From: Russet McMillan Subject: 3.5m Night Log 20050213 Date: Mon, 14 Feb 2005 06:36:26 -0700 (MST) Apache Point Observatory 3.5m Telescope Night Log Sunday, February 13, 2005 ACTUAL ASTRONOMER OBSERVER(S) INSTRUMENT START FINISH -------------------------------------------------------------------- E.Hoversten E.Hoversten DIS 18:50 00:09 T.Goto T.Goto DIS 00:10 06:04 INST SCHED(TWILIGHT) WEATH EQUIP OBS DAY NOT USED I/RO/DN START FINISH D B D B D B USE D B ---------------------------------------------------------------------- JH07/R 18:42 00:10 0 0.1 0 0.3 0.9 4.1 0 0 0 JH04/R 00:10 05:53 0 0 0 0.4 5.3 0 0 0 0 note: scheduled times listed include instrument change time ------------- ACTIVITY LOG -------------- 1st Half Observing Specialist: J.Barentine The night started out clear (remarkable, for this particular February) but we remained closed by high humidity. Shortly after sunset, the humidity dropped (for a change!) and we were open by 18:50. Things went quietly until about 21:30. The NA2 guider crashed hard enough to require being power cycled. Problem apparently solved, we returned to normal guiding. As Erik's concurrent DIS exposure read out at 21:45, the coundtown timer reached zero and a file appeared on disk with a zero file size. Attempts to initiate a followup exposure were met with an error message in the TUI log window about not being able to start an exposure while one was in progress. As this was similar to a failure mode of the NIC-FPS hub we have seen, I cleared the problem with a command to the DIS hub. That worked, but resulted in Erik losing a 15-minute integration. After that, things returned to normal for the remainder of the half. 2nd Half Observing Specialist: R.McMillan Second half was clear until after 04:00, with fairly good seeing, but the night was not very peaceful. Images on both slitviewer and guider were strongly elongated in the altitude direction. This appeared to be independent of focus, so it wasn't simple astigmatism, and it was quite pronounced even at moderately low airmasses. I pursued focus up and down the scale several times before accepting that the problem was something else. I finally realized, when the observer was having trouble identifying a field, that there had been a bad altitude magnesensor reading. Once recognized, this was quickly cleared up. I expected that altitude tracking and therefore image quality would improve, but the images looked just as bad. Later we had more bad magnesensor measurements. There has been some strange behavior of the altitude motor current recently, but I'm not aware of any on-sky effects noted before now. I could not confirm whether or not this was going on tonight because the altitude telemetry is no longer turned on. However, I speculate that the motor current oscillations may have caused some tracking oscillations, which in turn may have caused the bad magnesensor measurements (which always started out with a magnesensor crossing at tracking speed). The observer kindly delayed his morning cals so that I could use some of the bright twilight time to check out what was going on. With the Shack-Hartmann video camera, I was able to watch the tracking behavior and saw the star twitching in the altitude direction every 5-10 seconds. I hope this information will help in the diagnosis of the problem. ------- FAILURE LOG ------- PROG INST FAILURE MODE TIME (SEGDFNVO) TI/SHU START FINISH DESCRIPTION ----------------------------------------------------------------------- JH07 D T/H 21:30 21:33 NA2 guider crashed JH07 D I/S 21:30 21:50 DIS exposure lost JH04 D T/H 01:55 02:07 Bad alt magnesensor reading JH04 D T/H 03:25 03:33 Bad alt magnesensor reading JH04 D T/H 04:45 04:49 Bad alt magnesensor reading ---------------- FOCUS LOG --------------- Air/Truss Wind Time Instrument Focus Az El Temp-C Dir MPH filt FWHM --------------------------------------------------------------------- 19:01 DISslit -100(771) 199 76 -0.2/2.4 30 16 - 1.16 19:09 NA2gdr -3463(27536)205 75 -0.3/2.4 1 7 R 1.09 ------------- WEATHER LOG ---------------- Wind Precip.or Time Temp F Dewp F MPH Direction Dust Sky Conditions ------------------------------------------------------------------ 16:01 33 29 5 275 (W) MstlyClr none 17:01 33 30 4 345 (NNW) MstlyClr none 18:01 32 28 6 353 (N) Clear none 19:01 31 24 11 9 (N) Clear none 20:01 33 26 15 12 (NNE) Clear none 21:01 35 18 10 7 (N) Clear none 22:01 34 21 8 6 (N) Clear none 23:01 34 24 17 23 (NNE) Clear none 00:01 36 12 14 23 (NNE) clear none 01:01 35 11 6 20 (NNE) clear none 02:01 33 22 13 3 (N) clear none 03:01 35 6 6 8 (N) clear none 04:01 33 23 11 356 (N) mstly clr none 05:01 38 -4 19 301 (WNW) ptly cldy none 06:01 40 -5 13 280 (W) ptly cldy 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. Note: The Tower Dust counter appears to be down at this time TELESCOPE STATUS Telescope drives operational. Current Remark version: 2.85b Current TCC version: 2.7.2 Current TUI version: TUI 0.94b2