def gmosn_ham_dateobs(hdulist, verbose=False):
    """
    Correct DATE-OBS keyword in PHU.

    Parameters
    ----------
    hdulist : HDUList

    Returns
    -------
    A boolean indicating whether the header needed updating or not.

    """

    # DATE is normally okay.  Use that to correct DATE-OBS.
    date = hdulist[0].header['DATE']
    dateobs = hdulist[0].header['DATE-OBS']

    updated = False
    if date != dateobs:
        hdulist[0].header['DATE-OBS'] = date
        updated = True
        if verbose:
            print('DATE-OBS update the value of DATE, {}'.format(date))

    return updated