TVo, Dan, Stefan

When I came in, the IFO was lock (by itself?) in low-noise, but quite a bit of low frequency noise. That noise was due to a bad A2L and a bad SRCL decoupling, presumably due to the bad SOFT and PRC1 loop position.

- First we ran an A2L, which indeed fixed the low frequency ASC noise. But we will have to redo that with good RG.

- Next we tuned the SOFT and PRC1 loop positions at 2W, to see where we can get with the recycling gain in that state. We recovered a RG of 48.1 at 2W. 
- That's a slightly lower than the before the vent and TCS pre-loading (we had around RG=50). But note that if the pre-loading adds extra arm-scatter-loss, then it is most likely due to the CO2 heating. (The ring heater lens is very clean.) But the CO2 heating will be backed off anyway at high power.
- Offsets at 2W:
   DSOFT  P  +0.03  Y  -0.02
   CSOFT  P  +0.02  Y  +0.07
   POP_A  P  -0.65  Y  -0.15

- So we went to 20W with these offsets. Initially the RG dropped to 41.6. But through careful tuning we got it back up to 47.7. The attached plot shows our offset-walk.
- Offsets at 20W:
   DSOFT  P  +0.19  Y  -0.32
   CSOFT  P  +0.03  Y  +0.03
   POP_A  P  -0.52  Y  -0.03

- On top of the SOFT and and PRC1 offsets (i.e. the pointing loops), we also noticed that PRC2 liked some small offsets:
    H1:ASC-PRC2_P_OFFSET +20
    H1:ASC-PRC2_Y_OFFSET -30
  (We also checked MICH OFFSETS, but that didn't make a difference. We haven't checked INP1 and the SCL loops.)