galpy.orbit.Orbit.U¶
- Orbit.U(*args, **kwargs)[source]¶
Return Heliocentric Galactic rectangular x-velocity (aka “U”).
- Parameters:
t (numeric, numpy.ndarray or Quantity, optional) – Time at which to get U. 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:
U(t) in km/s.
- Return type:
float, numpy.ndarray or Quantity [*input_shape,nt]
Notes
2019-02-21: Written by Bovy (UofT)