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orbits
For my uncle Zbys who watched the planets and stars.
Types and functions for dealing with Kepler orbits.
The main data type is Orbit
, which describes the path of a body in orbit.
Nomenclature
Symbol  Meaning  Notes 

a  Semimajor axis  Negative for hyperbolic orbits 
b  Semiminor axis  Negative for hyperbolic orbits 
e  Eccentricity  
q  Periapsis  
i  Inclination  
μ  Standard gravitational parameter  
Ω  Longitude of the ascending node  
l  Semilatus Rectum  
n  Mean motion  
p  Period  
t  Time since periapse  
M  Mean anomaly  
E  Eccentric anomaly  Only for elliptic orbits 
H  Hyperbolic anomaly  Only for hyperbolic orbits 
ν  True anomaly  
h  Specific angular momentum  
ε  Specific orbital energy  
εp  Specific potential energy  
εk  Specific kinetic energy  
v  Orbital speed or velocity  
r  The radius to the orbiting body  
φ  Flight path angle 
Note that in the Haskell source uppercase symbols such as Ω and M are written with a leading underscore.
Implementation
This package makes use of the
units
package to ensure that the
implementation is correct regarding units of measure.
Contributing
Contributions and bug reports are welcome!
Please feel free to contact me on GitHub or as "jophish" on freenode.
Joe