code: def helioY(self,*args,**kwargs):
          
          _check_roSet(self,kwargs,'helioY')
          X, Y, Z= self._helioXYZ(*args,**kwargs)
          return Y
docs: NAME:
             helioY
          PURPOSE:
             return Heliocentric Galactic rectangular y-coordinate (aka "Y")
          INPUT:
             t - (optional) time at which to get Y
             obs=[X,Y,Z] - (optional) position and velocity of observer 
                           (in kpc and km/s) (default=Object-wide default)
                           OR Orbit object that corresponds to the orbit
                           of the observer
                           Y is ignored and always assumed to be zero
             ro= distance in kpc corresponding to R=1. (default=Object-wide default)         
          OUTPUT:
             helioY(t) in kpc
          HISTORY:
             2011-02-24 - Written - Bovy (NYU)