[amsat-bb] Re: O/OREOS TLE errors ?
rcaron at gmail.com
Tue Nov 30 10:21:58 PST 2010
The O/OREOS TLEs consistently do not have valid checksums (last digit of
each line). I submitted a comment about this on their website but I have
not heard back. The correct checksums are 2 & 3, and not the 6 & 5 that
If, by the time you read this, the posted TLEs are not 6 & 5, then the
TLEs have been updated and you'll have to generate new checksums. The
formula is a sum of all numerical characters on the line, including the
line number, treating minus signs as a one and everything else (letters,
+, spaces) as a 0. Then take modulus 10 of the sum (i.e. last digit of
the sum). Look it up on wikipedia for more details.
I've made a spreadsheet to fix this, but it is still a manual operation
for me (got to write a script at some point). Some programs disregard
the the checksum, which is why HRD & the website still work and your
tracking tool doesn't. Predict/GPredict, my tools of choice, require
valid checksums, making proper TLEs a pet peeve of mine. I don't know
what NOVA's up to.
In terms of "swarm spread" (i.e. how small delta-V between spacecraft
that shared the same ride, which in this case is just done by compressed
springs, translates into spatial differences), 35 minutes of separation
is pretty high for just 10 days after launch. With all the latest TLEs
from the three websites, I show O/OREOS being 3.5 minutes ahead of RAX,
and RAX being a 1.33 minutes ahead of FAST1/2.
On 11/30/10 4:54 AM, amsat-bb-request at amsat.org wrote:
> Message: 4
> Date: Mon, 29 Nov 2010 22:55:16 +0100
> From: PA3GUO<pa3guo at upcmail.nl>
> Subject: [amsat-bb] O/OREOS TLE errors ?
> To:amsat-bb at amsat.org
> Message-ID:<19767175.1291067716437.JavaMail.root at viefep21.chello.at>
> Content-Type: text/plain; charset=utf-8
> Dear all,
> I keep on having troubles with the O/OREOS kepler sets.
> RAX and the others are fine.
> With todays version (as from the O/OREOS dashboard on the web)
> - NOVA gives O/OREOS just a bit behind RAX
> - HamRadioDeluxe give O/OREOS 35 minutes behind RAX
> - The O/OREOS web (dashboard graphic) shows O/OREOS 35 minutes behind RAX
> - My private antenna tracking tool does not recognize the keplerset of O/OREOS
> Anyone else has experienced this (and maybe even a solution) ?
> Henk, PA3GUO
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