usrp project
instructions on adding potential into galpy framework to be found here: http://galpy.readthedocs.io/en/latest/potential.html#adding-potentials-to-the-galpy-framework
galpy on github: https://github.com/jobovy/galpy
galpy documenation: https://media.readthedocs.org/pdf/galpy/v0.1/galpy.pdf