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Not all input values are required to call the API. For example, the Closest Satellite – Alt Az Dist endpoint only requires longitude, latitude, and elevation. The API will find the closest satellite based on that information.

Values that take a time array also need:

• Sample size: the number of data points you want
• Time interval: the number of seconds into the future you want to compute

Formula for time step (dt):

dt = (time interval) / (sample size - 1)

Alt Az Dist

This endpoint helps you find the direction in the sky to a space object from your location on Earth. Enter your latitude, longitude, and elevation to receive two angles:

• Altitude (deg_alt): Angle above or below the horizon, measured in degrees up to 90°.
• Azimuth (deg_az): Angle around the sky from true north, measured clockwise from 0° to 360°.

Note:

• Longitudes are assumed positive east. To use a west longitude, enter it as a negative value (e.g., 110° W → –110°).
• Latitudes are assumed positive north. To use a south latitude, enter it as a negative value (e.g., 30° S → –30°).

Lat Lon Dist

This endpoint computes the latitude and longitude (from the center of the Earth) of the desired celestial object.

State Vector

There are many reference frames in astrophysics, but this one is a bit unusual. It’s an inertial frame (so normal Newtonian physics applies) rotated so that:

• The x̂-axis points to latitude 0°, longitude 0°
• The ẑ-axis points to the North Pole

At the exact time you call the API, the returned (x, y, z) coordinates place the satellite correctly relative to the rotating Earth (assuming the x̂ direction is at lat 0°, lon 0°, and north is along ẑ).