---"Sue J. Worden" <worden@uts.cc.utexas.edu> wrote: > Is not the QuickSat "sun-object-observer angle", i.e., > angle sun->satellite->observer, the same as the Jim's > "angle subtended from sun to satellite to observer"? > > I am very confused at this point. I would appreciate > someone shedding some light on this, and at full phase > illumination, please. :-) No, you're not confused, I was. I confused "phase angle" for "phase," as in lunar phase = % illuminated. I got into the habit of ignoring both the phase and phase angle as useful quantities because most satellites don't show that much brightness variation due to phase. I guess I got so good at ignoring phase and phase angle I forgot their respective definitions. I do apologize to anyone I may have confused! And Richard Clark is correct: phase angle is a 2-D angle subtended between two 3-D vectors, while the az-el quantities are 3-D because they are in essence unit vectors. Whew. __________________________________________________ Jim Varney 121.398W 38.458N 8m Sacramento, CA jamesv@softcom.net, sat_watcher@rocketmail.com _____________________________________________________________________ Sent by RocketMail. Get your free e-mail at http://www.rocketmail.com