Date: Wed, 19 Aug 1998 06:11:21 -0600 From: tia@tycho.apo.nmsu.edu (Tia Hoyes) Subject: 3.5m obslog 980818 TUESDAY AUGUST 18, 1998 APACHE POINT OBSERVATORY OBSERVING LOG ACTUAL ASTRONOMER OBSERVER INSTRUMENT DATE START FINISH York Stoughton/Richards DIS 8/18 19:00 06:00 INST SCHEDULED OBS WEATH EQUIP DAY NOTUSED I/RS/DN START FINISH D B D B D B USE D B UC05/R 21:13 01:10 0 0 3.9 0 0 0 0 0 0 PU01/S 01:10 02:00 0 0 0 0 0.8 0 0 0 0 UC01/R 02:00 05:01 2.2 0.8 0 0 0 0 0 0 0 (note: times listed include instrument change time) ACTIVITY LOG The telescope was opened tonight at 2:00. Chris Stoughton was the observer for UC05. He left early in the evening and turned his time over to Gordon Richards.(This was due to the fact that it was pouring rain) COMMENTS:After the rain and threat of rain let up, we were able to get 3 30 minute spectra plus some standards. Things worked reasonably well, except as indicated in the lengthy comment below. Gordon It was raining early tonight, so I decided to spend some time looking at the DIS grating calibration procedure. Normally, I just increment the step position until I get the central wavelength that I want, but this is rather time consuming. The official procedure as documented at APO is to put the zeroorder spectrum at a certain pixel on the chip (which is different for each grating in each grating bay). However, when re-calibrating the gratings tonight, I found that the position of the zeroorder spectrum that makes Remark give the correct central wavelengths is not anywhere near the positions listed in the documentation. It seems then, that one of two things is likely to be wrong. Either the assumption that the pixel value of the zeroorder spectrum is a constant is wrong, or the pixel values in the table are wrong. Given that the grating calibration procedure is clearly still not robust, I'd like to suggest 4 things: 1. Whomever makes the grating change should not only check the location of the zeroorder spectrum but also that the actual central wavelength agrees with the reported Remark wavelength to within 1/2 of the number of Angstroms per step (this value seems to be different for every grating in every bay). 2. Given that the above is rather time consuming, grating changes should not be permitted after afternoon checkout. 3. The current grating calibration procedure should be re-evaluated. 4. If someone makes any changes to DIS's grating status, they should let the observing specialist know -- otherwise the gratings may not be calibrated properly for the next observer. In addition, there seems to be a problem with the implementation of the grating change procedure, as I found that the low res gratings are currently calibrated improperly. Whenever they were last recalibrated, the zeroorder spectra were placed at the center of the chip rather than at the prescribed pixel values. Therefore the central wavelengths that appear in Remark are, in fact, wrong. For the low res gratings this is really of little consequence; however, for the medium resolution gratings, such an error is likely to produce a gap between the blue and red spectra. As long as I've gone on this long, I might as well do my civic duty and grumble about the arc lamp web page again... Gordon I ran the cloud cam for 4 hours without having to refill it! Also, the Lens Monitoring time was given to UC05 and UC01 due to SPICAM problems. (at the very end of the night, I checked DIS LN2 STATUS and found the red camera was warming. I topped the dewar) Forecast:(4:30am) TODAY...INCREASING CLOUDINESS WITH SCATTERED AFTERNOON THUNDERSTORMS. .TONIGHT...VARIABLE CLOUDINESS WITH SCATTERED SHOWERS AND THUNDERSTORMS...MORE NUMEROUS BEFORE MIDNIGHT. LOCAL EAST WINDS 10-20 MPH AND GUSTY THROUGH CANYONS. .THURSDAY...VARIABLE CLOUDS WITH A CHANCE OF MORNING SHOWERS...THEN SCATTERED AFTERNOON THUNDERSTORMS. (* means a trouble report has been issued or appended to) FOCUS LOG AUGUST 18, 1998 Best Telescope Wind Seeing Time Inst Focus Az El Temp# Dir MPH filter FWHM " 02:20 DIS -100(6555) 265.0 69.8 12.7/13.72 163.8 10.3 empty **** ****Used the slit viewer to focus**** # The first temp is air, the second is truss, both in degrees C. WEATHER AUGUST 18, 1998 Wind Time Temp F Dewp. MPH. Dir. DUST Sky Precip. 16:01 58 47 10 105 (ESE) 553 overcast rain 17:01 56 47 13 70 (ENE) 285 mostly cloudy rain 18:01 57 50 8 81 (E) 364 mostly cloudy rain 19:01 56 47 11 81 (E) 234 mostly cloudy drizzle 20:01 55 48 15 74 (ENE) 302 overcast none 21:01 57 47 6 155 (SSE) 723 overcast drizzle 22:01 54 45 0 125 (SE) 136 overcast rain 23:01 55 44 3 95 (E) 140 overcast drizzle 00:01 57 45 6 167 (SSE) 579 clearing none 01:01 55 45 7 137 (SE) 465 clearing none 02:01 54 44 5 164 (SSE) 477 partly cloudy none 03:01 54 44 7 175 (S) 512 clearing none 04:01 55 46 5 161 (SSE) 519 clear none 05:01 55 47 4 102 (ESE) 594 clear none 06:01 54 47 2 194 (SSW) 629 clear none note: the wind was coming from the azimuth listed. The convention used is north=0 degrees, east=90 degrees. The dust count is particles >1 micron per 0.1 cu. ft. TELESCOPE STATUS Primary, secondary, and tertiary mirrors in place and collimated. Primary support system operational. Mirror ventilation system in place. Telescope drives operational. Current Remark version: 2.42a Current guide software version:GIm Ctrl v3.0b 15.out -Tia