Instability in Telescope Trajectories as Elevation Approaches Horizon

On the afternoon of 05 February, Tom Sargent and Dave Ashby were working with the LFBG rotator when they noticed it was oscilating back and forth. By the time Michele got involved, the rotator was humming along nicely again. Michele pulled the PCS recorded trajectories from the mountain; she found some interesting features in that day's data, as well as data collected over the next three days. It should be noted that after a night of observing, the three axes of the telescope are typically put into a hold state. On this day, the rotator had not been put into hold, so it was free to follow the PCS tracking polynomials. The PCS is typically left running; it will continue to track the last observed target, even as the target sets and rises.

-- MicheleDeLaPena - 10 Feb 2009