Evan H, Sheila, Elenna, Nutsinee, Dan B

After maintence wrapped up we tried to relieve the OMC suspension so that our OMC ASC will work. 

The idea is that the beam hitting OM3 is set by the AS centering loops.  Without OMC suspension drives there are three things that can be adjusted to set the alignment onto the OMC QPDs, AS_A + AS_B DC offsets and OM3 pointing.  I first attempted to set OM3 to zero the error signal from OMC QPD A, then move AS_A offsets to bring the beam on OMC QPD B towards it's set point.  This sort of worked, I moved H1:SYS-MOTION_C_PICO_C_MOTOR_1_X_POSITION by from 6500 to 4438 to move the beam on AS_A up (This was a larger move than we could test out using offsets in the AS centering loops).  After turning the AS centering back on and readjusting OM3 poniting for OMC QPD A, this at first seemed to help bringing OMC QPD B closer to it's set point.  As we got close to zero this strategy stopped working well. 

Evan then adjusted OM3 sliders and AS_A and AS_B offsets simultaneously to zero the OMC QPD error signals (the OMC QPD offsets are actually in two different places, but we zero the error point after all offsets are added).  At this point things were close enough that offsets in the AS WFS DC could bring the OMC QPDs to their zero points, in combination with OM3.  Evan then turned off the AS centering loops (but didn't clear the history on the OMs) and used the AS WFS pico's to bring the beams to the center of the AS WFS.  We were then able to engage the AS centering loops and use the normal OMC QPD ASC without saturating the OMC suspension.  

When we relocked the IFO, the guardian locked the OMC and we went to DC readout without difficulty and without saturating the OMC suspension.  We didn't relieve the yaw offsets so there is still a yaw and longitudnal drive (yaw drive is feedforward to long) that use up half the range on LF and RT osems.  

Edited to add:  There is an ndscope that is useful for this exercise in sheila.dwyer/ndscope/OMC/pico_AS_for_OMC_QPDs.yaml