![\"Simultaneous](\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2025\/08\/Simultaneous-Visible-Spectrophotometry.png\")
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\n Reflectance spectrum of 3I\/ATLAS. Also, Mahlke templates of S-, D- and Z-type asteroids are shown (Mahlke et al. 2022). Shaded areas indicate the standard deviations of the template spectra. \u2014 astro-ph.EP <\/p>\n
3I\/ATLAS, also known as C\/2025 N1 (ATLAS), is the third interstellar object (ISO) discovered in July 2025.<\/p>\n
ISOs are particularly interesting because characterizing their physical properties helps us understand and test our knowledge of Solar System formation. Several quick response observations of 3I\/ATLAS were performed during the first few days after the discovery, and various results, such as reflectance spectra, have been reported.<\/p>\n
We performed simultaneous visible spectrophotometry of 3I\/ATLAS from data taken using the TriColor CMOS Camera and Spectrograph (TriCCS) on the Seimei 3.8 m telescope. The Seimei\/TriCCS observations of 3I\/ALTAS were obtained in the g, r, i, and z bands in the Pan-STARRS system on UTC July 15, 2025.<\/p>\n
Our lightcurves show no significant variations during the 2.3 h observation, which is in good agreement with previous studies. Visible color indices of 3I\/ATLAS, g\u2212r=0.603\u00b10.031, r\u2212i=0.210\u00b10.031, i\u2212z=0.117\u00b10.046, and r\u2212z=0.327\u00b10.035 suggest it has a red surface similar to, or slightly redder than, that of D-type asteroids.<\/p>\n
Continuous observations of 3I\/ATLAS before and after its perihelion passage in October 2025 are desired to investigate its physical properties.<\/p>\n
Jin Beniyama<\/p>\n
Comments: 6 pages, 4 figures, accepted for publication in PASJ Letter. This is a pre-copyedited, author-produced version of an article accepted for publication in \u201cPublications of the Astronomical Society of Japan\u201d following peer review. The version of record is available online at https:\/\/apps.crossref.org\/pendingpub\/pendingpub.html?doi=10.1093%2Fpasj%2Fpsaf097<\/a><\/p>\n Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2508.08829 [astro-ph.EP] (or arXiv:2508.08829v1 [astro-ph.EP] for this version)
https:\/\/doi.org\/10.48550\/arXiv.2508.08829<\/a>
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Related DOI:
https:\/\/doi.org\/10.1093\/pasj\/psaf097<\/a>
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Submission history
From: Jin Beniyama
[v1] Tue, 12 Aug 2025 10:37:07 UTC (1,646 KB)
https:\/\/arxiv.org\/abs\/2508.08829<\/a>
Astrobiology,<\/p>\n","protected":false},"excerpt":{"rendered":"Reflectance spectrum of 3I\/ATLAS. Also, Mahlke templates of S-, D- and Z-type asteroids are shown (Mahlke et al.…\n","protected":false},"author":3,"featured_media":145103,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[25],"tags":[492,159,67,132,68],"class_list":{"0":"post-145102","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-physics","8":"tag-physics","9":"tag-science","10":"tag-united-states","11":"tag-unitedstates","12":"tag-us"},"share_on_mastodon":{"url":"","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/145102","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/comments?post=145102"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/145102\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media\/145103"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media?parent=145102"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/categories?post=145102"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/tags?post=145102"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}