From: Subject: 3.5m Night Log 20090412 Date: Mon, 13 Apr 2009 12:52:20 +0000 (UTC) Apache Point Observatory 3.5m Telescope Night Log Sunday, April 12, 2009 ACTUAL ASTRONOMER OBSERVER(S) INSTRUMENT START FINISH ------------------------------------------------------------------- S.Hawley R.McMillan Echelle,Tspec 19:40 20:40 M.Strauss M.Strauss,X.Liu Tspec 20:40 06:20 INST SCHED(TWILIGHT) WEATH EQUIP OBS DAY NOT USED I/ROW/DN START FINISH D B D B D B USE D B ---------------------------------------------------------------------- UW12/W 19:40 20:40 0 0 0 0 0.2 0 0.8 0 0 PU07/R 20:40 05:39 0 0 0 0.3 2.3 6.4 0 0 note: scheduled times listed include instrument change time ------------- ACTIVITY LOG -------------- Observing Specialist: R.McMillan Weather was generally better tonight, with clear skies much of the time and moderate seeing (1.6" with echelle, 1.2 with Triplespec). There were some struggles with equipment, however. After last night's somewhat inconclusive experiments with changing the azimuth PE.RATE, at the beginning of the night tonight I tried changing it in the opposite direction to 0.12. This looked mostly reasonable on the dataq (some spikes), but on the sky I saw some rather strange behavior with the echelle, offsets moving in unexpected ways. The azimuth telemetry profile for these offsets looked odd, and it was in the northwest, a part of the sky which can be difficult for the azimuth to track in. I changed the PE.RATE back to 0.06 and the offset behavior improved. I think this value is the best given the limited testing I've done: it allows for reduced noise during slews and good tracking and offset behavior on sky. It doesn't eliminate the spikes we've been seeing for moderate magnesensor errors, so this is still a matter of concern. We also had some guiding difficulties with Tspec. These were difficult to attribute, because we had faint targets, faint guide stars sometimes in non-optimal positions on the chip, and occasional clouds coming and going. We struggled with one particular target for nearly half an hour, and lost some time during that struggle; this unfortunately also involved several user errors to complicate the mix. But there was at least one case of clear misbehavior, an offset from position A to B at UT 07:20 which went fairly far off, at a time when the users were not messing with anything. This happened at moderate altitude in the southern sky, so not a position where the azimuth should be struggling -- however, the rotator was upside-down. Although I wasn't getting any error messages from the rotator and it reported that it was keeping position, I suggested to the observer to change rotations by 180 degrees. After that, behavior seemed to improve, at least so far as we could tell with the continuing challenges of faint targets and occasional clouds. I consider this to be inconclusive, but we do know that Triplespec is rotationally out of balance and has a history of guiding problems in parts of the sky that are usually no trouble for alt or az. Also, given the instrument's orientation, it would tend to be upside down for default rotation of 0 Object for stars in the popular southern half of the sky. I would like to see some more tests along these lines -- note the rotator position whenever poor tracking is seen with Triplespec, and try alternate rotations to see if that improves behavior. The weather pages went down for a short while around 9 UT and then came back up again by themselves, but the tower dust info never came back. ------- FAILURE LOG ------- PROG INST FAILURE MODE TIME (SEDFNVOG) TI/SHU START FINISH DESCRIPTION ---------------------------------------------------------------------- PU07 T T/H 00:05 00:20 guiding problems ---------------- FOCUS LOG --------------- Time Instrument Focus Az El Temp Strc Prim Sec Air filt FWHM ------------------------------------------------------------------------- 19:59 ECHELLE 250( -721) 239 50 1.9 2.3 1.9 2.1 1.9 - 1.60 ------------- WEATHER LOG ---------------- Wind Precip.or Time Temp F Dewp F MPH Direction Dust Sky Conditions ------------------------------------------------------------------- 16:00 37 21 28 293 (WNW) 239 ptly cldy none 17:00 39 22 22 329 (NNW) 256 ptly cldy none 18:00 38 23 12 300 (WNW) 223 ptly cldy none 19:00 37 26 9 350 (N) 379 ptly cldy none 20:00 35 27 12 357 (N) 371 mstly clr none 21:00 36 27 13 1 (N) 771 mstly clr none 22:00 36 26 9 16 (NNE) 719 mstly clr none 23:00 37 26 6 300 (WNW) 897 clear none 00:00 37 25 12 325 (NW) 1958 ptly cldy none 01:00 36 25 14 356 (N) 1554 ptly cldy none 02:00 35 25 19 3 (N) 2864 ptly cldy none 04:00 34 24 10 10 (N) ptly cldy none 05:00 34 24 9 20 (NNE) ptly cldy none 06:00 33 25 11 28 (NNE) 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. TELESCOPE STATUS Telescope drives operational. Current TCC version: 2.10.0 Current TUI version: TUI 1.5.1