Sheila, Jenne, TVo

When locked on PRMI, Sheila noticed an odd oscillation that was prevalent in PRX and even in single bounce off ITMX.  We noticed that SRM was saturating its DAC even though we had misaligned it and left it damping for at least a few hours. We ended bringing the SRM to SAFE and then to MISALIGNED. The damping loops started to ring up again and there was still a lot of motion going on. So the culprit was the MISALIGN settings were too high and in the wrong direction for the SRM alignment offsets we had gotten earlier to get SRY flashes.  

We were able to catch this using Jenne's new SUS saturation monitor in the control room and we flipped the sign of the misalignment test filters to fix this problem.  It might be worth investigating the linear position of the flag on the individual OSEMs so that we can make sure they're not too far away.  Sheila took a spectra (attached) that shows a shift in the 20hz line to about 22hz between the misaligned and aligned states.

One thing to take away from this is that SRM's alignment offsets to get SRY flashes is pretty close to railing the DAC because we moved SR2+SR3 to center on AS_C and AS_A/B.  That being said, we moved the AS_C picomotor a few weeks ago because we couldn't find it, which means it's not a very good reference to use for alignment anymore.  We can try walking the beam  with SR2+SR3 to relieve SRM while trying to move the picomotor to maintain an alignment on AS_C