Date: Thu, 7 Oct 1999 07:23:43 -0600 From: Dan Long Subject: 2.5m obslog 991006 ( MJD 51458 ) WEDNESDAY OCTOBER 6, 1999 APACHE POINT OBSERVATORY SDSS 2.5m OBSERVING LOG Observering team: Dan Long (APO) Steph Snedden (APO) Connie Rockosi (UC) Jim Gunn (PU) Tonight's plan was to obtain imaging data on the equatorial stripe 82 and get a FASTT field. Some engineering imaging was also on tap. This included trying to identify the rotator difference between a powered scan and a parked one, and trying some of Steve Kent's test tracks. Depending on weather conditions we could switch to spectroscopy to do up to three plugged cartridges. The weather tonight was poor enough that spectroscopy would not have been fruitful. Partly cloudy skies and 2 to 3 arcsecond seeing characterized the night. We chose instead to exercise the telescope by tracking serveral of Steve Kent's fast tracks. Within the constraints imposed by the seeing, most of the scans looked good, except the one which went within 5 degrees of the zenith. This one showed smeared and sometimes doubled images, but there were no indications of axes or optics oscillation. We did a FASTT field at the end of the night in 1.5 to 2.0 arcsec seeing ( run 1006 ). Run 997: The first scan we did was parked on the equator and meridian. The rotator error was .015 deg from 89.848 mount. Run 998: Next we did a powered scan in essentially the same place, using stripe 82. This time rotator error was in the noise of the calculation. We noticed that the seeing from the imager frames was much worse than what the DIMM was registering. It was about 2 arcseconds for the imager and sub arcsecond on DIMM. We convinced ourselves that the poor images from the 2.5m were not due to tracking or optics. The best guess is that the clouds caused the seeing to degrade on minute time scales but not on DIMM's short exposures ( seeing was dramatically worse when the imager was looking through these mid-level clouds ). Below is a list of the track commands issued for various run numbers. TRACK/ScanVelocity=(-0.00029101,0.00416792) 358.349,44.944 run 1000 TRACK/ScanVelocity=(-0.00033326,0.00416476) 30.714,52.929 run 1001 TRACK/ScanVelocity=(0.00218782,0.0035945) 36.2765,28.886 run 1002, 1003 TRACK/ScanVelocity=(0.00079084,-0.00410254) 25.0345,48.441 run 1004 track 60.1333,0 fk5 /scanvel=(.00417807,0.) /rota=0 /rotty=obj run 1006 axis stop axis stat track 334.1183,54.4110 mount /rota=68.3104 /rotty=mount Run 1000: We started running Steve Kent's fast track scans. We found the rate to be too slow .004155 deg/sec instead of .00417807 deg/sec due to the wrong conversion from civil to sidereal time. Once that was sorted out. Run 1000 has the correct velocity. There was an interesting light pattern which evolved over the course of 60 frames. Starting at around frame 100 a streak of light a few 10s of dn above sky showed up on the I chip in dewar 3. It grew brighter until around frame 130 then faded out slowly. The telescope went from 177.2,63.3,170.0 to 185.5,54.2,185.1 in Az, El, and Rot during this time. It seems likely that some reflected light, possibly from Holloman AFB is still making it to the array despite all the baffling. A similar event occurred in run 1003 around frame 65 on chip 33. Runs 1002 and 1003 are interesting in that they were very close to the zenith. 1002 was a short run with a multiLskip. 1003 was a longer run and had smeared or doubled images. It is a bit puzzling since no axes oscillations or optics oscillations were observed. When the tpm-realtime display was quite zoomed in one could see a 1 to 3 times per minute square wave on the position of each axis. The magnitude of the amplitude is not clear from the plots. It may well be insignificantly small. These square waves were visible on later runs where the tracking was quite good. Run 1005: Setup for FASTT field about an hour west. Sky gang didn't show any catalog stars for our equatorial stripe. This is what it was fed. skyGang 1005 15 35 -node 95.0 -incl 0. 5 -ha -15. -dec 0. Run 1006: FASTT field ( we hope ). We set up by going to an equatorial scan about 15 minutes ahead of the field. Once there doing an axis stop, and an axis stat, then issuing a slew in mount coordinates to where we were. The real-time display of the watcher never showed any info tonight. In a possibly related event, the watcher never complained when the tapes filled up. MIRROR NUMBERS Primary: setmir: 0 -27.4 7.8 427 1495 galil: 6400, -3350, -450, 11050, 7350, 7050 linear gauges 1 = 1.9265 2 = 0.5600 3 = 0.5590 5 = 1.9055 6 = 0.4065 4 = 4.5100 7 = 4.5560 8 = 4.7270 Secondary: ( inst=imager focus=-1410 alt=57.4 deg ) setmir: -181 -110.4 45 0 147.8 galil: -412655, -260078, -12128, -9490, -6741 TPM data was logged for most of the night in "/mcptpm/tpm-51458". The imager is on the telescope. The telescope was closed up at around 06:30. Like the last couple nights, the primary went into oscillation during the stow process. It was backed off to the reverse limits. Nitrogen notes: Both spectrographs were filled at 18:30, spectro 2 again at 02:00, and both at about 06:15. The imager dewar was changed at about 18:00. EndNight -doImager for MJD 51458 was started. Note: We put in the last set of sequentially numbered tapes into the drives when we swapped during the night. More tapes will have to be labeled during the day Thursday. WEATHER Skies tonight were partly cloudy most of the night. The temperature was in the low 50s. Winds were from the south to southwest at 15 to 35 MPH, humidity was around 50%, and dust counts were under 1000. Seeing tonight was between 1.5 and 3.5 arcseconds on the imager, but .8 to 1.5 arcseconds on DIMM. Dan