Hanjie Tan, Guoyou Sun, Mi Zhang, Xing Gao (Xingming Observatory), report ~3.0 mag outburst in a known variable star ( 16.41 r ) which is 19.39 rmag in Pan-STARRS DR1 catalogue. The transient was discovered on several 120-s survey images ( limiting mag about 18.0 ) taken by Xing Gao at Xingming Observatory #3 ( N88 ) around Dec. 22.56358 UT using a unfiltered CCD ( 0.3-m f/3.6 reflector ). Images can be found at: http://xjltp.china-vo.org/xm21ht.html
XM21HT C2020 12 22.56358 21 57 16.47 +52 12 00.8 16.41 r N88
*Known VS V1404 Cyg