Gaia21fgn: long fading tail AM CVn star? YYYYMMDD(UT) mag observer 20220921.5188 19.038zr (ZTF Alert DC mag (Masci+ 2019)) 20220927.5071 19.079zr (ZTF Alert DC mag (Masci+ 2019)) 20220927.5120 19.063zr (ZTF Alert DC mag (Masci+ 2019)) 20220930.5089 18.962zr (ZTF Alert DC mag (Masci+ 2019)) 20220930.5140 19.146zr (ZTF Alert DC mag (Masci+ 2019)) 20220930.5191 19.160zr (ZTF Alert DC mag (Masci+ 2019)) 20221006.5101 19.174zr (ZTF Alert DC mag (Masci+ 2019))