Aha, yes, your math is correct & explains the "10"! I was not-fully-awake figuring the opposite compass-heading as (360-282.2), which is actually just the oppos

Aha, yes, your math is correct & explains the "10"! I was not-fully-awake figuring the opposite compass-heading as (360-282.2), which is actually just the opposite-rotation-from-north, not the 180"-opposite direction. Got my symmetries mixed-up.