29 October 2011: Alignment, Collimation and Pointing with Rigid Secondary

Problems yesterday afternoon in powering up and communicating with the hexapod. After much discussion between Guido and the Arcetri group (Armando, Marco X) there was a workaround developed and by early morning the hexapod was on and secondary was up and running. For details see

Pointing and Collimation Models made active for the rigid secondary alignment, collimation and pointing:
  • LEFTPOINTINGMODEL MODSSX.20110213.ptmod (in /home/telescope/TCS/Configuration/PCS/PCSInstrument.conf)

Wanted to do some MODS calibrations before sunset, but could not wake up MODS. Called Rick.
  • mods1data could be pinged, but we could not ssh into mods1data.
  • KVM switch showed isis6 (now mods1data) up and running. Note that the original mods1data is down after the problems of last Saturday which necessitated swapping out this machine.
The machines are as originally labeled. mods1data is off (switch at back above power plug in OFF position). isis6 was on.
  • But, isis6 screen was blank/black.. Looked siezed up, which could explain why we could not ssh to mods1data.
  • Used rocker switch on front to power off/on isis6. Came up OK and Rick talked me through starting up MODS programs.
  • execMODS ~MODSeng/modsScripts/Support/sieveSnap.pro OK

~01:00 Andrew and Steve aligning secondary. Bright star found, but highly comatic.

* Collecting data for collimation model*
  • Steve using xephem to select stars at range of elevation
  • Persson stars ideal, but few
  • Pointing stars and not too far off axis guide star ok (use showFC task)

elevation (degrees) WFSCImage# Star GS
59 11 BS9188 on-axis
66 28 WT10_362 1
74 35-37 ACT0336 1
77:40 43 WT10_349 1
80:20 50-52 WT10_334 1
53 61-62 BS9177 on-axis
38 67-68 BS9169 on-axis
27 82 BS9156 on-axis
86 93 WT10_321 1
82 101-102 ACT0336 1
44 113 WT10_386 1
33 123 ACT0395 1

  • elongation in both guide image and wfsc image.
    • appears to be stronger at lower elevation
    • not a problem of being way off axis (guide/collimating on-axis)
    • elongation is not along rows or columns.
    • see left_guiderimage000911.fits and corresponding left_wfscimage0082.fits (strong elongation at 27 deg)
    • also left_wfscimage0068.fits and corresponding guide star probably show similar.
    • at 44 deg, see left_guiderimage001104.fits and left_wfscimage000109.fits (001141 and 000113 also)
    • at 55 deg, see left_guiderimage006443.fits and left_wfscimage000781.fits which do not show this elongation.

03:30 Investigating elongation.
  • Slew and collimate on-axis at BS9156. Elongation still there.
  • Collimate on guide star 2 (bright off-axis star). See elongated image in guider.
  • Take MODS 1 sec images at g and r. mods1r.20111029.0002.fits and mods1b.20111029.0002.fits --- stars near center look round.

~03:45 Observers practice MOS alignment and take some spectra.
  • noted that lower left alignment star a little to the upper-left of center.
  • how is plate scale?

05:24 Andrew e-mailed new collimation models. I copied them to /scratch/20111029 and to SXPMMODSCollimation.dat and SXSMMODSCollimation.dat. Steve initialized on the PSF GUI to pick up these models.
  • checking new models
    • star at 65 deg:
    • AO PM: 0 0 0.012 0 0
    • AO SM: 0.192 -0.383 0.094 39.951 19.999
    • /Repository/20111029/GCS/left_wfscimage000315.fits
    • in table, trying to note AO offsets, but refer to wfscimage in case I didn't catch these before new preset.
elev wfscimage AO PM X Y Z RX RY AO SM X Y Z RX RY
65 315 0 0 0.012 0 0 0.192 -0.383 0.094 39.951 19.999
83 319 0 0 0.022 0 0 0.151 -0.389 0.051 40.530 15

05:43 stop/start GCS reloading parameter file which Doug had changed to remove the astig correction for the adaptive secondary.

elev wfscimage AO PM X Y Z RX RY AO SM X Y Z RX RY  
28 324 0 0 0.032 0 0 0.173 -0.582 0.055 63 18 off-axis

05:55 Pointing over all sky has been good with previous MODS pointing model from 0213. Decide to skip collection of pointing data.

  • StoneA1_1647 (agwxgp=72.024, agwygp=-147.844). Guide star very faint. 30-sec exposure at g (b 6) and r (r 9) Both images show stars as series of dots, telescope jumps. Guide
star may have been lost.
  • Switch to brighter guide star StoneA1_1647 (agwxgp=-8.623, agwygp=-97.380) OK after few, I think (b 7-9; r 10-12)
  • Switch fields to StoneA2_1076 (agwxgp=-53.030 agwygp=-36.374) OK. (b 10; r 13)
  • preset failed for StoneA2_1477 because guide star not accessible

06:25 Collecting field aberration data:
  • in /OldRepository/AGW_Data/20111029/field/
  • agw_set_station, MODS
  • irc_register
  • field_collect
    • selected list called: BS9107_field_0.list
  • field_collect for BS9107_field_45.list
  • failed on star 50.
  • field_collect, star=2 to try on-axis and star 50 only... failed. 50 is close to edge.
  • edited BS9107_field_45_edit.list to replace 50 with star 24.

07:07 Make corrections to correct for binodal astigmatism (Andrew & Steve doing this --- notes may be sketchy or incorrect).
  • Star 36 (BS9107) is about directly south of BS9107.
  • parallactic angle is -100, putting the star-gs axis about along AZ/tilt.
  • Andrew sent +10 coma-free pointing tilt in Left PSF arbitrator (appears in manual pointing offsets). Steve applied -10" CA which brought star back.
  • another +10 tilt and -10 CA... and further adjustments which Steve is noting.
  • Remove corrections. Maybe wrong axis... because it is not having much effect on reducing focus and astigmatism errors seen from field_collect data.
  • Now trying tip and IE. +10" tip and -10" IE. and further adjustments... which Steve is noting.
  • Leave these final tip/IE adjustments and go back to collimate on-axis.
  • Back to GS 36 with zernike sending turned off.
  • Same preset to GS 35 with zernike sending turned off. Looks bad.
    • Star is really bright, so we put in ND1.0 filter. The exposure time was not adjusted (still complained it was below lower limit). Resent the preset and it looks still like the exposure time is not adjusted, although the new acquistion image shows the star much weaker. ???
  • Andrew saying that, while he gave 40" tip (compensated by -40" IE from Steve), he doesn't see the expected focus change - it should be about 1000 nm. The wfe from the field collection measurements were not that great, and this lack of significant focus change is puzzling. Probably will hand over to LBTB soon and leave this to an LBTO technical night. NOTE: the small change in z4 was because adjustments were sent with the arbitrator in split mode.
  • +60" IE and -60" tip to remove what was sent earlier. Manual Pointing Offsets now all 0's.
  • Sending presets to diff GS's with zernikes turned off and watching z4.

*Was going to edit IE/CA into pointing model (SX_Gregorian.20111029.ptmod is a copy of SX_Gregorian.20111018.ptmod and ready to be edited). But we notice that the model I thought I'd put in place is not what I'd thought. Instead we have SX
changing to
LEFTPOINTINGMODEL       SX_Gregorian.20111018.ptmod

elev wfsimage
81 505

09:13 Andrew and Steve back on same field PS9107. Now coma-free pointing tip/tilt will be applied to M2 only. But still the Z4 values are much smaller, about 3x smaller, than expected when tip/tilt applied.

09:35 Copied SX_Gregorian.20111018.ptmod SX_Gregorian.20111029.ptmod and edited SX_Gregorian.20111029.ptmod to be:
LBT left Pointing Log, 2011 Oct 18
T   31   2.8140    0.000   0.0000
  IA       -361.8962     1.45219
  IE        -65.0000     1.90593
  NPAE      +35.0298     1.27626
  AW         +7.0190     0.61047
  AN        +21.0041     0.60234
  HSCA2      -2.1144     0.77055
  HECA3      +1.5370     0.74061
  CA        +36.0000     2.0
  TF        -38.5718     7.62852
  TX        +24.9236     3.47847
  HESA3      +1.3366     0.72292

elev left_wfscimage000xxx.fits
39 638
45 681
49 719
55 781

09:37 PCS restarted. Steve going to slew to a few different stars to check this pointing model.

-- OlgaKuhn - 28 Oct 2011
Topic revision: r4 - 29 Oct 2011, OlgaKuhn
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