From: "S. A. Snedden"
Subject: 2.5m obslog 990814 (MJD 51406)
Date: Sat, 14 Aug 1999 23:31:55 -0600
                                SATURDAY AUGUST 14, 1999
                   APACHE POINT OBSERVATORY SDSS 2.5m
                                      OBSERVING  LOG
 Observing team:
 Steph Snedden (APO)
Just like last night, the agenda for tonight was to slew in all three axes
simultaneously with the TCC. Several test slews were made, some over very
large angles, and the telescope performed well. I then allowed the telescope
to track for long periods of time. Tracking appeared to work well. Alan
Uomoto suggested I let the telescope track near the zenith for a while,
which I did. As the telescope tracked across zenith, it started moving in
the azimuth and rotator axes, which may have been normal as the object had
just transited with a 90 degree altitude, however a strong vibration also
started in the altitude axis. At this point, I hit an e-stop. It would
probably be a good idea to track near zenith again, and let the telescope
complete its motion, if the vibration is not potentially damaging. Alan and
Scott had mentioned that the rotator vibrated when tracking near the zenith,
in the past. I did not notice this tonight.
The weather was mild, (60-65 degrees F while I was working), with 20 mph
winds out of the southeast. Gusts went to 25 mph. Relative humidity ranged
from 40-50%. The dust count went from about 1200-1600
while I was working. The skies stayed partly cloudy, with thunderstorms far
away in the WNW.
Steph