Theodolite survey of dome from ao9 monument july03

Jul. 2003

links to plots:
The pitch, roll, focus errors (relative to the reflector) from the theodolite survey

links to sections:

09jul03: The theodolite results.


    The elevation rails were shimmed and the dome lifted 1.65 inches in feb03.  A theodolite survey from ao9 was done on 17feb03. This was before all of the final adjustments were done (see feb03 survey). A survey from ao9 to measure the shimming/domemotion results was done on 09jul03 followed by a nights worth of az, za spins using the tilt sensors. Below is a summary of the theodolite results. Pitch, roll, and focus errors as derived by lynn baker from the theodolite measurements are plotted. Lynn used the center of curvature as the reference (not ao9).

09jul03 The theodolite results   (top)

    A survey was done from ao9 on 09jul03 starting at  10 pm and going until 3 am. 2 za strips were done at az=242.87 and az=302.87 followed by two azimuth swings at za=5 degrees and za=15 degrees. The data was reduced by lynn baker and the pitch, roll, and focus error were computed relative to the reflector center of curvature (as computed by lynn). The tiedowns were left off during the measurements. The average height of the platform from the distomats was 1256.23 feet. The platform moved about .2 inches in height (up) during the 5 hours of the measurement. The pitch, roll, focus errors (relative to the reflector) from the theodolite survey (.ps)   (.pdf) are shown in the plots. The jul03 data is  compared with the data taken on 17feb03 (towards the end of the shimming).     The maximum pitch, roll error (added in quadrature) is about .12 degrees (staying above za=3). The focus error goes from about -1.8 to 1.8 inches. There is an error in the measurements caused by the drift of the platform during the measurements of about .25 inches. I guess i could take a linear ramp out of the focus error (with cos(za)) and ignore it's affect on the pitch,roll (or lynn could rerun the data...). We need to verify that the focus position used (center of the reflector) corresponds to the focus position that maximizes the focus curves. In the past they were off by 1 to 2 inches. home_~phil