Ryan C, Sheila D
15:32 to 16:01 UTC we dropped Observing to do some range checks/investigations.
Sheila and I did some range checks following the wiki. Running the coherence check showed high coherence with CHARD and the SQZer BLRMs did not look as good as previous locks, particularly in the 10-20, 20-34, and 60-100 HZ bandwidths. So we decided to drop out of observing since LLO was down to run the SQZ alignment and angle scans and I concurrently ran the A2L_min script (TJs alog78552). After these finished we also took 5 minutes of NO_SQZ time starting at 15:49 UTC which showed that the extra noise is not coming from the SQZer. We gained a few Mpcs from the SQZ scan and A2L_min script.
Coherence comparison before and after SQZ and A2L checks
Quickly checked temperature.
LVEA diurnal temperature swing is larger than usual in the past 4 days or so (e.g. zone 1B 0.33 Celsius pp instead of 0.15) but I don't see correlation with the range drop.
Attached is a spectrum comparison for a 159 Mpc time from last night to 149 Mpc this morning. The issue is between 30-70 Hz, where Ryan's coherence plot doesn't show much.
The second attachment shows that today's poor range time is similar to what happened after Tuesday maintenance (78954).
We tried the no squeezing time because we've seen in the past that the squeezer was adding noise around this frequency range, 78033 77969 77888 . In these past times were at times when we had moved the spot position on PR2, and we also had the intermittent squeezing problems that we seem not to have this week. We reverted PR2 spot moves because of this suspicion (77895 78012) and the issue seemed to go away, but we thought it might be simply that the intermittent squeezer issue happened to get better.
The third attached screenshot shows a similar trends for the times when we moved PR3 in May to move the spot on PR2 (77949), that was a ~3 times larger move than the one we did last week (78878).
