eric has prepared a new version of obstac that (potentially) addressed the problem that the queue empties occasionally while obstac is running. We will use this version during the engineering nights. No particular tests are planned but we would like to run this for an extended period (2-3 hours) to see if there are no unintended side effects.

Pointing Model Tests

Tim and the TCS team would like to take data to study the pointing model used by the telescope control system. We are planing to use two separate configurations: first, with the active system (AOS) off and the hexapod values fixed to the values from zenith. For the second test will allow the AOS to adjust the position of the hexapod at each position.

Pointing Model Test 1

  • Move telescope to zenith
  • Switch to AOS-1 mode
    • On the Architect Console select the AOS role (on the left) and then enter the command init_pid 1 in the command field (upper right)
    • On the ICS Hexapod GUI (see screen shot below) click on the Trim button and in the pop-up window enter 0 in all fields except for focus (3rd field from the left)
  • Take a few exposures (30 seconds each in r filter) to allow the AOS to adjust the focus.
  • On the ICS Hexapod GUI uncheck the Telescope (Lookup) box. This will keep the hexapod fixed at the current values (except for focus).
  • Slew telescope by a few degrees, take an exposure and verify that the hexapod values do not change. (except for focus)
  • Run the PointingMap.json script from the engineering_20130918 directory.
    • Verify that the trim values stay at 0 (except for focus)
    • Verify that the hexapod position doesn't change (except for focus) - if this does change stop and call Klaus or Ann
  • On observer2 go to the image directory (/data_local/images/fits/2013A_9999) and for each exposure run the check_offset scripts.
    check_offsets -x <exposure number>
    
    For example:
    [DECamObserver@observer2 2013A-9999]$ check_offsets -x 228827
    Expid  228827  tim:  ['-6.9', '-19.9']  center:  ['-5.2', '-19.8']  Hexapod:  [1000.941, 2447.446, 2278.99, -136.057, -95.603, -0.0]
    
    • this runs the kentools tim command, center command and extracts the hexapod values [Note that the kentools results are presented as error, not offsets (there is sign difference to the normal center command)]
    • record these values in a text file

Pointing Model Test 2

This is the same as the previous test with the exception that we now use the telescope LUT to adjust the hexapod as we slew the telescope.
  • Move telescope to zenith
  • Make sure that the telescope LUT is enabled (This is the default but if you continue from the previous test, you must use the ICS Hexapod GUI and check the Telescope (Lookup) box.)
  • Switch to AOS-1 mode
    • On the Architect Console select the AOS role (on the left) and then enter the command init_pid 1 in the command field (upper right)
    • On the ICS Hexapod GUI (see screen shot below) click on the Trim button and in the pop-up window enter 0 in all fields except for focus (3rd field from the left)
  • Take a few exposures (30 seconds each in r filter) to allow the AOS to adjust the focus.
  • Run the PointingMap.json script
  • For each exposure record the offsets and hexapod position using the check_offets tool as described above
  • When done set the AOS back to AOS-5 mode using the Architect Console
    • Select the AOS role
    • Enter the command initpid 2

Sky brightness test

This is only useful under photometric conditions, and standard stars must be taken. Seeing doesn't matter.

The sky brightness test consists a sequence of exposures covering different angles from the moon and zenith. There is a stand-alone script that generates observing scripts that can be loaded into SISPI to perform such sequences. It can be run like this:

setup obstac
python ~sispi/neilsen/moon_sky_script.py 2013-09-19T01:00:00Z moon_sky.json ~sispi/obstac/DES/obstac-nosispi.conf

The first argument is the time at which the script is to be started, the second the name of the json file it should write the observing script to, and the third the obstac configuration file to use. The last should remain as above.

You should be able to run the script for a time a few minutes in the future, load the script into SISPI, and hit go.

Because the test depends on different pointing being at specific zenith angle, the script should be generated for a time very close to the time at which it is actually executed.

What the script does is this:

  • Select a sequence of fields 30 degrees from the moon, at zenith angles that are 15 degrees apart, and observe each in all filters.
  • Select a sequence of fields 50 degrees from the moon, at zenith angles that are 15 degrees apart, and observe each in all filters.
  • Select a sequence of fields 70 degrees from the moon, at zenith angles that are 15 degrees apart, and observe each in all filters.
  • Select a sequence of fields 90 degrees from the moon, at zenith angles that are 15 degrees apart, and observe each in all filters.

and so forth until it can get to further.

Deep Y band observations, fringe tests

(from Peter Nugent and Paul Martini)

Summary:

We'd like 60 Y-band exposures (each 90sec) to measure the amplitude of the fringe pattern. 10 dithered images per deep SN field and the corresponding 2 adjacent shallow sub-fields would be ideal, as that may be useful for calibration and photo-z work too. This should take a total of 2-3 hours.

Instructions:
  • Point at an SN field C1, C2, C3 and X1, X2 and X3. (coordinates are on this page: https://cdcvs.fnal.gov/redmine/projects/des-sn/wiki/Fields_Selection) SN-C3 and SN-X3 are top priority
  • All of these fields are up in the second half of the night, they do not have to be directly overhead, secz < 2.0 is fine
  • Run the above json scripts (linked to field names) to take 10 exposures for each one, these are in a 3-4-3 pattern of equilateral triangles separated by 30" on a side. Please check these json files, it's my first attempt at them.
  • Repeat for the next field

AOS/Donuts tests

AOS Part One of Two (about 1 hour). Requires seeing <1.2" and galactic plane (or other dense star region)

  • Move the telescope to a location with high stellar density (ideally galactic latitude around 15 degrees). Telops can usually assist with this. We will be tracking the same location on the sky for around an hour. Otherwise contact Kevin Reil ().
  • Run the script aos_focus_align.json - this will take 5 * 30 second 'r' band exposures to get the telescope in focus and aligned. (10 minutes)
  • Run the script aos_on_grizy.json - this will take 2 * 30 second exposures in focus for 5 (grizy) bands with the AOS on (normal operations). (20 minutes)
  • Defocus the telescope by moving the hexapod +1500 microns
    • This can be confirmed using the ICS Hexapod gui (shown below).
    • Snapshot of the Hexapog gui on  the ICS screen
    • Note the current hexapod Z value (above is 2975.3 but your value when you do this will be different)
    • Go to the Architect Console
    • Scroll down on the left hand side and click on Hexapod (running) under ics1.
    • Under System Control (top right) there are three text entry boxes. Two will be prefilled to ICS and HEXAPOD.
    • Snapshot of the hexapod architect control for AOS tests
      • In the third entry box, type: "setrelpos 1500" (without quotes) and press enter
      • The hexapod will move. Confirm the new Z value (should be previous+1500)
  • Run the script aos_off_grizy.json - this will take 2 * 30 second exposures out of focus for 5 (grizy) bands with the AOS off. (20 minutes)
    • Here, the AOS system will simply not be triggered and the hexapod should not move at all during this script as LUT, AOS and GUIDER are all disabled)
  • Refocus the telescope by moving the hexapod -1500 microns
    • As before except change to "setrelpos -1500" for Architect Console/ Hexapod

AOS Part Two of Two (about 30 minutes). Requires - any time.

  • Move the telescope to zenith (we willl be tracking the sky from here)
  • Run the script aos_focus_align.json - this will take 5 * 30 second 'r' band exposures to get the telescope in focus and aligned. (10 minutes)
  • Make a note of the current "focus" value (focus_before=Z_zero)
  • Run the script aos_zenith_pupil.json (15 minutes).
    • The hexapod will move to z=10,000. Script may time out. If so, clear the queue and restart script.
  • Refocus the telescope by moving the hexapod focus back to focus=focus_before
    • This can be confirmed using the ICS Hexapod gui (shown above).
    • Go to the Architect Console
    • Scroll down on the left hand side and click on Hexapod (running) under ics1.
    • Under System Control (top right) there are three text entry boxes. Two will be prefilled to ICS and HEXAPOD.
      • In the third entry box, type: "setabspos Z_zero" (without quotes and fill in Z_zero value). Press enter.
      • The hexapod will move. Confirm the new Z value (should be equal to Z_zero value)

If at anytime the above plan is not working as expected, focus can be restored by clicking the "Init. z trim" button on the ICS/Hexapod control and running the aos_focus_align script.

Regression Script

Three versions of regressions script have been loaded to the engineering_20130918 directory.

  • Regression_Observations_All.json - the standard regression script. Run this first in AOS-5 mode and then (next night) in AOS-1 mode
  • Regression_Observations_Absolute.json - the same script but instead of letting the telescope track for the 4 exposures we move back to the grid point between the exposures. Run this in the 3rd night
  • Regression_Observations_Compensate.json - a version of the script that attempts to correct pointing errors by compensating for the hexapod trims. We won't be using this script during this run.

Calibrate Stars around BD+17 4708

  • Observe a set of 3 standards fields (low-, intermediate- and high-airmass), make sure they include u-band standards
  • then observe the attached json script to calibrate stars around BD+17 4708
  • then observe a second set of 3 standard star fields (again include u-band)

LUT tests

  • Move to zenith, take a few exposures to set the focus
  • Turn of the AOS (exclude AOS; this will be manual exposure requests)
  • determine the new focus = current focus + 1500
  • Take an image with the new focus, AOS and Guider off (but LUT on) -> Exposure Control: select exptime 30 (?), filter i, exclude AOS, Guider, leave coordinates empty -> we ask the operator to slew
  • Slew to 30 from zenith and step through HA (maybe 8 steps) Ask the operator to slew, when in position submit the exposure (might have to click GO every time)

Go back to zenith, take a couple of exposures with the AOS and the Guider in focus -> sets the alignment
Then repeat the slews to the same position (again manually with the help of the operator). At each position take two exposures -> the first one to allow the AOS to settle, the second to see how good the wavefront/alignment is.
Maybe a bit longer to get enough donuts? 50 seconds?

Please mark the first/last exposures for each of these sets in the eLog

AOS minimum vs hexapod position

We would like to to perform a second test to check out image quality (whiskers) vs hexapod alignment.

Pick a telescope position maybe 30 degrees from zenith where we can observer for about an hour.
Ask the operator to move the position.
Take two exposures to set the (AOS) alignment
Write down the hexapod settings from the ICS hexapod GUI
Move back to the original position (HA/DEC) since the telescope will have tracked for a few degrees

We know want to take exposures with different hexapod settings scanning in x and then in y in 500 micron steps.

x:
  1. Take an exposure at the nominal position, exclude AOS
  2. Ask the operator to slew back
  3. Use the trim button on the hexapod GUI to change x by -2000 relative to the current value
  4. Take an exposure, exclude AOS
  5. Ask the operator to move back to the original position to compensate for the (small) change due to tracking
  6. repeat, adding +500 to the hexapod x trim value until you are at +2000 relative to the start value

y:
repeat the same adjusting the y trim value keeping the hexapod x at the original value.