There's a lot of interest in Betelgeuse party because of it's recent fainting behavior, and despite being so close, the huge uncertainty in it's distance due to its fickle photocenter:

Soon the asteroid 319 Leona will pass in front of Betelgeuse.

Question: Is this occultation a rare and valuable opportunity to learn things about Betelgeuse itself and whatever might be around it (e.g. dust rings, etc.)? If so, what's been organized to maximize the granularity and diversity of measurements?

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    $\begingroup$ FWIW, 319 Leona has been in retrograde motion since early November and will resume prograde motion in early February. Here's a geocentric plot of its J2000 ecliptic longitude & latitude, using a 2 day timestep i.sstatic.net/XhHoT.png (with numeric labels every 30 days) $\endgroup$
    – PM 2Ring
    Commented Dec 7, 2023 at 2:35
  • $\begingroup$ @PM2Ring Beautiful! I'll bet you can add Betelgeuse's trajectory fairly easily (hint hint) :-) $\endgroup$
    – uhoh
    Commented Dec 7, 2023 at 5:05
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    $\begingroup$ The ecliptic coords of Betelgeuse are lon 88.755, lat -16.027. That plot is from the centre of the Earth, so it's of limited use in determining the exact time of occultation. I only posted it to give a rough idea of how 319 Leona is currently moving. $\endgroup$
    – PM 2Ring
    Commented Dec 7, 2023 at 6:24
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    $\begingroup$ Discussed on Phil Plaits newsletter badastronomy.substack.com/p/big-body-briefly-blocks-betelgeuse $\endgroup$
    – James K
    Commented Dec 11, 2023 at 19:51
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    $\begingroup$ Something similar happened in 2022 regarding Pluto to get a "weather report" for Pluto. Apparently Mike Skrutskie of U Virginia is a seasoned occultation observer, and does events like this a couple of times a week at home, “but mostly asteroids”. Apparently it is how the rings or Uranus & Neptune were found. $\endgroup$
    – Fred
    Commented Dec 14, 2023 at 6:00

2 Answers 2


Unfortunately, I have not found much information. On the website of the "Societé Astronomique de France" they say:

A team of researchers from Paris Observatory – PSL under the direction of Dr. Miguel Montargès (author of the study published in Nature, "A dusty veil shading Betelgeuse during its Great Dimming") is mobilizing the amateur astronomer community to acquire photometric and spectroscopic data on this occasion. The collected data will be used to characterize Betelgeuse’s photosphere in the visible and, potentially, to reconstruct its image and the velocity distribution of the convective cells.

Ref. Occultation of Betelgeuse by asteroid (319) Leona on 12/12/2023 – Press release

I also found: Asteroidal occultations of stars are frequent phenomena but the occultation of Betelgeuse by Leona will be extremely important and unique. It represents an extraordinary opportunity to analyze the diameter and brightness distribution of Betelgeuse’s photosphere by studying the light curve as the asteroid progressively occults the star from different points on Earth and at different wavelengths. In the overwhelming majority of the stellar occultations the diameters of the stars are tiny compared to the angular size of the solar system body that passes in front of them so the occultations are not gradual, but in this case, the huge angular diameter of Betelgeuse will give rise to a different phenomenon of “partial eclipse” and “total eclipse” (provided that Leona’s angular diameter is large enough compared with that of Betelgeuse).

Ref. The stellar occultation by (319) Leona on 13 September 2023 in preparation for the occultation of Betelgeuse

The "International Occultation Timing Association / European Section e.V." made a Call for Observations: Occultation of Betelgeuse by (319) Leona on 2023 Dec 12

And they have published on their website a follow-up of the occultation: News Feed – Occultation of Betelgeuse by (319) Leona

This Spanish website invites amateur astronomers to make observations of the occultation: La ocultación de Betelgeuse del 12 de diciembre de 2023

The dimming of Betelgeuse due to the occultation, captured by an amateur in Spain this past night, can be seen here, (Betelgeuse is the bright star at the top, a little to the left).

Occultation of Betelgeuse (Betelgeuze) by 319 Leona (Jörg Schoppmeyer)

Best regards.

UPDATED: Light curves and videos of the occultation are being uploaded: Observations of the Occultation of Betelgeuse by (319) Leona (IOTA/ES)


On https://www.virtualtelescope.eu/webtv/, Gianluca Masi, the Italian astronomer and developer of "THE VIRTUAL TELESCOPE PROJECT", has posted the following announcement :

Next event: “Betelgeuse occultation by Leona: live view” – 12 Dec. 2023, starting at 01:00 UTC

The Virual Telescope Project uses multiple robotic telescopes to perform observations.

More details here: https://www.virtualtelescope.eu/2023/12/04/the-extremely-rare-betelgeuse-occultation-by-asteroid-319-leona-online-event-12-dec-2023/

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    $\begingroup$ That's interesting to know - but it misses at least half the #question of "what can be learned" or "what do they expect to learn" (however the question title is broader than explained in the question...) $\endgroup$ Commented Dec 10, 2023 at 12:09
  • $\begingroup$ I think this is for entertainment purposes for the public to watch, rather than for astronomical measurements. I would not call this a real astronomical observation campaign. $\endgroup$
    – uhoh
    Commented Dec 10, 2023 at 20:22

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