Pep Covas, Sheila Dwyer

Earlier today we added some notches to top mass damping and ASC loops to try to address some of the lines in DARM Pep writes about here: 48947  We went through a similar exercise in 2016, some links are included here: 31553

We found that the 40.9Hz HSTS resonances weren't notched in the ASC signals sent to PRM, PR2, SRM or SR2, so Pep added notches to all of those loops in M3 LOCK P and Y. 

We also suspected that the 46.09 Hz line might be an HLTS resonance, in the resonance wiki they are predicted to be at 44.73Hz, but we weren't able to find measurements.  Pep added notches for 46Hz to the top mass damping for both SR3 and PR3.  

We also looked around a bit for something that could be done for the 27.7 Hz line, in the wiki the closest frequency is MC2 but it is not an perfect match.  One thing that we can try is adding HSTS notches to the MCWFS loops, which are currently missing them.  

It seems as though this has helped with the 46Hz line, and Pep is going to look more closely at the 40.9 Hz line with more data.