DX warnings for b1 on 20230209

[sybenzvi]

The majority of science exposures on 20230209 have an excessive DX warning for b1 (see the exposure table here). Compared to 20230208, DX shifted by about 1 pixel, so it's a sudden change rather than a slow drift. Keep an eye on this to see if it resolves itself.

[sybenzvi]

We've barely had enough data in the past few weeks to guarantee the DX shift in b1 is not persisting, but I am not seeing it in recent MAIN or BACKUP exposures so I'm closing this ticket.