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arXiv · 2511.20810

Tracking the Activity of the Interstellar Object 3I/ATLAS through its Perihelion

T. Marshall Eubanks·Craig E. DeForest·Kevin J. Walsh·Simon Porter·Thomas Lehmann·Bruce G. Bills·Adam Hibberd·W. Paul Blase·Andreas M. Hein·Robert G. Kennedy III·Adrien Coffinet·Pierre Kervella·Carlos Gomez de Olea Ballester
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Abstract

In order to facilitate interplanetary spacecraft observationsof 3I/ATLAS, we have monitored and predicted the optical properties of its coma using both ground and space-based observations. Here, we describe how the data from space-based solar coronagraphs and the PUNCH mission enabled tracking of 3I/ATLAS's optical magnitude throughout its entire perihelion passage, including the period between October 8 and 30, 2025, when it was not visible from Earth.

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T. Marshall Eubanks, Craig E. DeForest, Kevin J. Walsh, Simon Porter, Thomas Lehmann, Bruce G. Bills, Adam Hibberd, W. Paul Blase, Andreas M. Hein, Robert G. Kennedy III, Adrien Coffinet, Pierre Kervella, Carlos Gomez de Olea Ballester. 2025-11-25. Tracking the Activity of the Interstellar Object 3I/ATLAS through its Perihelion. https://arxiv.org/abs/2511.20810

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