Comet ATLAS, formally designated as C/2019 E3, is an Oort cloud comet with a very distant perihelion of 10.30 AU (1.541 billion km), the third known comet with a perihelion distance beyond 10 AU after 167P/CINEOS and C/2003 A2 (Gleason). Precovery observations of this comet all the way to 2016 (and later 2012) have revealed that the comet had produced some cometary activity more than 20 AU (3.0 billion km) from the Sun, making it the fourth known distant comet to produce such activity at large distances after C/2010 U3 (Boattini), C/2014 UN271 (Bernardinelli–Bernstein), and C/2017 K2 (PanSTARRS).
References
External links C/2019 E3 at the JPL Small-Body Database