[amsat-bb] AO-7 orbit count.

[Alan]

Greg,

Fortunately this is not a TEOTWAWKI Y2K issue.  Unlike most of the other
numbers in the Keps, the orbit count has nothing to do with predicting the
orbit, and can be completely ignored.  Some programs do that.  Others
compute backwards and forwards from the reference epoch and orbit number in
the Keps they are using.  I am most familiar with SatPC32, and when working
on prelaunch Keps recently, I found that if you ran it backwards in time
before the launch, it will happily show negative numbers.  ;)

The problem is that when the specification for the Keps we use was created,
it only allowed 5 digits for the orbit count.  That seemed enough, and comes
from Space Track that way.  So like an odometer it just rolls over.  In
principle, software could look for that, and automatically compensate.

I can't speak for all the software out there, but in most cases they will
just roll over and keep on tracking.

73,

Alan
WA4SCA




<-----Original Message-----
<From: Greg D [mailto:ko6th.greg at gmail.com]
<Sent: Monday, July 02, 2018 11:29 AM
<To: APBIDDLE at MAILAPS.ORG; 'Tom Schuessler' <tjschuessler at verizon.net>
<Cc: 'AMSAT BB' <amsat-bb at amsat.org>
<Subject: Re: [amsat-bb] AO-7 orbit count.
<
<Hi Alan,
<
<Other shoe, please?  What happened to the world's prediction software
<(if, indeed, we even had any back then) when it rolled over?  What is
<expected this time?
<
<We survived Y2K, but did we learn anything from it?
<
<Greg  KO6TH
<
<
<Alan wrote:
<> Tom,
<>
<> It has in fact turned over once already.
<>
<> 73,
<>
<> Alan
<> WA4SCA
<>
<> Sent from my Waring blender.
<>
<>
<> <-----Original Message-----
<> <From: Tom Schuessler [mailto:tjschuessler at verizon.net]
<> <Sent: Monday, July 02, 2018 09:03 AM
<> <To: APBIDDLE at MAILAPS.ORG
<> <Cc: AMSAT BB <amsat-bb at amsat.org>
<> <Subject: Re: [amsat-bb] AO-7 orbit count.
<> <
<> <12.5×365×45 equals 205,312..5. Based on that you think it had Brolley a
<> <diameter the second time already but it might have been hiring slower
<when
<> <originally launched.
<> <
<> <Sent from my iPhone
<> <
<> <> On Jul 2, 2018, at 02:47, Alan <wa4sca at gmail.com> wrote:
<> <>
<> <> Tom,
<> <>
<> <> According to the Keps, AO-7 makes 12.54 orbits per day.  It will hit
99999
<> <> on the 30th or so.  You can use the Preview function to find out
exactly
<> <> when.
<> <>
<> <> 73,
<> <>
<> <> Alan
<> <> WA4SCA
<> <>
<> <>
<> <> <-----Original Message-----
<> <> <From: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] On Behalf Of
<> <> <tjschuessler at verizon.net
<> <> <Sent: Sunday, July 01, 2018 23:56 PM
<> <> <To: 'AMSAT BB' <amsat-bb at amsat.org>
<> <> <Subject: [amsat-bb] AO-7 orbit count.
<> <> <
<> <> <Now I see looking at SatPC32 that it shows AO-7 in the 99,625 range
in
<> <> orbit
<> <> <count.  If memory serves me right though, doesn't the TLE orbit count
<roll
<> <> <over at 99,999 (Just like a car odometer), so that would mean that we
<> <would
<> <> <be coming up to the 200,000th rev is that right?  If I am right, then
this
<> <> <will be coming up in less than a month.  Does anybody know exactly
<when
<> <> that
<> <> <will be?  I am doing a presentation for a local club and would like
to
<> <> throw
<> <> <out that fact if I could.  Also the day of that event would be good
AO-7
<> <> <operating day I would think.
<> <> <
<> <> <73
<> <> <
<> <> <Tom Schuessler, N5HYP
<> <> <EM12ms
<> <> <
<> <> <
<> <> <
<> <> <_______________________________________________
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<> <> <expressed
<> <> <are solely those of the author, and do not reflect the official views
of
<> <> AMSAT-
<> <> <NA.
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<bb
<> <>
<>
<> _______________________________________________
<> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum
<available
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<Opinions expressed
<> are solely those of the author, and do not reflect the official views of
<AMSAT-NA.
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