From: Russet McMillan Subject: 3.5m Night Log 20000302 Date: Fri, 3 Mar 2000 06:08:56 -0700 (MST) THURSDAY MARCH 2, 2000 APACHE POINT OBSERVATORY OBSERVING LOG ACTUAL ASTRONOMER OBSERVER(S) INSTRUMENT DATE START FINISH York Woodgate,Palunas, Fabry-Perot 3/2 18:55 00:10 Weingarten Woodgate Woodgate,Palunas, Fabry-Perot 3/3 00:10 05:35 Weingarten INST SCHEDULED WEATH EQUIP OBS DAY NOTUSED I/RS/DN START FINISH D B D B D B USE D B UC06/S 18:55 00:10 0 - 0 - 5.3 - 0 0 - DD02/S 00:10 05:35 0 0 0 0 4.9 0.5 0 0 0 (note: times listed include instrument change time) ACTIVITY LOG (* means a trouble report has been issued or appended to) First-Half Observing Specialist: Deglman Opened at 17:25. Second-Half Observing Specialist: McMillan Second half remained clear with excellent seeing, in disagreement with the DIMM measurements. We had several hours of subarcsecond seeing with the guider (15 second exposures), delivering 1.1 arcsecond or better on the instrument (15 minute exposures). On some occasions, the guider was actually getting better than 0.8 arcseconds, so that it was undersampled. The observers considered changing the binning on their instrument but decided against it. Our seeing was somewhat worse at higher airmass (up to 1.7 arcseconds on the guider at 2 airmasses), but still better or much better than what DIMM was showing. It was established that for a large portion of first half, possibly ever since the first focus run, the focus had not been set to the best value but was accidentally left at the final setting from the focus run. Once we realized what was going on, we began to focus more frequently in order to take advantage of the seeing. Partly as a result of the excellent seeing, it was very easy to see from the guider offsets when an image jump occurred. From around 23:00 to 02:30, we tracked a single target from near the meridian toward the west, and during this time we were seeing approximately one jump every five minutes on average. Most of the jumps seemed to correct themselves after a minute or so; i.e., we would see a guider correction larger than one arcsecond in a certain direction, then a few small corrections, then another large correction in the opposite direction. I made note of several of these jumps in the MC as they occurred, and I believe they should be fairly easy to extract from the TCC log of the guider corrections. Even with longish 15-second guider exposure times, we found that these jumps were having little effect on the science exposures, so apparently the guider was doing its work well. * The new guider shutter consistently opens all the way and seems quite stable, but unfortunately it's a little too small and vignettes the corners of the guider chip. This will slightly reduce the odds of finding a good guide star at any random position, but it will have a very strong impact on the use of guiding for horizon rotation with DIS. DIS users are still requested to consider very seriously whether they truly need horizon rotation for their science, because they can be virtually assured of losing photons to guiding difficulties. We are considering whether a new DIS instrument block would improve the blind tracking in horizon rotation. In the meantime, it is possible with a little work to place the slit at the parallactic angle without actually *tracking* the parallactic angle; this might make a good compromise for DIS observations at high airmass. OBSERVER COMMENTS As promised, the observers say they are ecstatic about the good seeing. FOCUS LOG MARCH 2 2000 Wind Time Inst Focus Az El #Temp Dir MPH filt FWHM " 18:34 GFab-Per 125( ) 249 84 1.5/2.2 294 9 6563 0.92 22:45 Fab-Per 75(334) 155 73 1.7/1.1 275 11 6563 0.9 22:55 NA2gdr 2000(60000) 00:00 F-P 125(389) 216 71 2.1/1.4 251 8 6563 0.8 00:10 guider 2500 02:05 F-P 100( ) 258 49 2.4/1.7 258 11 6563 #First temp is air, second temp is telescope. WEATHER MARCH 2 2000 Wind Time Temp F Dewp F MPH Direction Dust Sky Precip. 17:01 38 10 18 296 (WNW) 197 clear none 18:01 35 10 14 303 (WNW) 241 clear none 19:01 35 10 13 280 (W) 202 clear none 20:01 36 10 17 280 (W) 353 clear none 21:01 35 11 10 287 (WNW) 417 clear none 22:01 35 12 12 290 (WNW) 453 clear none 23:01 35 12 7 265 (W) 494 clear none 00:01 36 11 7 257 (WSW) 464 clear none 01:01 35 7 7 229 (SW) 390 clear none 02:01 37 5 9 269 (W) 363 clear none 03:01 36 -1 11 243 (WSW) 255 clear none 04:01 33 5 9 194 (SSW) 396 clear none 05:01 33 6 8 189 (S) 413 clear none 06:01 33 2 11 221 (SW) 348 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: 2.60. Current guide software version: GIm Ctrlv3.0b27. Current TCC version is 2.2.2. - Frank Deglman, Russet McMillan