[amsat-bb] Re: Satellite location prediction weeks away and JOTA

Ransom, Kenneth G. (JSC-OC)[BARRIOS TECHNOLOGY] kenneth.g.ransom at nasa.gov
Thu Sep 20 04:00:54 PDT 2012

Predicting ISS out that far is more challenging than the other satellites as the ISS has frequent orbital maneuvers that most of the other amateur satellites do not. The significant factor affecting the other static amateur satellites is variations in orbital drag due to solar activity. ISS is much more dynamic being controlled by reboosts and occasionally maneuvered to avoid debris. Even the crew members moving around can cause subtle changes in the orbit.

Best to use ISS predicts that far ahead as a ballpark estimate instead of a pinpoint prediction.

Kenneth - N5VHO

-----Original Message-----
From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On Behalf Of Gus 8P6SM
Sent: Thursday, September 20, 2012 12:23 AM
To: amsat-bb at amsat.org
Subject: [amsat-bb] Re: Satellite location prediction weeks away and JOTA

On 09/20/2012 12:42 AM, James Luhn wrote:
> I will be working with a Boy Scout troop on October 20 participating
> with JOTA (Jamboree On The Air). Is there an easy way to predict when
> the various satellites and ISS will be passing overhead on October 20?
> It would be nice to know the times and locations for October 20 weeks
> ahead.

Tracking software should be able to give you an 'ephemeris' table for 
each pass for the day.  For example, the software I use lists FOUR 
passes on 20th October, for ISS.  The best of these is 11:59:20 to 
12:09:55 (nearly 13 minutes!).  If I drill down on that pass, it lists 
times, AZ/EL angles, range, doppler correction, etc, from AOS (314°/0°) 
thru TCA (233°/40°) to LOS (157°/0°) in increments of 30-40 seconds.  I 
would expect any halfway decent tracking software should be able to give 
the same sort of info.

So, tell us what software you want to use, ande maybe someone who uses 
that particular software can tell you how to get the ephemeris info for 
the particular date, QTH and satellite(s) you want.

But consider that "weeks ahead" means that you are using elements that 
are weeks old!  (Or, they will be, weeks from now when you need to use 
the data.)  So any ephemeris data generated "weeks ahead" should be 
regenerated periodically as new elements become available, so your 
ephemeris becomes more accurate the closer you get to the date of interest.
73, de Gus 8P6SM
The Easternmost Isle
Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
Not an AMSAT-NA member? Join now to support the amateur satellite program!
Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb

More information about the AMSAT-BB mailing list