Hello,

I think I know how to determine whether a fixed star is permanently hidden or circumpolar (having permanent curtailed passage) using the declination of the star and geographical latitude.

I wonder if there is a simple way to know whether a star that are neither circumpolar nor permanently hidden is either curtailed passage or arising but lying hidden in some part of the year.

Thank you!

declinations and geo lats have signs associated with them as used below:

south: -
north: +

This is open to correction, but I believe a point is circumpolar if for the northern hemisphere:

decl >= 90 - geo lat

for the southern hemisphere:

decl <= -90 - geo lat


Similarly for curtailed:

northern hemisphere:

decl <90>= 90 + geo lat