Evan, Lisa

Evan started locking early in the afternoon.

He collected 10+ successful locking sequences in a row without manual adjustment (WOW!), see first plot. 

However, in order to keep the interferometer locked on the operating point, he had to open most of the alignment loops, keeping closed only DHARD and BS. We realized later that it was due to some low frequency oscillation in the CHARD loop, which was triggered by closing the SRM/PRM loops. We decided to keep those loops opened for now.

We then realized that the power build up has been consistently low for a while (second plot - the beginning of the plot corresponds to  March 9 , when a manual adjustment of the ITMs brought the arm power to its maximum ~ 1100 counts), so we decided to go through the initial alignment and re-look at the ITMs position..and an earthquake happened..


P.S.: All of the above happened with DARM locked on RF.