LWS
News Update for 31 Oct 1998

LWS in its Laboratory Handling Cart

First Night Sky Commissioning Run A Success!

LWS had its first night sky testing on the Keck I telescope 31 Oct 1998, Halloween, and 01 Nov 1998. Many of the scheduled engineering tasks were completed and much progress was made towards commissioning the instrument. Accomplishments include:

The run was deemed successful as many goals were achieved. Of course not all was perfect and few problems arose. In particular, a baffle in the LHe fill neck designed to damp out He oscillations became frozen in place on the second day of the run. The LHe was venting ok and thus not a safety risk to the instrument or personnel . The frozen baffle did prevent getting more LHe into the dewar. Using what LHe remained in the dewar we proceeded with observing and were able to work for several hours into the second night. The dewar held for > 30 hours exceeding the 24 hour specification. There were some other problems encountered include glitches the chop-nod operations.

The next run is scheduled for 02Dec1998 and 03Dec1998. The frozen baffle problem and chop-nod irregularities will be among the priority tasks to work on for the next run.

Images and Data From First Commissioning Run

11.7 µm LWS image mosaic of Saturn

This false color image has been enhanced.

Primary Mirror Focus Mode Image Mosaic.

Chop-Nod Guiding Performance.

The Plot shows the X (top) and Y (bottom) centroids on LWS while tracking a bright source, Beta Peg, for about 1 hour during transit. Images were written to disk at a rate of 1 Hz during the acquisition of 4 seperate fits files. The plot shows a minimum scatter of about 0.1 arcsec with occasional increases in guide errors possibly due to chop-nod operations. There is also some longer term errors perhaps caused by differential flexure between LWS and the guider.

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Last modified: Tue Feb 2 14:45:18 HST