{{lastupdated_at}} by {{lastupdated_by}}

{{>toc}}

h1. GSkyDir

The @GSkyDir@ class implements a direction on the sky, given either in equatorial (FK5 J2000) or Galactic coordinates.

The coordination transformation (a simple rotation) is checked in @test_GSky.py@ in @Test.test_fk5_to_galactic()@.
The @gammalib@ results agree with "PyAST":http://dsberry.github.com/starlink/pyast.html within 10 milli-arcseconds for the whole sky.

Once we consider adding astronomical time and coordinate functionality to @gammalib@, this might be a useful reference:
https://github.com/astropy/coordinates-benchmark