Return the great-circle separation between two sources.

Arguments:

Source source1

The first of the two sources.

Source source2

The second of the two sources.

Returns Double

The great-circle distance between the two sources, in decimal degrees.

Example 1:

The following example displays the separation between the sun and the current source, in degrees.

  print $separation(sun, current)

Context:

This function calculates and returns the great-circle distance between two sources on the sky. This could, for example, be used to dynamically check whether a source was too close to the sun to be observed.