Apache Point Observatory
                      3.5m Telescope Night Log
                      Tuesday, August 18, 2026

PROG  PI ASTRONOMER      OBSERVER(S) 
--------------------------------------------------------------------
OU06  G.Jewett          M.Kilic,J.Brouwer,M.Dill
UW05  C.Chandler        C.Chandler            

                         ON-SKY
PROG  INSTRUMENT     START   FINISH
--------------------------------------------------------------------
OU06  ARCTIC         20:14   01:12   
UW05  ARCTIC         01:13   05:40

   PROG       SCHEDULED      WEATH     EQUIP     OBS     NOT USED
 I/ROW/DTN  START  FINISH   D    B    D    B    D    B    D    B
-----------------------------------------------------------------
OU06/R      19:53  01:10    0    0    0   0.3  2.1  2.9   0    0
UW05/R      01:10  06:21    0    0    0    0   5.2  0.0   0    0

note: scheduled times listed include instrument change time

              ------------- ACTIVITY LOG --------------
Observing Specialist: A.Townsend

Nearby storms and clouds this afternoon cleared up before sunset and we had a clear night with good seeing! 

Tertiary fault at start of night when setting inst to ARCTIC. See separate email for details. We got on sky a little after sunset but with plenty of time for twilight flats. 

At 22:32 dust counters went offline, so I took measurements with the handheld throughout the rest of the night: 

23:30 1380
00:15 1410
01:30 1510 
02:45 1540
03:50 1440
04:35 1370
05:15 1470

                    ------- FAILURE LOG -------

              FAILURE MODE     TIME
PROG   INSTR     TI/SHU    START  FINISH  DESCRIPTION
----------------------------------------------------------------------
OU06  ARCTIC     T/U      19:53   20:14  Tertiary amplifier fault

            ---------------- FOCUS LOG ---------------
Time  Instrument  Focus     Az  El  Temp Strc Prim  Sec  Air  filt  FWHM
--------------------------------------------------------------------------
 20:30 arctic   595( 1655)  60  78  18.3 20.6 19.6 20.6 18.5   BG40  0.73
 01:21 arctic   260( 1257) -22  41  18.3 16.5 17.1 16.2 16.8   CUVR  1.04

               ------------- WEATHER LOG ----------------

                                   Wind                      Precip.or
     Time   Temp F Dewp F  MPH  Direction    Dust    Sky    Conditions
    ------------------------------------------------------------------
     16:00    70    49      8   219   (SW)   2457  ptly cldy   none 
     17:00    67    49      3   313   (NW)   2441  ptly cldy   none 
     18:00    72    50      5   279    (W)   2494  ptly cldy   none 
     19:00    68    47      3   253  (WSW)   2398  ptly cldy   none 
     20:00    66    44      3   227   (SW)   2242 mstly clr    none 
     21:00    65    43      2   240  (WSW)   2070    clear     none 
     22:00    65    42      5   240  (WSW)   1964    clear     none 
     23:00    62    43      7   244  (WSW)           clear     none 
     00:00    61    41      3   244  (WSW)           clear     none 
     01:00    61    42      2   251  (WSW)           clear     none 
     02:00    64    43      5   258  (WSW)           clear     none 
     03:00    63    42      6   263    (W)           clear     none 
     04:00    63    41      7   263    (W)           clear     none 
     05:00    61    41      7   272    (W)           clear     none 
     06:00    63    41     10   326   (NW)           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 > 1u per 0.1 cubic feet.

              ----------  TELESCOPE SOFTWARE  ----------

Current TCC version: 1.4.2
Current HUB version: v20171231_01
Current TUI version: 3.2.2