Date: Sun, 5 Sep 1999 06:56:57 -0600 From: Dan Long Subject: 2.5m obslog 990904 ( MJD 51427 ) SATURDAY SEPTEMBER 4, 1999 APACHE POINT OBSERVATORY SDSS 2.5m OBSERVING LOG Observering team: Dan Long (APO) Stephanie Snedden (APO) Jim Annis (FNAL) Francisco Castander (UC) David Schlegel (PU) Bob Nichol (CMU) Tonight the engineering camera was on the telescope. The plan was to re-collimate the primary, get a small pointing model, then put on the imaging camera and take some equatorial and off equatorial scans. Sadly we were only able to get as far as collimating the primary tonight. There is something wrong with the primary support system. The instrument change from the spectrographic cartridge from the previous night, and the engineering camera went smoothly. The cartridge and corrector are on the Lindy cart in the shed. One minor problem discovered with the Menu program, is that if you select the "empty" position for the counterweights, they go all the way up rather than down. One can still use ^ to specify a numeric value for the weights, but the empty preset should be fixed. Engcam without spectroscopic corrector counterweight position was about 100. The drive surfaces were cleaned this evening, but by morning an impressive number of squashed moths adorned the drive surfaces. Sigh. The fiducials were set without difficulty, however sometime during the night the rotator got off by more than 100 degrees, but as an indication of how the night went, we didn't even notice until we closed up. This afternoon both primary and secondary galils were in a lost state. I homed both and all seemed well. Once it was dark, we slewed to a nearby FK5 star, but it was nowhere to be found. I tried a brighter star and used a white card to get it on the chip. It was off by .01, .045 deg in Az and El respectively. It was also horribly out of focus. It was also the most distorted donut I think I've ever seen ( /data/spectro/guider/gimg0187.fits way of of focus, and 194 closer to focus... if you have the stomach for it ). The mig numbers were strange as well. A later check of my notes Tonight gave for 0 0 0 0 0 setmir mig readings of 1 = 2.1530 1.9310 2 = 0.7780 0.5570 3 = 0.7830 0.5575 5 = 1.8770 1.8890 6 = 0.4115 0.4135 4 = -0.6240 7 = -7.7030 8 = -1.1220 The first thing I noticed was that channel 7 was very different from 4 and 8. A piston of the secondary changed each of 4, 7, and 8 by the same amount. Homing the secondary again maintained the difference between them, so I took it as being what it should, and that it was not the cause of the horrible images. With the primary at all zeros in setmir terms and relaxed, I proceeded to make changes in tilt. However, even a 40 arcsecond tilt resulted in no change in shape, and even more disturbing, it didn't shift on the chip. Close scrutiny of the migs showed things were moving little or not at all. I tried homing the primary, and the mig numbers still didn't change, though the galils were happily reporting different numbers as the position changed. The primary was obviously not moving even though the galil commands were executing successfully. This was eventually traced to the mirror support system. It was getting no power! The cause was the power plug in the power strip at the top of the rack containing the pumps etc not being plugged in all the way. Once pushed in, the cards on the box had power and the system seemed to be working. The mig numbers changed with setmir commands and the focus changed from +2500 to -2400. It appears the primary was stuck near the home position once the mirror support lost power. We continued with collimation of the primary and got the numbers shown below ( see gimg0264.fits ). MIRROR NUMBERS Primary: setmir: 0 -15.6 15.6 854 854 galil: 5650, -3400, 400, 800, 21850, 21250 linear gauges 1 = 1.9290 2 = 0.5595 3 = 0.5560 5 = 1.9225 6 = 0.4240 4 = 4.0470 7 = -3.0570 8 = 3.5300 Secondary: 57 deg El. Engcam as instrument SecOrient= -2400, 7.5, 25, 0, -158 galil: -3058550, -2973800, -3038200, 9900, 11500 We seemed to be getting somewhere, when on a trip to the telescope I heard the low pressure alarm on the support system. It was down around 30 PSI, but the vacuum was OK at around -10. House air was over 90 PSI. Taking the telescope to zenith made matters worse. The pressure dropped to between 25 and 27 and the primary went into oscillation. The oscillation remained even when slewed back to 57 deg. I powered off the support electronics, and the pressure climbed back to about 42 PSI, and the vacuum dropped to -17 PSI over the course of about a minute. I then powered it back up and the pressure dropped back to between 32 and 35 PSI but did not oscillate. In this fragile state I was able to align the finder scope and verify that the collimation numbers were correct. At this point it was nearly 04:30, so we decided to close up. One note about the PMSS pressure. It was back to within acceptable limits with the telescope in stow, so whatever problem there is seems to be in an axial sector ( a leak in the pressure side perhaps? ). Near the end of the night TELRUN died in a most peculiar way. All TELRUN and TCCINTERP sessions had the windows lock up or disappear. Any TCC25M windows open to the $ prompt seemed unaffected. When I typed TELRUN the software started up from scratch. The telescope had been tracking and I was taking engineering camera images at the time. This happened sometime between 03:30 and 04:00. Finally the rotator ending up some 100 degrees off was discovered at the end of the night. I suspect it happened fairly early on as PTERR was not applying corrections properly, and the instrument block shouldn't be far off. TPM data was logged for most of the night using the "start data" command. Nitrogen notes: Both spectrographs were filled between 21:00 and 21:30. The 180 L dewar for the imager was changed at about 03:30. I filled the spectrographs just before I left at 06:45. Unfortunately the connector froze while filling the second dewar. I left it connected but shut off at the 180 L dewar. If someone could disconnect it during the day when it thaws out, I'd appreciate it. WEATHER Weather tonight was mostly clear. Winds were out of the west to southwest at the start of the night, changing to east around 22:00. Temperatures were in the upper 50s most of the night. Humidity ranged from 40% to 75%. DIMM reported seeing from as good as 0.8 to as bad as 1.7 arcseconds with the mean somewhere around 1.3. Dan