find_passes

ssapy.compute.find_passes(orbit, observers, tStart, tSpan, dt, propagator=KeplerianPropagator(), horizon=np.float64(0.3490658503988659))[source][source]

Find satellite overhead passes for a collection of observers.

Uses a brute force test of a grid of time points from tStart to tStart+tSpan separated by dt.

Returns passes even if they occur during the daytime or if the satellite is not illuminated by the sun. The only criterion for a successful “pass” is for the topocentric altitude of the satellite to be above the input horizon. More details about a pass can subsequently be obtained by running the refine_passes function.

Note this function is only suitable for EarthObserver instances and not OrbitalObserver instances.

Parameters:

  • orbit (Orbit) – Satellite orbit in question.

  • observers (List of EarthObserver.) – Earth observers for which to check satellite visibility.

  • tStart (float or astropy.time.Time) – Beginning of search window. If float, then should correspond to GPS seconds; i.e., seconds since 1980-01-06 00:00:00 UTC

  • tSpan (float or Quantity) – Time span in which to search for passes. If float, then seconds.

  • dt (float or Quantity) – Time increment to use during search. Satellite visibility will be computed every dt increment. Smaller values will decrease the probability that a short duration pass will be missed, but will make the search take longer to complete. If float, then seconds.

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

  • horizon (float or Quantity, optional) – Minimum altitude for which to consider a satellite “visible”. If float, then should be in radians.

Returns:

passDict – keys are EarthObserver instances. values are lists (possibly empty) of astropy.Time corresponding to visible passes of the satellite. Only one time is returned per pass, so multiple times in the return list indicate multiple distinct passes.

Return type:

dict