# Active Asteroids (citizen science project)

Active Asteroids is a NASA partner citizen science project that successfully discovered active asteroids, including main-belt comets, quasi-Hilda objects, and Jupiter family comets. The project is hosted on the Zooniverse platform and is funded by a NSF Graduate Research Fellowship Program. It uses images from the Dark Energy Camera (DECam) to search for tails around asteroids and other minor planets. The research team is led by Colin Orion Chandler. As of April 2024 about 8300 volunteers carried out 6.7 million classifications of 430 thousand images. At the time only 60 active asteroids were known and 16 new active objects were discovered by this project, significantly increasing the sample of known objects.

## Pre-launch preparation

Before the team launched the project, the team gained experience with DECam and published three papers. These include detection of activity around previously known active asteroid (62412) 2000 SY178, revealing 6 years of avtivity on (6478) Gault and activity discovered on the centaur 2014 OG$_{392}$.

## Discoveries

The project uses a pipeline called HARVEST, which compares metadata from astronomical image archives with the data from the Minor Planet Center and produces images at positions of minor planets. It also excludes images with no detection or images that cannot detect asteroids. Since February 2024 the team also used a Convolutional Neural Network (CNN), called TailNet, to filter out bad images before they are shown to volunteers and to identify high-likely candidates. This CNN uses classification-labels made by the volunteers and is constantly improved with new classifications. One of the first discovery was made in September 2022, when the team published a paper describing that 282P/(323137) 2003 BM$_{80}$ showed sustained activity over 15 months in 2021-2022. Activity was previously reported in 2012-2013 and the team analysed the orbit, finding that it is an outbursting quasi-Hilda object.

### List of discoveries

| Name | family | type of activity | year-month of disovery | Reference | Previous discovery of activity |
| 2015 TC$_1$ | Jupiter-family comet | | 2022-01 | | no |
| 2017 QN$_{84}$ | Jupiter-family comet | | 2022-01 | | no |
| 282P | quasi-Hilda object (former Centaur or Jupiter-family comet) | volatile sublimation | 2013-06/2022-09 | | yes, Bolin et al. |
| 2015 FW$_{412}$ | main-belt comet candidate | sublimation | 2023-02 | | no |
| 2015 VA$_{108}$ | main-belt comet candidate | volatile sublimation | 2023-02 | | no |
| 2009 DQ$_{118}$ | quasi-Hilda object (former Jupiter family comet or Centaur) | sublimation of volatile ices | 2023-03 | | no |
| 2010 LH$_{15}$ (aka 2010 TJ$_{175}$) | main-belt comet | | 2023-03 | | no |
| (588045) 2007 FZ$_{18}$ | main-belt comet candidate | two tails | 2023-05 | | no |
| 2018 CZ$_{16}$ | quasi-Hilda object | thermally driven activity indicative of water-ice sublimation | 2023-05 | | no |
| 2005 XR$_{132}$ | Jupiter-family comet | | 2021-04/2023-07 | | yes, Cheng et al. |
| 2004 CV$_{50}$ | quasi-Hilda object | | 2023-11 | | no |
| (551023) 2012 UQ$_{192}$ | Jupiter-family Comet | recurrently active, sublimation | 2023-12 | | no |
| 2019 OE$_{31}$ | vacationing Centaur | volatile sublimation | 2023-12 | | no |
| 2008 QZ$_{44}$ | Jupiter-family comet | | 2023-12 | | no |
| 2018 VL$_{10}$ | Jupiter-family comet (Mars crossing) | | 2023-12 | | no |
| 2018 OR | Jupiter-family comet (Mars crossing) | | 2024-01 | | no |
| (410590) 2008 GB$_{140}$ | main-belt comet candidate | | 2024-02 | TailNet identified activity | no |
| 2016 UU$_{121}$ | main-belt comet candidate | | 2024-02 | TailNet identified activity | no |
| 2011 UG$_{104}$ | Jupiter-family comet | | 2024-05 | TailNet identified activity | no |
| 2015 VP$_{51}$ | Jupiter-family comet | suspected sublimation | 2024-09 | TailNet filtered, identified by citizen scientists | no |
| 2010 MK$_{43}$ (aka 2010 RA$_{78}$) | Jupiter-family comet (former quasi-Hilda object) | | 2024-09 | TailNet filtered, identified by citizen scientists | no |