RE: [amsat-bb] AO40 orbit drifting south, then north?

[Estes Wayne-W10191 <W10191@xxxxxxxxxxxx>]

Ken wrote:

Are you continually
updating to the most current Keplerian elements, or propagating one set
long-term using SGP4.

Wayne replies:

I used the most recent Keplerian elements for my long-term prediction.  I don't know how to create "future" keps.  How does one do that?

There is definitely a southward trend of the apogee SSP in the last 9 months, from about +4 degrees to about -4 degrees now.  A few months ago the maximum AO40 elevation at my QTH was about 45 degrees.  Now it's about 40 degrees.  A few months ago at my QTH, AO40 rose above the eastern horizon in a gap between trees.  Now it rises a little to the south of that gap.

I'm just curious if the actual limits and period of the SSP movement are close to what my crude long-term SGP4 predictions indicated: amplitude of 16 degrees, period of 32 months.

Wayne Estes W9AE
Mundelein, IL, USA

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