[amsat-bb] SATPC32 Question

Alan wa4sca at gmail.com
Wed Aug 27 11:44:30 UTC 2014

As you mentioned, they frequently raise the height of the ISS to compensate for the relatively high
drag.  For every km the orbit is raised, the AOS shifts approximately 19-20 seconds per day compared
with the old Keps.  It is usually a few km boost, so the error adds up quickly.  As a result, you need
to update the Keps frequently from CelesTrak or directly from Space-Track.  The NASA.ALL Keps are
selected for satellites of interest to hams, but are only updated weekly.  Fortunately the Keps change
very slowly for other satellites, except in the last few days before reentry.



<-----Original Message-----
<From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On Behalf Of Koos van den Hout
<Sent: Wednesday, August 27, 2014 2:27 AM
<To: wa7eth at frontier.com
<Subject: Re: [amsat-bb] SATPC32 Question
<Quoting wa7eth at frontier.com who wrote on Wed 2014-08-27 at 00:15:
<> I am having difficulty with SATPC32 tracking the ISS accurately.  All other satellites appear to
track OK but the ISS is
<way off compared to several web based tracking sites.  I would appreciate any tips on how to
troubleshoot this
<problem.  Please respond off the AMSAT-BB to WA7ETH at frontier.com
<Have you updated your TLEs recently? I noticed a few times predictions of
<ISS can be way off in gpredict/amsatdroid and it was always fixed when I
<updated the TLEs.
<My theory is that this is due to the corrections the ISS makes to stay at
<the right height and avoid space debris which makes it less predictable
<than amateur satellites that just stay in orbit and can't correct their
<course. I am open to corrections on this theory.
<                                            Koos van den Hout
<Koos van den Hout,           PGP keyid DSS/1024 0xF0D7C263 via keyservers
<koos at kzdoos.xs4all.nl
<                                Visit the site about books with reviews
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