MASTER OT J211322.92+260647.4 possible superoutburst YYYYMMDD(UT) mag observer 20210710.6470 <158c (Yutaka Maeda) 20210713.6794 <144c (Yutaka Maeda) 20210715.7275 <158c (Yutaka Maeda) 20210719.5771 <160c (Yutaka Maeda) 20210727.6599 150cG (Yutaka Maeda) 20210728.6675 153:cG (Yutaka Maeda)