# Is there a real absorption line at 266.94 GHz in the Venus spectra? · Phosphine in the clouds of Venus > Three answers have been proposed. None is ahead on the evidence yet. Three are still possible. Of the one narrower question under it, none is answered yet. Source: https://mysteriesdept.com/mysteries/venus-phosphine/questions/QST0CQY1TFR14XV/is-there-a-real-absorption-line-at-266-94-ghz-in-the-venus Publisher: Mysteries Department Licence: CC BY 4.0 (credit Mysteries Department and link the page) Updated: 2026-10-26T11:59:05+00:00 --- **0** # Is there a real absorption line at 266.94 GHz in the Venus spectra? Asked 26 Oct 2026 by [**apollo** ](https://mysteriesdept.com/u/apollo)·3 answers·0·0 following **Three answers, none ahead** None is ahead yet. See what would settle it. ## Where it stands Three answers have been proposed. None is ahead on the evidence yet. Three are still possible. Of the one narrower question under it, none is answered yet. ## Why it matters Everything else depends on it. The line is a few parts in ten thousand of a very bright continuum, and its significance changes with how the instrumental baseline is removed⁠[[1]](https://mysteriesdept.com/sources/SRC0CQY1HEP0S8P/re-analysis-of-the-267-ghz-alma-observations-of-venus)⁠[[2]](https://mysteriesdept.com/sources/SRC0CQY1HPG5VT4/the-statistical-reliability-of-267-ghz-jcmt-observations-of)⁠[[3]](https://mysteriesdept.com/sources/SRC0CQY1K5C5E45/low-levels-of-sulphur-dioxide-contamination-of-venusian). This is a methodological question that public data and open code can answer. ## Answers 3 [**A real absorption feature from Venus's atmosphere is present in both the JCMT and ALMA data.** ](https://mysteriesdept.com/mysteries/venus-phosphine/answers/ANS0CQY1VF01P0K/a-real-absorption-feature-from-venuss-atmosphere-is-present) Tested, but the results don't decide it Evidence: 4 for, 4 against Disputed [**None of these.** ](https://mysteriesdept.com/mysteries/venus-phosphine/answers/ANS0CQY1YMJ238H/none-of-these) Not tested enough to call either way Evidence: none yet Still possible [**The feature is an artefact of baseline fitting and calibration, not a property of Venus.** ](https://mysteriesdept.com/mysteries/venus-phosphine/answers/ANS0CQY1XNA2472/the-feature-is-an-artefact-of-baseline-fitting-and) Tested, but the results don't decide it Evidence: 2 for, 1 against Disputed ## History 1. 2020[Greaves et al. puts forward: a real absorption feature from Venus's atmosphere is present in both the JCMT and ALMA data.](https://mysteriesdept.com/sources/SRC0CQY1GQ84YF1/phosphine-gas-in-the-cloud-decks-of-venus) 1. 2020[Snellen et al. puts forward: the feature is an artefact of baseline fitting and calibration, not a property of Venus.](https://mysteriesdept.com/sources/SRC0CQY1HEP0S8P/re-analysis-of-the-267-ghz-alma-observations-of-venus) 1. 2020[Snellen et al.: the 12th-order polynomial used on the ALMA data creates five other features above 10 sigma nearby; an…](https://mysteriesdept.com/sources/SRC0CQY1HEP0S8P/re-analysis-of-the-267-ghz-alma-observations-of-venus)Against: A real absorption feature from Venus's atmosphere is present in both the JCMT and ALMA data. 1. 2020[Thompson: bootstrap tests of the JCMT data with several baseline methods recover no significant line.](https://mysteriesdept.com/sources/SRC0CQY1HPG5VT4/the-statistical-reliability-of-267-ghz-jcmt-observations-of)Against: A real absorption feature from Venus's atmosphere is present in both the JCMT and ALMA data. 1. 2020[Snellen et al.: following the published recipe produces other strong spurious lines within 60 km/s.](https://mysteriesdept.com/sources/SRC0CQY1HEP0S8P/re-analysis-of-the-267-ghz-alma-observations-of-venus)For: The feature is an artefact of baseline fitting and calibration, not a property of Venus. 1. 2020[Thompson: polynomial fitting of the JCMT spectrum produces false positives.](https://mysteriesdept.com/sources/SRC0CQY1HPG5VT4/the-statistical-reliability-of-267-ghz-jcmt-observations-of)For: The feature is an artefact of baseline fitting and calibration, not a property of Venus. 1. 2021[Akins et al.: interferometric filtering of the bright disk complicates the detection of a broad, weak line.](https://mysteriesdept.com/sources/SRC0CQY1JXJ6BWR/complications-in-the-alma-detection-of-phosphine-at-venus)Against: A real absorption feature from Venus's atmosphere is present in both the JCMT and ALMA data. 1. 2021[Greaves et al.: the team reports the line at about 5 sigma in ALMA data reprocessed with the revised calibration.](https://mysteriesdept.com/sources/SRC0CQY1H6W1K9Y/reply-to-no-evidence-of-phosphine-in-the-atmosphere-of-venus)For: A real absorption feature from Venus's atmosphere is present in both the JCMT and ALMA data. 1. 2021[Greaves et al.: the team reports the feature in data reduced with revised calibration and in new JCMT data.](https://mysteriesdept.com/sources/SRC0CQY1H6W1K9Y/reply-to-no-evidence-of-phosphine-in-the-atmosphere-of-venus)Against: The feature is an artefact of baseline fitting and calibration, not a property of Venus. 1. 2022[Greaves et al.: after removing sulphur dioxide contamination, both spectra show 6–8 sigma absorption of similar depth.](https://mysteriesdept.com/sources/SRC0CQY1K5C5E45/low-levels-of-sulphur-dioxide-contamination-of-venusian)For: A real absorption feature from Venus's atmosphere is present in both the JCMT and ALMA data. 1. 2024[Clements: phosphine and HDO lines are recovered in the first JCMT-Venus campaign with Fourier ripple removal.](https://mysteriesdept.com/sources/SRC0CQY1MM82G3E/venus-phosphine-updates-and-lessons-learned)For: A real absorption feature from Venus's atmosphere is present in both the JCMT and ALMA data. 1. 2026[Tang et al.: jCMT-Venus announces a re-detection of phosphine.](https://mysteriesdept.com/sources/SRC0CQY1MW2501X/jcmt-venus-long-term-monitoring-of-chemical-variability-in)For: A real absorption feature from Venus's atmosphere is present in both the JCMT and ALMA data. 1. 26 Oct 2026Asked on this site ## Discussion 0 [Add to the discussion](https://mysteriesdept.com/signin?next=/mysteries/venus-phosphine/questions/QST0CQY1TFR14XV/is-there-a-real-absorption-line-at-266-94-ghz-in-the-venus%23discussion) Help with this question [ **Propose an answer** Something the evidence could support or rule out ] [ **Propose an answer** Something the evidence could support or rule out ](https://mysteriesdept.com/signin?next=/mysteries/venus-phosphine/questions/QST0CQY1TFR14XV/is-there-a-real-absorption-line-at-266-94-ghz-in-the-venus%23add-answer) [ **Add evidence** A result for or against an answer ] [ **Add evidence** A result for or against an answer ](https://mysteriesdept.com/signin?next=/mysteries/venus-phosphine/questions/QST0CQY1TFR14XV/is-there-a-real-absorption-line-at-266-94-ghz-in-the-venus%23add-evidence) [ **Ask a sub-question** A smaller question that would help settle this one ] [ **Ask a sub-question** A smaller question that would help settle this one ](https://mysteriesdept.com/signin?next=/mysteries/venus-phosphine/questions/QST0CQY1TFR14XV/is-there-a-real-absorption-line-at-266-94-ghz-in-the-venus%23add-question) [ **Add a source** A paper, archive record or image ] [ **Add a source** A paper, archive record or image ](https://mysteriesdept.com/signin?next=/mysteries/venus-phosphine/questions/QST0CQY1TFR14XV/is-there-a-real-absorption-line-at-266-94-ghz-in-the-venus%23add-source) Where it fits Phosphine in the clouds of Venus **Is there a real absorption line at 266.94 GHz in the Venus spectra?** Key question · you're here [If the line is real, is it phosphine or sulphur dioxide?](https://mysteriesdept.com/mysteries/venus-phosphine/questions/QST0CQY1TQJ1W8Q/if-the-line-is-real-is-it-phosphine-or-sulphur-dioxide)Open · 3 answers, inconclusive [ Ask a question under this one ]