Date: Thu, 5 Feb 2004 04:14:48 -0700 (MST)
From: John Barentine
Subject: 3.5m Night Log 20040204
                         Apache Point Observatory
                         3.5m Telescope Night Log
                        Wednesday, February 4, 2004
                                                          ACTUAL
 ASTRONOMER      OBSERVER(S)            INSTRUMENT     START FINISH
 --------------------------------------------------------------------
 B.Gillespie     J.Barentine            GRIM           --:--  --:--
  INST        SCHEDULED      WEATH     EQUIP     OBS     DAY  NOT USED
 I/RO/DN     START FINISH   D    B    D    B    D    B   USE   D    B
 ---------------------------------------------------------------------
 EN01/R      18:33  06:01   0  11.5   0    0    0    0    0    0    0
  note: scheduled times listed include instrument change time
                  ------------- ACTIVITY LOG --------------
 1st Half Observing Specialist: J.Barentine
 Scattered snowshowers and a nearly overcast sky around sunset.  So we did
some off-sky tasks to pass the time.
 First, a longstanding suspicion about the apparent flakiness of GRIM
concerns whether its anomalous "quad-dropping" behavior depends on the
rotation angle of the instrument.  Since the root cause of the problem has
been located to the inside of the dewar (see message 733 on
apo35-general), so the thinking goes, perhaps the flexure of some
component in the dewar under gravity loaading at different rotational
angles explains the quad-dropping.  To test this possibility, I mounted
GRIM at NA2 and, while tracking (to simulate otherwise "normal" observing
conditions), took GRIM "biases" at rotation angles from 0 to 360 in
increments of 2 degrees.  "Biases" are here defined as GRIMages taken with
the shortest allowable exposure time, 1.22s.  At the time of the test, the
interior air temperature of the dome was around -7 degrees C, and we were
tracking around 45 degrees up in the northeast.
 In true GRIM form, all four quadrants functioned properly during the
test.  Still, to look for any rotation-dependent anomalies, I ran
statistics on each of the four quads.  The results show a fairly
well-defind sinusoid for each of the quadrants, approximately in phase,
but differing in amplitude for plots of the mean bias value in a quad
versus rotation angle.  The magnitude of the effect is approximately 15
ADU.  Plots are available at:
	http://users.apo.nmsu.edu/~jcb/apo/grim/rotation/
and also posted on the bulletin board in the ops building.
 We also continue to try to track down the cause of echelle slitviewer
camera failures.  Tonight, during a sequence of slitviewer images started
more than 24 hours previous, I tried some of the following:
	o Turned on/off enclosure lights
	o Turned on/off truss lamps
	o Turned telex fans on/off (humidity too high for intex fans)
	o Took an echelle bias
None of these actions had an effect on the slitviewer.  At about 22:00,
the slitviewer quit on its own.  I left the slitviewer software in the
condition it was at the time it stalled for Craig to have a look at
tomorrow.
 Got the late instrument fills at 04:00 and called it a night.
                        ------- FAILURE LOG -------
 PROG   INST   FAILURE MODE     TIME
      (SEGDFVO)    TI/SHU   START  FINISH  DESCRIPTION
 -----------------------------------------------------------------------
                ---------------- FOCUS LOG ---------------
                                        Air/Truss   Wind
 Time   Instrument   Focus     Az  El    Temp-C    Dir MPH  filt  FWHM
 ---------------------------------------------------------------------
                   ------------- WEATHER LOG ----------------
                                 Wind                       Precip.or
     Time   Temp F Dewp F  MPH  Direction    Dust    Sky    Conditions
     ------------------------------------------------------------------
     16:01    20    15     12   251  (WSW)         MstlyCldy  lt snow
     17:01    21    12     14   266  (W)           MstlyCldy  lt snow
     18:01    20    11     13   267  (W)           MstlyCldy  lt snow
     19:01    19    12     23   265  (W)           Overcast    none
     20:01    17    16     11   321  (NW)          Overcast    none
     21:01    17    15      9   328  (NNW)         Overcast    none
     22:01    17    14      9   318  (NW)          Overcast    none
     23:01    16    15      7   273  (W)           Overcast    none
     00:01    17    16      2   275  (W)           Overcast    none
     01:01    17    16      9   270  (W)           Overcast    none
     02:01    18    15     13   304  (NW)          Overcast    none
     03:01    17    13     12   303  (WNW)         Overcast    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.
   Note: The weather tower dust counter is out of commision
                               TELESCOPE STATUS
   Telescope drives operational. Current Remark version: 2.85b
   Current guide software version: guider v4.1b4
   Current TCC version: 2.7.2  Current TUI version: TUI-0.82