[Cheryl, Joe, Giacomo]

Yesterday evening, we removed two of the irises that were used in the past as references for the IMC (in front of MC2 and MC?), to be used in front of PRM and PR2 as references for the pointing into the PRC. We adjusted their height to ~159 (for PRM) and ~170 (for PR2) mm. The following steps were performed:

- the iris on HAM3 was centered horizontally wrt PR2, by measuring its position wrt the barrel of the optic using a ruler. Its height was set to nominal, but seemed well centered to PR2.

- IM4 offset were adjusted to center the beam on the iris (new values: pitch = -2900, yaw = 1250)

- at this point, the beam seemed already centered on PRM to <2 mm, so we considered it good

- we aligned the iris on HAM2 (inside PR cavity) to be centered on the beam (again, leaving the height nominal)

At this point, we put a mirror between the iris and PR2, and used it to retroreflect the beam all the way to PRM through both irises. We finally steered PRM to send the beam back again to PR2. This is not a very fine alignment (the beam become pretty big at each bounce with this setup), but was just done to verify taht PRM pitch/yaw were not badly off (infact, the alignment crew had some difficulty with their equipment and could only very the propoer position of the center of the PRM optic, but not its orientation).