galpy.df.StreamTrack.pmphi1

StreamTrack.pmphi1(tp, **kwargs)[source]

Proper motion in custom-frame phi1 along the track, multiplied by cos(phi2).

Requires custom_sky_transform to have been set at construction.

Parameters:

  • tp (float, array, or Quantity) – Curve parameter(s); Quantity inputs are parsed per parameter_kind. Out-of-range entries return NaN.

  • ro (float or Quantity, optional) – Distance scale (kpc); overrides the stored value.

  • vo (float or Quantity, optional) – Velocity scale (km/s); overrides the stored value.

  • use_physical (bool, optional) – Override the object-wide physical-units default.

  • quantity (bool, optional) – Return an astropy Quantity if True.

Returns:

pmphi1 * cos(phi2) in mas/yr.

Return type:

float, numpy.ndarray, or Quantity