09-10 October 2008

Observers: D. Thompson, J.Hill (Tucson), LUCIFER folks (N.Ageorges,W.Seifert, et al)
Software Support: C.Biddick, D. Cox in Tucson
Telescope Operators: D.Gonzalez-Huerta, W.Wack

Summary

Rotator failure fixed - traced to a SW problem and a voltage threshhold due to being on generator power (which we are still on). Confirmed offsets in detector coordinates works through a pointing origin update. Finished astrometric analysis from the previous couple of nights. We closed for high winds at ~10:30MST.

Details

New build installed this afternoon, implementing relative offsets and pointing origin updates through OFFSET_DETXY offsets.

Windy, and we see strong trailing in LUCIFER in the EL direction. Take some time to investigate. It does not seem to be a balance problem, just wind gusts.

Correct initial pointing/collimation

Initial pupils way out of focus, obvious coma visible.

GCS has a bug reporting the peak value is zero even when the star is centered and well-detected. Torsten called, he is looking into it. GCS was double-subtracting the background, Torsten fixed it. There may be a similar problem with the WFS. Also fixed at least enough to go on. Back working 9:09pm.

We are still getting a failure from the guider, message: "couldn't adjust exposure time to meet low counts requirement. Star too dim or guide rate too high."

Confirm new collimation and pointing models implemented correctly

Confirmed. The new collimation and pointing models are loaded by default from the configuration files.

Implement orientation correction for LUCIFER
  • may not be needed, current orientation off by ~0.07 degrees

Test offsetPointing functionality in new TCS build
  • Preset in POSITION, PARALLACTIC modes
  • Send offsets in DETXY coordinates
  • Note that there still is probably an X flip in the offsets

Starting image BS9188 at 1035 1088 offset DETXY 10 arcsec "N" (up) and the star moved up and to the left, now at 971 1142

Preset from LUCIFER: 1031 1087 Offset DETXY 0.0 10.0 -> star went up to 1029 1173, coords the same as preset. Offset DETXY 10.0 0.0 -> star went left (offset was east on LUCIFER UI but it went west)

Fixed a bug or something in LUCIFER and now the DETXY offsets work as expected. We confirmed the X axis is reversed from the IRTC, also as expected. This is apparently due to the readout software in LUCIFER, so we will have the X flip in their software.

Closed UT~05.30

Finished analysis of the 4 astrometric fields we took 2 and 3 nights ago:
Xscale Yscale PAreq PAach Field_ID Filter
0.12024 0.12008 90.00 90.17 BS9107 Ks
0.12010 0.12016 0.00 0.20 M103 Ks
0.11990 0.12004 270.00 270.22 Stone P K
0.12029 0.11976 45.00 45.05 Stone A K

  mean stddev median min max
Xscale 0.12013 1.7462E-4 0.12017 0.11990 0.12029
Yscale 0.12001 1.7397E-4 0.12006 0.11976 0.12016

X max/min shows 0.3% range (same for Y)
2sigma/mean also 0.3%

There does appear to be scale variations in this admittedly small sample at the 0.3% level. This is high enough that it bears further investigation. I suggest ~20 pairs of cluster or low Galactic latitude fields with higher stellar densities than seen in these 4 images. I note that I made no correction for radial scale distortions for this analysis.

There appears to also be a residual mean rotational offset of 0.16 degrees (correct IAA by this amount).


No luck getting anything below here:

For Andrew
  • Collect through focus images when the telescope is well collimated. A sequence of images with ~5", ~2.5", in focus, ~2.5", ~5" image diameters.
  • Log of z corrections on M1 during say 10 minutes of active collimation.
  • Gather scale check data

Recalibrate AGw coordinate system
  • Requires LUCIFER in good orientation
  • Requires LUCIFER flexure compensation in place so rotator center does not wander on the detector.
  • Follow 481g221d procedures.

LUCIFER morning twilight flats?

If there is time during the night:
  • Gather low-EL AGW dataset for binodal astig (need appropriate target field).
  • Usable guide star magnitude (record Rmag, FWHM, peak counts)
  • Others?

-- DavidThompson - 09 Oct 2008
Topic revision: r6 - 19 Oct 2008, JohnHill
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