M. Heintze, K. Izumi, T. Sadecki, J. Kissel

After a harrowing few days playing the alignment game, we've accomplished Michelson fringing with the ITM alignments, as measured by a centered beam through the SRM -- and moved the OFI into position such that this fringing is seen through the OFI. The only remaining IFO alignment task is to flash the DRMI with the IMC bypass, and alleviate IM4 bias which is now closer to saturation. Today was a good day. Blow-by-blow below.

Picking up where we left off at lunch (see LHO aLOG 12779), we
- Restored BS alignment to pre-vent value because it's the only optic whose alignment has been preserved from HIFO-XY. (P = +180, Y = -266)
- Re-checked PR3 and PR2 centering, and saw it mis-centered on PR2 (not because anything changed, just we didn't get it perfect before lunch)
- Walked IM2 & IM3 to bring input beam UP in pitch on PR2
- Tweaked IM4 in Yaw -- which is now *very close* to saturation, or will be after pump-down (LL = -93630 [ct] (71% range), UR = +95966 (73% range))
- Once we hit the center of PR2, we needed no further tweaks to PR2 or PR3 or BS -- the beam was centered on ITMX and ITMY and both X-ARM and Y-ARM paths hit SR3 and SR2.
- Blocked ITMY beam, centered X-ARM beam on SR2 and SRM (only small moves needed for SR3 and SR2)
- Unblocked ITMY, steered ITMY a little to get Michelson fringing at and behind SRM. GOOD!
- Saw beam missing OFI by ~300 [urad] of Yaw at SR2 
- While gathering OFI pusher materials, tried to get flashing of SRC with SRM alignment; got close but we were ready to move before we saw flashing. During this exploration, we increased the damping gains on SR3 and SRM to try and reduce motion. They remain high, but no need to keep them that way permanently.
- Moved OFI using pushers -- Front (closest to SRM) ~3/4 [in] (~20 [mm]) in +X, back ~ 3 [mm] in +X (so a slight translation in +X and a twist in -yaw) 
- Moved SRM AR Baffle ~1 [in] (~25 [mm]) in +X direction to center beam through aperture
- Reinstalled SR3 AR Baffle, setting dog-clamps to locations as defined by D1201315.
- As we left the chamber, beam is centered on SRM, at the input to OFI, and into HAM6 septum hole, with fringing visible all the way into HAM6.
WIN.