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So no detectable gas. (The positioning of the label in fig 2 indicating the band where CN should appear is unfortunate. At a casual glance it looks like the hot pixel there is a signal. Given that they took 6 spectra it is surprising they did not remove them)
Water detected and possible large icy grains, ApJL preprint: https://arxiv.org/abs/2508.04675
Vera C. Rubin Observatory Observations of Interstellar Comet 3I/ATLAS (C/2025 N1)
https://arxiv.org/abs/2507.13409
Alex.
I love the 112 authors not listed. How many words is that per author?
Is this going to happen whenever the LSST consortium publish?
An ApJL preprint on archive today “JWST detection of a carbon dioxide dominated gas coma surrounding interstellar object 3I/ATLAS”
Says the coma is CO2 dominated, with enhanced outgassing in the sunward direction, and the presence of H2O, CO, OCS, water ice and dust. The coma CO2/H2O mixing ratio is among the highest ever observed in a comet – the authors discuss why this might be the case depending on its origins.
I love the 112 authors not listed. How many words is that per author?
Is this going to happen whenever the LSST consortium publish?
Astronomy is now reaching the point particle physics reached about fifty years ago.
Big collaborations collecting vast amount of data which requires enormous amounts of computation to convert that data to information.
It is getting that way in biology. I’m a co-author on a few genetics papers published by the Flybase Consortium which have numerous authors, though admittedly not over a hundred.
Welcome to the new world.
I know I am possibly opening Pandora’s Box but there seems to be a blizzard of speculation about this comet reported on social media and I thought that perhaps some sensible conversation here would be a good idea. If people can provide links to reputable sources of observations and reporting that would be a start. Obviously as an interstellar comet any observation that differs from the norm is going to be of great interest but needs to be viewed dispassionately. I have already had one person I know ask me in a serious way if I thought there was anything to worry about because his wife was concerned. I think not talking about this subject on this forum is perhaps the wrong thing to do.
Bob King does confront this nonsense in an amusing way in his S&T newsletter article. (click out and back in if you get a “subscribe” pop up)
https://skyandtelescope.org/astronomy-blogs/explore-night-bob-king/all-eyes-on-interstellar-comet-3i-atlas/?utm_source=cc&utm_medium=newsletterRobin
Isn’t it amazing enough that we have the opportunity to observe a comet from another star system? I imaged it this morning and it is where it should be which is absolutely no surprise.
https://britastro.org/observations/observation.php?id=20251109_060935_f9c3c09eb9bd6dc2
What will our nutty Harvard prof do when it just keeps on moving out of the Solar System and no alien attack ships arrive? What will Harvard do about him? That is a greater mystery than the comet.
I’m really looking forward to seeing this in the eyepiece, as well as recording it. Perhaps Avi Loeb is being very clever and ‘taking one for the team’? Science is becoming an ‘un-American activity’, so by promoting and supporting ga-ga conspiracy theories he’s saving Harvard from swingeing cuts in funding… 🙂
Loeb has linked to an image in our gallery:
See the second link in the first sentence. I’m not sure what point Loeb is trying to make in the subsequent text but Michael and Frank’s image of the tails of 3I is very impressive.
The green glow from the coma, presumably Swan band emission from C2 in that image is interesting. This is of course very typical of most comets but spectra taken on approach suggested it was very deficient in C2 relative to CN. See page 9 of this paper
https://arxiv.org/pdf/2509.01647
The ratio may have increased since though, as happened with 2I/Borisov. (I would love to try for a spectrum but the weather here has been hopeless the past month or more with little sign of improvement)Cheers
RobinPerhaps we’re no longer having a ‘nutty news’ section in the Christmas Meeting Sky Notes, but as expected, we’re seeing headlines like
“Stunning Dawn Spectacle: Comet 3I/ATLAS Blazes Across The Morning Sky”
Alex.
Alex – Yes, I should have plenty of material for the Christmas sky notes what with all this alien nonsense and the reports of spectacular meteor storms and auroral displays that appear regularly in the media.
A spectrum of 3I. Just your average comet, here compared with 2020 F3
Robin
“NASA will host a live event at 3 p.m. EST, Wednesday, Nov. 19, to share imagery of the interstellar comet 3I/ATLAS collected by a number of the agency’s missions. The event will take place at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.”
https://www.nasa.gov/news-release/nasa-to-share-comet-3i-atlas-images-from-spacecraft-telescopes/
“The event will air on NASA+, the NASA app, the agency’s website and YouTube channel, and Amazon Prime.”
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