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R: Re: Calculating Ascending Node?




----- Original Message -----
From: Robert McGwier <rwmcgwier@comcast.net>
To: <amsat-bb@AMSAT.Org>
Sent: Monday, April 01, 2002 12:30 AM
Subject: RE: [amsat-bb] Re: Calculating Ascending Node?


> The latest version does this but only for "circular"
> orbits.  I made a decision as to which was more
> important,  subsat at Apogee or ascending node
> for each satellite class, highly elliptical or
> near circular LEO.  I believe I could reconstruct
> that calculation if it is required.
>
> Bob
> N4HY
>
> -----Original Message-----
> From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org]On
> Behalf Of Ronald Long
> Sent: Saturday, March 30, 2002 1:45 PM
> To: amsat-bb@AMSAT.Org
> Subject: [amsat-bb] Re: Calculating Ascending Node?
>
>  > I know someone on the list asked how to do this for using OSCARLOCATOR
>  > charts. Did anyone come up with an answer? I've been trying to figure
how
> to
>  > do the calculation myself, but no joy.
>
> A great old DOS program called QuikTrak by Bob Mc Gwier  did this. I don't
> know if the latest version still has that feaure, or if it works for
AO-40,
> or only for circular orbits, but it is worth a try. Check the AMSAT web
> site for details.
>
> ron w8gus.

Hi Bob,

Before the introduction of keplerian elements and preparing for PHASE III A
i developed a P3 Tracker using the same metod actually described by Martin,
K2UBC in "The Satellite Experimenter's Handbook, 2nd Edition page 12-6

The only difference with it was that i developed the ground track overlay
and the rest of tabulations for AZ and EL with reference at time and
longitude of the ascending node instead at apogee.

I think that there is no difference to set the reference time at the equator
crossing or at apogee for the tracker but the real problem with high
elliptical orbits is that the ground track as well the rest of tabulations
to get the AZ and EL after the elapsed time from one or the other
reference time must be uptodate very often as the ArgP changes.

Of coarse this is not neaded for near circular LEO orbits and i wonder if
someone nowdays will be interested or not to use a P3 Tracher  with large
polar maps,bearing curves and ground-track-overly  having to uptodate
his papers almost every tree months.

In any case the use of  an OSCARLOCATOR for high elliptical orbits like
that of AO40 is a very educational exercise to try.

73" de i8CVS Domenico

>
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