python cartography

On the plane to Paris I worked out how programming/scripting in Python works. I can fully understand why the open-source side of the astronomical community is migrating to Python! Indeed, I was reading up on Python because we intend to make all of the astrometry.net software open-source and cross-platform, for the obvious reason that we want everyone to run it! Already Mierle is writing most of his astrometry.net code in Python.

My first Python project is going to be some simple celestial cartography; I also worked out on the plane all the equations I need for putting polygons and great and small circles on the sphere and projecting them onto the plane. First rule of astrometry and celestial cartography: Don't use RA, Dec pairs to locate objects, use unit vectors on the sphere. No coordinate singularities or discontinuities, and spherical trig turns into simple vector operations.