The three thresholds of the Visible pass rule, for a caller whose definition of visible differs from the common one: a darker sky for astrophotography, a higher horizon for a city street, a fainter limit for binoculars.
The faintest it may look, as an apparent magnitude.
The lowest the Satellite may stand, in degrees above the horizon.
The highest the Sun may stand for the Observer to be in Night, in degrees (negative: below the horizon).
The three thresholds of the Visible pass rule, for a caller whose definition of visible differs from the common one: a darker sky for astrophotography, a higher horizon for a city street, a fainter limit for binoculars.