After in-vac alignment work last night, PRC is flashing brighter than PRMI alignment last week.
My hypothesis is that "we aligned PRM to junk MI fringe last week". Possibly, we used MI fringe caused by AR reflection of ITMs, or MI fringe reflected from SRM.
PRC flashing last week (youtube, elog #8085, elog #8091)
PRC flashing this time (Lens in-front of AS camera was taken out)
My hypothesis can explain:
- why we had dimmer POP last week (flash in half-PRC was way brighter even when we had more attenuators (youtube))
- why I thought AS55 is broken (AS was too dim)
Be careful of junk beams.