Coordinate propogater #211
Description
given that the database should have coordinates and epochs and proper motions for star-like objects, we should be able to have a function which propagates coordinates to any epoch. This would be very useful for users in their Phase 2 proposals for space-based and queue observations.
We just a wrapper around this astropy functionality:
https://docs.astropy.org/en/stable/coordinates/apply_space_motion.html