[dpechwkd] Limited astronomy

Block off the parts of the day in which it is too light out to see stars.  The times of dusk and dawn change througout the year and depends on latitude.

Block off a chunk of the year because it's too cold to be outside at night.  One could formulate a model of this based on latitude.

Block off a chunk of the sky which is too close to the horizon, perhaps obscured by terrain, buildings, trees, pollution.  As a simple model, one can view only within a cone of a specified angle around the zenith.

Block off a chunk of hours that you'd rather be asleep than stargazing.

Narrow to the subset of astronomical objects that are bright enough.

Given all these constraints, what portion of the celestial globe are you able to observe at some point during the year?  Which points at what time?

This could be an app.