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Re: How often do I need to update Keps for STSORBITPLUS?



----- Original Message -----
From: Frank Grossman <71042.1303@compuserve.com>
To: <AMSAT-BB@AMSAT.Org>
Sent: Thursday, April 13, 2000 11:53 PM
Subject: [amsat-bb] How often do I need to update Keps for STSORBITPLUS?


> I make most of my satellite contacts on the "FM birds" using a five watt
HT
> and 19 in. "rat tail," with tracking information from STSPLUS.  Under
these
> conditions how often do I need to download updated kep files for adequate
> orbital predictions?

Frank -

For fixed antennas, updating once per month should be more than adequate for
satellites with an altitude above 500 km (i.e, mean motion of 15.2 or less).
Lower altitude satellites with a mean motion of 15.2  or higher should be
updated more frequently (every 1-2 two weeks) because of atmospheric drag
effects.  The Space Shuttle is a special case since it usually has daily
thruster firings that change the orbit; you generally need to do daily
updates.

I generally recommend at least weekly updates if you're using tracking
antennas and/or automatic Doppler compensation.

73, Ken N2WWD

Ken Ernandes
n2wwd@amsat.org
http://www.mindspring.com/~n2wwd





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