Date: Tue, 18 May 1999 06:29:44 -0600 (MDT) From: Russet McMillan Subject: 3.5m Night Log 990518 MONDAY MAY 17, 1999 APACHE POINT OBSERVATORY OBSERVING LOG ACTUAL ASTRONOMER OBSERVER(S) INSTRUMENT DATE START FINISH Galarza Galarza SPIcam 5/17-18 21:32 00:10 Krisciunas McMillan,Krisciunas SPIcam 5/18 00:10 02:10 Wallerstein Hughes SPIcam 5/18 02:10 04:27 INST SCHEDULED WEATH EQUIP OBS DAY NOTUSED I/RS/DN START FINISH D B D B D B USE D B NM08/R 21:32 00:10 0 0 0 0 1.6 1.1 0 0 0 UW02/S 00:10 02:10 0 - 0 - 2.0 - 0 0 - UW09/S 02:10 04:27 0.1 - 0 - 2.3 - 0 0 - (note: times listed include instrument change time) ACTIVITY LOG (* means a trouble report has been issued or appended to) Observing specialist: R. McMillan The night was clear, but the weather was not perfect. After a brief period of stable temperatures and low winds allowing sub-arcsecond seeing, the wind shifted east and the seeing went downhill rapidly. Rising humidity in the pre-dawn hours caused us to close at 04:20. Salman Hameed opted to give the time scheduled for NM09 to Vanessa Galarza instead, and we installed a special NMSU Halpha filter for her use. Once the telescope temperature had caught up to the cooling air, the image quality was quite good for this program. For most of the night, the pointing was poor but manageable. However, there were two examples of egregious pointing which could indicate a serious problem. The last target of UW02 involved a slew from almost due north to almost due south, and the TCC decided to take the azimuth axis up to 355, near the counterclockwise limit. When we took an exposure, the galaxy came up more than an arcminute from the center of the frame (see /export/images/lowz_sn/990518/sn1999ac.0001). I tried a pointing correction, but the FK5 star did not appear in the guider frame. Estimating the direction and amount of the correction needed, I did an offset calib/pabs 0.01,0 -- belatedly it occurred to me that I should have used a relative correction rather than an absolute one, but this worked well enough and on the subsequent pointing correction, the star came up in the guide frame. However, it still wasn't centered on spicam; in fact, it was almost as far from the center as before, only in the other direction (see sn1999ac.0002). To save time, rather than doing calib offsets we simply used an object offset to move the star closer to the center of the frame. We did not do another pointing correction here. I slewed to the north to make the filter wheel change without shining lights on any other telescopes. The first target for UW09 was in the west, and I immediately did a pointing correction. The pointing star was in the very corner of the guider frame, requiring a large correction -- but at least this time the correction worked, and the field was correctly placed on spicam. However, the appearance of large pointing errors in conjunction with the failure of a pointing correction to center the target on the chip could indicate a serious problem not just with the pointing model, but also with the guider instrument block. I don't know if it was related to the telescope being so close to its counterclockwise limit. (Also, recall that yesterday night, one target came up 16 arcseconds from the DIS slit immediately after a local pointing correction). With the help of Dan Long, I tried to eliminate some of the more obvious culprits. We were guiding for most of the night without any trouble aside from the terrible seeing. There was no sign that the rotator was having trouble tracking, and at each filter change it was confirmed to be at zero. The magnasensor errors were somewhat large (>5 arcseconds), but no single one stood out. It is also worth noting that another field near the zenith, viewed with spicam at object rotation 0, was definitely rotated with respect to an image of the same field from a few nights ago, also taken with spicam at rotation 0. On the basis of what I've seen over the last few nights, I recommend that redoing the guider instrument block and NA2 pointing model should be made a high priority. OBSERVER COMMENTS FOCUS LOG MAY 17 1999 Wind Time Inst Focus Az El #Temp Dir MPH filt FWHM " 20:45 SPIcam -150(6472) 196 56 10.2/13.2 126 18 R 1.4 21:00 SPIcam -250(6330) Halpha 1.6 21:10 guider -219(6340) [Halpha] 21:10 guider 2359(6440) 208 54 9.8/11.6 111 16 [R] 23:30 SPIcam 0(6454) 234 67 10.9/10.3 150 20 R 0.83 00:30 SPIcam -125(6293) 136 60 8.3/9.2 109 21 R 1.9 #First temp is air, second temp is telescope. WEATHER MAY 17 1999 Wind Time Temp F Dewp F MPH Direction Dust Sky Precip. 16:01 63 20 11 232 (SW) 1314 clear none 17:01 68 20 9 258 (WSW) 1363 clear none 18:01 64 18 12 235 (SW) 1380 clear none 19:01 61 15 8 254 (WSW) 1407 clear none 20:01 55 11 1 245 (WSW) 1504 clear none 21:01 50 28 14 111 (ESE) 1135 clear none 22:01 50 25 18 126 (SE) 1377 clear none 23:01 52 19 16 142 (SE) 1357 clear none 00:01 49 21 18 111 (ESE) 1322 clear none 01:01 46 30 15 89 (E) 1503 clear none 02:01 43 32 14 87 (E) 1637 clear none 03:01 40 33 11 88 (E) 1593 clear none 04:01 39 34 11 87 (E) 1712 clear none 05:01 37 33 8 69 (ENE) 2108 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 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: 2.52 Current guide software version: GIm Ctrlv3.0b17. - Russet McMillan