Add a boolean setting "Recalibrated PHD2 after Meridian flip", "Calibrate PHD2 on sequence start" and maybe "Recalibrate PHD every X photos"

[Ronon Dex]

On my mount I can get 0.3" - 0.5" RMS in guiding performance increase if I recalibrate after a big slew or each 2 hours or so (guiding performance gradually decreases over time on the Celestron AVX if you keep using the same calibration).

[Johannes Josefsen]

This would also add further automation when starting a session.

My normal workflow is to slew to near my target, calibrate and then start the target. If NINA could initiate a calibration automatically I would't have to do that part myself. :)

[Matt Clements]

Auto PHD re-calibration is absolutely required if using a camera rotator and/or imaging multiple targets.

so an additional option: re-calibrate PHD2 after rotation change or sequence start.

[Stefan B]

Forced calibration can be done with the start guiding instruction in the adv. sequencer