Date: Fri, 27 Aug 1999 23:31:43 -0600
From: "s. a. snedden"
Subject: 2.5m obslog 990827 (MJD 51419)
                        Friday August 27, 1999
                              (MJD 51419)
                   Apache Point Observatory SDSS 2.5m
                           Observing Log
Tonight's Observing Team:
                Ellyne Kinney (APO)
                Jeffrey Hayes (APO)
                Stephanie Snedden (APO)
Tonight we planned to test the MCP and assist Connie in collimating the
primary. The weather cleared out enough by 20:00 to allow us to open.
After some initial problems with the laptop (a loose ethernet plug
connection, as it turned out), the telescope was slewed to zenith and
the engineering camera was installed. Cartridge 1 is now stored on the
rack in the support building.
**Please note that the spectro 1 door sticks out and catches on the slit
head during cartridge change. The door has to be manually moved anywhere
from 2 to 5 cm. This needs to be fixed. Also, when trying to close the
spectro 1 door after the cartridge was removed using the MCP menu, we
got the error message that the door was in an "inconsistent state", and
could not get the door to close using the MCP. We finally closed it
manually.
Also note that the MCP locked up at approx. 21:45. We tried a soft
reboot, but it did not work. A hard re-boot was needed.
We set the counterweights to 320 (which felt balanced at zenith). As we
were bringing the telescope down from zenith in order to set the
altitude fiducial, we heard a grinding noise from the area of the
windscreen drive. Telescope motion stopped, then reversed direction and
ran away toward the zenith. This occurred at an altitude of about 40
degrees. We tried changing the counterweight values to see if it was a
balance problem causing this, but it had no effect. We noticed that the
windscreen drive chain seemed very taut and tried pinching the links
together to check for play in the chain, but could not get them to
budge. We also noticed that the Belleview washers had gaps, spaced
regularly, every 6 to 8 washers apart. In the end, we brought the
telescope down with the pendant and closed up. The counterweights were
left at a setting of 250.
The weather was partly cloudy with lightning on the south, west and
north horizons. Wind was from the ESE at 15-20 mph with gusts to 25 mph.
Humidity was around 50% and the dust count was about 300. The
temperature was mild, about 60 degrees F.
We closed at about 22:30.
Jeff, Ellyne & Steph