Varun, Sheila, Jenne, Dan B, Georgia

Arm Alignment:

Thinking about the observations from last night alignment work, it sounds as though the X arm camera is not a good reference for our alignment from before the vent.  To summarize observations after the alignment of the X arm to the camera reference yesterday:

• ITMX oplev and sliders indicated it was off in yaw,
• ETMX was also different than before the vent, and
• PR3 was moved according to both its OpLev and sliders,
•  the diff beatnote was misaligned. 

This morning Varun and I moved ITMX back towards its alignment at the end of O3a, according to the sliders and oplev, and let the green WFS run to ETMX and TMSX, which ended up in more similar alignment to where they were in O3a, we moved PR3 back to where it was in O3a and this recovered the X transmission diode and the COMM beatnote.  Then we realigned the beamsplitter to get the DIFF beatnote and MICH fringes to look OK, we have COMM at -2dBm and Diff at -13dBm.  

Vertex alignment (AS_C centering):

• We struggled for a while to get IR aligned to the X arm after this, we aligned by hand carefully and Jenne found that the power normalization was set for 10W, although we only had 2W input.  (We aren't sure why that happened, the power adjust guardian normally takes care of that). 
• We had an easy time with the input alignment, MICH, and PRX. 
• Varun the sliders for SR3 back to their alignment from O3a, which restored the optical lever.  Varun also checked the top mass witness and sliders for SR2.  (sliders at 962 for P, 260 for Y)
• I ran AS centering loops and monitored the sum on AS_A and AS_B while moving SR2 to look for clipping on the OFI.  For pitch the sliders can be between 1180-870 without clipping, for yaw we get clipping at 438 and at 127 we start to rail OM2.  
• We decided to use the slider values from the end of O3a, even though we are off center on AS_C, we are suspecting that this is not a good reference after the septum window change, so we aligned SRM by hand and skipped SRC align. 
• Both PRMI and DRMI locked without much issue, PRMI asc worked well. For DRMI we manually set offsets in AS_C, and we have now let all the loops except SRC1 come on with the gaurdian, which is working OK.  SRC1 Y error signal seems fine, but pitch does not have a good zero crossing.
• Drmi acquisition has been fairly fast, we 5 or fewer minutes each time.

Seismic things:

• We had some difficulty with locking ALS, mostly because ETMX pitch was swinging by ~1urad.  Once everyone left the VEA and Jim changed us to 90mHz blends, ETMX was much quieter.   Jim has made a new state in SEI CONF called "UGLY" which does this configuration (52686).  We can use this for situations where the EX BRS is not working, the wind is low and the microseism is moderate.  Jim has also asked for help with getting the BRS running again.  
• This morning Jenne and Jim found some kind of error in the configuration of the corner station, which was probably the cause of the unstable PRMI locks last night, and fixed it.  Things look much better now. 

Carm offset reduction:

We had no issues with the TR_CARM or RF DARM handoffs, but lost lock a in the later CARM offset reduction stages.  

• Try 1: We made it to CARM_OFFSET_REDUCTION, but the guardian wouldn't move on because the calculated carm offset for the transition to Refl 9 was out side the limits, meaning the recyclying gain is unually low.  I attempted to move CHARD P but we lost lock.  
• Try 2: We lost lock after a couple of steps in CARM_OFFSET_REDUCTION, didn't get to the point where the guardian checks the drop in REFL before we lost lock.
• Try3: Tried to do the first steps of CARM offset reduction manually and adjusted CHARD alignment which increased refl power slightly.  As the alignment improved things started swinging more and we lost lock.
• Try4: Tried to go through the CARM_OFFSET_REDUCTION state using the guardian again, but this didn't work.  Edited the gaurdian to pause at the step where TR_CARM offset is -20 if the recycling gain is bad, so that we will have a chance to try aligning there.
• Try5: Even stopping at a TR_CARM offset of -20, DHARD was moving a lot and saturating suspensions.  It looks like we need to stop earlier and really try to align better.