I believe that the 17 Hz broad structure on SIDE is just because of a bad rotational angle of the SIDE OSEM.
The same structure had been observed on the EMTY_UR, and the structure became narrower after we repositioned/rotated the OSEM yesterday.
My guess is that the SIDE OSEM is now in a place where the OSEM is quite sensitive to the bounce mode
and creating the broad structure due to a bi-linear coupling between the bounce mode and low frequency signals.
There is something defintely wrong with the side sensor. It might be the electronics as it also has this problem with it slow channel readings (my previous elog today).