Hi Sats Observation folks: I am curious why do we need to specify elevation in addition to longitude and latitude. Does this affect the precise apparent positioning fixing of satellite?What is the error involved comparing say Sea-level vs someone high up in Colorado.. Does not seems to affect my observations of sats... thanks & rgds ykChia -- Visit My Web Site http://www.geocities.com:80/CapeCanaveral/Cockpit/9033/index.html Special Interest : Iridium Flares, Comets, IC objects