2025/07/15 by Belyakov, Matthew, Fremling, Christoffer, Graham, Matthew J. +7 · 3 citations
#Astrophysics of Galaxies (astro-ph.GA) #Earth and Planetary Astrophysics (astro-ph.EP) #FOS: Physical sciences #Instrumentation and Methods for Astrophysics (astro-ph.IM)
paper · doi:10.48550/arxiv.2507.11720
On July 1st 2025 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 C2.