The typical strong glitch that occurs about once per month, and already described in logbook entries 64928 or 64804, has occured again on 2025-01-29 around 12h13 UTC.
This is a large glitch occuring in NE mirror control signal Sc_NE_MIR_Z_CORR that introduces a glitch in hoft_raw. This glitch pollutes the TF used to do the online noise subtraction. This TF is updated every 4mn. As can be seen on the attached plot, the noise subtraction then introduces wrongly some noise in the band 8-40 Hz during 4 mn. Such event has variable consequences on h(t) (sometimes it does not deserve a CAT1 flag offline) but it is seen by gating, then by StochMon monitor (see here for instance). Origin of those Sc_NE_MIR_Z_CORR rare glitches are not yet understood. A protection on the online h(t) noise subtraction is currently under study.