def read_ring_images_index():
meta = read_cumulative_iss_index()<EOL>ringfilter = meta.TARGET_DESC.str.contains("<STR_LIT>", case=False)<EOL>return meta[ringfilter]<EOL>
Filter cumulative index for ring images.

    This is done by matching the column TARGET_DESC to contain the string 'ring'

    Returns
    -------
    pandas.DataFrame
        data table containing only meta-data for ring images