JCMT detection of HCN emission from 3I/ATLAS at 2.1 au

Iain M. Coulson; Yi Jehng Kuan; Steven B. Charnley; Martin A. Cordiner; Yo Ling Chuang; Yueh Ning Lee; Min Kai Lin; Stefanie N. Milam; Bannawit Pimpanuwat; Nathan X. Roth; Michał Żółtowski

doi:10.1093/mnras/stag063

JCMT detection of HCN emission from 3I/ATLAS at 2.1 au

Iain M. Coulson^*
, Yi Jehng Kuan^*
, Steven B. Charnley
, Martin A. Cordiner
, Yo Ling Chuang
, Yueh Ning Lee
, Min Kai Lin
, Stefanie N. Milam
, Bannawit Pimpanuwat
, Nathan X. Roth
, Michał Żółtowski

^*Corresponding author for this work

Department of Earth Sciences (Include Institute of Marine Environmental Science and Technology)

Research output: Contribution to journal › Article › peer-review

Abstract

We report the detection of HCN($J=3-2$) rotational emission from comet 3I/ATLAS at a heliocentric distance of 2.13 au with the James Clerk Maxwell Telescope (JCMT). Observations were conducted between 2025 August 7 and 2025 September 14 (ut) using the $^{^{\prime }}\, \overline{U}\, ^{^{\prime }}\, \overline{u}$ heterodyne receiver and ACSIS (Auto Correlation Spectral Imaging System) spectroscopic backend. The HCN line was detected at $> 6 \sigma$ on 2025 September 14 (ut) and a production rate of $Q({\rm HCN})=(4.0\pm 1.7)\times 10^{25}$ s$^{-1}$ was derived by non-LTE radiative transfer modelling. Preliminary estimates of the HCN/H$_2$O and CN/HCN abundance ratios suggest values similar to Solar system comets.

Original language	English
Article number	stag063
Journal	Monthly Notices of the Royal Astronomical Society
Volume	546
Issue number	2
DOIs	https://doi.org/10.1093/mnras/stag063
Publication status	Published - 2026 Feb 1

Keywords

comets: individual: 3I/ATLAS

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1093/mnras/stag063

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@article{b424e5d95ce643ff9fe788cb8209bf65,

title = "JCMT detection of HCN emission from 3I/ATLAS at 2.1 au",

abstract = "We report the detection of HCN(\$J=3-2\$) rotational emission from comet 3I/ATLAS at a heliocentric distance of 2.13 au with the James Clerk Maxwell Telescope (JCMT). Observations were conducted between 2025 August 7 and 2025 September 14 (ut) using the \$\textasciicircum{}\{\textasciicircum{}\{\textbackslash{}prime \}\}\textbackslash{}, \textbackslash{}overline\{U\}\textbackslash{}, \textasciicircum{}\{\textasciicircum{}\{\textbackslash{}prime \}\}\textbackslash{}, \textbackslash{}overline\{u\}\$ heterodyne receiver and ACSIS (Auto Correlation Spectral Imaging System) spectroscopic backend. The HCN line was detected at \$> 6 \textbackslash{}sigma\$ on 2025 September 14 (ut) and a production rate of \$Q(\{\textbackslash{}rm HCN\})=(4.0\textbackslash{}pm 1.7)\textbackslash{}times 10\textasciicircum{}\{25\}\$ s\$\textasciicircum{}\{-1\}\$ was derived by non-LTE radiative transfer modelling. Preliminary estimates of the HCN/H\$\_2\$O and CN/HCN abundance ratios suggest values similar to Solar system comets.",

keywords = "comets: individual: 3I/ATLAS",

author = "Coulson, \{Iain M.\} and Kuan, \{Yi Jehng\} and Charnley, \{Steven B.\} and Cordiner, \{Martin A.\} and Chuang, \{Yo Ling\} and Lee, \{Yueh Ning\} and Lin, \{Min Kai\} and Milam, \{Stefanie N.\} and Bannawit Pimpanuwat and Roth, \{Nathan X.\} and Micha{\l} {\.Z}{\'o}{\l}towski",

note = "Publisher Copyright: {\textcopyright} Published by Oxford University Press on behalf of Royal Astronomical Society 2026.",

year = "2026",

month = feb,

day = "1",

doi = "10.1093/mnras/stag063",

language = "English",

volume = "546",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

publisher = "Oxford University Press",

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TY - JOUR

T1 - JCMT detection of HCN emission from 3I/ATLAS at 2.1 au

AU - Coulson, Iain M.

AU - Kuan, Yi Jehng

AU - Charnley, Steven B.

AU - Cordiner, Martin A.

AU - Chuang, Yo Ling

AU - Lee, Yueh Ning

AU - Lin, Min Kai

AU - Milam, Stefanie N.

AU - Pimpanuwat, Bannawit

AU - Roth, Nathan X.

AU - Żółtowski, Michał

PY - 2026/2/1

Y1 - 2026/2/1

N2 - We report the detection of HCN($J=3-2$) rotational emission from comet 3I/ATLAS at a heliocentric distance of 2.13 au with the James Clerk Maxwell Telescope (JCMT). Observations were conducted between 2025 August 7 and 2025 September 14 (ut) using the $^{^{\prime }}\, \overline{U}\, ^{^{\prime }}\, \overline{u}$ heterodyne receiver and ACSIS (Auto Correlation Spectral Imaging System) spectroscopic backend. The HCN line was detected at $> 6 \sigma$ on 2025 September 14 (ut) and a production rate of $Q({\rm HCN})=(4.0\pm 1.7)\times 10^{25}$ s$^{-1}$ was derived by non-LTE radiative transfer modelling. Preliminary estimates of the HCN/H$_2$O and CN/HCN abundance ratios suggest values similar to Solar system comets.

AB - We report the detection of HCN($J=3-2$) rotational emission from comet 3I/ATLAS at a heliocentric distance of 2.13 au with the James Clerk Maxwell Telescope (JCMT). Observations were conducted between 2025 August 7 and 2025 September 14 (ut) using the $^{^{\prime }}\, \overline{U}\, ^{^{\prime }}\, \overline{u}$ heterodyne receiver and ACSIS (Auto Correlation Spectral Imaging System) spectroscopic backend. The HCN line was detected at $> 6 \sigma$ on 2025 September 14 (ut) and a production rate of $Q({\rm HCN})=(4.0\pm 1.7)\times 10^{25}$ s$^{-1}$ was derived by non-LTE radiative transfer modelling. Preliminary estimates of the HCN/H$_2$O and CN/HCN abundance ratios suggest values similar to Solar system comets.

KW - comets: individual: 3I/ATLAS

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UR - https://www.scopus.com/pages/publications/105029480653#tab=citedBy

U2 - 10.1093/mnras/stag063

DO - 10.1093/mnras/stag063

M3 - Article

AN - SCOPUS:105029480653

SN - 0035-8711

VL - 546

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 2

M1 - stag063

ER -

JCMT detection of HCN emission from 3I/ATLAS at 2.1 au

Abstract

Keywords

ASJC Scopus subject areas

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