This is a delayed report.

• I measured the mirror height with respect to the reference produced by Terada-san.
• I actually measured the position of horizontal indentations in the recoil mass, which are aligned with the mirror centre.
• I used the laser level.
• The keystones at the GAS filters were set very closely to zero for this measurement.
• The mirror is ~ 3.6 mm below the appropriate level.
• We still have to account for the bouyancy correction.