Kiwamu, Matt

Thanks to the new cross-correlation data, we can make an updated mystery noise budget.  This time, the recently remembered RF AM noise is included.  There is some calibration correction required to make the uncorrelated noise flat (zero at 193Hz, pole at 215Hz), but this might be expected due to calibration drift over the run.

The curves on the attached plot are:

• black - total measured noise
• grey - measured cross-correlation
• yellow - measured cross-correlation minus correlated noise (including mystery noise)
• purple, red, light blue - known quantum, coating thermal and RF AM noises
• green - a 1/f² mystery noise.  This is the shallowest slope and highest value that seems to make sense.
• blue - sum of known noises and mystery noise
• orange - same as blue, but without shot noise (so, just correlated noises)

The conclusion is that there is no "great mystery noise" any more.  It looks like the unaccounted for noise, in this simple noise budget, is mostly just scattering peaks.  A 1/f² curve is included to give the total a reasonable shape and to guide the eye, but it shouldn't be taken too seriously.  (See 23350 for a real H1 budget, and 25092 for L1.)

Suggested course of action:

1. work on reducing the shot noise (increasing the power)
2. and the scattering between 60 and 100Hz
3. look for coherence between 45 and 55Hz