The suspension seems to be healthy, when compared to its condition before the pumping down, according to some transfer functions measurements. I still have to carry out more TF measurements.

The highlights were

• Around the time in which Mirapro was working around the vacuum chamber, a day before the pump down, the IP suddenly chaged position. The event happened on 16-02-2019 at 10:18 hrs. JST (01:18 hrs, UTC). See the first picture. The positions before and after the event were
  • H1: 487 µm ⇒ 402 µm.
  • H2: 441 µm ⇒ 4143 µm.
  • H3: -44 µm ⇒ 1062 µm.
  • In between there were about two hours without LVDT signals. I do not know yet whether cables were disconected or not.
• Surprisingly, during the pump down the IP didn't move as expected. See the second picture picture. I recovered the position of the IP using the horizontal fishing rods.The positions of the motors and LVDTs before and after recovery were
  • H1: -120,000 ⇒ -125,000 steps.
  • H2: -20,000 ⇒ -15,000 steps
  • H3: 45,000 ⇒ 40,000 steps
  • H1:  402 µm ⇒ 467 µm.
  • H2:  4143 µm ⇒ 363 µm.
  • H2:  1062 µm ⇒ -181 µm.
• The IM drifted in yaw when they turned the turbo pump on Saturday. See third picture.
• I moved the BF keystone to zero.
  • LVDT: -464 µm ⇒ zero.
  • Stepper motor: 385,000 steps ⇒195,000 steps.
  • Temperature: T = 24.7 ºC (25 ºC requested).
• A sudden change of the position of the F1 keystone happened at 14:41 hrs. JST (05:41 hrs. UTC). At that time the pressure was already very low and the IPs were not drifting fast anymore. The keystone moved from 404 µm to 1897 µm in a span of three minutes. The movement sudden happened with large oscillations. See the fourth picture.