For future reference I took a spectrum of the 5 HSTS (MC1 MC2 MC3 PR2 PRM) from monday morning before the corner station was vented.

The isolation and damping on HAM2 and HAM3 ISIs were ON, and feedforward was OFF. The suspensions damping loops were closed. The chambers were under vacuum.

The attached pdf shows a comparison between the 5 HSTS, for every "mass" levels (M1 M2 and M3) and every degree of freedom.

Few things to notice on the plot :

- The performances are really consistent from one chamber to an other

- Signal is really close to sensor noise, especially at the bottom mass

- There is an interesting feature between ~0.1Hz and ~1Hz seen for longitudinal transverse and vertical dofs. This is something I would need to double check, but I'm pretty sure it is transmitted ground motion.