The ALS system is iffy tonight.
After putting the cable back to the RF spectrum analyzer (it had been taken to test the frequency counter setup, and not put back), I had a good Yarm beatnote, but again this evening the Xarm beatnote is small. I touched up the PSL table alignment (very, very little needed, but it did double my peak height). I *think* that this is happening because we haven't settled into a good IFO alignment place, so the arm pointing keeps changing very slightly, which means that the PSL ALS alignment needs touching. Anyhow, even after alignment the Xarm beatnote is only -36 dBm at 81 MHz. It should be at least -25 dBm or so, although I haven't seen it any larger than about -35 dBm since the IFO beam was lost last Friday.
I am not able to hold ALS lock long enough to scan the arms and find the IR resonances. The only optics that I am actuating on this evening are the 2 ETMs. When I lose lock and look at the watchdogs, the ETMs are the only optics that have largeish numbers, which comes from the ALS lockloss. So, I don't think I am suffering from the ITM suspension kicks tonight. Rather, I think that it's that the ALS system isn't tuned up nicely.
I think that it is past time we tuned up and checked out the ALS PDH setup. Q: Can you please measure the loop TFs for both of the ALS PDH boxes tomorrow? At the very least we want to know what we're working with.
Evan: What is the status with the ISS?
I am going to try tomorrow to look at the suspensions, and see if I can track anything down. I feel like I see the kicks more often when the arms are locked, i.e. we are sending an LSC signal to them. The LSC POS signal is a factor of a few hundred larger than the damping SUSPOS signal is. Are we saturating something somewhere? Why is this a new thing? We certainly do see kicks when the LSC is not engaged, so this may not be the right path, but it is something concrete to look at.