Near-Discovery Observations of Interstellar Comet 3I/ATLAS with the NASA Infrared Telescope Facility
Theodore Kareta (Villanova U.), Chansey Champagne (NAU), Lucas McClure (NAU), Joshua Emery (NAU), Benjamin N.L. Sharkey (UMD), James M. Bauer (UMD), Michael Connelly (UH/IRTF), John Rayner (UH/IRTF), Cristina Thomas (NAU), Vishnu Reddy (UAz), Megan Firgard (UCF)

TL;DR
This study presents early infrared and optical observations of interstellar comet 3I/ATLAS, revealing its spectral properties and lack of water ice signatures, providing insights into its composition and differences from Solar System comets.
Contribution
First near-infrared spectrum and detailed optical observations of 3I/ATLAS, highlighting its unique spectral features and potential compositional differences from Solar System comets.
Findings
Spectral slope indicates a complex grain composition.
No obvious water ice signatures detected.
Color and spectrum similar to other near-discovery observations.
Abstract
Interstellar Objects are comets and asteroids that formed around other stars but were ejected before they could accrete into exoplanets. They therefore represent a rare opportunity to compare the building blocks of planets in the Solar System to those in other stellar systems. The third Interstellar Object, 3I/ATLAS, is the newest, brightest, potentially largest, and fastest member of this population. We report observations of 3I/ATLAS taken on 2025 July 3 and 4 with the NASA Infrared Telescope Facility just days after its discovery. In r'-band imaging with 'Opihi, we see no obvious lightcurve variability and derive a g'-i' color of 0.98+/-0.03 which is consistent in spectral slope to other near-discovery observations. We obtained the first near-infrared (NIR) reflectance spectrum of 3I/ATLAS with SpeX. The visible color and NIR spectrum show a linear, red visible slope, a somewhat less…
Peer Reviews
No public reviews on file for this paper yet. If you reviewed it on a platform where reviews are public (OpenReview, ICLR, NeurIPS, ICML), you can paste yours below so the community can read it here.
Videos
No videos yet. Explain this paper in a talk, walkthrough, or lecture? Add one.
Taxonomy
TopicsAstro and Planetary Science · Gamma-ray bursts and supernovae · Planetary Science and Exploration
