Date: Tue, 8 Jun 1999 06:10:46 -0600 (MDT) From: Russet McMillan Subject: 3.5m Night Log 990607 Apache Point Observatory, Sunspot, NM Monday, June 7, 1999 3.5-meter Night Observing Log Actual ---------------------------------------------------------------------- ASTRONOMER OBSERVER(S) INSTRUMENT DATE START FINISH ---------------------------------------------------------------------- Krisciunas Krisciunas, Stubbs GRIM, SPIcam 6/7-8 21:50 22:15 Holtzmann Holtzmann SPIcam 6/8 -- -- Duric Duric SPIcam 6/8 02:10 04:14 ---------------------------------------------------------------------- INST SCHEDULED WEATH EQUIP OBS DAY NOTUSED I/RS/DN START FINISH D B D B D B USE D B ---------------------------------------------------------------------- UW02/R 21:50 23:50 1.6 - 0 - 0.4 - 0 0 - NM10/R 23:50 02:10 2.3 - 0 - 0 - 0 0 - NM02/S 02:10 04:14 0 0 0 0 0.2 1.9 -------------- Activity Log -------------- * Indicates that a problem report has been issued. Observing Specialist: R.McMillan The weather tonight was clear, but a shift in the wind in the evening caused the humidity, dust, and seeing to turn bad until things had settled down. We were closed from 22:15 until 23:55. During this time, the official dewpoint depression never reached the two-degree limit. But the air outside smelled very moist, the rails were moderately sticky, and the RH sensor for the press fans read over 90%. On the other hand, the dewpoint read by the Cosmic weather station was lower than the measurement of our sensor (anyone know what kind of sensor Cosmic has?). All this made it very hard to make decisions about closure. In the end, I based my decisions on the dust, which rose and fell at the same time as the humidity. NM10 and UW02 swapped their originally-scheduled times during first half, with UW02 getting the twilight time. When we re-opened after the dust dropped, the seeing was so poor that Jon Holtzmann decided there was no point in his observing at all, and he gave some of his time to UW02 and some to NM02. I listed this as weather-lost time for NM10. A cautionary tale: the alert reader may notice some wild values in the focus log below. This was because I forgot to turn the fans back on after re-opening. At first the omission was deliberate, because the humidity and dust were still marginal. But long after the weather had improved, the fans slipped my mind. When they were turned back on, the focus changed radically. This is undoubtedly the reason why our seeing all night long was much worse than DIMM's (although even DIMM did show a definite degradation in seeing when the wind shifted). I should really not have been running the telescope at all without at least the telex fans on, which was my oversight. But the failure to turn on the fans wouldn't have affected the focus quite so badly (and might also have been recognized earlier) if we were getting a measurement of the primary mirror temperature, and using that temperature for focus adjustments, instead of the truss temperature. There are a number of sensors already on and around the primary mirror; is there a good reason why they have never been activated? OBSERVER COMMENTS FOCUS LOG June 7 1999 Best Telescope Temp Wind Seeing Time Instrmnt Focus Az El Air/Truss Dir MPH filter FWHM" --------------------------------------------------------------------- 21:10 GRIM -200(6802) 143 51 16.2/17.5 238 9 J 0.90 00:10 SPIcam -100(6685) 248 29 12.4/13.3 132 29 R 3.4 00:45 SPIcam 250(7007) 269 29 12.4/12.9 125 24 I 2.3 01:10 SPIcam 400(6974) 203 66 12.6/12.6 134 24 R 03:40 SPIcam 0(6557) 201 61 12.3/12.3 149 25 8410 1.2 WEATHER LOG June 7 1999 Wind Time Temp-F Dewp-F MPH Direction Dust Sky Precip ------------------------------------------------------------------ 16:01 72 24 11 215 (SW) 1958 clear none 17:01 73 24 15 205 (SSW) 1821 clear none 18:01 73 24 14 214 (SW) 1995 clear none 19:01 68 18 14 226 (SW) 1520 clear none 20:01 63 20 11 226 (SW) 2033 clear none 21:01 61 20 5 259 (W) 1983 clear none 22:01 56 45 24 143 (SE) 3666 clear none 23:01 55 48 15 133 (SE) 3422 clear none 00:01 54 41 21 120 (ESE) 2285 clear none 01:01 55 37 22 133 (SE) 1775 clear none 02:01 55 36 18 142 (SE) 1499 clear none 03:01 55 36 19 154 (SSE) 1613 clear none 04:01 54 37 25 180 (S) 2099 clear none 05:01 55 40 20 175 (S) 2563 clear none 06:01 53 40 23 198 (SSW) 2295 clear none used is north=0 degrees, east=90 degrees. The dust count is for the 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 Ctrl v3.0b 18.out - RM