Daniel, Alexa, Keita, Arnaud, Sheila

Tonight we measured the same noise spectrum of the normalized arm PDH spectrum that we measured tuesday night, with the WFS on at low gain.  The noise was not improved, it even seemed worse. 

We then tried feeding the normalized PDH back to the CM board though input 2.  With a gain of 18 in -500 in REFL_DC_BIAS and 0 in the CM board Input 2 and positive polarity.

We saw that the error signal was supressed.  The transfer function we measured for this loop didn't make sense, we measured a ugf of 500Hz and 180 degrees phase.  We weren't able to calibrate the nosie spectrum we then measured, not trusting the measurement of the loop gain. 

The transmitted power fluctations were reduced by adding the feedback from the IR, but still fluctuated from 1 to 0.5, at around half a hertz. 

The IR was locked to the cavity starting at around 6:30 UTC, most of the time until the ITMX ISI tripped at around 7:30  UTC.  I reset the target offsets before bringing it back up, after which Alexa realinged the cavity by moving ITMX 2.5urad in pitch.  Trying to bring it up I tripped it twice more trying to reengage the Tcrappys (even though everything was green, it seems we need to wait until the number are around a few hundred.) Arnaud brought it back by switching to Tcrappy one DOF at a time on stage 2, and sensor correction is now left off.