altaz

ssapy.compute.altaz(orbit, time, observer, propagator=KeplerianPropagator(), obsAngleCorrection=None)[source][source]

Calculate observed altitude and azimuth of orbiting objects as viewed at specified times and locations.

Parameters:

  • orbit (Orbit or list of Orbit (n,)) – Orbits for which to calculate direction cosines.

  • time (array_like or astropy.time.Time (m,)) – If float (array), then should correspond to GPS seconds; i.e., seconds since 1980-01-06 00:00:00 UTC

  • observer (EarthObserver) – Where on Earth to compute alt and az.

  • propagator (Propagator, optional) – The propagator instance to use.

  • obsAngleCorrection ({None, "linear", "exact"}, optional) – Correct actual angle to observed angle, meaning account for light-time delay, and aberration due to the observer’s velocity. None means don’t do any correction. “linear” means do an aberration correction and first order light-time correction. “exact” means do an aberration correction and iteratively solve for the exact light-time correction. (The “linear” correction is almost always sufficiently accurate).

Notes

If orbit is scalar-valued (an Orbit instead of a list of Orbit), then that dimension will be squeezed out in the return value. Likewise, if time is scalar, that dimension will be squeezed out.

For Keplerian orbit propagation it is more efficient to use a “vector Orbit” instead of a list of single scalar Orbits.

When doing light time corrections, the time argument is the arrival time of the photons at the observer, as opposed to the emission time at the satellite.

Returns:

alt, az – Altitude and azimuth in radians.

Return type:

array_like (n, m)