def achromatic_lightness_correlate(Q):
    """
    Returns the *achromatic Lightness* correlate :math:`L_p^\star`.

    Parameters
    ----------
    Q : numeric
        Achromatic response :math:`Q`.

    Returns
    -------
    numeric
        *Achromatic Lightness* correlate :math:`L_p^\star`.

    Examples
    --------
    >>> Q = -0.000117024294955
    >>> achromatic_lightness_correlate(Q)  # doctest: +ELLIPSIS
    49.9998829...
    """

    return Q + 50