# galpy.orbit.Orbit.helioX¶

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

NAME:

helioX

PURPOSE:

return Heliocentric Galactic rectangular x-coordinate (aka “X”)

INPUT:

t - (optional) time at which to get X

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; Note that when Y is non-zero, the coordinate system is rotated around z such that Y’=0

ro= distance in kpc corresponding to R=1. (default=Object-wide default)

OUTPUT:

helioX(t) in kpc [*input_shape,nt]

HISTORY:

2019-02-21 - Written - Bovy (UofT)