arXiv · 2508.20215
The Ongoing Decline in Activity of Comet 103P/Hartley 2
Abstract
We report photometric observations of Comet 103P/Hartley 2 during its 2023 apparition. Our campaign, conducted from August through December 2023, combined data from a global network of citizen astronomers coordinated by Unistellar and the Association Fran\c{c}aise d'Astronomie. Photometry was derived using an automated pipeline for eVscope observations in partnership with the SETI Institute and aperture photometry via AstroLab Stellar. We find that the comet's peak reduced brightness, measured at $G_{\rm min} = 10.24 \pm 0.47$, continues a long-term fading trend since 1991. The decline in activity follows a per-apparition minimum magnitude increase of $\Delta G_{\rm min} = 0.59 \pm 0.11$ mag, corresponding to an approximately $42\%$ reduction in brightness each return. This trend implies that the comet's active fraction has declined by about an order of magnitude since 1991 and may indicate that Hartley 2 is no longer hyperactive by definition. The fading is consistent with progressive volatile depletion rather than orbital effects. These results offer insight into the evolutionary processes shaping Jupiter-family comets.
Explore related subjects
Keep this discovery
Explore connections, maps & timelines
Ariel Graykowski, Guillaume Langin, David Chiron, Bruno Guillet, Franck Marchis, Nicolas Biver, Gérard Arlic, Bernard Baudouin, Etienne Bertrand, Randall Blake, Cyrille Bosquet, John K. Bradley, Isabelle Brocard, Christophe Cac, Alain Cagna, Nicolas Castel, Eric Chariot, Olivier Clerget, Tom Coarrase, Lucas Cogniaux, Julien Collot, Christophe Coté, Michel Deconinck, Jean-Paul Desgrees, Josselin Desmars, Giuseppe Di Tommaso, José Donas, William Drapeaud, Todd Forrester, Florent Frémont, Keiichi Fukui, Paul Garde, Jérôme Gaudilliere, Pascal Gaudin, Alexis Giacomoni, David Gineste, Patrice Girard, Jean Claude Gomez, Chuck Goodman, Gerard-Philippe Grandjean, Philippe Guiglion, David Havell, Patrick Huth, Kachi Iwai, Marc-Etienne Julien, Rachel Knight, Ryuichi Kukita, Petri Kuossari, Jean-Michel Ladruze, Anis Ben Lassoued, Cédric Latgé, Jean-Marie Laugier, Matthieu Lauvernier, Patrice Le Guen, Jean-Charles Le Tarnec, Didier Lefoulon, Liouba Leroux, Niniane Leroux, Arnaud Leroy, Chelsey Logan, Yohann Lorand, Elisabeth Maris, Jean-Pierre Masini, Nicola Meneghelli, Laurent Millart, Eric Miny, Mike Mitchell, Baptiste Montoya, Fabrice Mortecrette, Anouchka Nardi, Antoine Ngo, Denis Nicolas, Raphael Nicollerat, Takaya Okada, Wataru Ono, George Patatoukas, Jacqueline Payet-Ayrault, Patrick Picard, Claude Porchel, Kanai Potts, Michel Quienen, Martial Relier, Fabien Richardot, Darren Rivett, Matthew Ryno, Fadi Saibi, Sophie Saibi, Christian Sartini, Hiromichi Sasaki, Philippe Seibert, Masao Shimizu, Lucas Sifoni, Georges Simard, Petri Tikkanen, Ian Transom, Bernard Tregon, Frank Tyrlik, Laurent Vadrot, Michel Veuillet, Christian Voirol. 2025-08-27. The Ongoing Decline in Activity of Comet 103P/Hartley 2. https://arxiv.org/abs/2508.20215
Cite the original work for its findings. Save a collection to share your selection of sources.