I just compared BNS and IR/GR XY trans Norm for the recent 22 days as Fig.1.

• GRX is almost constant except for a slight drop at some point, while GRY increased at some point and has remained almost constant. On the other hand, IRXY keeps decreasing. The relative alignment for IR and GR is now aparting with each other?

Recent IRXY trans situation (Fig.1).

Temperature in each station (Fig.2) . EY1F change is remarkable. So I decreased the heater power by 300W around 10:00.

After almost 20 hours continuous lock, finally IFO was unlocked because of an earthquake around 16:00.

Fig.1 shows the IRXY trans just before the unlock. They seemed to slightly increase, different from the long term trend of decrease. it can be a hint for the alignment drift and/or frosting.

I noticed that the heater power adjustment for IY/EXIM influenced on the IRXY trans power as shown in Fig.1. In this case, I reduced the heater power for IY/EX IM to avoid too much heatup of IMs because of the very long continuous lock.

As you notice, the IRXY trans power increased slightly. One possibility is the mirror alignment  change because of the heater lines' extension/shrinking due to the change of current in them and temperature. 

However, this also shows that the present ASC/BPC/ADS resulted in the slow drift of global alignment because the IRXY trans can be enhanced with different alignment.