I have now briefly reviewed the results of Hveto and Omegascan on 2/10~12. Scattered light glitches appear mostly in YAW and SUM of Yend's GR QPD. The number of times scattered light glitches appear in the PIT signal is much less than in YAW and SUM. Also, Yend GR scattered light glitches do not necessarily occur at the same time as scattered light glitches such as POP PD. In some cases, only one of the glitches may be seen.
I roughly estimated the frequency of scatter object by counting the number of scattered light glitches according to the previous report.
There are 7 turns over in 9.75 seconds from fig1. This means that the scatter object is moving about 0.359 Hz. For comparison, the frequency of scatter object was calculated from the scattered light glitch of the POP PD to be 0.433 Hz (fig.2). This frequency is almost consistent with previous scatted light glitch studies. This suggests that the scatter object of the Yend GR QPD scattered light glitch may be different from POP PD and others. One possibility exists for a Type-A Y TM-chain 0th eigenmode at 0.345 Hz. However, we do not know why scattered light glitch appears only in Yend and is not visible in Xend.
