ASASSN-17qh superoutburst YYYYMMDD(UT) mag observer 20200121.5572 <155c (Yutaka Maeda) 20200128.5642 <145c (Yutaka Maeda) 20200201.5388 136cG (Yutaka Maeda) precursor? 20200202.5786 <144c (Yutaka Maeda) 20200204.6163 133cG (Yutaka Maeda) 20200205.6173 134cG (Yutaka Maeda)