def ra(self,*args,**kwargs):
        """
        NAME:
           ra
        PURPOSE:
           return the right ascension
        INPUT:
           t - (optional) time at which to get ra
           obs=[X,Y,Z] - (optional) position of observer (in kpc) 
                         (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:
           ra(t)
        HISTORY:
           2011-02-23 - Written - Bovy (NYU)
        """
        _check_roSet(self,kwargs,'ra')
        radec= self._radec(*args,**kwargs)
        return radec[:,0]
NAME:
           ra
        PURPOSE:
           return the right ascension
        INPUT:
           t - (optional) time at which to get ra
           obs=[X,Y,Z] - (optional) position of observer (in kpc) 
                         (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:
           ra(t)
        HISTORY:
           2011-02-23 - Written - Bovy (NYU)