Orbit data different between programs

[chadgibeaut]

Hello all, im pretty new to amature satt. I currently have both Orbitron and HRD satellite tracking running on my computer. Both have been updated recently. but i am getting two different locations on the satellites. Any ideas?

[K2WH]

Hello all, im pretty new to amature satt. I currently have both Orbitron and HRD satellite tracking running on my computer. Both have been updated recently. but i am getting two different locations on the satellites. Any ideas?

Don't know why you are using 2 different programs but if you are getting different locations, I would alternate between both, find out which one is accurate and dump the other. It could also have something to do with your computer clock interpretation or setting.

K2WH

[K0RGR]

I would go to the AMSAT site and run your predictions there. Then, compare it to your programs. That might clue you in on which one is correct. If you end up with three different answers, I'd say both your programs are wrong.

I've probably made every mistake possible in setting up satellite software. The most common one is inputting your location incorrectly. Some programs want the latitude and longitude in minutes and seconds, some want it in decimal fractions of a minute.

Also be sure that your PC is set for the correct time, and the correction for GMT is accurate.

[W9GB]

I currently have both Orbitron and HRD satellite tracking running on my computer. Both have been updated recently, but I am getting two different locations on the satellites. Any ideas?

YES, that outcome is entirely possible.

WHY? I can be attributed to the mathematical models and algorithms being used for the calculations.
SGP4 (Simplified General Perturbations Satellite Orbit Model 4) is a NASA/NORAD algorithm of calculating near earth satellites (i.e. calculating their orbital state vectors relative to the Earth Centered Inertial coordinate system).
http://en.wikipedia.org/wiki/SGP4

The SGP4/SDP4 orbital model is the most commonly used -- and was developed to reduce the computational burden of tracking thousands of earth satellites. There are other approaches.

T.S. Kelso at Celestrak has the specific explanations as well as source code (FORTRAN, Pascal, C, C++, MATLAB) for the SGP4/SDP4 orbital model he uses.
http://celestrak.com/
http://www.sat.dundee.ac.uk/~psc/sgp4.html
http://www.zeptomoby.com/satellites/

w9gb