Space Track Report No. 3 (was Re: Globalstar flares; definition of "LEO" )
Mon, 16 Feb 98 12:40:42

--- On Mon, 16 Feb 1998 10:57:58 EST wrote:

>Sounds like the 225 minute period "boundary" for LEO cited by Jeff may 
>come from the SGP4/SDP4 utilization boundary.  IIRC, when using the 
>NORAD orbit propagators SGP4/SDP4 for satellites with periods greater 
>than 225 minutes the SDP4 analytical method should be used for orbit 
>determination and propagation.
>For periods less than 225 minutes SGP4 is okay.  I don't have the 
>Spacetrack #3 report handy, but I'll bet the demarcation is mentioned in 

Yup, it sure is.

See Alex A. Sergejew's

Thanks for clearing the cobwebs.

Jeff Hunt <>