Jenne, Young-Min, Ansel

 

Two issues raised by today's DQ shifter (Beverly Berger) were followed up.

 

Issue 1: The IMC bit was red, despite being locked. Beverly noted that the WFS control bit was also off, which seemed to be the underlying cause.

 

Follow up: The gain on the IMC WFS was changed from 0.1 to 0.04 on Nov 5 (alog 31246). This caused a threshold test against H1:IMC-ODC_WFS_GAIN_GT_EQ_TH to fail. To fix this issue, Jenne simply changed the threshold from 0.099 to 0.03 . 

 

Issue 2: Under ISC > LSC Saturations, Beverly noted that REFL 45 showed dark red during the lock around 15:00 UTC. It was not immediately clear what this meant.

 

Follow up: It appears that the rms for REFL A RF45 was considerably larger during this lock than the previous one (summary page plot, note difference between 15:00 and 11:00). Jenne tracked this down to PRCL1 FM3, which boosts gain below 10 Hz and was off during the lock stretch in question, unlike the previous lock. It is not clear why this happened, but during O2 something like this should be caught by the SDF difference monitor (the observe .snap file is set correctly, and a lack of FM3 would register as a difference).