With Hirata-san and Washimi-san.

Pictures at SR3 remedying work after O3.

• Temperature when we began working: 22.9 degrees.
• We put the H1 OSEM flag back onto the IM.
• We removed the ballast mass stacks from the top IM. Amount and location cas be found in this notebook page.
• We prepared two new stacks 38 grams lighter each.
• We put them in their respective places on the IM.
• We released the mirror, RM and IM, in this order.
• We closed the chamber and went for lunch to let the suspension motion damp.
• After lunch the condition of the suspension is as follows:
  • The IM seems to be oscillating freely.
  • BF LVDT: 580 um; the aim is 311 um but the FR is not in midrange yet. See this picture.
  • H1 OSEM is not installed.
  • Vertical OSEMs seem to be out of range.
  • The orientation in of the mirror and IM does not seem to have changed significaly in IM-Y, IM-T, TM-Y and TM-P (TM DoF measured in normalized displacement units). See this picture. 
  • IM-Y and TM-Y changed by small amounts, but this is expected because BF keystone moved up and there is a coupling via cables.
• Then we moved the BF fishing rod to midrange.
  • We need to move it by 225,000 additional steps (575,000 steps in total from upper limit and yesterday we moved it by 350,000 steps).
  • Motor initial: 334,533 steps. (Yesterday's final.)
  • Motor final: 559,533 steps.
  • Final position of BF LVDT: -252 um. See this picture.
  • Vertical OSEMs seem to be in range.
• I calculated that the mass needed to raise the BF keystone to 311 um is 24 grams, 12 grams from each stack. See this notebook page.
• After we removed 12 grams from each stack we realized pitch was disturbed by approximately 600 urad. We recovered the pitch by temporarily putting 4 grams on the -Y side of the IM.

Tomorow we will continue.