I performed the lockloss investigation for the lockloss which happened between 2025/10/16. The previous lockloss investigation was posted in klog35276.

• 1444666741.4375 (duration 17915 s)
  • As reported in klog, K1:ASC-PRC2_P_OUT_DQ shows the drfit from +0.5 to -1.5. (fig1)
  • K1:ASC-DSOFT_P_IN1_DQ shows the oscillation just before the lockloss with 0.039 Hz. (fig2)
  • The ASC controls for arms were stable.  
• 1444670416.3125 (duration 928 s)
  • This lock was not enough long. So the drfit of PRC2 PIT was not related to the lockloss.
  • The IR trans gradually droped over 12 s.
  • no earthquake
  • Figure 3 shows the large amplitude on K1:LSC-DARM_OUT_DQ at -30s. K1:ASC-DSOFT_P_OUT_DQ shows the coincident behavior (Figure 4). The similar behaviour can be seen in PRCL (Figure 5).