[amsat-bb] AO-7 orbit count.

Wed Jul 4 00:24:31 UTC 2018

I ran a simulation on my cell phone app HamSat. 
I know it isn’t perfect. I found that orbits rolled over from 99999 to 100000 at 04:13:28 EDT (091228 UTC). The resultant map shows it over Mongolia. So, I’m just letting my curiosity run rampant and thinking out loud. Considering that it’s period has changed over time, what constitutes an orbit? How does the software account for that?

73
EMike

EMike McCardel, AA8EM
Rotating Editor AMSAT News Service
Sent from my iPhone

> On Jul 2, 2018, at 2:05 PM, Pedro Converso <pconver at gmail.com> wrote:
> 
> Hi all,
> 
> Nice idea to celebrate AO-7 200th orbit anniversary, our beloved
> grandfather bird merits it.
> 
> Looks that 200k orbit will happen around August the 1st see:
> http://amsat.org.ar/ao7-200k.gif .
> 
> http://amsat.org.ar/pass?satx=ao-7 account for orbits above 100k.
> 
> We hams should be thankful to have AO-7 alive, duly recognizing those
> that made it possible .
> 
> 73, LU7ABF, Pedro
> 
>> On 7/2/18, Alan <wa4sca at gmail.com> wrote:
>> 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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>> views
>> of
>> <> <> AMSAT-
>> <> <> <NA.
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>> <bb
>> <> <>
>> <>
>> <> _______________________________________________
>> <> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum
>> <available
>> <> to all interested persons worldwide without requiring membership.
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>> 
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> _______________________________________________
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