After seeing the reflected spots on the PSL Quad display this morning and the "ISS diffracted power low" notification, since no one was using the beam today I performed a remote beam alignment tweak for both the PMC and RefCav. I started shortly after 10am, after Masayuki and I finished his PMC measurements and sufficient time had passed for the PMC to recover. The PMC Refl spot looked brighter on the left side vs. the right, indicating a potential alignment shift in yaw, while the RefCav Refl spot looked like it needed a pitch adjustment.
Starting with the PMC, with the ISS OFF there was ~103.3 W in transmission and ~25.0 W in reflection. Tweaking beam angle (entirely in yaw as expected based on the Refl spot, pitch adjustment acheived nothing) resulted in ~105.2 W transmitted and ~22.7 W reflected; walking the beam got things a little better, with ~105.5 W transmitted and ~22.3 W reflected. Seems this drop in PMC transmission was due to a slow alignment drift as the enclosure recovered from our NPRO swap ~10 days ago. With the ISS ON and diffracting ~3.8% (I had to adjust the RefSignal to -1.97 V from -1.95 V due to the increase in PMC transmission) the PMC is now transmitting ~105.7 W and reflecting ~22.4 W.
Moving on to the RefCav, with the IMC locked the RefCav TPD was ~0.79 V. Adjusting the beam angle got things a little better, with a TPD of ~0.82 V; as expected this adjustment was almost entirely in pitch. While walking the beam alignment the IMC unlocked and was having a hard time relocking, so I asked TJ to take it to OFFLINE while I finished the alignment; I note this as with the IMC unlocked the RefCav TPD is generally a little bit higher than with the IMC locked. With the IMC now unlocked I was able to get the RefCav TPD to ~0.86 V by walking the beam alignment. While I was not able to get the TPD higher than this, the Refl spot on the PSL Quad display still looks like there's some alignment work to do; the central spot is usually centered in the ring that surrounds it, but now it looks a little low and left. I don't have an explanation for this currently, we'll keep an eye on this in the coming days and see if/how things change. TJ relocked the IMC and it did not have a problem this time.