Catch the
quiet flyover.

Read the pass in three pieces.

The station cards show a predicted peak time, maximum elevation, and track direction. Elevation is the angle above a level horizon: 0° lies on the horizon, 45° is halfway up, and 90° is directly overhead. Azimuth measures compass direction clockwise from north. A west-to-east track tells you how the object moves, not which side of a building is clear.

Our pass window begins when the satellite climbs above 10° and ends when it drops below 10°. That deliberately excludes the lowest part of the sky, where obstructions and atmospheric effects are more troublesome. It is not a prediction of the moment the station first becomes visible.

Arrive early, identify the start direction, and scan with your eyes. If the pass is high, allow room to turn and follow it. A clear line of sight matters more than a perfect compass reading. Do not watch while driving or standing near traffic.

There are two skies to consider.

You can be in darkness while a station hundreds of kilometers above Earth is still in sunlight. That geometry can make it possible to see reflected sunlight against a darker sky. If the station moves into Earth’s shadow, it can fade even though your local sky remains clear.

The default filter asks for a sunlit satellite above 10° while the observer’s Sun is below −6°. It is a useful screening condition, not an optical brightness calculation. A result labeled “lighting window” does not guarantee a naked-eye sighting. Cloud, haze, the station’s orientation, distance and local light all matter.

“All geometric passes” includes daylight or shadowed passes. Use this mode to understand the orbit, not as a claim that every listed pass is visible. The model uses a simple cylindrical Earth shadow and omits penumbra and atmospheric effects on satellite illumination.

An orbit has a use-by date.

A pass prediction starts with a dated set of orbital elements. Atmospheric drag changes low orbits, and maneuvering stations can change their paths. Propagating an old orbit into the future gives a smooth-looking calculation, but smooth is not the same as accurate.

This site bundles a snapshot for the International Space Station and Tiangong. The retrieval date is always displayed, and each pass includes the element epoch. The calculator refuses any station whose orbit is more than seven days from any part of the selected window. This is a conservative product limit, not a guarantee that younger elements are accurate to a particular number of seconds.

The snapshot is not refreshed automatically. When it ages out, station estimates stop while the Sun and Moon planner continues to work. Historical dates near the snapshot remain a learning aid, not a reconstruction validated against observed flight paths. For a real outing, cross-check a current authoritative prediction.

Identify with caution.

A satellite often looks like a steadily moving point of light. Aircraft can show flashing or colored lights, but viewing conditions can make identification uncertain. Do not identify an object from this page’s pass time alone. Timing, direction and elevation should agree, and a missed or unexpected light is not evidence of an unusual event.

The station calculator handles only two objects. It is not a catalog of every satellite, a collision-warning system, an aircraft tracker, or a source of operational navigation data. Enjoy the view without assigning more certainty than the model can support.