Left Back Bent Gregorian Focal Station Commissioning Plan

Prerequisites DONE

  • Day time commissioning of AGW1. Able to position AGw on-axis, wfs apert. coincident w/rotator center DONE
  • AGW1 installed on telescope @ LBBG (done) DONE
    • Front cover (mirror side) reinstalled on AGW1
  • AzCam readout and bias levels configured and tested. DONE
  • IRTC installed on telescope @ LBBG (done) DONE
  • M3 angle surveyed to the proper position ALERT!
  • BP13 patched for IIF and PCS to talk to LBBG rotator DONE
  • Update hotspot coordinates in GCS configuration files based on Jesper's realignment in August 2011. DONE

Initial Pointing and Collimation of LBBG DONE

Initial Pointing and Collimation with IRTC DONE

  • Switch PCS to be Monocular Left-sided on IIFGUI.
  • Determine initial pointing model and collimation zero points
    • Reset AZ and EL encoders
    • Point to very bright source, e.g.:
      • Vega at 18 36 56.3364 +38 47 01.291
      • Pollux at 07 45 18.9503 +28 01 34.315
      • Regulus at 10 08 22.3107 +11 58 01.945
      • Arcturus at 14 15 39.6720 +19 10 56.677 (watch out for high proper motion)
      • Note: these 4 stars are now in the default catalog used by "pointto".
    • take an image with IRTC, or put IRTC into continuous readout mode
    • collimate (by eye) to correct focus and coma. [Andrew says move only M2 RX/RY for initial collimation.]
    • offset M2 X/Y to center star on detector
    • iterate the collimation adjustment
  • Update the pointing model DONE
    • All the left (SX) focal stations are using the same pointing model, so we don't expect that any refinement of the pointing model will be required.

Initial Rotator Zeropoint with IRTC (open loop) DONE

  • PCS/MCSPU: Check Position Angle and Rotator Motion with IRTC
    • It was hard to find asterisms, so we make the first cut by offsetting the telescope in known directions.
      • Preset in TRACK mode and center the star with IE/CA.
      • Offset the telescope and observe which way the star moves on IRTC
      • Be certain that you are sending your offsets in RADEC space and not DETXY space.
    • take IRTC images/cubes at several Position Angles
    • verify sign (parity) and zeropoint of the Position Angle for IRTC
    • Adjust LEFTZEROPOINT in PCSInstrument.conf to refine the Position Angles

Adjust M3 selector angle and tip-tilt (partially done)

This is a new procedure not previously included in AGw checkout. We previously set the position from the laser tracker measurement.

AGw Commissioning for AGW1

AGw Guider Initial Calibration DONE

Measure Rotator Center and establish the position of the optical axis DONE (Repeat for Dec 2011)

  • Determine rotator center in AGw space DONE
    • Start up the AGW unit
    • Move AGw probe to nominal on axis position
    • Rotate the rotator (TO command) while taking a 70 sec exposure on the guide camera
    • Reposition AGw stage to align with rotator center (Jesper)
    • Repeat as needed to position rotator center on WFS aperture
  • Verify Rotator Center in IRTC space

Guiding Tests DONE

  • Test closed loop guiding on-axis with GCS
    • Did the acquisition offset center the star in the guide box?
    • Is the guiding stable to perturbations, or does the star drift off in the wrong direction?
  • Sort out required parameter changes to make guiding stable.
  • Repeat the test and Guide off-axis to verify rotator rates and flip parameters

AGw WFS Camera Initial Calibration

Warning: AGW2 WFS camera is upside down compared to AGw3 and AGw4. This is because of clearance issues for the new flexible cables.

Find Hotspot on Guider to put star in center of WFSC pinhole DONE

  • Send a GUIDE preset
  • Acquire star on WFSC
    • Option A
      • Place star on nominal "Center of WFSC Pin Hole" position (guiding is doing this)
      • If no S-H spots, then stop guiding and move guide probe small amounts in spiral pattern until spots found
      • Move guide probe in +x,-x, and +y,-y till spots are vignetted
    • Option B
      • Stop guiding
      • Move telescope around with IE/CA to search for spots
    • Note guider (x,y) image position of "Center of WFSC Pin Hole" and guide probe position of "Center of WFSC Pin Hole". Adjust the configuration file as needed.

Initial Check of Active Optics Corrections DONE

  • Option A - GCS
    • Send preset to on-axis star in ACTIVE mode with sending corrections to PSF blocked
    • Calculate Zernike aberrations, send them manually with PSF starting with focus, then coma, then astigmatism, trefoil
    • Calibrate orientation of Z's, single mode, and adjust rotation of zernikes as needed.
  • Option B - IDL
  • Use Z9, Z10 to refine the Doug's angle offset
  • Verify that both IDL and GCS agree on the angles and flips.

Initial Closing of Active Optics Loop DONE

  • Option A - GCS
    • Send preset to on-axis star in ACTIVE mode with sending corrections to PSF enabled
    • Calculate Zernike aberrations, send them manually with PSF starting with focus, then coma, then astigmatism, trefoil
  • Option B - IDL
  • Verify that both IDL and GCS agree on the convergence of the active wavefront solution.

Off-axis Active Optics

  • Verify the pupil positioning for off-axis stars is going in the right direction. DONE
    • First on the Y-axis
    • Then over the whole field
  • Verify the range of pupil motion available on the WFS camera. DONE
  • Verify active optics convergence at extreme field positions
  • Calculate Zernike aberrations, send them manually with PSF starting with focus, then coma, then astigmatism, trefoil
  • Verify that both IDL and GCS agree on the angles and flips.
  • Refine the pupil centering position. (Doug)

Focus the Guider relative to IRTC DONE

This procedure needs good seeing. 0.6 arcsec or better in order to achieve sufficient precision.

  • This is the fast procedure which does NOT run Active Optics while stepping the secondary mirror.
    • Preset in ACTIVE mode
    • Allow a few minutes for active optics to collimate.
    • Record the nominal focus offset and the present off-axis position.
    • Press StopWFS button on GCSGUI
    • Run a script to take a series of image cubes while offsetting focus. (for IRTC: cl < home$focus_seq.cl )
  • Repeat the procedure several times until you've converged on a value for the focus offset.

  • The slow procedure would make steps in the nominal probe focus offsets and run active optics at each step. This turns out to be vulnerable to changes in the seeing over the tens of minutes that the procedure.

Check X-Y position of probe relative to focus position

This procedure does not care so much about the seeing.

See BGTechProcedures for the procedure.

Initial Calibration of AGw coordinate transform DONE

See document 481g221c "AGW Coordinate Transformations and their Calibration".

Preset to one of the Stone fields close to the meridian listed in StarCharts. Only these Stone fields with good astrometry and proper motions are useful.

Use the IRAF transtar script described in JohnSpecial. Doug should also have a new IDL command to test. Script needs some modification for using LUCI images. With LUCIFER, make sure flexure compensation is on!

Note: ImportantParameters in LBTtools for RFBG/LFBG/LBBG

Be sure that you are taking IRTC data in H-band. If you want to use J-band, it will be necessary to change LEFTWAVELENGTH/RIGHTWAVELENGTH in the appropriate place in /home/telescope/TCS/Configuration/PCS/PCSInstruments.conf.

Please record the current value of LEFTZEROPOINT/RIGHTZEROPOINT.

Measure Position of Rotator Center on IRTC DONE (Repeat for Dec 2011)

This number is used by IDL in the Transform Data pre-processing.

    • Rotate the rotator (TO command) while taking a 90 sec series of exposures on the IRTC

Collecting Transform Data DONE

The initial transform needs about 25 stars. Seeing should be no worse than 0.8 arcsec.

Detailed instructions appear in TransformationData , but better instructions in ComTools .

ATTENTION: The analysis of the transform data requires the know position of the rotator center on IRTC.

Collect Data for Refinement of AGw coordinate transform DONE (but there are issues with the analysis) (Repeat for Dec 2011)

After installing the initial transform.....
As above, but we want ~50 stars on a single field over a range of position angles.

Check of Field Aberrations with M2 collimation table DONE (pending data analysis)

See the detailed setup in AOwithIDL , and see the more general description in FieldAberrationMeasurementDetails , but better instructions in ComTools.

Because all the left (SX) focal stations are using similar collimation models, these field aberration measurements are only a check.

AGw On-Sky Commissioning

Calibrate WFS corrections

    • Take Intra/Extra-focal Image Pairs adjusting focus with M2
      • optimize size of the extrafocal pupils
      • take multi-extension image cubes for averaging the atmosphere (40 sec)
      • verify sign and rotation of EF corrections by applying known wavefront distortions to M1

Photometric Performance of Guider

Rick points out that this was done for MODS using the stars in the Stone astrometric fields used for the transformations. We would want to take some bits of transformation data in different filters. (The other filters could be postponed until later.)

Astrometric Performance of Guider

Flexure During Guiding

See section 6.5 of Jesper's AGW Commissioning Plan. Measure flexure as AGw rotates crossing meridian at several elevations. It probably isn't possible to measure the AGw flexure with LUCI imaging, as the flexure is dominated by LUCI internal flexure. Maybe there is a trick you can do with a slit mask to measure the flexure at the LUCI telescope focal plane.

A guiding test at low-elevation (E/W with rapid elevation change) will also serve to test the moving hotspot feature of GCS implemented in BP13.

Set the default binning of the guider to 2x2

Verify angular offsets on sky

Need to think about which coordinate system to make these tests in. At minimum we should verify the expected scale of motion. Does the transformation data already take care of this? Postpone until performance verification with Dice5 data, or take a small set of Dice5 data here.

Walter would like us to verify the precision of repositioning after we've offset to a sky position away from the source for ~10 minutes.

Big W aliveness and sensitivity tests

Put starlight onto W to verify that it sees light and has basic alignment as expected. (requires cooperation from Arcetri).

This document has a heritage in GregorianCommissioning which was used for LFBG and LDG, and Com201003AOPlan which was used for RFBG. JMH has rearranged the order of some activities to match practical reality.

-- JohnHill - 25 Oct 2011
Topic revision: r10 - 06 Dec 2011, JohnHill
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