From: Russet McMillan Subject: 3.5m Night Log 20060917 Date: Mon, 18 Sep 2006 06:08:36 -0600 (MDT) Apache Point Observatory 3.5m Telescope Night Log Sunday, September 17, 2006 ACTUAL ASTRONOMER OBSERVER(S) INSTRUMENT START FINISH ------------------------------------------------------------------- M.Klaene R.McMillan,G.Saurage SPIcam,S-H, 20:30 05:20 NA2gdr INST SCHED(TWILIGHT) WEATH EQUIP OBS DAY NOT USED I/ROW/DN START FINISH D B D B D B USE D B --------------------------------------------------------------------- EN01/W 20:00 05:55 0 0 0 0 7.2 2.7 0 0 0 note: scheduled times listed include instrument change time ------------- ACTIVITY LOG -------------- Observing Specialists: R.McMillan,G.Saurage During the day, the top end was removed again for some work on the transverse actuators and encoders -- unfortunately, they were still not ready by tonight. Shims were also added to move the mirror away from M1 by 0.8 mm based on last night's focus measurements -- unfortunately, I had worded my log unclearly and what was actually needed was about twice that much. In fact, based on tonight's measurements and trying to ensure that the focuses for the various instruments end up evenly distributed around the mirror's center of travel, I recommend raising the top end by an additional 1.0-1.2 mm from where it is tonight, or a total of 1.8-2.0 mm from where it was last night. Work on the telescope was finished a little after sunset; it was still slightly out of balance at the lower altitudes, but better than last night. The PMSS dataq was working again, so we were able to properly relax the PMSS. It only acted up a couple of times during observations. We started with SPIcam, to establish the new focus values and to figure out if the guider was giving correct images again. The guider had been reset during the day, but we couldn't be sure if it was working properly until we checked it on the sky. It turned out that the focus had changed exactly as expected and the guider images were in the correct format, so we moved on to a pointing model. This came out with an RMS of 7 arcseconds, larger than we like to see. The reason for the increased scatter was in the altitude direction and might point to trouble with altitude magnesensors. Other possible explanations: serious altitude backlash (not really supported by what we saw on-sky) or tertflop (which shouldn't be confined only to the alt direction). With the telescope now fairly close to thermal equilibrium, we switched to the Shack-Hartmann and adjusted collimation (since the day's work had changed the mirror position again). Then we did another altitude sweep, this time managing to get down below 40 degrees but not by much. I tried to use the information from the altitude sweep to update the algorithm for focus vs. altitude, but I found it unexpectedly difficult. There were several moderately large focus adjustments from last night and tonight that I couldn't ascribe to altitude or temperature. I decided it might have something to do with the telescope being slower than I thought to equilibrium, so at last I tried for another altitude sweep, late in the morning with fairly stable temperatures. The wind shifted to the east, but seeing remained good long enough for me to get several measurements between altitude 30 and 35; after that I had to move higher because seeing was degrading. This attempt provided more consistent results, and I developed an algorithm for focus vs. altitude. Tomorrow night we can try using the Shack-Hartmann at the same altitude while the telescope cools, to get focus vs. temperature. Sag in translation vs. altitude also needs to be analyzed, but the data we already have should be usable for that purpose. So aside from the pointing model, Shack-Hartmann work took up most of the night, and I still wasn't entirely confident in the results. Cooling behavior will need to be watched more closely tomorrow night. Fortunately, all tracking, pistoning, and tilting tests on sky indicate that the top end is very steady. And although it's too soon to say for sure, I have a sense that it's more resistant to wind as well (as expected). Fastcam work can tell us more about that. ------- FAILURE LOG ------- PROG INST FAILURE MODE TIME (SEDFNVOG) TI/SHU START FINISH DESCRIPTION ---------------------------------------------------------------------- ---------------- FOCUS LOG --------------- Air/Truss Wind Time Instrument Focus Az El Temp-C Dir MPH filt FWHM --------------------------------------------------------------------- 20:42 SPIcam -1750(-657) 121 54 9.8/11.2 269 17 r 1.01 ------------- WEATHER LOG ---------------- Wind Precip.or Time Temp F Dewp F MPH Direction Dust Sky Conditions ------------------------------------------------------------------- 16:00 55 30 14 300 (WNW) 731 clear none 17:00 53 26 3 331 (NNW) 536 clear none 18:00 53 29 12 288 (WNW) 642 clear none 19:00 50 30 9 269 (W) 677 clear none 20:00 49 30 10 271 (W) 631 clear none 21:00 50 35 12 270 (W) 771 clear none 22:00 49 34 13 262 (W) 798 clear none 23:00 49 34 15 270 (W) 771 clear none 00:00 49 35 12 279 (W) 911 clear none 01:00 48 33 8 301 (WNW) 834 clear none 02:00 47 31 17 7 (N) 951 clear none 03:00 47 19 11 24 (NNE) 774 clear none 04:00 46 14 11 12 (NNE) 325 clear none 05:00 45 12 10 20 (NNE) 220 clear none Note: the wind was coming from the azimuth listed. The convention used is north=0 degrees, east=90 degrees. The dust count is particles > 1u per 0.1 cubic feet. TELESCOPE STATUS Telescope drives operational. Current TCC version: 2.8.4 Current TUI version: TUI 1.2