new_contents: # coding: utf-8
  
  """ """
  
  from __future__ import division, print_function
  
  __author__ = "adrn <adrn@astro.columbia.edu>"
  
  # Standard library
  import os, sys
  
  # Third-party
  import numpy as np
  from numpy import cos, sin
  
  import astropy.coordinates as coord
  import astropy.units as u
  
  __all__ = ["gsr_to_hel"]
  
  def gsr_to_hel(l, b, v_gsr, v_sun_lsr=[10.,5.25,7.17]*u.km/u.s, v_circ=220*u.km/u.s):
      """ Convert a velocity from the Galactic standard of rest (GSR) to 
          heliocentric radial velocity. 
      """
      assert hasattr(v_gsr, 'unit')
      assert hasattr(l, 'radian')
      assert hasattr(b, 'radian')
      
      v_lsr = v_gsr - v_circ * sin(l.radian) * cos(b.radian)
      
      # velocity correction for Sun relative to LSR
      v_correct = v_sun_lsr[0]*cos(b.radian)*cos(l.radian) + \
                  v_sun_lsr[1]*cos(b.radian)*sin(l.radian) + \
                  v_sun_lsr[2]*sin(b.radian)
      v_hel = v_lsr - v_correct
      
      return v_hel
subject: add gsr to hel function to coordinates