From: Russet McMillan
Subject: 3.5m Night Log 990724
Date: Sun, 25 Jul 1999 05:45:24 -0600 (MDT)
                          SATURDAY JULY 24, 1999
                         APACHE POINT OBSERVATORY
                              OBSERVING  LOG
                                                          ACTUAL
ASTRONOMER      OBSERVER(S)        INSTRUMENT   DATE   START FINISH
Duncan          Duncan             Echelle    7/24-25  21:44  03:56
Turner          McMillan           SPIcam       7/25   03:56  04:36
 INST        SCHEDULED     WEATH     EQUIP      OBS    DAY   NOTUSED
I/RS/DN    START FINISH   D    B    D    B    D    B   USE   D    B
UC03/R     21:44  03:56   0    0    0    0   6.1  0.1   0    0    0
PU02/S     03:56  04:36   0    -    0    -   0.7   -    0    0    0
(note: times listed include instrument change time)
                              ACTIVITY LOG
(* means a trouble report has been issued or appended to)
Observing specialist: R. McMillan
Another night of surprisingly decent weather, with excellent seeing
and only some moderate cirrus to contend with.  During the evening, we
had another example of a freeze-up in communications, very similar to
last night's incident, which was partially traced to the MC.  A proper
fix will need more time, but it appears that the hangup clears itself
after about five minutes.  The trigger for the freeze is not obvious;
it may be related to attempting to stop a slitviewer sequence during
readout.  Because of the good weather, we didn't have the opportunity
to play around with the slit camera to try to induce an artificial
failure.
In this particular case, it appears to have been set off by some
rather extreme observer abuse of the Autoexpose button, which is not
very robust to begin with.  However, there's no such obvious
explanation for the similar occurrence the previous night.  Tonight's
freeze occurred in the middle of a long echelle exposure, and the
telescope continued to track adequately, so no actual time was lost.
During test images, SPIcam showed more of the familiar diagonal noise
pattern, at a level of about 2 DN.  No noise was visible in the data
images.  Cloud camera images after 4 in the morning show an
interesting kind of haze developing.  While some of this might be
accumulated sediment on the mirrors (which should really be cleaned),
flux counts in the guider also reflected some sort of hazy
obscuration.  The dust levels were fairly steady during this period; I
don't know what we were seeing.  By dawn, some low clouds were
visible, but they seemed more distinct than what was on the cloud
camera.
                            OBSERVER COMMENTS
                                FOCUS LOG
                              JULY 24 1999
						 Wind
Time   Inst        Focus     Az  El   #Temp    Dir  MPH  filt  FWHM "
21:15  Echelle  -104(5844)   22  59 16.1/17.0  229   12   ND1  0.96
23:25  Echelle   -77(5788)  -10  62 16.1/15.3  240   10  clear 1.09
03:50  SPIcam   -140(6500)  189  60 15.2/14.1  264    7   R    0.71
#First temp is air, second temp is telescope.
                                 WEATHER
                               JULY 24 1999
                               Wind
     Time   Temp F Dewp F  MPH  Direction    Dust      Sky      Precip.
     16:01    67    49      7   264  (W)      879    ptly cldy   none
     17:01    65    47     12   201  (SSW)   1096    ptly cldy   none
     18:01    67    47      8   207  (SSW)   1192    ptly cldy   none
     19:01    64    48      5   255  (WSW)   1215    ptly cldy   none
     20:01    63    47      8   211  (SSW)   1096    mstly clr   none
     21:01    61    47     10   204  (SSW)   1174    mstly clr   none
     22:01    61    47      7   195  (SSW)   1249    ptly cldy   none
     23:01    61    46      5   230  (SW)    1322    ptly cldy   none
     00:01    61    46      6   228  (SW)    1439    mstly clr   none
     01:01    60    46      6   206  (SSW)   1677    mstly clr   none
     02:01    58    46      5   253  (WSW)   1699    mstly clr   none
     03:01    58    45      5   257  (WSW)   1737    mstly clr   none
     04:01    59    44      5   266  (W)     1696    mstly clr   none
     05:01    59    44      6   274  (W)     1596    mstly clr   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
> 1 micron per 0.1 cu. ft.
                             TELESCOPE STATUS
Primary, secondary, and tertiary mirrors in place and collimated.
Primary support system operational.  Mirror ventilation system in
place.  Telescope drives operational.  Current Remark version: 2.55b5.
Current guide software version: GIm Ctrlv3.0b27.
- Russet McMillan