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Re: Re: P3E keps



----- Original Message -----
From: "Wayne Estes W9AE" <w9ae@earthlink.net>
To: <amsat-bb@amsat.org>
Sent: Friday, April 15, 2005 6:51 PM
Subject: [amsat-bb] Re: P3E keps

> Dave WB6LLO wrote:
>
> Put the following into your tracking program, if you have not already done
so:
>
> P3E
> 1 55002U 05055B   06215.60600000 -.00000001  00000-0  10000-4 0    25
> 2 55002  48.7459 176.4760 7509770 242.6730   0.0000  1.71429000 08609
>
> Wayne W9AE replies:
>
> I loaded those keps in SatPC32, and the orbit isn't what I imagined a
Molniya orbit would be.  The apogee occurs at about 4 degrees South
latitude, and the northernmost SSP occurs at perigee.  Is that really the
intended orbit of P3E?  Is that a Molniya orbit?
>
> This orbit would still give great DX, though.
>
> Wayne Estes
> Mundelein, IL, USA

Hi Wayne W9AE

The effect that you reported is because the above epoch time is
06215.60600000 or 08/03/2006 but you run your PC with the current date.

If you want to see how the P3E orbit will look like you have to change the
time of your PC at least 08/03/2006

The effect that you noted is due to the fact that at epoch time the argument
of perigee is 242.6730°  but since the inclination is 48.7459° than the
argument of perigee is moving  at a rate of +0.145°/day.

At current date we are -474.0 days before the keps epoch time and so it
is like to have the argument of perigee retroceded at 174.06836° and this is
why you look the apogee to be at about 4° South latitude.

Of coarse if you change PC time at 08/03/2006 you will see that the apogee
occurs at about 53° North latitude at MA=128 and the perigee at about 58°
South latitude at MA= 256 obviously at epoch time and not now.

In any case P3E has an apogee kick motor and the final planned inclination
is near 63.43° where the argument of perigee will stop to move and the
apogee will occur at a North latitude greater than 53° depending on the
argument of perigee at the time of firing the kick motor for the final
orbit.

If you like to play with this nice near Molnia orbit use IT and key E to
look at the keplerian elements in AMSAT format.

Than key D to look at the derived values of keps adjusted to Present Time

Have a nice job and 73" de

i8CVS Domenico
----
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