2016 UU121: An Active Asteroid Discovery via AI-enhanced Citizen Science

We report the discovery of an active asteroid, 2016 UU 121 , for the first time via artificial intelligence-enhanced classification, informed by our NASA Partner program Active Asteroids , a Citizen Science project hosted on the Zooniverse platform. The early version of our deep neural network, TailNet , identified potential activity associated with 2016 UU 121 in 40 Dark Energy Camera (DECam) images from UT 2021 September 10 to 11. The discovery was vetted and confirmed by our Active Asteroids core science team. In total, 66 DECam images of this object showed clear activity in the form of a tail. 2016 UU 121 has a Tisserand parameter with respect to Jupiter of 3.161, thus we classify the object as an active asteroid. Moreover, the activity occurred near perihelion, so 2016 UU 121 is also a candidate Main-belt comet.