I'm thinking that this lower range is related to the squeezer. I've attached a screenshot fo the FDS DARM FOM where the live trace is above the refernece in the same frequencies that DARM seems to be higher than normal. I followed the instructions on the Troubleshooting SQZ wiki to adjust the sqeeze angle, but I wasn't able to make anything better, only worse.

I adjusted the sqz angle from 0630-0640 UTC.

Our range is staying low at ~125Mpc, there seems to be extra noise from 20-60Hz. Investigating.

There's a lot more coherence of PRCL and SRCL in the ongoing lock than the previous one. The thermalization cal lines are also very high in DARM and CHARD - maybe they weren't turned on until this new lock though.

Tagging CAL regarding the turn on of CAL_AWG_LINES for this 60W lock stretch -- thanks TJ!

Tagging DetChar as well -- to note that we have 8 extra calibrations on during this nominal low noise stretch that started at June 22 2023 05:04 UTC

These are in because we want to characterize the thermalization of the detector's DARM loop sensing and response functions now that we're operating at 60W rather than 75/76W. I hope to get a few more of these lock acquisitions with these extra lines on, and then we'll turn them off as we had done for the start of the engineering run.

If you'd like to create a data quality flag, you can find the status of these lines "in one go" by looking at the CAL_AWG_LINES guardian state channel, 
    H1:GRD-CAL_AWG_LINES_STATE_N
The numerical value of the channel is 10.0 when the extra calibration lines are ON (the state is called LINES_ON), and 2.0 when the lines are OFF (the state is called IDLE). See CAL_AWG_LINES_StateGraph for the flow of the state graph.

A retrospect on the lower range:

The solution was a lack of capturing the SRCLFF1 gain in SDF / Guardian during yesterday's power reduction from 75W to 60W LHO:70648.

See LHO:70712 and LHO:70710 where Tony recovered the correct gain of 2.1.

@DetChar -- it might be worth creating a data quality flag for this:
    Observation segment start (with SRCLFF1 Gain at 1.0): 
    2023-06-22 05:04:38 UTC
               22:04:38 PDT
               1371445496 GPS
    Observation segment stop (with SRCLFF1 Gain at 1.0): 
    2023-06-22 13:53:47 UTC
               06:53:47 PDT
               1371477245 GPS

RyanC just added the SRCLFF1 gain of 2.1 to lscparams, saved, and reloaded the ISC_LOCK guardian.  So, if we need to relock it'll come back on with the correct gain.  Note though, that we expect to update this yet again later today.

Adding a quick comment to Jeff's note about lines, with a bit of relevant info from ER15.

Abby Wang and Athena Baches recently analyzed lines in May 2023 data, grouping those that evolve similarly in time. They found a cluster of lines corresponding to the awg lines, but not including any other entries. This is good news; it implies that there are *not* strong narrow artifacts with very similar histories-- i.e. these lines aren't causing unexpected strong lines elsewhere, which ought to have shown up in the same cluster. (Note: it's still possible that there are weak artifacts which aren't caught by this analysis.)

The attached plots show what the time evolution looks: each row is a line (corresponding to 11.475, 11.575, 15.175, 15.275, 24.4, and 24.5 Hz) , yellow = above threshold and blue = below threshold.