I'm highly suspicious of that graphic, RJ. Something about the way that
tiny little Sun peels around Earth. Do we know the graphic's origin?

For something straight from Sirius, try

http://www.siriusradio.com/servlet/C...=1038414951381

If that doesn't work, Sirius.com -- About Us -- Image Library --
Miscellaneous -- Control Room

...then download and unzip the big image to see what's really going on to
create that Figure 8 effect. Three technicians in the control room; the large
view of the satellites in space and the four views of the ground track.

I see three orbits at right angles to one another. The ground tracking
matches in both graphics, but is it possible that the actual bird heading south
over MN is *not* the one that was heading north immediately prior? And that,
while the satellites' paths cross, they don't necessarily cross over Central
USA?

Jerome



"Robert J Carpenter" wrote in message
...

wrote in message ...
Sirius uses 3 satellites in a geosynchronous orbit.
XM uses 2 satellites in geostationary orbit.

Anyone know where I can find pictorials of these orbit paths?

http://www.cashflowbusiness.net/siri_orbit.htm

Note that three times a day both active Sirius sats are at the
crossover point of the figure-8. There won't be much of any spatial
diversity for an hour or two around this these times, ie: the two
acitve sats won't be much better than just one.

The two-line orbital elements can be obtained from:
http://celestrak.com/NORAD/elements/other-comm.txt
You can then use a program like NOVA and have your own display of the
orbits with a display of time and direction to each satellite. (XM-3
is the first replacement sat for XM).