Date: Sun, 11 Oct 1998 07:25:07 -0600 (MDT)
From: Russet McMillan
Subject: 3.5m obslog 981010
                         SATURDAY OCTOBER 10, 1998
                         APACHE POINT OBSERVATORY
                              OBSERVING  LOG
                                                          ACTUAL
ASTRONOMER      OBSERVER(S)        INSTRUMENT   DATE   START FINISH
Turner           Gloria             SPICAM      10/10  19:58 21:48
King            Walterbos             DIS       10/10  21:48 06:15
 INST        SCHEDULED      OBS      WEATH     EQUIP   DAY   NOTUSED
I/RS/DN    START FINISH   D    B    D    B    D    B   USE   D    B
PU01       19:58 21:48   0.6   0    0    0    0    0    0    0    0
NM04       21:48 06:15   1.2  5.5   0    0    0   1.7   0    0    0
(note: times listed include instrument change time)
                               ACTIVITY LOG
(* means a trouble report has been issued or appended to)
Karen Gloria: The telescope was opened at 18:45 MDT.  The sky was
clear and the winds had calmed down from earlier in the day.  I
observed for PU01 and obtained some good images with SPIcam.  Nicole
King and rene Walterbos were on site to observe for NM04.  We had a
few problems of note.  *DIS had some problems keeping its cameras
cool, which necessitated delays between exposures for cooling cycles.
*We had some pointing problems as well, with magnasensor errors of
greater than 11 seconds on one move and a subsequent pointing
correction of about an arcminute.
Russet McMillan: During the first few hours of the second half, DIS
seemed to be maintaining temperature better -- then it started to warm
again.  One time it warmed but corrected itself before the exposure
was over; several times after that it took twenty minutes of cooling
to get the temperature back down.  When the forced cooling cycle
began, the chip would actually WARM about ten degrees before it
started coming down again.  The transfer dewar was NOT empty (48 lbs,
pressure 9 psi), but for some reason the nitrogen wasn't getting into
the instrument properly.  When I went up to check the dewar during a
forced cool cycle, I noticed that the nitrogen was only flowing
intermittently, not continuously.  By the end of the night, even
twenty minutes of forced cooling would not bring the temperature down
below 90 degrees.  I submitted a second problem report for this
problem, since Karen's report only went through email and not the
official reporting system.
By the end of the night, the transfer dewar WAS empty.  I filled it
after closing, but the temeperature on the red camera climbed to 201K
(the blue camera remained happy at less than 80K).  On Karen's
recommendation, I turned the cameras off to let them warm.
We saw a tracking problem on one occasion, when the object suddenly
moved across the chip even though guiding was on and appeared to be
working properly.  There were also pointing problems during slews,
with corrections of greater than an arcminute.
OBSERVER COMMENTS
We measured a read-noise on the red chip of about 30 electrons.
The double peaked histogram remains, with a difference between
the peaks of 32 ADU.
The pointing was off by an arcminute 2 times during the
beginning of the night, and by half an arcminute, once, later.
There were a few times when the telescope would skip during an
exposure.
                                 FOCUS LOG
                              OCTOBER 10 1998
                  Best      Telescope             Wind          Seeing
Time   Inst       Focus      Az  El   #Temp      Dir MPH  filt  FWHM "
19:55  SPIcam  -150(6541)   123  45.0  12.7/14.1    ???     r'   1.14
20:05  guider  51536(6535)  124  46.0  12.8/13.9    ???     R    1.45
21:22  DIS       0(6611)    125  84.0  12.4/13.3    ???    yes   1.17
#The first temp is air, the second is truss, both in degrees Celsius
Azimuth is measured from North to East
                                  WEATHER
                              OCTOBER 10 1998
                               Wind
     Time   Temp F Dewp F  MPH  Direction    Dust      Sky      Precip.
     16:01    64    32                                Clear      None
     17:01    60    26                                Clear      None
     18:01    59    27                                Clear      None
     19:01    55    24                                Clear      None
     20:01    55    25                                Clear      None
     21:01    54    26                                Clear      None
     22:01    56    25                                Clear      None
     23:01    56    20                                Clear      None
     00:01    55    18                                Clear      None
     01:01    55    18