Date: Sat, 28 Aug 2004 06:00:59 -0600 (MDT)
From: John Barentine
Subject: 3.5m Night Log 20040827
                         Apache Point Observatory
                         3.5m Telescope Night Log
                        Thursday, August 27, 2004
                                                          ACTUAL
 ASTRONOMER      OBSERVER(S)            INSTRUMENT     START FINISH
 --------------------------------------------------------------------
 J.Holtzman      P.-L.Lim               Echelle        21:30  01:00
 T.Snow          T.Snow,M.Drosback      Echelle        01:05  05:40
  INST        SCHEDULED      WEATH     EQUIP     OBS     DAY  NOT USED
 I/RO/DN     START FINISH   D    B    D    B    D    B   USE   D    B
 ---------------------------------------------------------------------
 NM06/O      20:29  01:00   0    0    0   1.0   0   3.5   0    0    0
 CU02/R      01:00  05:40   0    0    0    0   0.9  3.7   0    0    0
 note: scheduled times listed include instrument change time
                  ------------- ACTIVITY LOG --------------
 Observing Specialist: J.Barentine
 Opened at 19:40 to cool.  Skies were mostly clear with some thin cirrus
overhead.
 We had trouble with telescope pointing during twilight.  Around 20:15
when I took control of the telescope and the NA1 guider to focus, I
noticed that the pointing was well off of the guider frame.  I tried an
iteration of Russet's echpoint script, which predicted tertiary tilts that
at first seemed to send the pointing off in exactly the wrong direction
(i.e., were the signs on the tert tilt coefficients flipped?)  I tried
finding bright stars Gemma (alpha CrB) and Deneb; using the glow from
Deneb, I blindly changed the tert tilt coefficients by hand until I got
the pointing in a reasonably good state.  The next time I ran echpoint, it
evidently predicted the correct sign on the coefficients.  I changed them
according to its recommendations and had the observers slew to their first
object, considerably far from (and at lower elevation than) Deneb.  The
pointing remained good from then on.
 Russell Owen, who was looking in on the activities, and I then noticed
that the temperature sensors upstairs were showing a difference of 7
degrees C between the telescope truss and the air temperature on the Met
tower.  The temperatures were also not changing, out to the last decimal
place, in the regular update interval.  Craig checked the sensor
controller and found it to have died in an unhappy state; he kicked it and
the reported temperatures immedately became more sensible.  That, in turn,
caused a fairly large focus jump which I corrected manually.  Fortunately,
pointing was good for the remainder of first half.
 Second half was photometric and very quiet right up until the very end.
With only about 20 minutes to go, the wind rapidly swung round to the
east, the air temperature rapidly took a dive while the dewpoint spiked.
I asked the observers to finish ASAP, which they did diligently, and I ran
upstairs to close as the humidity passed 90%.  The rails on the observing
level felt a little damp but there was not yet any signifcant condensation
on them.
                      ------- FAILURE LOG -------
  PROG   INST   FAILURE MODE     TIME
       (SEGDFVO)    TI/SHU   START  FINISH  DESCRIPTION
 -----------------------------------------------------------------------
 NM06     E          T/S     20:29  21:30   Bad pointing with echelle
                 ---------------- FOCUS LOG ---------------
                                          Air/Truss   Wind
 Time   Instrument   Focus     Az  El    Temp-C    Dir MPH  filt  FWHM
 ---------------------------------------------------------------------
 No focus measurement from Echelle tonight; focus loops in the early
evening would not converge and we did not stop to focus later on.
                ------------- WEATHER LOG ----------------
                                  Wind                       Precip.or
     Time   Temp F Dewp F  MPH  Direction    Dust    Sky    Conditions
     ------------------------------------------------------------------
     16:01    74    26      7   271  (W)            PtlyCldy    none
     17:01    71    24      6   246  (WSW)          PtlyCldy    none
     18:01    70    25      7   265  (W)            PtlyCldy    none
     19:01    67    26      2   229  (SW)           MstlyClr    none
     20:01    63    29      1   208  (SSW)           Clear      none
     21:01    60    35      7   114  (ESE)           Clear      none
     22:01    61    31      8   171  (S)             Clear      none
     23:01    62    33      8   187  (S)             Clear      none
     00:01    62    33      9   221  (SW)            Clear      none
     01:01    60    33      5   178  (S)             Clear      none
     02:01    61    31      3   247  (WSW)           Clear      none
     03:01    62    28      1   254  (WSW)           Clear      none
     04:01    62    28      2   252  (WSW)           Clear      none
     05:01    51    40     20    74  (ENE)           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 STATUS
     Telescope drives operational. Current Remark version: 2.85b
     Current TCC version: 2.7.2  Current TUI version: TUI 90b2