K. Izumi, J. Kissel, M. Heintze

Picking up from where we left of yesterday, we were able to confirm full DRMI flashing with very little effort. However, upon moving towards mechanically relieving IM4 alignment biases, opening the WEST side of HAM2 bumped the IMC bypass path once again. Rather than repeat all-day yesterday, we've elected to move on -- begin the close-out process for HAMs 4 and 5, and BSC3, resume IAS alignment of ITMY reaction chain and use the *misaligned* bypass beam as a reference (using REFL WFS A and B DC signals in HAM1). We're half-way through getting IM4 de-biased, feeling lost in the weeds, and finding out again how terrible it is to balance these SUS. But we'll get it back, or die trying.

Blow-by-blow
- Went into HAM5, took a look at SRM found no beam
- Found SR3 offsets and damping off. Turned on SR3 offset and found spot and fringing immediately, with some SRM flashes
- Move to aligning PRM to get PRMI flashes, tweak alignment by removing Pitch offset (from P=-505 to P = 0), and going from Y=-408 to Y=-395
- Also saw good spots on REFL WFS A nd B DC
- Also saw good beam on ISCT1.
HAPPY HAPPY!

- Vote to declare DRMI flash victory and move on to IM4 de-biasing
- Went to HAM2 to check on REFL path going into HAM1, before debiasing, because we plan to use REFL WFS path as reference
- Found REFL beam mis-centered/clipping ALIGO IO STRAGHT HA13 baffle (D1101416) in REFL path, just before going into HAM1.
- Found beam is mis-centered in yaw only on PR2 and behind SRM.
- Conclusion: In opening and closing WEST side of HAM2, cover bumped Bypass mirrors again. 
FECAL MATTER.
- Since we see only a yaw badness, we hoped it was just one mirror that was bumped. 
- Attempted to recover by moving temporary bypass mirror 2 (the one closer to MC3) by just glancing the yaw knob, using alignment on IM4 TRANS QPD as a reference but returning IM4 trans to correct yaw did not regain PRM reflected beam at PR2 or SRM, and moving PRM by gross amounts made no difference. 
- Conclusion: both mirrors got bumped.
VERY VERY SAD.

DECISION / MOTIVATION TO MOVE FORWARD
- Given that we have seen DRMI flashing with well-aligned bypass beam, we know that all core optic suspensions are in the right place (within range of OSEM control).
- PRM only needed moving 10 [urad] in yaw and 500 [urad] in pitch from pre-vent alignment to get DRMI flashing with well-aligned bypass.
- (before opening WEST side of HAM2) We saw PRM REFL beam on REFL WFS DC and on ISCT1 (with well-aligned bypass beam).
- REFL path is determined entirely by IM1 and IM2. We know we have pitched UP IM2 (to bring beam UP on PR2 and IM4 TRANS after IMC realignment of MC1 to get good IMC flashes after MC2 2 [mm] move), but we have NOT moved yaw at all. So *real* IMC path (not bypass) should still be aligned out to REFL path 
- With the now-bumped by-pass path, we see good light still on HAM1 REFL WFS, and on IM4 TRANS QPD. So, we still have a good reference for debiasing IM4, regardless of whether its still aligned to the DRMI.

- Captured WFS REFL DC alignment references with PRM aligned to this morning's flash
- Began following instructions in E1300646
- Trouble with IM4 baffle. 
	- need to remove baffle to get at lock nut that releases pitch adjuster.
	- difficulty removing baffle
	- LHO aLOG 5633 helped determine that we needed to loosen bottom EQ stop brackets on front face to remove baffle
	- Got it off eventually.
- Began debiasing IM4, but immediately found that pitch adjuster and lock nut are fighting each other, and even worse -- pitch debiasing is causing YAW motion, as determined by the OSEMs on IM4.
- Right now, decided to take a break because we've lost the beam on REFL WFS, we're off in yaw after adjusting only pitch. So right now our only metric is the OSEMs. Deep breaths.