def METHOD_NAME(self):
    """
    An array containing magnetic field data.
    Returns
    -------
    `~astropy.units.Quantity`
    """
    path = f"data/{self.subname}/fields/B"
    if path in self.h5:
        units = _fetch_units(self.h5[path].attrs["unitDimension"])
        axes = [self.h5[path][axis] for axis in self.h5[path]]
        return np.array(axes) * units
    else:
        raise AttributeError("No magnetic field data available in HDF5 file")