From: Russet McMillan Subject: 3.5m Night Log 20000531 Date: Thu, 1 Jun 2000 05:34:21 -0600 (MDT) WEDNESDAY MAY 31, 2000 APACHE POINT OBSERVATORY OBSERVING LOG ACTUAL ASTRONOMER OBSERVER(S) INSTRUMENT DATE START FINISH Pindor Pindor DIS 5/31 23:35 01:00 Kim Kim DIS 6/1 01:00 04:25 INST SCHEDULED WEATH EQUIP OBS DAY NOTUSED I/RS/DN START FINISH D B D B D B USE D B PU03/R 21:09 01:00 2.4 - 0 - 1.4 - 0 0 - PU04/R 01:00 04:53 0.5 - 0 - 3.4 - 0 0 - (note: times listed include instrument change time) ACTIVITY LOG (* means a trouble report has been issued or appended to) Observing Specialist: McMillan Opening was once again delayed by clouds and threat of rain. The clouds cleared off for the middle portion of the night, and we opened at 23:35. After 3:30, clouds began to reappear, and by 04:25 they were consistently too thick to permit science, so we closed. Seeing as judged by the guider was generally poor, usually worse than 1.5 arcseconds with only about half an hour of approximately 1-arcsecond seeing. The telescope and instruments behaved very well. Pointing was fair but not excellent, though it was difficult to judge since almost all the night's targets were pairs. Zeroing the guider offset did not make a noticeable difference; the offset motion seemed to be at right angles to the perceived direction of (subtle) drift. Although only one explicit focus run is shown in the log below, as usual with DIS I tinkered with the focus whenever a decent comparison star could be included on the slitviewer. I've been noticing a pattern; the initial focus is be high, then it drifts downward perhaps 100 steps for a few hours, then it would climb again to return very near where it started. This pattern was also present tonight, but not so strongly. I suspect this is because the "structure" temperature (on which the automatic temperature/focus adjustments are based), is the slowest part of the telescope to respond to temperature changes. When the entire telescope is at equilibrium, the algorithm works well. But when the mirrors are much cooler than the structure, the best focus is lower than expected. After a sunny day, it can take the telescope five or six hours to catch up with a rapidly-dropping air temperature. Tonight it wasn't so extreme because the day was very cool and the telescope equilibrated more quickly. OBSERVER COMMENTS FOCUS LOG Time Instrument Focus Az El #Temp Dir MPH filt FWHM " 23:40 DISslit 175(879) 286 66 14.3/14.1 96 6 -- 1.43 23:45 Guider 875 1.31 #First temp is air, second temp is telescope. WEATHER Wind Time Temp F Dewp F MPH Direction Dust Sky Precip. 17:01 58 34 25 44 (NE) 563 cloudy sprinkles 18:01 53 40 21 73 (ENE) 644 cloudy none 19:01 54 38 39 68 (ENE) 589 cloudy none 20:01 58 32 20 49 (NE) 676 cloudy none 21:01 57 33 8 333 (NNW) 1077 cloudy none 22:01 59 31 2 265 (W) 854 mstly cldy none 23:01 59 33 1 255 (WSW) 867 ptly cldy none 00:01 59 32 0 345 (NNW) 1025 mstly clr none 01:01 59 32 3 266 (W) 951 mstly clr none 02:01 59 32 6 277 (W) 1054 mstly clr none 03:01 57 32 5 193 (SSW) 841 ptly cldy none 04:01 53 37 5 171 (S) 511 mstly cldy none 05:01 53 41 12 190 (S) 604 mstly 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 > 1 micron per 0.1 cu. ft. TELESCOPE STATUS Primary, secondary, and tertiary mirrors in place and collimated. Primary support system operational. Mirror ventilation system in place. Telescope drives operational. Current Remark version: 2.55b5. Current guide software version: GIm Ctrlv3.0b27. Current TCC version is 2.2.9. - Russet McMillan