Have had a decent night tonight. However at around 12:30utc noticed H1 range taking a noticeable dip from 70Mpc down to 62Mpc. All of this happened within an hour time frame (appears to be coming back up near 70Mpc. There is nothing obvious in the BLRMS seismic traces (well, for high freq the Corner Station seismometer there is a bump which sort of lines up...but the corner station has many of these bumps and the other ones don't drop the range.) Anyway, it was a curiousity.
There was a small EQ around this time, but it was after the fact and fairly quick.
Overall the H1 range tends to show very slow oscillations in range values and one would think it was useism, but they also don't match up. I'm just curious about why our range fluctuates on a slow time scale like this & how it's curious it doesn't match seismic (L1's range appears to follow seismic more obviously...atleast from my glances at their range and seismic screenshots.)
Attached is a look at the last 12 hrs for the H1 range & also the 3-10Hz & 10-30Hz seismic bands. It's looks like the range drop mentioned above corresponds with the bump seen on both seismic bands. I'd like to know what this could be.
It's interesting that other "bumps don't have noticeable effects on H1 range. So I'm guessing it's a specific line we're sensitive to, and I'm curious what it could be.
See the DQ shift aLog where we report
The excess noise appears to extend up to about 100 Hz and can easily cause the range drop. Today's example of an h(t) spectrogram is attached.