ASASSN-21nf: likely a nova Moriyama-san detected red color. YYYYMMDD(UT) mag observer 20210727.5344 14.93C (Masayuki Moriyama) 20210727.5371 14.55V (Masayuki Moriyama) 20210727.5398 13.30Ic (Masayuki Moriyama) 20210727.5427 14.47Rc (Masayuki Moriyama)