Date: Wed, 13 Oct 1999 07:44:28 -0600 From: Dan Long Subject: 2.5m obslog 991012 ( MJD 51464 ) TUESDAY OCTOBER 12, 1999 APACHE POINT OBSERVATORY SDSS 2.5m OBSERVING LOG Observering team: Dan Long (APO) Jeff Hayes (APO) Steve Kent (FNAL) Dave Schlegel (PU) Scott Burles (UC) Tonight's plan was to test the new MCP version. Once done proceed to spectroscopy, and swap to imaging once the image quality got good. Available plates for observing are Cartridge Current Plate 2 189 21:00 4 205 01:00 5 209 02:30 1 235 05:00 Afternoon checkout/setup was done between 17:45 and 19:15. The MCP test showed that the new version does not apply the brakes when the telescope goes out of closed loop, so we reverted to the previous version. It was about 20:30 when this was finished, and the imager was still on the telescope, so we decided to take a quick scan to see how the image quality was. There was some sign of temperature effects in the primary, but we were still getting 1.2 to 1.5 arcseconds across the array, so the decision was made to leave the imager on. The first stripe was the equatorial stripe 82. We first tried setting up far enough west to get the stripe started at 20:40 RA using the track ... fk5 followed by track axes position mount. Steve Kent was not comfortable trying to back out proper position in skyGang without using headers, so we opted for the powered scan version. In the case of each scan using scanStripe tonight, we had to move the telescope south about an arcminute to get the observed position to match skyGang's catalog position. It is not clear why this is. The telescope is almost certainly pointing much more accurately than this. A possible hint is that when setting up on the equator either using mount coordinates or scanStripe 100..., skyGang showed things lining up properly. The following is a run by run account of the night. 1028: Bias 1029: Setup for 20:40 RA on equator ( 100,N ) using track fk5, followed by mount when slew done track 300,0.1048 fk5 /rota=0 /rotty=obj /scanvel=(.00417807,0.) track -30.6126,53.3234 mount /rota=64.5252 /rotty=mount neeed offset rotator -.078 1030,1031: Changed to powered scan with scanStripe 100 304 -strip N needed offset rotator -.064 Tried a couple different lambdas. Realised that telescope wouldn't slew to anywhere but meridian if stripe 100 was used in the scanStripe command, so decided to go for stripe 82. 1032: Setup for 82.... scanStripe 82 127 -strip N needed rotator offset -.082 After running skyGang it said we were off by 1 arcminute, and needed to move south. I made this change with OFFSET OBJ for this run. 1033: Science scan with seeing of 1.5 arcsec at start ( 22:20 ), improving to sub-arcsecond across some of the array around 23:00. It went back to about 1.5 arcseconds by midnight and jumped to nearly 2" by the end of the scan at 00:35. RA range for scan 317 - 355 ( deg ) 1034: setup for stripe 76 S... scanStripe 76 170 -strip S needed rotator offset -.08 bore offset changed from -.10483 to -.1210 to make fit better in skyGang 1035: Science scan started 01:20. Ran until about 03:15. spectro dewars needed filling, so topped them off prior to setup for next scan. Seeing for this scan 1.2 to 1.5 arcseconds typically. RA range for run 6 - 35 ( deg ) 1036: Setup for stripe 86... scanStripe 86 -152 -strip S needed rotator offset -.077 bore offset changed from -.10483 to -.1298 to make fit better in skyGang 1037: Science run started about 04:00. This run continued until dawn. It was about half an hour outside the survey area by then. RA range of run 40.5 - 70.9 ( deg ) Notes: The azimuth fiducial number 33 did not show up when crossed tonight, so 32 ( the one at 105 deg ) was used to set the azimuth position as it has been for the last night or two. We had trouble with the cloud camera. It stopped running around 21:30 and never complained that it had stopped. It also failed to restart when we tried. When using astrom, be sure you are running v2_14. Using the rhl version will cause skyGang to bomb out when you try boresighting the display ( O, C, B ). v2_14 should now be the default version you get when typing setup astrom, but you might want to check just to be sure. Three times tonight there was an error from tape drive 2 on id4. It was labeled as a Random Mechanical Positioning Error. It never seemed to cause problems with archiving, but as it repeated three times, I thought it worth mentioning. 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 = 0.5590 5 = 1.9065 6 = 0.4075 4 = 4.8040 7 = 4.8850 8 = 5.0350 Secondary: ( inst=imager focus=-1717 alt=63.3 deg ) setmir: -485 -110.6 45 0 158.7 galil: -796353, -643776, -395307, -10323, -7551 TPM data was logged for the start of the night in "/mcptpm/tpm-51464". It was stopped at 19:30 when a hard reboot was done on the mcp during the testing. Unfortunately I didn't notice this until near the end of the night. Nitrogen notes: Both spectrographs were filled at 18:30, and at about 03:15. The imager dewar was changed at about 05:00, but it wasn't empty. The pressure was nearly zero however. It was discovered that the gas bottle had been valved off at the end of the chain of regulators on the bottle downstairs. The 180 L dewar was swapped and the valve opened. Hopefully this ends our short hold time troubles with the 180 L dewars. EndNight -doImager for MJD 51464 completed successfully! WEATHER Skies tonight were clear. The temperature was steady in the low 50s. Winds were light and variable mostly from the North and East, humidity was around 40%, and dust counts were under 1000. Seeing tonight was between 0.9 and 2.2 arcseconds on the imager, and between 1.2 and 4.0 arcseconds on DIMM. Dan