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

Computes rigorous great circle arc distances.

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)

float or array-like

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


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