Coalignment should check whether two maps have approximately the same observer location and time

[wtbarnes]

When performing coalignment between two images, the inherent assumption is that the coalignment is done only in the plane of the sky and that the two images reside in the same plane. When two images are taken by spacecraft at approximately the same location and at approximately the same time, this assumption is valid.

However, if two observers have significantly different separation in latitude and longitude or the times of the two observations are significantly different, this assumption may be invalid and will result in a poor coalignment between the two images. As such, we should have a check for whether the separation between the two image planes is above some tolerance and warn if it is.

The time and separation checks could effectively be implemented as a single check by setting a tolerance on separation and then translating the difference in time to a separation angle based on solar rotation.