def katdal_uvw(uvw, refwave):
    """
    Converts AIPS UVW coordinates in wavelengths *at the reference frequency*
    to katdal UVW coordinates in metres. Set :function:`aips_uvw` for
    further discussion.

    Parameters
    ----------
    uvw : np.ndarray
        AIPS UVW coordinates in wavelengths at the reference frequency
    refwave : float
        Reference wavelength in metres

    Returns
    -------
    np.ndarray
        katdal UVW coordinates, in metres
    """
    return refwave * uvw