Virgo Logbook

AdV-PAY (NI and WI Payloads)

benedetti, Majorana, Pinto, Ruggi - 16:28 Wednesday 22 July 2026 (69411)

WI payload works

In the morning we completed the works concerniing the WI payload installation.

The balance was done and the mirror reuslted misaligned WRT the maiornette, similarly to the NI case, by non-negligible values.

TY= +3700 urad ; TX= -500 urad ; Tz= +2000 urad. The OpLev sensing will be reset later on.

The system behaves normally.

The flange has ebeen closed and the pumping is goin on. Pictures will follow.

Excellent ciollaboration by all the teams involved: VAC, Clean-Operaiton, in-vac-Cabling

We noticed two spots on the rear face of the mirror. They appeared as the first contact was peeled-off.

Later on Suzanne and Eugenio took some pictures to verify the situation. It has been decided not to touch. Another dedicated entry will follow.

Comments to this report:

melo, majorana, nardecchia - 17:03 Wednesday 22 July 2026 (69412)

During the WI payload works we also verified that the PAM system is well aligned with the mirror center. The led of the PAM system on the tower base was swicthed on and Ettore from inside the tower verified that the led beam was reaching the same place it was before. The baffles around the payload were taken as reference for this check.

melo, benedetti, majorana - 17:11 Wednesday 22 July 2026 (69413)

While inspecting the WI payload we noticed three spots on the AR surface of the mirror. Looking through the CP, we can see two spots in the right lower direction from the center and one is located in the left lower direction from the center. All of them are within a range of 10 cm from the center.

Some remarks: the spots do not look like point absorbers. PAs are usually sub-micrometer scale and these are round cloudy mm-scale spots. A cleaning operation would be very risky and we decided not to touch the mirror, also motivated by the fact that the spots are NOT located in the HR surface of the mirror.

Some pictures will follow when the network is back.

melo, benedetti - 21:11 Thursday 23 July 2026 (69424)

Here the pictures of the spots found yesterday.

Images attached to this comment