Date: Tue, 22 Aug 2000 05:39:43 -0600 From: Dan Long Subject: 2.5m obslog 20000821 (MJD 51778) APACHE POINT OBSERVATORY SDSS 2.5M OBSERVING LOG Monday August 21 2000 (MJD 51778) OBSERVING TEAM: =============== Dan Long (APO) Steph Snedden (APO) Anders Jorgensen (LANL) PT VISITORS: ========= Scott Burles (UC) David Schlegel (PU) THE PLAN: ========= Continued shakedown. Further definition ( and resolution ? ) of fiducial problems seen in previous nights. SYNOPSIS: ========= With alt #2 encoder providing data, position error corrections were usually small enough to be applied. By the end of the night we had a 70 point model with 3.6" rms, with test slews showing stars within 5" of target position. Note that azimuth and rotator position errors are not being corrected. GENERAL COMMENTS (see Problems below for details): ================================================== After a conversation with Bill Boroski we tried both alt encoders to see which one the mcp had a scale factor for. It was encoder #2. Typical position errors of 50 to 100 counts were seen between fiducials. When encoder #1 was connected to the mcp typical position errors were around 2500 between fiducials. Since we were unsure of the encoder #1 scale factor and how to change the scale factor in the mcp, we went with encoder #2 for the model even though it is not as accurate as encoder #1. For the record the file containing the scale factor is /p/mcp/v4_3_2/mcp-new/axis.h. If this file can be edited and re-read by the mcp, it would be possible to switch back to the less noisy encoder #1. We found out that azimuth and rotator fiducial errors are not corrected, only noted. There are apparently no reference values for the azimuth fiducial positions ( except for the one at 121 deg ). The 70 point model showed about 5 arcsecond sky rms. The residuals were mostly in azimuth. This was about twice the error seen in the model two nights ago. It was decided to try again with a grid that had less randomness in azimuth ( like none ). The starting point of the grid was also changed to be in the NW instead of SW in order to move the discontinuity in the model away from the south where most of the observing is done. This second 70 point model had 3.6 arcseconds sky rms and looked very good in the south half of the sky. Some test slews after the model was implemented showed pointing errors of 5 arcseconds or less. This should be good enough to acquire guide stars on spectroscopic plates with little or no searching. See end of log for statistics of pointing models. There is a problem with the way large errors are handled. When a fiducial reports an error too large to correct, the mcp disables MS.ON so that fiducial error correction is not applies. This is what it should do. What it should not do is keep MS.ON disabled when the error from subsequent crossings of the same or other fiducials is *not* too large to correct. Right now if you ever get a bogus error value from a crossing it permanently turns off error correction until you explicitly issue an axis init from the tcc. (PR mcp/1270). Large errors ( ~|80000 - 300000| cts ) were seen upon crossing alt fiducials on numerous occasions. In fact it happened somewhere between 1/4 and 1/2 of the time. It did not seem correlated to slew speed, direction, or any particular fiducial. It did seem to come and go in waves, sometimes going dozens of crossings without a large error. Other times it would show large errors on nearly every crossing. (PR mcp/1271). There was one time tonight when the altitude went out of closed loop and drifted up to the zenith limit since it was a little bottom/back heavy. Moving the telescope off the hard limit by hand and initializing the axis got us going again. It is another example of the need to get the altitude brake so that it comes on ( like it used to ) when the axis goes out of closed loop. DATA ACQUISITION (see IOP/SOP output below): =========================================== IMAGING: -------- Run Type --- ---- 1639 bias test SPECTROSCOPY: ------------- Frame Exposure (sec) Flavor/comments ----- -------------- --------------- OFFSETS: Cart - ---: Calib offsets 0, 0, 0. Meridian scale 1.000000 TAPES: None. MIRROR NUMBERS ============== PRIMARY: -------- MIGS TONIGHT SHOULD BE Axial A: 1.9310 1.9310 Axial B: 0.5580 0.5585 Axial C: 0.5550 0.5560 Trans D: 0.4065 0.4065 Lateral E: 1.9150 1.9165 Lateral F: 0.4160 0.4170 GALILS Commanded: 4751., -2743., 591., -10848., 14572., 14119. Actual: 4750., -2750., 600., -10850., 14550., 14100. SETMIR VALUES primDesOrient: 0.00, -2.30, 11.70, 640.50, 128.10 primOrient: 0.00, -2.28, 11.84, 639.70, 127.98 SECONDARY: ---------- Focus: -2200 Temp: 12.7 Altitude: 64.4 MIGS Axial A: 2.352 Axial B: 2.454 Axial C: 2.400 Trans D: 0.273 GALILS Commanded: -3094374., -3132968., -3062382., 2194., -3019. Actual: -3094246., -3132980., -3062397., 2200., -3000. SETMIR VALUES secDesOrient: -2457.58, -20.00, -8.00, 50.00, -91.09 secOrient: -2457.98, -19.98, -8.05, 49.83, -91.32 FOCUS LOG: ========== M1 Piston M2 Piston Temp Wind Time Inst setmir TCC setmir Az Alt C Dir MPH filt FWHM " 22:45 Engcam 0 -2200 -2458 -4 64.4 13.8 94 16 - 1.5 WEATHER SYNOPSIS ================ Skies were clear or mostly clear all night. Brisk east to southeast winds made for poor seeing. WEATHER DATA: ============= Wind Time Temp F Dewp F MPH Direction Dust DIMM Sky 16:01 68 38 15 73 (ENE) 613 - Partly Cloudy 17:01 68 37 12 65 (ENE) 667 - Mostly Clear 18:01 66 36 16 79 (ENE) 575 - Mostly Clear 19:01 64 33 15 76 (ENE) 539 - Clear 20:01 61 33 17 83 (E) 683 - Clear 21:01 60 36 17 89 (E) 867 2.5 Mostly Clear 22:01 59 39 18 76 (ENE) 947 1.4 Mostly Clear 23:01 57 41 20 81 (E) 1024 2.2 Clear 00:01 55 43 13 103 (ESE) 1027 2.4 Clear 01:01 55 43 16 86 (E) 1028 2.9 Mostly Clear 02:01 54 42 13 77 (ENE) 1053 2.2 Clear 03:01 54 42 12 78 (ENE) 991 1.8 Clear 04:01 53 42 10 84 (E) 1028 1.3 Clear 05:01 53 41 9 90 (E) 1014 1.7 Clear LN2 SCHEDULE: ============= Spectrographs were filled at 05:00. 05:00 Dewar wt 20 lb Imager dewar was changed during the day. 05:00 Dewar wt 196 lb TELESCOPE STATUS: ================= Stowed at 30 deg alt, engineering camera installed INTERLOCKS: =========== none bypassed SOFTWARE USED: ============== IOP/SOP: v3_16_2 Watcher: v2_8_2 MCP: v4_2_4 TPM: v1_0_8 AstroDa: 14_28 TCC: 2.2.9 DATA LOGS FROM IOP/SOP: ======================= POINTING MODEL DETAILS: ======================= * inmod tdat:telmod.dat;6 DKA300:[TCC]PTERR T 70 2.2487 IE -149.8901 IA -216.2715 AN -3.3833 AW -57.6771 HWCA2 -0.8336 HWSA2 -0.2450 HNCA1 +0.1813 HNSA1 -0.7739 CA +17.1550 PZZ1 -142.5665 ACEC -0.7044 ACES -2.4541 TX -1.9221 END * getdat PTERR_20000822.DAT;2 Read 67 data points * fit coeff change value sigma 1 IE +5.874 -144.02 2.376 2 IA +9.624 -206.65 2.558 3 AN -2.229 -5.61 0.791 4 AW -7.020 -64.70 0.781 5 HWCA2 +4.053 +3.22 1.001 6 HWSA2 +1.885 +1.64 1.087 7 HNCA1 -0.818 -0.64 1.189 8 HNSA1 +4.226 +3.45 1.189 9 CA -14.341 +2.81 1.916 10 PZZ1 +2.360 -140.21 7.153 11 ACEC -4.256 -4.96 1.399 12 ACES -0.254 -2.71 1.439 13 TX +2.204 +0.28 3.200 Sky RMS = 4.21 Popn SD = 4.69 * inmod tdat:telmod.dat;6 DKA300:[TCC]PTERR T 70 2.2487 IE -149.8901 IA -216.2715 AN -3.3833 AW -57.6771 HWCA2 -0.8336 HWSA2 -0.2450 HNCA1 +0.1813 HNSA1 -0.7739 CA +17.1550 PZZ1 -142.5665 ACEC -0.7044 ACES -2.4541 TX -1.9221 END * getdat PTERR_20000822.DAT;4 Read 69 data points * fit coeff change value sigma 1 IE +7.813 -142.08 2.275 2 IA +2.304 -213.97 2.333 3 AN -1.299 -4.68 0.687 4 AW +0.778 -56.90 0.686 5 HWCA2 +0.479 -0.35 0.864 6 HWSA2 -2.457 -2.70 0.933 7 HNCA1 -1.503 -1.32 1.006 8 HNSA1 +3.036 +2.26 1.014 9 CA -13.130 +4.02 1.767 10 PZZ1 +16.798 -125.77 7.237 11 ACEC -1.433 -2.14 1.205 12 ACES +0.403 -2.05 1.205 13 TX -4.318 -6.24 3.331 Sky RMS = 3.61 Popn SD = 4.00