Abstract:

There are two lockloss due to the drift of PR3 pitch, which implies that PRC2 PIT ASC becomes unstable again.

Detail:

We succeeded to reach PRFPMI_RF_LOCKED with new fiber laser.
At this moment, we achieved RF lock two times but the lockloss for both of them seemed triggered due to PR3 pitch alignment drft.
Figure 1 and 2 show the alignment of XARM when the two locklosses happened (2025/10/16 04:11:05 UTC and 2025/10/16 05:47:21 UTC).
Left and right T cursors show the time when starting PR3 pitch drift and happening locklosses.
In both cases, PR3 pitch drift seemed to start well in advance, which implies that the instability of PR3 ASC.