The SkyFrameSkyFrame constructor function is particularly simple and a SkyFrame with default attributes is created as follows:
#include "ast.h" AstSkyFrame *skyframe; ... skyframe = astSkyFrame( "" );
Such a SkyFrame would represent the default celestial coordinate system which, at present, is the ICRS system (the default was "FK5(J2000)" in versions of AST prior to 3.0).