LBC Checklists

Daily, during science blocks:

Before each science block:

  • Do daily checks
  • Obtain a set of flat fields (5 each on blue/red)
    • to build up database
    • to check for any dirt on filters
    • to insure filters are aligned, shaft/encoder has slipped in the past, see IT #3091
  • Check and correct pointing, co-pointing using lbcrangebal
    • this will necessarily require running dofpia.
  • Run an OB (as in science mode - focus/collimate before hand) which uses guiding (i.e. exptime must be > 40 sec), dithering, and has stars on AO tech chip for tech-chip focusing to verify:
    • guiding
    • tech-chip focus corrections being sent
    • dithering is working as expected
  • If this is the first ScienceOps night after the LBC cryostat has been mounted:
    • measure rotator center (should not change by more than a few pixels)
    • check tilt (should not have been introduced - shims are consistently put in place)
    • confirm focus offset zeros, which are determined for V-BESSEL and r-SLOAN, are consistent with past values. (should be no change)
  • Not required for every science block, but maybe monthly: Verify that the time on the CMU is correct and synchronized with our GPS
    • ssh telescope@lbccontrol
    • run /usr/sbin/ntpdate -q gps0 on the CMU. If the offset is less than a few milliseconds it is fine.
    • See IT #3145 for background on this issue.
  • Not required for every science block, but maybe monthly: Verify time on the Windows PCs is correct
    • power each of the Windows PCs with on the CMU
    • VNC into the Windows PC (password is the CMU lbccontrol password)
    • right click on the time in the lower right of the Windows desktop and choose "Adjust Date/Time"
    • in the "Internet Time" tab of the window that pops up, verify the machine has sync'ed with and is correct:

Check stability of cameras

  • Obtain biases and a dark.
    • OBs for this are in /home/LBTO/Calib_OBs/BIASDARK and are 10Bias_Bino.ob and 2Darks_Bino.ob.
    • Biases should be taken with lights OFF. If going to take biases with the lights ON, please use the script "_10Bias_Bino_Checkout.ob" instead.
  • Start up RB_Science script to view these as they are taken.

Flat Fields

  • Obtain flats in at least one pair of blue/red filters and at one PA. These are useful to:
    • check that there is nothing vignetting the field
    • build up a database of twilight sky flats from which to monitor stability.
    • Flat field OBs are created by in /home/LBTO/Calib_OBs/Mkskyflat1/
  • Exposure time scalings were established using the following OBs. These scalings could be refined...but changing factor affects all the others...
    • Two OBs to generate a set of flats through all filters from which we can measure relative count rates. All red filters are measured against V-BESSEL and all blue filters against r-SLOAN (red).
      • Blue_SkyFlatScalings.ob --- cycles through all blue filters while keeping red filter set at V-BESSEL
      • Blue_SkyFlatScalings2.ob --- repeats the last 3 blue filters, since the filter changes in Blue may mean that the last few filters in Blue are done after and are non-simultaneous with Red.
      • Red_SkyFlatScalings.ob --- cycles through all red filters while keeping blue filter set at V-BESSEL
      • Red_SkyFlatScalings2.ob --- repeats the last few red filters

Pointing Check

  • OBs in /home/LBTO/RB_VV_PointingOBs/
  • Slew to pointing star from list
  • Use LBTtools.Observe.lbcrangebal to correct pointing and co-pointing. If monocular, use LBTtools.LBC.ptautoadjust to correct pointing.

Measure focal plane tilt (if there is reason to suspect it may have changed since the last science block)

  • the two methods to measure defocus across the field are described below:


  • Obtain focus sequences for at least 2 position angles (0 and 180, e.g.)
  • OBs are in/home/LBTO/Calib_OBs/SUPERFOC/ are are:
    • RB_rVsuperfoc.ob7, RB_rVsuperfoc7_pa90.ob, RB_rV_superfoc7_pa180.ob and RB_rV_superfoc7_pa270.ob.
  • Analyze in two ways (more details in TiltDataAnalysis)
    • run nmisc.starfoc for stars in subregions of each chip, usually top, middle, bottom, to produce an array of 12 best-focus values.
    • use script in LBTtools.Sandbox and gnuplot to generate and display this array of best-focus values.
      • (focfit3 uses Source Extractor to measure average FWHM in a bin. The number of bins along X and Y can be set).

4-chip extra/intra focal images

  • Obtain extra-/intra-focal image pairs for at least 2 position angles
  • OBs are in /home/LBTO/Calib_OBs/FOCUS and are:
    • RB_rVexin4.ob, RB_rVexin4_pa90.ob, RB_rVexin4_pa180.ob and RB_rVexin4_pa270.ob (extra then intra-focal image) and
    • RB_rVinex4.ob, RB_rVinex4_pa90.ob, RB_rVinex4_pa180.ob and RB_rVinex4_pa270.ob (takes intra- then extra-focal image)
    • Alternating exin and inex reduces the number of mirror focus (Z) moves and saves a few seconds.
  • More details on the TiltDataAnalysis


Measure Rotator Center

  • Slew to a star field at moderate elevation and collimate. A set of star fields from RA=19:30 to 03:30 is at LBCStarFields.
  • Take a pair of 5-sec images at two diametrically opposed position angles (0 and 180, e.g.). Good idea to obtain at least two pairs.
    • Ask the operator to slew.
    • OBs are rotatorcenter_pa0.ob and rotatorcenter_pa180.ob (these do not slew the telescope) in /home/LBTO/Calib_OBs/ROTCEN_Check/
  • Run script LBTtools.LBC.rotcenter to compute rotator centers.
    • Update eight header template files, blue_ehu_sci{1,2,3,4}.hdr and red_ehu_sci{1,2,3,4}.hdr on CMU: /lbccontrol/current/conf/ by updating the values for CRPIX1 and CRPIX2 in lines 2 and 3.
    • Define:
      • Delta_X = RotCen_X(new) - RotCen_X(old) and
      • Delta_Y = RotCen_Y(new) - RotCen_Y(old)
      • Then for chips 1,2,3:
        • CRPIX1(new) = CRPIX1(old) + Delta_X and
        • CRPIX2(new) = CRPIX2(old) + Delta_Y
      • And for chip 4:
        • CRPIX1(new) = CRPIX1(old) + Delta_Y and
        • CRPIX2(new) = CRPIX2(old) - Delta_X

Collect data for making a collimation table

  • Make sure there is no focal plane tilt
  • Slew to ~10 stars at a range of elevations from 25 to 90 degrees, run dofpia to collimate, then obtain a pair of blue/red images, run lbcrangebal on these to copoint and range-balance, and finally repeat the exposures. Record the timestamps of these last range-balanced, copointed and collimated pupil images.
  • The step-by-step procedure is:
    1. Slew to a pointing star or a field centered about a star, e.g. a USNO-B1 catalog star, with well-known coordinates.
    2. Run dofpia to collimate both sides.
    3. Obtain quick, 1-sec, exposures with both the blue and red cameras.
    4. Run lbcrangebal on these to range-balance and co-point while maintaining collimation.
    5. Repeat the 1-sec exposures with both blue and red cameras.
    6. Record the timestamps of these final exposures. The mirror positions, telescope elevation and temperatures which are needed for the collimation model will be read from these image headers.
    7. Go back to 1. and repeat for about 10 stars.
  • (I'd noted that collection of these data was no longer necessary, since data from headers of images taken immediately after focus/collimation during science nights can be used. But whether these data are also range-balanced and co-pointed at every elevation seems questionable, since the range-balancing and co-pointing calculation may only be done once during the night, and at a single elevation).

Collect data for Pointing Model

A 28 star pointing run would be good for a "spring" set of pointing data. We have winter sets and can investigate any temperature dependence of the pointing model
  • Insure Rotator Center is correct in headers (CRPIX1, CRPIX2 of chip 2 are the most recent values for the rotator center)
  • Make sure the correct, most recent, collimation model is loaded.
  • To obtain data for a pointing model:
    1. Ask OSA to start mount logging
    2. Slew to a WT or ACT pointing star (using Pointing star OB) (sequence determined from /home/LBTO/POINTING/Pointingstars5).
      • OBs to slew and obtain images of Pointing Stars are at /home/LBTO/RB_VV_PointingOBs/
      • The program /home/LBTO/POINTING/Pointingstars5 will output a sequence of stars which will sweep the hemisphere back and forth so that the minimum subset of 14 stars will cover it once, a better subset of 28, twice, up to the full set of 56 stars.
    3. Run dofpia to collimate
    4. Take B/R images (Pointing star OB will do this)
    5. Run 'lbcrangebal' to range-balance and co-point while maintaining collimation
    6. Run OB again to take B/R images (whose headers will give the mirror positions).
    7. Go back to step 2, using the next star indicated by the Pointingstars5 program.

Make a Pointing Model

Measure filter focus offsets

These should not change with the hub move, but it would be helpful to take some focus sequences.
  • OBs in /home/LBTO/Calib_OBs/SUPERFOC/
  • Make image list (in real time) with LBTtools.LBC.foclist
  • Run nmisc.starfoc to measure best focus for the sequence. Concentrate on region around rotator center. Be consistent.
  • Procedure for obtaining these data:
    • Slew to a field with many stars, though not too dense
    • Run dofpia
    • Run a few superfoc sequences using different filter pairs but always include the reference pair using the rV filters (RB_rV_superfoc.ob). Improved fits come from the longer version of the superfoc sequences, RB_rV_superfoc7.ob. These take 7 10-second images, with a focus step of 0.06mm between these.
    • Repeat these two steps (dofpia, superfoc sequences).
      • Be sure to repeat each filter 3 or more times; and
      • Be sure to always include a reference pair using the r-SLOAN and V-BESSEL filters.

Test guiding, dithering (need to have a quick reduce script)

  • Develop OB - plan to have guide/focus stars on tech chips for all dither positions.
  • Check/correct pointing/co-pointing before: lbcrangebal script
  • SN target at 16hrs
  • M16 at 18hrs
  • There are additional targets in Calib_OBs/ASTRONtest

Rotator Zero Point update:

  • Current (Oct 2011) values are 90.34 (Blue) and 90.00 (Red)
  • Apply WCS to science images, measure average rotator offset from requested PA
  • Update config files:
    • Edit bluechannel.conf (redchannel.conf)
    • Set Rotator.PositionAngleOffset
    • Restart with and
  • Verify on subsequent science data
  • Notify LBC Software support of the results

Check or refine calibrations if necessary:

  1. Astrometry - obtain one astrometric field. OBs are in /home/lbcobs/REDCOMMISSIONING/ASTROMETRIC_STD/
  2. Throughput - obtain one standard star field if photometric. OBs are in Calib_OBs package, in STANDARDS directory.

Investigate recently uncovered or ongoing problems with LBC or telescope:

Implement tools to aid observers and LBTO staff

LBCStarFields (Relatively dense star fields for superfoc, extra/intra focal pupil images and FPIA work)

Observing Plan (copy and paste this to the nightly logs)

  • Closed dome SW tests, if requested
  • Open dome SW tests, if requested

  • Run a "science" OB which dithers, guides (M16)
    • Create OB to put guide stars on both tech chips today.
    • Before running OB
      • Slew to nearby pointing star and correct pointing IE/CA
      • Correct copointing with Red and Blue images of pointing star
      • Load science OB and slew to target position
      • collimate/focus
      • Run science OB

  • Check existing collimation model
    • Take new data if necessary
    • Stable conditions!

  • Check existing pointing model
    • Implement new collimation model if necessary
    • Stable conditions!
    • Take 12 points, with pointing log on...
    • Take full set (56 points) if the first 12 points are off.

-- OlgaKuhn - 27 May 2010
Topic revision: r34 - 27 Dec 2020, OlgaKuhn
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