March BG Com Night 13, UT 2009 March 19

Observers: Dave Thompson, NAgeorges, MJuette, WSeifert (@LBT) later Andrew Rakich in Tucson
Telescope Operator: DGonzalez-Huerta
SW Support: TSargent
Telescope Support: DOfficer, JLittle

Summary:

  • Improved pointing model (3.2 arcsec rms) generated. May be compromised by lack of use of one term, see IT#2075. This pointing model is not implemented by default, load manually: LUCIFERSX.20090317b.ptmod
  • Implemented Jesper's latest transform code in oacontrol (expect only minor improvement over last night).
  • Collected a different set of data for Jesper, described below.
  • Adjusted M2 by 3.5" tip and took many field data points to verify correction.

Details:

Improved pointing model available, but not made the default yet.
LUCIFERSX.20090317b.ptmod in the PCS configuration directory.
Email exchange with Pat Wallace would indicate that we are not likely using the AZ scale error term in the pointing model, and that modifications to PCS will be necessary to implement this. This term has a larger effect at low EL and will significantly improve presetting there. Residuals in the above model are also larger at zenith. See Issuetrak#. This should be a high priority fix for April, and implementing this will give us the experience needed to implement corrections for temperature and/or gradients when they become available.

Improved oacontrol transformation implemented. Jesper found a bug in his fitting code used for the transform in place last night. Only a small improvement is expected.

18:51:24.904 Initial preset for pointing correction: no star on LUCIFER!
19:05:08.443 Trying a second star. Calibration unit was in, oops.

Pointing correction: IE from -27.116 to 4.09, CA from 0.00 to 24.96
19:12:41.230 Preset to BS9118 to collimate, OK, lots of coma. Initial collimation all to M1, wfs rms: 1592, 1398, 1331, 1190 (first 4, only focus and coma terms applied), 1201, 983, 784. FWHM on guider is ~0.9 arcsec, EL~56. Guiding lost...it looks like there was a jump large enough to take the star out of the guide box (about MST 19:21). Re-sending the preset.

Tair = 4.4, RH=27.1%, wind ~3m/s. M1 temp is 5.1C.

19:21:27.649 Preset again. M1 hit the Y=-2.6 limit. Applied 1mm offset to M1 and M2.
19:24:01.137 Preset again. Need another 1mm on each mirror. Briefly lost guide star but it came back in soon enough that guiding kept going. WFS rms: 539, 404, 429, 271, 451, 311, 157. FWHM~1.0 arcsec.

Switch to "split" mode

Check pointing: IE now 24.48 CA now -0.97

MST 07:39 LUCIFER to run a script on one of their targets (about 1 hour).


Jesper's suggestion was to dither in a regular array (5x5) using offsets and the same guide star, instead of using multiple guide stars at the same PA. Preference for dense enough stars that an astrometric solution can be applied.

  • BS9122_GS39 PA=42, preset at 20:11:00.858 successful. Guide star is 185 arcsec off-axis and should be in the patrol field for all points in the grid. The Grid X script traverses a 5x5 regular grid of points at 50 arcsec spacing with the primary motion in the X direction (good for looking into hysteresis). The Grid Y script does the same points on sky, but with the primary motion in the Y direction. About 1 minute spent at each position to allow the WFS to keep up with the collimation. BrGamma filter used to minimize saturation on several of the field stars.

Script luci_20090318_agw MST Notes
Grid X 0001 - 0025 20:20 - 20:59 PA=42. 57%, see below
center 0026 21:00 Returned to center by hand for comparison
Grid Y 0027 - 0052 21:03 - 21:45 PA=42. 55% Preset to start pos'n, center included in script
Grid X 0053 - 0077 21:46 - 22:29 PA=12. Time includes the preset. 55.6%
center 0078 22:31 Returned to center by hand for comparison

For the script: (25 x 1 min open shutter) / (39 min clock time + 3 min slew + 2 min collimation) = 58%
The 3 minutes slew and 2 minutes collimation are just estimates, I only timed the start and end of the script. For Grid Y: (26 x 1) / (41 + 3 + 2) = 56.5%
For Grid X the second time: (25 x 1) / (43 + 2) = 55.6%

Checked the offset between frame 0001 and 0027 (the first exposure of Grid X and Grid Y) and dX=-0.851 pixels (102 mas) and dY=0.083 pixels (10 mas). The offset was measured with 42 visually confirmed and well-detected, unsaturated sources in each image and has an rms at 0.006 pixel (0.7 mas). Note that the first step in the script is an offset to the corner of LUCIFER, so backlash should not be responsible for this larger offset in X. Nancy suggests we repeat Grid X at a different PA, same field, so we also did it at PA=12, as it is in the rotational offsets that she sees the largest differences.

  • BS9134_GS28 PA=349 22:32:05.858 preset command started...worked.

Grid X 0079 - 0104 22:53 - 23:40 PA=349

Mar 18 22:35:24: transfer of centroids to PCS failed. (first one)
Mar 18 22:35:24: WFS: error: triggerWFS: WFS image didn't arrive within timeout of 37716 ms (first one)
But PCS is receiving guiding corrections and applying them. WFSing is not working. Restarting GCS.

22:49:33.217 Preset again, allow to recover the lost collimation from not having wfs running for 10 minutes. 22:53 back to collimated and can restart the script. Time lost between presets = 21 minutes.

DGH reports that the Left M1 ventilation was off since the beginning of the night. The GUI was reporting it active, but the supply temps did not agree. It was either a tripped circuit breaker or the associate reset button for the blower.

MST 23:41 AGW acquisition CCD/probe orientation test
Stop guiding at current field, then manually take acquisition images to determine if there is a sign error in the guiding offset calculations (CCD XY to PCS XY rotation). Data are in /Repository/AGW_Data/AGW_orient/.

image AGW offset motion
0001 0.0, 0.0 on hotspot
0002 4.0, 0.0 moved to right, larger X
0003 -4.0, 0.0 moved to left, lower X
0004 0.0, 4.0 moved up, larger Y
0005 0.0, -4.0 moved down, lower Y

MST23:46 Taking in/out of focus images by moving the LUCIFER detector stage, for Andrew. Junk, guiding/wfsing turned off for previous test.

MST00:01:48.875 Preset started to return to collimation, take the in/out of focus data for Andrew.
MST00:06:29.134 Preset to a different field because the previous was at EL~40, FWHM on guider ~0.8 arcsec. Is better seeing necessary to see what Andrew wants to see? EL~55 on new field, FWHM~0.5 arcsec.
See: luci_20090318_0053-0055

MST12:36 Collect another ~24 points for the pointing model to investigate temperature effects.
luci_20090318_ptg_NNNN
pointing log file = /home/telescope/20090319.ptlog
StarID NNNN StarID NNNN StarID NNNN
WT10_40 0001 WT10_173 0009 WT10_190 0017
ACT0365 0002 WT10_243 0010 WT10_075 0018
ACT0397 0003 WT10_230 0011 ACT0135 0019
ACT0350 0004 WT10_315 0012 WT10_309 0020
ACT0269 0005 WT10_328 0013 WT10_256 0021
ACT0184 0006 WT10_298 0014 ACT0218 0022
ACT0258 0007 WT10_247 0015 WT10_288 0023
ACT0086 0008 WT10_294 0016 ACT0324 ?? 0024
ACT0350 0025 WT10_286 0026 ACT0203 0027
WT10_408 0028 WT10_404 0029 WT10_241 0030
WT10_073 0031 ACT0156 0032 ACT0279 0033
WT10_213 0034 ACT0330 0035 WT10_354 0036
WT10_343 0037   00   00

MST 02:00 Pointing correction: IE from -0.97 to -12.13, CA from 24.96 to 17.28

Andrew to work more on the field aberrations.
MST02:03 Checked BS9177 - EL=32.5d still too low
MST02:07 BS9152 in GUIDE mode for Andrew
Cleared all active optics, offloads, initialized to collimation model on both M1 and M2. ~200 nm level Collimating in IDL with 10 s integrations to quickly converge (wfsc 4-12), we converge to .

Based on information in the log from 20081113 our last M2 adjustment was -11" M2 tip. this reduced the sine curve for focal plane tilt from an amplitude of 600 nm to ~ 200 nm, and this residual of 200 nm has now been fairly constant for several months. Tonight we put in another -3.5" M2 tip which should further reduce the focal plane tilt down to something unmeasurable, and here come the field data to prove it:

2:35 have adjusted M2 tip -3.5" and reset IE -24.6 CA 22.0 2:38 notice ~70 nm of Z22, Dave says chillers are working, sending -180 nm Z22 in M1 PSF GUI, go down to -10 nm Z22.

Persson's Star = BS9152
Start time =

Guide Star x y PA Doug's Angle wfscimage000*
0 0.22 612.62 0 -181 22-34
17 1.24 437.35 124.77 -315 35-37
0 0.1 612.37 124.77 -317 38-41
18 1.3 427.15 65.44 -259 42-44
0 0.26 612.43 65.44 -260 45-50
7 1.03 501.5 10.54 -210 51-53
0 0.26 612.43 10.54 -212 54-56
4 1.04 476.43 338.61 -182 57-59
0 0.26 612.43 338.61 -182 60-62
1 0.721 501.7 229.72 -436 63-65
0 0.26 612.43 229.72 -437 66-67
9 0.726 480.8 168.12 -377 68-70
0 0.26 612.43 168.12 -378 71-74
17 1.24 437.35 124.77 -339 75-77
0 0.1 612.37 124.77 -340 78
18 1.3 427.15 65.44 -282 79-81
0 0.26 612.43 65.44 -283 82-83
7 1.03 501.5 10.54 -229 84-86
0 0.26 612.43 10.54 -230 87-88
4 1.04 476.43 338.61 -200 89-91
0 0.26 612.43 338.61 -201 92-93
1 0.721 501.7 229.72 -453 94-96
0 0.26 612.43 229.72 -455 97-101
9 0.726 480.8 168.12 -395 102-104
0 0.26 612.43 168.12 -396 105-106

4:10 Now going to BS9177, setting collimation to 15 s integration on WFSC and looping, to compare to earlier-tonight data @ 10 s integration time, wfsc 107-123
4:17 resetting exposures on WFSC to 20s and continuing with field aberration data...
4:50 wfsc suddenly not converging well, see wfsc 148-160, guide image more jumpy too, up-ing integration time to 30 s
Persson's Star = BS9177
Start time = 4:17
5:31 succeeded with double star

Guide Star x y PA Doug's Angle wfscimage000*
0 0.22 612.62 0 -458 124-127
43 -1.58 464.93 13.62 -473 128-130
0 .22 612.62 13.62 -474 131-133
47 -1.71 444.92 30.23 -491 134-135
0 .22 612.6 30.23 -492 136-138
61 -1.86 439.1 62.99 -525 139-141
0 .22 612.6 62.99 -526 142-144
63 -1.949 432.63 88.62 -193 145-147
0 .22 612.6 88.62 -194 148- 168 (scratch 169)
56 -1.95 436.6 129.4 -239 170-172
0 .86 611.87 129.4 -240 173- 177
41 -1.33 481.56 168.77 -281 178-180
0 .86 611.87 168.77 -283 181- 191
8 -1.88 431.17 249.23 -368 192-194
0 .86 611.87 249.23 -369 195-196
7 -1.75 428.8 285.87 -407 197-199
0 .86 611.87 285.87   200-201
15 -1.81 424.54 314.4 -438 202-204
0 .86 611.87 314.5 -439 205-206

5:45 finish with this with twilight, Nancy taking flats. I think that I have noticed some odd behaviour, after collimating on axis, racing off and measuring off axis, pushing the M1 PSF "collimate" button between exposures, I race back on axis within about 3 minutes and there seems to consistently be a largish jump in collimation in the first WFS image. Will look into this more in the data analysis.

-- DavidThompson - 16 Mar 2009
Topic revision: r8 - 27 May 2009, JohnHill
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