def zred_extra_dtype(nsamp):
    """
    Return the zred dtype to append.

    Parameters
    ----------
    nsamp: `int`
       Number of samples of zred to record
    """

    return [('ZRED', 'f4'),
            ('ZRED_E', 'f4'),
            ('ZRED2', 'f4'),
            ('ZRED2_E', 'f4'),
            ('ZRED_UNCORR', 'f4'),
            ('ZRED_UNCORR_E', 'f4'),
            ('ZRED_SAMP', 'f4', nsamp),
            ('LKHD', 'f4'),
            ('CHISQ', 'f4')]