def swe_headerfile_name(dt, infile_type):
    """Return SWE headerfile name for a given datetime"""

    dtstr = dt.strftime('%Y%m%d')

    if infile_type.upper() == 'UNMASKED':
        return 'zz_ssmv11034tS__T0001TTNATS{}05HP001.txt.gz'.format(dtstr)
    elif infile_type.upper() == 'MASKED':
        return 'us_ssmv11034tS__T0001TTNATS{}05HP001.txt.gz'.format(dtstr)