def normalize_lc(data):
    """
    Normalise light curve flux and flux_err

    Parameters
    ----------
    data : pandas.DataFrame
        DataFrame object to be normalised. Must contain:
        flux, flux_err
    """
    norm_factor = data['flux'].max()
    data['flux'] /= norm_factor
    data['flux_err'] /= norm_factor
    data['norm_factor'] = norm_factor

    return data