Chuck, Your reasoning is sound that polar orbit is unnecessary for a northerly azimuth to an observer.. However, Iridium appear to have polar orbits. Here is an example I picked up from http://www.heavens-above.com/satinfo.asp? SatID=25169&Session=kebgcfmbimjocfehobepmmfe (I'm not sure this link will be readable to those unregistered at heavens above). It is inclined 86 degrees.
Iridium 52 - Information Identification
USSPACECOM Catalog No.: 25169
International Designation Code: 1998-010-A
Satellite Details
Orbit: 776 x 779 km, 86.4°
Country/Org. of Origin: Irid
Intrinsic brightness (Mag): 6.0(at 1000km distance, 50% illuminated)
Maximum brightness (Mag): 4.9 (at perigee, 100% illuminated)
Launch
Date (UTC): February 18, 1998
Launch site: Vandenberg AFB, California, USA
---- Jim Cobb james@cobb.name On Jun 3, 2004, at 10:54 AM, Chuck Hards wrote:
I guess Iridium satellites are not geo-synchronous or they'd be concentrated near the equator no matter what your earthly viewpoint.
If that is the case, they can appear in polar sky regions even if not in a polar orbit, if the orbit is low enough in altitude and the inclination takes it to latitudes higher (or lower, if south of the equator) than the viewer.
C.
