Tonight the COMM handoff is stable even without the OpLev damping on.  This is interesting because we have farily high microseism (above the 90% percentile all night) so it is possible for us to have a good night even with high microseism. 

I was able to make some measurements of the COMM noise with and without the oplev dampng on, and it seems that the OpLev damping helps.  I repeated the measurement twice, the second time the ground motion was larger.  The RMS down to 0.02 Hz was reduced from 300Hz to 144Hz the frist time, and from 600 Hz to 235Hz the second time.  In this calibration I have removed the cavity pole at 42 Hz.  ( This file is saved in sheila.dwyer/ALS/COMM/COMM_Noise_March27.xml)

I also tried reducing the gain of the ALS COMM loop.  Since 18dB gave us a 35 Hz ugf, I turned off the common comp and moved the gain down to -2dB, where we should ave a ugf of 350 Hz.  This reduced the gain at high frequencies, but there must be an instability around 10Hz in this configuration.  A screen shot is attached, and the data is saved as COM_Noise_March27_reduce_gain.xml

I have now turned off the OpLev damping so Fabrice can have some data to look at without damping in the morning.  I plan to leave the guardian locking the arm on IR over night. This should be usefull data for anyone from DetChar who wants to look at the arm locked on IR, or seismic.