# galpy.orbit.Orbit.vll¶

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

NAME:

vll

PURPOSE:

return the velocity in Galactic longitude (km/s)

INPUT:

t - (optional) time at which to get vll (can be Quantity)

obs=[X,Y,Z,vx,vy,vz] - (optional) position and velocity of observer
in the Galactocentric frame (in kpc and km/s) (default=[8.0,0.,0.,0.,220.,0.]; entries can be Quantity) OR Orbit object that corresponds to the orbit of the observer Y is ignored and always assumed to be zero

ro= (Object-wide default) physical scale for distances to use to convert (can be Quantity)

vo= (Object-wide default) physical scale for velocities to use to convert (can be Quantity)

OUTPUT:

v_l(t) in km/s [*input_shape]

HISTORY:

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