After about 9 hours of being down, we are now in Observing. BUT we are not is our normal configuration setting. Here is what worked/changed:

• Saw that the ASC PRC2 was pushing PR3 and kept running away with the lock. This is a sign of bad alignment so I did an Initial Alignment.
• We played with blends in different configurations and tried to change them while in DC_READOUT(partially unsuccessful, read below for more). The 45mHz blends seemed to work best with this high useism.
• Kept the SOFT loops in Low Gain (accepted in SDF). These are normally changed to high gain in the ENGAGE_ASC_PART_3 step in the ISC_LOCK Guardian. We did not edit the Guardian with these new settings, we just manuvered around in manual and did some by hand. Sheila suggested that we could turn them to high gain later in the locking sequence, but risk dropping the lock. So after waiting in NLN for ~10min, we decided to leave them in low since the range seemed just as stable and the glitches were not any more frequent.

The current configuration settings that are different than our normal are: SOFT loops in low gain and BSC blends at 45mHz. Future operators may need to change these back for future locks, depending on conditions. (OpsInfo tagged)

More on the blend switching

The 90mHz blends seemed to not do well with the ALS during the high useism. Looking at the ALS X/Y power on Striptool, there is visible movement in the power while in the 90's, but not while in the 45Hz. After the the Engage ASC steps, it seemed as though the 45's would become unstable. Sheila thought that the 90's may be better after we have transitioned off of ALS, so we thought to try to switch blends after getting to DC_READOUT.

When we got to DC_READOUT I first changed the ETMX X blend from 45 -> 90. This worked with some disturbance seen in AS90. I moved on, with Jim W giving me some advice, and changed ETMX Y to 90. This also didn't drop us out of lock, but the AS90 trace wasn't getting any better. Next ETMY Y -> 90, same as the last two. And finally what did us in was ETMY X -> 90. Not sure if it just couldn't hold the instability anymore or if that particular dof just didnt agree with the change.

Since the ends were in 90 and the CS was in 45, I figured let's try it like that. ALS power looked slightly better than with 45 all around, but much more jagged and not as consistent of an oscillation as with all 45's. This configuration couldn't make past the first couple of steps, similar to all 90's.

Switched back to 45's and stayed here. When we got to DC_READOUT the next time all seemed well and we moved on to NOMINAL_LOW_NOISE.