ASASSN-15fu likely superoutburst YYYYMMDD(UT) mag observer 20210127.6792 <147c (Yutaka Maeda) 20210129.6890 <143c (Yutaka Maeda) 20210203.6915 <142c (Yutaka Maeda) 20210210.3762 15.514zg (Zwicky Transient Facility Lasair (Masci+ 2019))