galpy.orbit.Orbit.vll

Orbit.vll(*args, **kwargs)[source]

Return the velocity in Galactic longitude (km/s).

Parameters:
  • t (numeric, numpy.ndarray or Quantity, optional) – Time at which to get vll. Default is the initial time.

  • obs (numpy.ndarray, Quantity or Orbit, optional) – Position and velocity of observer in the Galactocentric frame (in kpc and km/s) (default=object-wide default) OR Orbit object that corresponds to the orbit of the observer. Note that when Y is non-zero, the coordinate system is rotated around z such that Y’=0.

  • ro (float or Quantity, optional) – Physical scale in kpc for distances to use to convert. Default is object-wide default.

  • vo (float or Quantity, optional) – Physical scale for velocities in km/s to use to convert. Default is object-wide default.

  • use_physical (bool, optional) – Use to override object-wide default for using a physical scale for output.

  • quantity (bool, optional) – If True, return an Astropy Quantity object. Default from configuration file.

Returns:

v_l(t) in km/s.

Return type:

numpy.ndarray or Quantity [*input_shape]

Notes

  • 2019-02-28 - Written - Bovy (UofT)