References: aLOG 6683, https://dcc.ligo.org/L1200282, https://dcc.ligo.org/T1200470, https://dcc.ligo.org/D1000313-V9

Attached shows the relative position of ALSX, ALSY and POP (from L1200282) together with two top periscope mirror profiles (equidistant from three beams and centered on ALSY, the latter is supposed to be the current configuration). Green and red circles show the beam diameter obtained from T1200470 and D1000313-V9 (V10 doesn't have the beam profile information).

With the "centered on ALSY" configuration POP is close to the edge of the mirror. Today HAM1 incursion team will move everything such that periscope and downstream will be equidistant from three beams though we have only the ALSX for the moment,. They'll also try to find POP in HAM1 again with the new alignment.