I could easily enage the ISS second loop, following the procedure described in 14291. It worked without problems.

However, the loop performances were very poor, as shown in the first plot. The dashed lines corresponds to the second loop open, the solid lines to the second loop closed. The inloop signal is squeezed down to a reasonable level. However, we're getting only a factor 10 of out-of-loop noise reduction. This is much worse than in the past.

I could improve a bit the situation re-centering the beam on the ISS QPD: it was quite far away. The second plot shows that the loop performance is improved, but still worse than what we got in the past. The thrid plot compares in-loop and out-of-loop signals when PD1-4  or PD5-8 are in loop. There is no significant difference, so it's not only one of the two PD sets to be misaligned.

Tomorrow I'll need to play again the picomotr game to recenter the photodiodes. The last centering was performed more than one month ago, on October 3rd, and then there has been no activity around the ISS, as far as I know. Therefore, it's maybe not surprising at all that the alignment is no more optimal. The IMC alignment might have changed.