Technical Requirements

Technical Requirements for Lucifer Commissioning

Telescope Bent Gregorian Performance Verification

Gregorian SX Pointing and Collimation

Prerequisites

  • Initial guess at pointing model (done by DJT)
  • Initial guess at primary mirror collimation model (done by JMH)
  • Align Gregorian secondary to SX Gregorian rotator axis (done by Brynnel, Zhelem, OBrien and friends 20080411 MST)
  • Able to preset, offset telescope through IRTC interface (done and tested 20080412 UT)
  • Able to set PA mode, request specific position angles (OK, need to verify angles)
  • Able to open-loop track at requested position (OK, need to build pointing models)
  • Able to position AGw on-axis, wfs apert. coincident w/rotator center
  • Able to acquire AGw (DMiller) and/or IRTC images (IRTC single images OK, data cubes also OK)
  • Running EF version (OK)
  • Check that MAT cameras work well in advance of on-sky run (MAT acting like MAT = not very well)

Pointing and Collimation

  • Determine initial pointing model zero points (completed 20080413 UT)
    • Reset AZ and EL encoders
    • Start PCS pointing logging
    • 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".
    • takepic an image with IRTC, or put IRTC into continuous readout mode
    • collimate (by eye) [Move only M1 for initial collimation.]
    • Offset dAZ, dEL to bring onto detector
      • Add zero point offsets to initial pointing model in /usr/commonsw/Configuration/PCS on lbtmu102
      • Load updated pointing model
    • Test that preset now gets you to that star
    • Pointing errors should now be dominated by tube flexure (mostly elevation).
    • Note star position on MAT camera data (helps with future pointing)

  • Establish initial (ON-AXIS) collimation lookup table (in progress 20080413)
    • Point to bright stars at a range of elevations
    • MAT may be useful to help point, else use spiral search
    • Take Intra/Extra-focal Image Pairs adjusting focus with M2
      • optimize size of the extrafocal pupils
      • test multi-extension image cubes for averaging the atmosphere
      • verify sign and rotation of EF corrections by applying known wavefront distortions to M1
    • Collimate (using EF) [Move only M1 for initial collimation.]
    • Implement initial collimation lookup table using mkcoll.pro

  • What if M1 does not have the range to achieve collimation? (we are slightly close to the M1 Y limit at mid-elevations)
    • Offset both M1 and M2 as needed to being them back on range. (offset M1 and M2 +1 mm in Y on 20080415)

  • Determine rotator center in IRTC space (done 08:32 UT on 20080404)
    • point to a cluster of stars
    • collimate
    • take two IRTC images 180deg rotation apart and determine rotcen
    • you must change the rotator angle with an offset command and not with a preset which can also shift the telescope

TCS Software On-Sky Verification Tests

  • PCS/MCSPU: Check Position Angle and Rotator Motion with IRTC (in progress 20080415, offset angle implemented in PCS) * point to clusters with known asterisms or double stars at several parallactic angles * (It was hard to find asterisms, so we made the first cut by offsetting the telescope in known directions.) * take images at several position angles * verify sign (parity) and zeropoint of the position angle for IRTC (zeropoint is OK, still need to check parity) * verify direction of the rotator

  • PCS: Send irc offset guiding commands to the telescope and verify magnitudes and directions of moition (done 20080417-18)

  • PSF: Send Active Optics corrections to M1, and to M2 (done for Active Optics, but issues for Instrument Offset angles)

  • PSF/OSS: Make coordinated moves of M1 and M2 in X, Y, Z to verify signs and directions (done 20080414)

  • GCS (interwoven with AGw activities below) [Anticipated to start Monday April 21]
    • acquire images
    • move stages
    • guide telescope
    • offset star onto wfs
    • acquire wfs images
    • process wfs images and send Zernike corrections for active optics

IRTC Camera On-Sky Verification
  • IRTC Optical Tests (zoom scales, field aberrations, etc) (done 20080414)

  • IRTC Detector Performance * 30 x 1 sec dark data (dome closed) * 30 x 1 sec blank sky data (3 dither positions) * Estimate point source and pupil SNR for stars of a known magnitude

Pretty Pictures with IRTC

The Bologna guys and others would appreciate seeing some nice pictures taken with IRTC. The core of M3 or the center of M82 come to mind as possible targets.

AGw Guider Camera Initial Calibration

  • Acquire on-axis start on Guider camera (done 20080423 UT)
    • Point telescope so star is on the center of rotation on IRTC
    • Move AGw guider probe to nominal on-axis position
    • If star not present, use "spiral.cl" routine to search for star
    • Once star is found then slowly walk star/guide probe to IRTC on-axis position
    • Note the nominal on-axis guide probe position

  • Determine rotator center in AGw space
    • Start up the AGW unit
    • Move AGw to nominal on axis position
    • point to a cluster of stars
    • take two images 180deg rotation apart and determine rotcen
    • Reposition AGw stage
    • Repeat as needed to position rotator center on WFS aperture
    • Note stage positions, we will need them again!

  • Establish initial pointing model - this should be identical to the IRTC pointing model, modulo any differential flexures between the AGw and IRTC which should be minimal.
    • Turn on mount pointing logging on PCS
    • Point to ~20 W&T pointing stars well-distributed across sky
    • position accurately on the WFS/rotcen
    • take an image, note time reasonably accurately (+/- 5s)
    • match source RA/DEC and mount pointing for tpoint
    • run tpoint to make new pointing model
    • install new pointing model
    • Hope that this gets us below ~10" rms

  • Test new pointing model.
    • Position AGw at the rotator center as above
    • Point to a few stars around sky to check pointing

  • Determine fixed angular offset for rotator
    • Point to wide double stars with known PAs
    • Determine PA offset for that camera
    • Implement in code (MCS?)
    • Check on a few doubles to be sure
    • may need different angles for IRTC and AGw

  • Improve the (ON-AXIS) Collimation lookup table
    • Point to bright stars at a range of elevations
    • Collimate (EF, WFS)
    • Implement improved collimation lookup table.

  • Test closed loop guiding with GCS

  • Guide off-axis to verify rotator rates

Initial Calibration of AGw coordinate transforms

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

AGw WFS Camera Initial Calibration

CollectionOfWFSCdata 24 April 2008

  • Acquire star on WFSC
    • Place star on nominal "Center of WFSC Pin Hole" position
    • If no S-H spots then move guide probe small amounts in spiral pattern till spots found
    • Move guide probe in +x,-x, and +y,-y till spots are vignetted
    • Note guider (x,y) image position of "Center of WFSC Pin Hole" and guide probe position of "Center of WFSC Pin Hole"

    • AG, wfs plate scale check
    • measure vignetting position of wfs entrance aperture.
    • Calculate Zernike aberrations, send them
    • Calibrate orientation of Z's, single mode.
    • Measure, correct focal plane tilt (rotation around on-axis point on M3?)
    • Laser tracker input to collimation LUT?

AGw On-Sky Commissioning [scheduled for May 11-15 with J. Storm]

Adjusting Field Aberrations with M2 collimation table

Tertiary Mirror Tests

Further Improvements

  • (Optional, sanity check) Re-determine rotator center
    • Position AGw at the rotator center as above
    • point to a cluster of stars
    • take two images 180deg rotaton apart
    • Determine rotcen as mean of average coords of matched sources
    • Reposition AGw stage
    • Repeat as needed to position rotator center on WFS aperture
    • Note stage positions, we will need this again!

  • Improve pointing model
    • Turn on mount pointing logging on PCS
    • Point to ~100 W&T pointing stars well-distributed across sky
    • spiral search to find if needed (hopefully not!)
    • position accurately on the WFS/rotcen
    • take an image, note time reasonably accurately (+/- 5s)
    • match source RA/DEC and mount pointing for tpoint
    • run tpoint
    • install improved pointing model
    • Hope that this gets us below ~5" rms

  • Extend AGw Collimation to off-axis positions
    • Point to bright stars at a range of elevations
    • Collimate (EF, wfs, ??)
    • Implement off-axis collimation lookup table.

  • Check vignetting off tertiary for the off-axis points in LUCIFER1


Tools/scripts needed:

For IRTC interface, scripts to do the following:
  • authorize (checks if this instrument is authorized on TCS GUI can be used to pretend to be LBC, MAT as well.
  • preset to source from internal catalog "pointto " reads coords from file based on name supplied include WTstars, Elias standards, ?? includes setting PA, off-axis guide stars
  • offset from current pointing "offset dNS dEW"
  • focus (both relative and absolute)
  • takepic (takes 1 pic with IRTC using given exp,framerate)
  • moveOPE (moves specific OPEs by requested amount & direction)
  • spiral search "spiral " where you go N times around the pattern
  • offsetAzEl (Zemax will give pointing changes in dAz, dEl) "offsetAzEl dAz dEl" will need to read PA and parall.ang from TCS to convert
  • Get useful info through IIF from GetMultiparam "getinfo " Use pre-defined set of useful information

There may be other scripts that are needed to stage a complete presetTelescope command.

For IRAF/LBTtools:
  • Display series of AGw/IRTC images, select one
  • Quick display, centroid
  • Determine offset, send through IIF?

For EF:
  • Script to extract the pupil images in the correct format for EF

-- DavidThompson - 10 Apr 2008 (from the draft of 17 Mar 2008); revised by JohnHill - 13 Apr 2008

This topic: Commissioning > Main > WebHome > GregorianCommissioning
Topic revision: 03 Mar 2009, JoarBrynnel
This site is powered by FoswikiCopyright © by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding Foswiki? Send feedback