def read_wavecat(filename):
    """Read wavelength catalog from ASCII file.

    Table must contain two columns without header.
    Comment lines are allowed and will be ignored.
    Columns are automatically named:

    #. ``OBSMODE`` - Observation mode.
    #. ``FILENAME`` - Corresponding wavelength table filename
       or parameters.

    Example::

        # WAVECAT.DAT -- Comments.
        # More comments.
        cos,fuv     (900.0,3000.0,1.0)
        cos,nuv     (1000.0,12000.0,1.0)
        acs,hrc     synphot$wavecats/acs.dat
        acs,wfc1    synphot$wavecats/acs.dat

    Parameters
    ----------
    filename : str
        Wavelength catalog filename. Must be ASCII format.

    Returns
    -------
    data : `~astropy.table.Table`
        Data table.

    """
    return ascii.read(filename, names=('OBSMODE', 'FILENAME'), guess=False,
        format='no_header', converters={'OBSMODE': [ascii.convert_numpy(str
        )], 'FILENAME': [ascii.convert_numpy(str)]})
