We checked the coherence using data from the Silent run state on April 14, 2025.
The witness channel used was K1:LSC-REFL_PDA3_RF45_I_ERR_DQ.
The coherence between the strain channel and this witness channel, from GPS time 1428686616 to 1428687640 (1024 seconds), is shown in Figures 1 to 4. In Figure 3, high coherence is observed at 240 Hz, 300 Hz, 360 Hz, 420 Hz, and 480 Hz.
We plan to apply noise subtraction to these high-coherence frequencies to see if we can reduce the coherence between this witness channel and the cleaned strain channel.
