As Ryan C notes in alog 70003, "IX12 & IY8 damping have changed phase, a negative gain damped IX12 down (-2, max of -4) instead of the +2 its set to in lscparams. IY8 also was rising, I changed its gain sign from 0.08 to -0.08 and it started to fall".
Both these modes have been falling well since but our troublesome ITMY Mode5/6 pair have been slowly rising. See attached. I first suspected the IY8 phase change could be causing this to turned the IY8 damping off for 20 minutes. IY8 stopped damping but IY5/6 continued to rise. I've now turned off the mode5 damping, will see what effect this has as I'm worried about adjusting it's phase.
ITMX: On Sunday 28th, Tony notes IX12 is ringing up 69972. Since then, operators have changed gain from +2 to -2 by hand (69973, 69994, 70003). I've updated this in lscparams but cannot reload violin damping until we are out of observing.
ITMY: On Monday 29th, Tony notes IY5, IY6, IY8 are ringing up 69991. He turned off the IY5 gain as I did, this stabilizes them but doesn't damp the modes. I've added this into lscparams to avoid ringing these up until we find damping that works. Plot of IY5/6 today attached. Tony turned IY8 gain to 0 but Ryan C found that -0.08 damps well so I'll add that to lscparams too.
We lost lock and I reloaded VIOLIN_DAMPING guardian so these lscparams changes (IX12 +2 to -2; IY5 +0.01 to 0, IY8 +0.08 to -0.08) will be in the guardian.
