Satellites Plugin for Stellatium
================================

INTRODUCTION
============

This feature has been requested so many times it's not funny.  Several
people have posted to the developer list saying they would like to have a
go and then the Yeti seem to get them and we never hear another thing.

Well, dagnammit, I thought I'd have a go.

Projection is done from the azimuth/elevation data which the SDP4/SGP4
library handily produces.  Probably not the "right" way to do it, but 
it works and I am lazy.


TODO
====

+ Detect when Satellite designations change in source data and repair 
  JSON data accordingly.
  - perhaps keep track of international designators from the TLE data?
+ Rendering of the actual satellite, not just a hint/label
  - calculation of brightness, eclipse etc.
  - iridium flares?
+ gravity labels

Longer term:
+ proper 3d positions (when SolarSystem is refactored so we can see
  satellite cloud from the moon / other bodies.


BUILDING THE PLUGIN
===================

Please note, these instructions are only directly applicable to Linux.
Windows and OSX targets will probably require modification of the
CMakeLists.txt file.

0.  Install and build the Bazaar version of Stellarium as per the 
instructions on the Stellarium wiki:

  http://stellarium.org/wiki/index.php/Compilation_on_Linux

1.  Set the environment variable STELROOT to the root of the Stellarium
source tree.  The Stellarium build directory is expected to be:

  $STELROOT/builds/unix 

2.  Create a sub-directory builds/unix and change into that directory.

3.  Run:

  cmake ../.. 
  make
  make install

If all goes well, the relevant files should be built and copied to your 
~/.stellarium/modules directory.


ACKNOWLEGDEMENTS
================

Re-write of orbital calculation routines by Jose Luis Canales, added 
Autumn 2010.

Original SGP4/SDP4 implementation taken from KTrack codebase. There were
some minor modifications to prevent conflicts with #defines and enums 
from the core Stellarium code, but nothing significant.

The code which uses the SGP4/SDP4 library was copied more or less 
verbatim from KTrack up to the point of getting the alt/azi and other
data out.


