Satellite Prediction Listing (SPL) is up and running. Utilizing a REST interface HTTP GETs are used to specify the propagation parameters. This web service is meant to be used by web or desktop apps removing the necessity to integrate an orbital propagation model into the application. Currently the SGP model is being used.

The entire Celestrak library is available as well as the classified TLEs published by Mike McCants. An autoupdate satellite library manager automatically refreshes the local cache of celestrak and classified tles. The entire library is flushed every 24 hours allowing for new additions to Celestrak to be added. Celestrak seems to be the best alternative to directly grabbing Space-Track.org elements which would violate the usage agreement if I understand correctly. All available spacecraft listed here: http://www.williamslabs.com/sat/validSats.py

Output formats include XML, HTML, and the Keyhole Markup Language (KML) allowing integration into Google Maps and Google Earth very easily. Documentation and instructions on how to use the service are available here: http://www.williamslabs.com/sat

Sample Google Maps / Earth integration examples here: http://www.williamslabs.com/sat/docs/kmlexamples.php

SPL uses the Open Source KepCalc Python library available here: http://sourceforge.net/projects/kepcalc KepCalc provides a simple propagation library with nearly identical implementations in C#, C++, Python, and Java.

Here are some examples of SPL:

All default parameters: http://www.williamslabs.com/sat/spl.py

100 samples of satellite Libertad-1 on May 1st between 00:00:00 and 12:00:00 UTC: http://www.williamslabs.com/sat/spl.py?Satellite=31128&TimeStart=2008-05...

A pass of default sat Genesat-1 over an update New York observer, one sample every 30 seconds: http://www.williamslabs.com/sat/spl.py?ObserverAltitude=300.0&ObserverLa...

Current position of the ISS in XML format: http://www.williamslabs.com/sat/spl.py?Output=xml&Satellite=25544

Position of AO-51 (28375) over the past hour with a sample every 60 seconds in KML format (try saving file as test.kml and load with Google Earth): http://www.williamslabs.com/sat/spl.py?Satellite=28375&Output=kml&Ti...

Feedback and questions are very welcome.

-Phelps Williams KI6GST