With Hirata-san.

• We measured the mirror height with respect to the reference produced by Terada-san.
• We  actually measured the position of horizontal indentations in the recoil mass, which are aligned with the mirror centre.
• We used the laser level.
• On the left side the indentation is 0.7 mm above the laser level.
• On the right side the indentation is 0.5 mm below the laser level.
• On average, the mirror is 0.1 mm above the appropriate position.
• The keystones of the GAS filters were set very close to zero.
• The roll of the IM (w.r.t. the IRM) was -26 µrad.
• We still have to account for the bouyancy correction.