Palomar and Apache Point Spectrophotometry of Interstellar Comet 3I/ATLAS
Abstract On 2025 July 1st the third interstellar object, 3I/ATLAS or C/2025 N1 (ATLAS), was discovered, with an eccentricity of e = 6.15 ± 0.01 and perihelion of q = 1.357 ± 0.001 au. We report our initial visible to near-infrared (420–1000 nm) spectrophotometry of 3I/ATLAS using both the Palomar 200 inch telescope and Apache Point Observatory. We measure 3I/ATLAS to have a red spectral slope of 19%/100 nm in the 420–700 nm range, and a more neutral 6%/100 nm slope over 700–1000 nm. We detect no notable emission features such as from C 2 .
Authors
- Bryce Bolin (ORCID: https://orcid.org/0000-0002-4950-6323)
- M. Ryleigh Davis (ORCID: https://orcid.org/0000-0002-7451-4704)
- M. J. Graham (ORCID: https://orcid.org/0000-0002-3168-0139)
- C. Fremling (ORCID: https://orcid.org/0000-0002-4223-103X)
- Matthew Belyakov (ORCID: https://orcid.org/0000-0003-4778-6170)
- Mukremin Kilic (ORCID: https://orcid.org/0000-0001-6098-2235)
- C. M. Lisse (ORCID: https://orcid.org/0000-0002-9548-1526)
- Ian Wong (ORCID: https://orcid.org/0000-0001-9665-8429)
- Carl Ingebretsen (ORCID: https://orcid.org/0000-0002-7053-5495)
- Gracyn Jewett (ORCID: https://orcid.org/0009-0009-9105-7865)
Publication Details
- Journal
- Research Notes of the AAS
- Published
- 2025-07-18
- DOI
- https://doi.org/10.3847/2515-5172/adf059
- Citations
- 10
- Primary Topic
- Astro and Planetary Science
- Type
- article
- Field-Weighted Citation Impact
- 11.55