This is to help troubleshoot the excess noise measured earlier.

The following channels were measured at GPS times 1258586880 s and 1258597457 s, corresponding to low and high Power Recycling Gain (PRG) respectively.

Excess noise was seen between 25-110 Hz in the high PRG case when compared to the low PRG case in the following channels:

C1:LSC-CARM-IN1_DQ (shown in Attachment 1 where the reference is low PRG)

C1:ALS-Y_ERR_MON_OUT_DQ

C1:ALS-BEAT{X,Y}_FINE_PHASE_OUT_DQ

C1:SUS-ETM{X,Y} _SENSOR_{LL,LR,UL,UR}

C1:ALS-TRX_OUT_DQ

Surprisingly, it was also seen to a smaller extent in (refer Attachment 3)

C1:SUS-ITMX_SENSOR_{LL,LR,UL,UR} 

A different type of noise spectrum, attributed to known electronic effects, was observed for

C1:SUS-ITMY_SENSOR_{LL,UL}    (refer Attachment 2)

These did not show any significant change in the noise spectrum:

C1:LSC-DARM-IN1_DQ (shown in Attachment 1 where the reference is low PRG)

C1:ALS-X_ERR_MON_OUT_DQ

C1:ALS-TRY_OUT_DQ

C1:SUS-ITMY_SENSOR_{LL,LR,UL,UR} 

C1:SUS-ITMY_SENSOR_{LR,UR}  (refer Attachment 2)

Broadband noise in:

C1:LSC-PO{X,Y}11_I_ERR_DQ