Error in set time calculation about astroplan

[bmorris3]

Hi @sarrvesh!

This issue is covered here in the FAQ. The problem here is that start_time is very close to the set time (within 4 minutes). As a result, the numerical horizon-crossing time calculation can "miss" the true set time near start_time.

You can avoid this behavior by starting your rise/set search at a different time. Here's a very small tweak that produces the result you expected.

start_time = Time('2023-01-01T00:00:00', format="isot", scale="utc") - 12*u.hour

Hope this helps!