Coherence from last night lock at 60W, with the correct 2.1 gain for the SRCL FF:
https://ldas-jobs.ligo-wa.caltech.edu/~gabriele.vajente/bruco_GDS_1371427218/
- Lot of coherence with SRCL, limiting below 40 Hz, and with MICH, would benefit from LSC FF retuning
- Some coherence with PRCL too, maybe we can see if we need a PRCL FF after SRCL and MICH are tuned.
- Some coherence with CHARD_Y, woul probablt benefit from tuning A2L like in 69082
- jitter is still important at higher frequencies, we should push on the online subtraction
- Also coherence with HAM1 signals: X, Z, RX, RY
With the improvement of HAM1 FF and the ITMY A2L gains (70730, 70727), there is a reduction in CHARD and DHARD coherence. The attached plot shows the coherences after these changes. I think this indicates that these changes were good, and we can probably claim we are not limited (much) by ASC noise right now. The biggest contender for coherence is DHARD Y, but that is mostly below 10 Hz. We would probably also improve the coupling of CSOFT P slightly by dropping the gain back to 20 (discussed and agreed in commissioning meeting).
Here's how much could be ganed with MICH and SRCL subtraction (or better tuned FF) and with jitter subtraction
