Subject: 3.5m Night Log 20250924 From: dembicky@apo.nmsu.edu Date: Thu, 25 Sep 2025 12:41:59 +0000 (UTC) Apache Point Observatory 3.5m Telescope Night Log Wednesday, September 24, 2025 PROG PI ASTRONOMER OBSERVER(S) -------------------------------------------------------------------- JH01 P.McCreery P.McCreery, K.Schlaufman UW10 S.Hawley S.Hawley, L.Heb0b ON-SKY PROG INSTRUMENT START FINISH -------------------------------------------------------------------- JH01 ECHELLE 19:05 01:10 UW10 ECHELLE 01:10 06:06 PROG SCHEDULED WEATH EQUIP OBS NOT USED I/ROW/DTN START FINISH D B D B D B D B ----------------------------------------------------------------- JH01/R 19:05 01:10 0 0 0 0 4.8 1.3 0 0 UW10/R 01:10 06:45 0 0 0 0 5.6 0.0 0 0 note: scheduled times listed include instrument change time ------------- ACTIVITY LOG -------------- Observing Specialist: J.Dembicky Dataq was stuck tonight. I used the quick method of turning off and on the data as described in the wiki. That worked! A few minutes later the Dataq frozen again. I restarted it again using the same procedure and it seemed to fix it. Humidity shot up right after sunset tonight. I stayed open as the mirrors were still fairly warm, so no threat of condensation. I did turn off fans and close louvers. Wind was out of the east which gave us horrendous seeing. Humidity finally started dropping again around the end of twilight. I turned the telescope fans back on around 21:00. The 3.5m dew point and 2.5m were in agreement when the humidity was high, but ours dropped and the 2.5m stayed relatively high for some reason. Not sure which one I was to believe but the inside 3.5m dome also dropped so I when with the best 2 out of 3. Pointing was a little off (BD28) when I slewed to focus at 01:10. We had been tracking one object the entire first half so maybe an error accumulated. I did a couple slews in alt/az and then back to the focus star to check pointing after crossing several magna sensors. My first half observers said pointing looked fine to them. Pointing was still a bit off. boresight @ 376,444, Star BD28 (not sure of proper motion) @ 407,184. I decided NOT to fix pointing, but if I did I would actually use a ref star and not BD28 to confirm and fix pointing. At some point during the night the Dataq again hung (lost connection). I took a pointing check image using a pt ref star at the end of the night. See ecam image 2835. This was about the same position BD28 was earlier. We may want to tweak the Echelle pointing a little. Well...the 3.5m humidity for the outside and the inside Optidew were reading wrong tonight. The SDSS was the correct one!. I did not discover this until the end of the night. I checked the primary mirror and it was fine but I saw condensation on the walls of the enclosure, which tipped me off something wasn't right. It also felt humid. The internal humidity was reading around 65% and SDSS was reading 86%, the outside 3.5m was reading 45%. At sunset, earlier in the evening, All three were in rough agreement with humidity between 85% and 91%. The 3.5m readings dropped but the SDSS one stayed around 86-89% for most all of the night. I assumed since the 3.5m ones moved and SDSS did not to go with the 3.5m readings. Apparently that was not a correct assumption as I discovered this morning. Humidity wasn't that excessive but higher than we usually would stay open for. On the good news side, we got lots of data with clear skies all night and the seeing settled down for 2nd half as well. ------- FAILURE LOG ------- FAILURE MODE TIME PROG INSTR TI/SHU START FINISH DESCRIPTION ---------------------------------------------------------------------- ---------------- FOCUS LOG --------------- Time Instrument Focus Az El Temp Strc Prim Sec Air filt FWHM -------------------------------------------------------------------------- 19:50 ecamera 546( 208) 137 82 9.3 12.1 12.4 11.3 9.6 Clear 1.87 01:15 ecamera 482( -75) 266 56 7.2 7.2 8.0 7.2 8.1 ND1 1.20 ------------- WEATHER LOG ---------------- Wind Precip.or Time Temp F Dewp F MPH Direction Dust Sky Conditions ------------------------------------------------------------------ 16:00 62 50 8 267 (W) 527 ptly cldy none 17:00 60 48 8 247 (WSW) 598 ptly cldy none 18:00 58 46 7 263 (W) 527 ptly cldy none 19:00 53 45 5 281 (W) mstly clr humid 20:00 49 46 11 56 (NE) clear humid 21:00 48 33 16 72 (ENE) clear humid 22:00 46 32 17 65 (ENE) 479 clear humid 23:00 46 32 17 63 (ENE) 451 clear humid 00:00 46 32 12 65 (ENE) 566 clear humid 01:00 47 25 11 38 (NE) 634 clear humid 02:00 47 31 6 345 (NNW) 551 clear humid 03:00 48 31 2 325 (NW) 581 clear humid 04:00 48 29 2 313 (NW) 579 clear humid 05:00 48 27 1 279 (W) 618 clear humid 06:00 49 27 5 352 (N) 608 clear humid Note: the wind was coming from the azimuth listed. The convention used is north=0 degrees, east=90 degrees. The dust count is particles > 1u per 0.1 cubic feet. ---------- TELESCOPE SOFTWARE ---------- Current TCC version: 1.4.2 Current HUB version: v20171231_01 Current TUI version: 3.1.8