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.

73s,

Alan WA4SCA

<-----Original Message----- <From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Koos van den Hout <Sent: Wednesday, August 27, 2014 2:27 AM <To: wa7eth@frontier.com <Cc: AMSAT BB <Subject: Re: [amsat-bb] SATPC32 Question < <Quoting wa7eth@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@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@kzdoos.xs4all.nl < Visit the site about books with reviews <http://idefix.net/ http://www.virtualbookcase.com/ <_______________________________________________ <Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available <to all interested persons worldwide without requiring membership. Opinions expressed <are solely those of the author, and do not reflect the official views of AMSAT-NA. <Not an AMSAT-NA member? Join now to support the amateur satellite program! <Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb

There is a version called SatPC32ISS.exe. It is in the same folder as the regular version. The only difference seems to be that it allows transmitting and receiving in the same band. It also does not appear to work with different configurations. Other than that it appears to be the same program so I do not believe it would solve your tracking issue.

W9KE Tom Doyle

On Wed, Aug 27, 2014 at 8:00 AM, Gus gus@8p6sm.net wrote:

On 08/27/2014 03:15 AM, wa7eth@frontier.com wrote:

...

I am having difficulty with SATPC32 tracking the ISS accurately.

Isn't there a separate app for tracking ISS?

-- Gus 8P6SM The Easternmost Isle

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Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb