Kurt: Orbital software can only be as accurate as the orbital elements for the object. The problem is that the uncertainty inherent in all orbital elements means they orbits they describe are only accurate for a very limited time. Even the elements for the major planets as listed in the Observer's Handbook are only good for six months. Asteroids and comets are worse because of solar radiation pressure on their much smaller masses and close approachs to Jupiter. It gets much worse for spacecraft, which are very light and have large surface area. Add in the drag effects of the atmosphere which vary with solar activity and the shelf life of the elements are very short. Best approach is to use an online service like Heavens Above that will update their orbits in a timely manner. You can go to NEOP and download elements for literally thousands of objects but they will be stale and inaccurate before you get to view even a fraction of them. So there isn't much point in having them on your hard drive. I only download elements for the few items of interest to me and only keep them on my pointing computer for a week. DT --- On Fri, 1/23/09, Canopus56 <canopus56@yahoo.com> wrote:

From: Canopus56 <canopus56@yahoo.com> Subject: [Utah-astronomy] Recommendations for satellite observing program To: "Utah Astronomy List Serv" <utah-astronomy@mailman.xmission.com> Date: Friday, January 23, 2009, 10:48 PM Does anyone have a recommendation for software to track satellites.  I have been looking at page http://www.satobs.org/orbsoft.html .  Most of the links are dated, but I am favoring Satbuster or Orbitron. - Kurt

P.S. - When a launch occurs what is the earliest that you can get a track for it, or is there sometype of pre-launch prediction?

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