[Keita, Louis, Caroline, Elenna]

We are much closer to getting the 3f transition. We have confirmed we can swap PRCL from 1f to 3f while maintaining the same gain (no need for a factor as in 89567).

We have also confirmed what the 27I matrix value for SRCL needs to be to subtract PRCL from the error signal (2.7). We still need to test the 135I input matrix value by putting it into a blank matrix row, but we think it should be roughly -4.

We still have yet to to figure out what the MICH matrix value needs to be, but we think if we follow the same procedure as we did for SRCL, we can get there.

Regarding the DRMI ASC, we have not been successful in putting together a good MICH ASC signal. Unlike PRMI, the AS B RF45 signal is not going to work, but it looks like neither does the AS A RF45 signal. We might need to do a full sensing matrix and then use both sensors to construct a sensible signal. We could also check the AS 36 signals in case they are better.

I checked the air 3f phases and changed them slightly while running a PRM line to maximize PRM in I for both 27 and 135. Attached are screenshots of my measurements and SDF. I first started checking the phases while the SRCL mode hop offset was on, but then I turned it off. With the offset off, the phasing still looks fine.

We have also noticed the SRCL gain seems low by a factor of 2 (with nominal -33 gain from guardian). This is based on the idea that we want SRCL to have a UGF closer to 30 Hz. We don't think this is causing much of a problem right now, but it's something worth checking out and maybe guardianizing.

The MICH OLG still looks very strange, so there must be some cross coupling somewhere, but it's hard to tell what because the air 1f phases look ok, or at least Keita says "it's not wrong".

Unfortunately the day ended a little roughly, because suddenly we went from having very stable long DRMI locks to short locks that ring up quickly. Nothing on our end changed, so we don't understand what happened.

Procedure:

• We can run through the PREP DRMI ASC state in ISC DRMI. After that state completes I manual to ZERO 3F OFFSETS
  • want to clarify that we tried letting the 3f transition state run once, and it failed, so we started working through it carefully loop by loop
• I manually put in the PRCL matrix value of -1.22 into REFLAIR 27I, set REFLAIR 9I to zero, and ramp the LSC input matrix.
• Louis and I checked the PRCL-out-of-SRCL value by measuring an SRM injecting in both REFLAIR 27I and 135I. We calculate that matrix value should be 2.7.
• Based on transfer functions between SRCL on air 1f and 37, we know that there is a sign flip between the 1f and 3f signal. We also think the gain is closely matched, but we aren't sure, and we want to check one more time before trying the switch.

Additional locking notes from the morning:

• Started with initial alignment, trended ITMs top mass osems to make sure there has been no significant shifts (oplevs are out right now due to GVs being closed)
• Locked PRMI, engaged MICH ASC following Keita's steps (91976).
  • MICH ASC for PRMI is now guardianized properly in ISC_DRMI, will run in PRMI ASC
• DRMI locked, I walked through the entire "DRMI locked" state by hand and everything engaged properly!
  • Did not check UGFs of LSC loops
• moved to DRMI WFS centering and started moving the BS around to check the MICH ASC error signal, may have caused a lockloss moving the BS too much in yaw
• [beckoff restart, meetings, etc]
• I rechecked the alignment, and we relocked DRMI. The alignment required a lot of touch up by hand. Howver! I was able to run all the way through to PREP DRMI ASC no problem
  • with touched up alignment, POP18 is 92, PO90 is 2.5
• MICH ASC error signal does not look right
  • both pitch and yaw do not maximize/minimize POP18/90 when crossing zero
  • Keita is checking AS WFS 45 phase
• Elenna checked REFLAIR 3f phases with PRCL line, small changes made it better (10 and 20 deg)
• PRCL 3f transition is fine