I'm familiar with 0 deg. azimuth being True North. The astronomy text book "Astronomy The Cosmic Journey", by William K. Hartmann, has, "Azimuth is the number of degrees around the horizon, starting from the north point (0 deg) and moving through the east (90 deg.)" Hope this isn't one of those Northern Hemisphere/Southern Hemisphere outlooks on life ;-) Jeff Hunt <firstname.lastname@example.org> --- On Fri, 18 Apr 1997 13:57:33 +0200 "Bjoern Gimle@tt-tech.se" <email@example.com> wrote: Bram Dorreman wrote : ... >But I do understand the coordinates with respect to the local horizon >better describe possible brightness changes. If I should report in >AltAz (Altitude and Azimuth) I normally add S=0 or N=0. I believe astronomy text books use S=0, "everybody else" N=0 ?