It seems like DHARD_Y has better SNR than DHARD_P to see peaks around 45 Hz. Interestingly, POS_SPOL also sees this motion (could be due to ITM birefringence). See attached. These channels would be useful for noise subtraction as well (sadly, they are 256 Hz DQ channels). See attached for noise subtration result using DHARD_Y with simple bandpass filters around these peaks.