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Discovery and Preliminary Characterization of a Third Interstellar Object: 3I/ATLAS
Darryl Z. Seligman, Marco Micheli, Davide Farnocchia et al., 2025. The Astrophysical Journal Letters.
The discovery paper for the third interstellar object, found by the ATLAS survey on 1 July 2025: eccentricity about 6.1, perihelion 1.36 au, inclination 175 degrees, excess velocity 58 km/s, a compact coma in deep CFHT and VLT stacks, little light-curve variation over four days and a red spectral slope like primitive Solar System bodies. ApJL 989, L36.
What it's used for here
The primary record of 3I's discovery and first properties.
Our copy
Research copy, for editors and curators. The work is the publisher's, so readers are sent to it. We keep this copy so the citation can be checked if the page changes or goes.
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Cited by on this site 3 records
1I/'Oumuamua
MYSThe mystery article
Cite it
Seligman, D. Z., Micheli, M., Farnocchia, D., Denneau, L., Noonan, J. W., Hsieh, H. H., Santana-Ros, T., Tonry, J., & Meech, K. J. (2025). Discovery and Preliminary Characterization of a Third Interstellar Object: 3I/ATLAS. The Astrophysical Journal Letters. https://doi.org/10.3847/2041-8213/adf49a
@article{seligman2025discovery,
author = {Seligman, Darryl Z. and Micheli, Marco and Farnocchia, Davide and Denneau, Larry and Noonan, John W. and Hsieh, Henry H. and Santana-Ros, Toni and Tonry, John and Meech, Karen J.},
title = {Discovery and Preliminary Characterization of a Third Interstellar Object: 3I/ATLAS},
journal = {The Astrophysical Journal Letters},
year = {2025},
doi = {10.3847/2041-8213/adf49a},
url = {https://doi.org/10.3847/2041-8213/adf49a}
}TY - JOUR TI - Discovery and Preliminary Characterization of a Third Interstellar Object: 3I/ATLAS AU - Seligman, Darryl Z. AU - Micheli, Marco AU - Farnocchia, Davide AU - Denneau, Larry AU - Noonan, John W. AU - Hsieh, Henry H. AU - Santana-Ros, Toni AU - Tonry, John AU - Meech, Karen J. PY - 2025 JO - The Astrophysical Journal Letters DO - 10.3847/2041-8213/adf49a UR - https://doi.org/10.3847/2041-8213/adf49a ER -
Seligman, Darryl Z. et al.. “Discovery and Preliminary Characterization of a Third Interstellar Object: 3I/ATLAS.” The Astrophysical Journal Letters (2025). https://doi.org/10.3847/2041-8213/adf49a.