Problem with SDP4?

Ron Dantowitz (
Fri, 13 Nov 1998 00:33:02 -0500 (EST)

Hello everyone-

I have a question for all: has anyone noticed any problems with SDP4 after
September 21 1998 at 12:00 UTC?  Although STSPlus uses SGP4 for satellites
like Intelsat 1-1 r or Comstar 4 r, when I use SDP4 there is a discontinuity
at the time mentioned above...

Has anyone else seen this?  I do not see a math error on my part, but you
never know when you stay up so late! :)

Thanks for the help!

-Ron Dantowitz
Boston Museum of Science
(617) 589-0272