CRTS J213937.6-023913 outburst Possible superoutburst? YYYYMMDD(UT) mag observer 20181021.3982 <152c (Yutaka Maeda) 20181024.3946 142cG (Yutaka Maeda) 20181024.5734 143C (Masayuki Moriyama) 20181025.3925 141cG (Yutaka Maeda)