Date: Tue, 5 Oct 1999 06:52:48 -0600 From: Dan Long Subject: 2.5m obslog 991005 ( MJD 51456 ) MONDAY OCTOBER 4, 1999 APACHE POINT OBSERVATORY SDSS 2.5m OBSERVING LOG Observering team: Dan Long (APO) Scot Kleinman (APO) Scott Burles (UC) Connie Rockosi (UC) Jim Gunn (PU) Robert Lupton (PU) Tonight's plan was to obtain spectroscopic data for the plates which the data was lost last night. We got data on plates 191, 217, 203, and 231. It was a very productive night with photometric skies and variable seeing ( 1.2" to 3.5" ). There were two occurrences of sector C of the primary going into oscillation when the telescope was brought to low elevation, however it was easily stopped and didn't restart at observing positions. We got four plates! The night started with an oscillation of the primary ( sector C ) upon slewing to the first target ( elevation 25 deg ). Looking at mig channel 3 one could see a slow ( several seconds ) periodic motion between about .3 and .7 when .55 is the nominal reading. Pistoning the primary to -80000 for actuators A, B, and C ( galil terms ), waiting for the mirror to stabilize ( by looking at migs ), then returning it to its nominal values, stopped the oscillation. It remained quiet after that. We got set up on plate 191 using cartridge 2 at about 21:00. It took about 8 arcseconds of offset to acquire the star. We were at 25 deg elevation. We got 5 15 minute exposures on this plate. The seeing during this time ranged from 2.3 to 3.3 arcseconds. The elevation changed from 25 to 50 during the time we tracked this target. This allowed us to track focus with elevation for some time although in relatively poor seeing. However I was able to get a crude estimate of piston of the secondary versus altitude. I added this coefficient into the DEFAULT.DAT file on the TCC. The value I got was -300 for the sin component. We swapped cartridge 2 plate 191 for cartridge 1 plate 217 between 23:35 and 23:50. The seeing improved significantly during this time. We got 1.2 to 1.6 arcsecond images from the plate. DIMM also showed improvement, going from around 3 arcseconds earlier to around 1.5 to 2.0 around midnight. There were 4 exposures taken with this plate. The change from 217 to cartridge 5 plate 203 was made between 1:45 and 2:00. After setup and calibrations, we were taking science exposures by 2:25. Seeing deteriorated somewhat on this plate with fwhm values of 1.5 to 2.0 arcseconds. We put cartridge 4 plate 231 on at around 04:30. We took 4 exposures, finishing up at 05:50. The telescope was closed at about 06:15. We had to reboot the spectro 1 mechanicals several times tonight, but never spectro 2. Note that the primary was left at -80000 for the three axials in galil terms, since it started to oscillate at low elevation ( sector C again ) when we stowed the telescope. MIRROR NUMBERS Primary: setmir: 0 -27.4 7.8 427 1495 galil: 6400, -3350, -450, 11050, 7350, 7050 linear gauges 1 = 1.9270 2 = 0.5600 3 = 0.5585 5 = 1.9060 6 = 0.4065 4 = 3.0280 7 = 3.0800 8 = 3.2430 Secondary: ( inst=spectro focus=1575 alt=56.2 deg ) setmir: 1325 -111.4 45 0 198.6 galil: 1484700, 1637261, 1888028, -12609, -9956 TPM data was logged for most of the night in "/mcptpm/tpm51456.dat". Nitrogen notes: Both spectrographs were filled at 19:40 ( once open ) and again at about 06:30. I ran endNight -doSpectro for MJD 51456. Everything seemed to go OK, at least to the point where I went to bed. It was on endNight scpPPD when I left. WEATHER Skies tonight were clear all night. The temperature was in the low 50s. Winds were light southerly, humidity was around 50%, and dust counts were 600 to 800. Seeing tonight was between 1.2 and 3.5 arcseconds with the best seeing in the middle of the night. Dan