From: Russet McMillan Subject: 3.5m Night Log 20000223 Date: Thu, 24 Feb 2000 05:45:50 -0700 (MST) WEDNESDAY FEBRUARY 23, 2000 APACHE POINT OBSERVATORY OBSERVING LOG ACTUAL ASTRONOMER OBSERVER(S) INSTRUMENT DATE START FINISH Gillespie McMillan SPIcam,S-H 2/23-24 18:44 04:40 INST SCHEDULED WEATH EQUIP OBS DAY NOTUSED I/RS/DN START FINISH D B D B D B USE D B EN01/S 18:49 05:44 0 1.1 0 0 3.4 6.4 0 0 0 (note: times listed include instrument change time) ACTIVITY LOG (* means a trouble report has been issued or appended to) Observing Specialist: McMillan The night started clear and became partly cloudy around 23:00. Seeing was generally good (1.0-1.2 arcseconds) with the guider and with SPIcam, until about 04:00, when it got suddenly worse. The telescope was closed at 04:40 due to clouds. Due to observing specialist absentmindedness, the telescope fans were never turned on during the night. This may have had an impact on several of the tests described below. The secondary motors were homed during the afternoon, and in the first images with SPIcam, the collimation looked so bad that I immediately did a sequence of images at different secondary tilt values. The best images I got were with tilts of 100, 100. The nominal tilts since January 26 have been 0, 0 (with an altitude dependence added on February 17). We've seen this kind of change between almost all of the five engineering nights since January 8. I believe the reason for this MUST be tracked down, because there is no way we can maintain image quality with the collimation wandering like this. Is part of the secondary support flopping? Are the secondary motors missing steps? Or is it the primary? We have seen such changes without homing the secondary, but their appearance tonight immediately after homing is suspicious. Still a mystery is how any optical component of the telescope could be moving enough to change the collimation as much as we've seen, without having a drastic and immediately noticeable effect on the pointing model. Also disturbing is the strange appearance of even the best collimated donuts, which show a dark outer arc on one side and a dark midpatch on the opposite side. I returned to the nominal tilts (as of February 17) and took Shack-Hartmann data at 7 altitudes with Frank's assistance. Jon Davis came in at this time and helped us home the tertiary axial actuators. Just out of curiosity, I did another secondary-tilt sequence at the same altitude as the first one (55 degrees) and obtained very similar results. I concluded that the collimation at the nominal tilts was just too poor, so I did tilt sequences at two other altitudes, for a full set including 36, 55, and 82 degrees. At all altitudes I found 100, 100 to be the best tilt values, so I entered these in the default file and removed the altitude-dependent coefficients. Then I took a 60-point pointing model with the new tilts, which yielded 3.5 arcseconds RMS around the sky. I wanted to take Shack-Hartmann data with the new tilts, but clouds had moved in so that I could only get decent counts on very bright stars. I did so at two altitudes, using Regulus and Spica. Jeff Morgan was not available to do a quick reduction, so the results of the S-H tests are not yet known. Next I moved on to tracking tests with SPIcam, which could be done easily through clouds. I did 20-minute series of 10-second exposures, both blind and guided, at the four compass points with altitudes around 45 degrees. The wind during these tests was approximately 20mph from the SSW. In the east, the telescope showed decent blind tracking with slow drift (just over 1 arcsecond in 20 minutes). With guiding on, the tracking was even better. In the west, blind tracking showed evidence of similar drift tendencies plus at least one large jump, which occurred during an exposure. Guiding for a 20-minute period showed two jumps which were adequately corrected by the guider, although those jumps did not occur during spicam images. Blind tracking in the south showed a stronger drift (~2 arcseconds during 20 minutes) and at least one large jump during an exposure. Guiding in the south showed two large jumps during 20 minutes -- one was compensated by the guider, and the other, apparently a 2-arcsecond jump, caused guiding to fail with the error "Center isn't locally highest pixel" (an error which does not turn off guiding or beep to notify the observing specialist). Blind tracking in the north showed a drift tendency of perhaps 1 arcsecond in 10 minutes, plus an apparent sudden jump between exposures. With guiding on, the drift was reduced; the guider compensated for two jumps (one nearly 1.5 arcsec) which occurred between SPIcam exposures. The guider shutter showed some problems as described in previous night logs, although it did not get to the point of being unusable. The telescope temperature was more than 3 degrees above freezing, considerably warmer than the other nights when the problem has been observed. The clouds got thicker around 04:30, so I stopped the sky tests, closed the telescope, and took Shack-Hartmann reference frames at various altitudes, as somebody or other had requested. OBSERVER COMMENTS FOCUS LOG FEBRUARY 23 2000 Wind Time Inst Focus Az El #Temp Dir MPH filt FWHM " 20:25 SPIcam 125(352) 4.0/4.0 215 16 R 1.14 20:50 S-H 200 00:45 SPIcam 0(334) 3.5/3.7 204 21 R 1.4 #First temp is air, second temp is telescope. WEATHER FEBRUARY 23 2000 Wind Time Temp F Dewp F MPH Direction Dust Sky Precip. 17:01 43 12 11 222 (SW) 172 clear none 18:01 38 10 16 210 (SSW) 249 clear none 19:01 38 7 19 196 (SSW) 269 clear none 20:01 38 -3 9 234 (SW) 296 clear none 21:01 40 -7 17 218 (SW) 244 clear none 22:01 39 8 16 221 (SW) 287 clear none 23:01 39 11 15 215 (SW) 323 ptly cldy none 00:01 40 13 21 201 (SSW) 449 ptly cldy none 01:01 38 12 18 202 (SSW) 381 ptly cldy none 02:01 40 8 22 183 (S) 335 ptly cldy none 03:01 39 8 22 195 (SSW) 343 ptly cldy none 04:01 38 11 19 203 (SSW) 411 ptly cldy none 05:01 37 10 12 195 (SSW) 462 ptly 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 2.2.2. - Russet McMillan