Leigh and others, My understanding is that one of the subscribers has volunteered to write a glossary related to satellite observing. Also, some of the subscribers are putting together a FAQ related to satellite observing. This glossary will be part of the FAQ. It's a slow process, as most, unlike myself, have real jobs ;-) In case you haven't come across it yet, the Visual Satellite Observer's Home Page has a page for sat tracking software grouped by platforms. Unfortunately, only one is listed for the Mac. Perhaps some on this list can add to this platform. http:www.physics.ox.ac.uk/sat/orbsoft.html I agree, we have a tendency to assume everyone (or most everyone) understands our terminology. Jeff Hunt <jhunt@eagle1.eaglenet.com>