gcirc

pydl.goddard.astro.gcirc(ra1, dec1, ra2, dec2, units=2)[source]

Computes rigorous great circle arc distances.

Parameters:
ra1, dec1, ra2, dec2float or array-like

RA and Dec of two points.

units{ 0, 1, 2 }, optional
  • units = 0: everything is already in radians

  • units = 1: RA in hours, dec in degrees, distance in arcsec.

  • units = 2: RA, dec in degrees, distance in arcsec (default)

Returns:
float or array-like

The angular distance. Units of the value returned depend on the input value of units.

Notes

The formula below is the one best suited to handling small angular separations. See: https://en.wikipedia.org/wiki/Great-circle_distance