Extended Data Fig. 1: Observed ALMA spectrum of comet 12P.
From: A D/H ratio consistent with Earth’s water in Halley-type comet 12P from ALMA HDO mapping
These data were observed using ALMA on 2024 April 18-25, and show the comet’s spectrum in the vicinity of the HDO 21,1 − 21,2 and CH3OH JK = 5K − 4K lines (labeled). The (continuum-subtracted) spectrum was extracted at the position of the continuum emission peak (the assumed location of the nucleus), and molecular lines were assigned using data from the Splatalogue (https://splatalogue.online/)39. Inset panel shows a zoom of the detected HDO line.
