Date: Thu, 19 Nov 1998 06:23:00 -0700 (MST) From: Russet McMillan Subject: 3.5m NightLog 981118 Wednesday, November 18th 1998 APACHE POINT OBSERVATORY 3.5-meter Observing Log ACTUAL ---------------------------------------------------------------------- ASTRONOMER OBSERVER(S) INSTRUMENT DATE START FINISH ---------------------------------------------------------------------- E.Turner C.Hastings SPIcam 11/18 18:26 19:16 C.Hoopes C.Hoopes DIS 11/18-19 19:16 00:10 R.Wyse M.Houdashelt SPIcam 11/19 00:10 05:11 ---------------------------------------------------------------------- INST SCHEDULED WEATH EQUIP OBS DAY NOTUSED I/RS/DN START FINISH D B D B D B USE D B ---------------------------------------------------------------------- PU01/S 18:27 19:16 0 - 0 - 0.8 - 0 0 - NM03/S 19:16 00:10 0 - 0.9 - 4.0 - 0 0 - JH02/R 00:10 05:11 0 - 0 - 5.0 - 0 0 - -------- ACTIVITY LOG -------- 1st half Observing Specialist: Camron Hastings The dome was opened at 17:30 MST with fairly clear skies and low humidity. I talked with Mark and we came to the conclusion that DIS seems to be dumping its LN2 whenever it is in a camera-up orientation. (90 or 270 degrees of rotation) Mark sent an email regarding this. Tonight at 05:20 UT the mirror support seemed to start oscillating. The guider images were smeared all over and the slit image of the object started to bounce all around. We manually kept the object, which luckily was an HII region so we had a little slop, in the slit until the end of the exposure, which turned out useful. On my way up to check the valve voltages I switched the system to dry nitrogen. When I checked the voltages they all appeared normal at about 254mV. After this check we reslewed and began imaging again. The mirror appeared stable until Charles was finished. It must have been the nitrogen purge that cured it. 2nd half Observing Specialist: Russet McMillan Second half started well, with clear skies and sub-arcsecond seeing. Around 02:30 some cirrus started to show up, and the seeing deteriorated. By 04:00 the clouds had cleared away again, but the seeing was still so-so. Watching the guider monitor, I saw a few sudden, short-term increases in FWHM (01:40, 02:29, 02:52), which also appeared on the data images as elliptical PSFs. These were less dramatic than the troubles Camron reported, but I switched the PMSS over to nitrogen in hopes that would help. Unfortunately, the nitrogen couldn't seem to maintain enough pressure for more than an hour or so. Karen told me to make sure the valve was open; it was, and the gauge on the bottle ran between 200 - 600 psi, but the PMSS alarm kept going off. The occasional elliptical images showed up even when the nitrogen was on, and of course each time I switched around more twitches would appear. Eventually, I gave up and left the system on air, but the low-pressure alarm went off again. All the hoses seemed fine, and the compressor in the utility building was behaving normally. Since the PMSS was only slightly underpressure (38 psi), I just killed the alarm and kept an eye on it until twilight. I noticed something interesting when we refocused partway through the morning: the new best focus position was 40 steps different according to Remark's relative measurement, but the secondary piston position was the same (see the focus log for details). Since the telescope was at the same altitude as the previous focus measurement, I presume the difference was due to corrections for temperature (the air temp had not changed, but the telescope temp had). Even more interesting is that the piston position (but not the relative position in Remark) was the same as the best focus for last night, when it was considerably warmer. Could this indicate that the focus is actually less sensitive to temperature than the automatic corrections assume? ----- OBSERVER COMMENTS ----- M.Houdashelt (JH02) Night went fairly smoothly. A few images were degraded (FWHM and ellipticity of stars about 10% larger than normal), possibly due to PMSS glitches, but all data is probably usable. PMSS had problems maintaining sufficient pressure. FOCUS LOG November 18th 1998 Best Telescope Temp Wind Seeing Time Instrument Focus Az El Air/Truss Dir MPH filter FWHM" ---------------------------------------------------------------------- 18:20 SPIcam +200(6536) 165 60 5.5/7.4 262 9 r' 1.12 19:10 DIS -050(????) 296 71 5.5/7.1 265 10 none 1.32 00:35 SPIcam -180(6114) 103 66 4.3/5.2 260 19 V 0.93 00:40 guider 50500(6114) 106 67 4.1/5.1 265 18 R 1.09 03:55 SPIcam -140(6115) 254 67 4.2/4.2 281 19 V 1.07 WEATHER LOG November 18th 1998 Wind Time Temp-F Dewp-F MPH Direction Dust Sky Precip ------------------------------------------------------------------ 16:01 48 22 13 250 (WSW) cirrus none 17:01 43 21 16 238 (WSW) cirrus none 18:01 42 21 9 236 (SW) cirrus none 19:01 43 23 13 259 (W) cirrus none 20:01 40 25 16 254 (WSW) cirrus none 21:01 41 27 22 262 (W) mstly clr none 22:01 42 25 20 268 (W) clear none 23:01 42 25 15 266 (W) clear none 00:01 41 25 17 264 (W) clear none 01:01 40 26 18 261 (W) clear none 02:01 40 26 17 261 (W) lt cirrus none 03:01 40 24 15 270 (W) cirrus none 04:01 39 22 11 268 (W) mstly clr none 05:01 39 22 18 302 (WNW) clear none 06:01 39 20 15 302 (WNW) 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 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: 2.42a Current guide software version: GIm Ctrl v3.0b 15.out - Camron Hastings, Russet McMillan