craig.cahillane@LIGO.ORG - posted 03:49, Saturday 02 March 2019 - last comment - 15:30, Saturday 02 March 2019(47242)
Locking notes
Dan, Alexei, Georgia, Craig - FSS was refusing to lock after the 1 AM lockloss tonight, or losing lock soon after acquiring. The problem went away by itself after about 30 minutes. - Still dealing with 1 Hz ASC oscillation in full lock causing PRG and POP18 dippiness. Likely DHARD. - Lost lock three times at RESONANCE. We were losing after increasing the DHARD gains. Possible bad alignment heading into RESONANCE, I touched up the corner alignment and this help get through the fourth time. - Lock lock from 1 Hz ASC oscillation during power up twice.
If you are still having trouble with a 1 Hz instability in DHARD P, you could try reverting the change to the DARM loop that was made yesterday. The boost shouldn’t make DARM unstable, but DHARD does seem to be cross coupled with Darm.
The changes that Jenne and I made only happen in the state Lownoise ASC, so they would not be causing problems during power up.
If you do decide to try reverting the changes to DHARD P, you can search the guardian for “March 1” to find all the changes.