TITLE: 11/27 Eve Shift: 0030-0600 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 158Mpc
INCOMING OPERATOR: TJ
SHIFT SUMMARY: 1 lockloss this shift (IMC tagged LL), DRMI struggled at first but after an IA relocking was smooth. There were FSS oscillations during initial alignment. The range has been hovering just under 160Mpc.
LOG:
| Start Time | System | Name | Location | Lazer_Haz | Task | Time End |
|---|---|---|---|---|---|---|
| 23:58 | CAL | Tony | PCal Lab | Local | Measurement | 00:04 |
| 01:18 | CAL | Tony | PCAL lab | Local | Check shutter | 02:10 |
- 01:34 UTC lockloss
- 01:55 I adjusted ETMY_Y a few steps as guardian wasn't making any progress on it (it had been trying for 20 minutes and already went through increase flashes and the camera looked very yawed). It locked almost immediately after my adjustments.
- DRMI was taking a while to lock despite good flashes (200 and 150), even after a round of PRMI it was still not locking. It was able to lock once but as soon as ASC turned on it lost it
- Sometimes I would see light on the HAM6 OMC TRANS camera while DRMI was flashing, I can't remember if this is typical
- 02:48 UTC I dropped to do an IA as DRMI didn't seem to be making much progress
- 03:00 UTC After finishing INPUT_ALIGN the IMC lost lock as usual but the FSS started oscillating and didn't stop for over 10 minutes, after it stopped the FSS and IMC relocked. alog81509
- The FSS_NPRO_TEMP channel and the PMC_HV_MON have the same triangle shape during the first oscillation
- Jason says if you turn off the ISS it should help the FSS to lock faster (OPS info) if this happens again
- 03:30 UTC DRMI locked after 1.5 minutes now.
- 04:05 UTC Observing
- I tested out the original settings for ETMY mode 1 as the microseism has decreased. It damped mode 1 but also slowly rang up mode 6. The new settings damped it faster without a noticeable mode6 rise.
- I also tried the original settings for ITMY mode5/6 and it seems to damp fine, the line is shrinking on DTT, the modes drive is converging and both long monitors (ITMY modes 10 & 20) are also going down. It looks to damp at the same rate as the new settings.
This is not the FSS oscillating, it's the FSS having trouble acquiring lock; the FSS Trans PD signal (TPD) is zero (cavity unlocked) except for when the cavity is near resonance (these are the peaks seen in the TPD during this relocking period). The autolocker fails to lock so the TPD drops back to zero and the temperature search continues. The pattern seen in the PMC_HV signal is the PMC following the NPRO frequency change as the FSS autolocker slowly ramps the NPRO crystal temperature to try to lock the RefCav (this is why the NPRO temperature channel has the same shape as PMC_HV). Not clear why the RefCav doesn't want to lock as quickly with this NPRO as it did with the previous ones, but we did see this behavior upon FSS recovery last Friday (I had to lock the RefCav manually so we could move on with PSL recovery as the autolocker was taking too long). I recall seeing this behavior in the past (pre-COVID) and at the time we couldn't figure out the cause. Will look into this more after the Thanksgiving holiday.