A great fireball of magnitude -9 appeared above the center of France on July 26th, 2020, at 23h12m UT. It has been seen from all over France and neighboring countries and sonic booms were heard from around Paris.
1 Introduction
The night of 26–27 July 2020, I decided to observe comet C/2020 F3 Neowise. It was the last day to see it without moonlight. I had the chance to be in a holiday place in Cerilly, Auvergne, France, with a nice dark sky.
Figure 1 – Light pollution map center of France (courtesy www.avex-asso.org)
At 23h12m UT, 30 minutes after the moonset, I was making pictures of comet Neowise with Ursa Major when I saw a bright fireball beginning to appear from near my zenith and descending during 10 seconds to the horizon displaying an intense bright green light! It ended disintegrating into small pieces. It was the most beautiful fireball I’ve seen in real life!
Luckily, the fireball crossed the field of my camera.
Figure 2 : Fireball, comet C/2020 F3 Neowise and Ursa Major – Cerilly, France – 26 July 2020 23h12m UT
canon 700D(aps-c) + sigma 17-70mm @17mm, 60s, F/3.2, ISO800 on star adventurer, fov 66°x47°.
The fireball has also been observed from all over France and even from Belgium, Germany, Switzerland, the Netherlands, as reported by nearly 150 people on the IMO website.
Figure 3 : 149 reports on 3741-2020 event IMO page.
Sounds like rumble, detonations and booms was reported by about thirty witnesses around Paris.
Julien A. at Athis-Mons (fr) reported : « about 1 or two minutes after low pitched attenuated rolling boum during 2 sec »
Nicolas B. at Sainville, Centre-Val de Loire (fr) said : « double detonation at 1h16min00 + -3s exactly, not necessarily linked?»
Figure 4 : map of 28 witnesses report sound on 3741-2020 event IMO page.
2 Observational data
The fireball occurred on 2020 July 26 at 23h12m23s UT and has been caught by many cameras in France: 12 of the FRIPON network, 4 of the BOAM network and furthermore by some individual amateurs.
According to the data from the FRIPON network, the fireball reached its maximum brightness of magnitude –9 at an altitude of 55 km.
The fireball crossed the whole field of view of the Rasberry Meteor System camera, FR000A, located at Cérilly, Auvergne, France. It is the longest trajectory recorded by a camera during 9.30 seconds.
Figure 5 : The 9.30 seconds duration fireball trajectory by the FR000A RMS camera at Cérilly, Auvergne, France.
Three other cameras of BOAM network caught the event: two all sky cameras and a 60° FoV camera.
Figure 6 : Fireball 2020 July 26, 23h12m23s UT at Chaligny, France (courtesy Marc Herrault).
Figure 7 : Fireball 2020 July 26, 23h12m23s UT at Chinon, France (courtesy Astro Chinon).
Figure 8 : Fireball 2020 July 26, 23h12m23s UT at Fléville, France.
An independent amateur station based in Reuil-Malmaison, Paris region, was particularly well placed, on the trajectory of the fireball. A first south-facing camera recorded the meteoroid coming in and starting to split into several pieces and a second facing northwards shows the object breaking up at the end of its light path.
https://www.facebook.com/dominique.andre.7/posts/3196697100366958
see also the second video in comment
Figure 9 : Fireball 2020 July 26, 23h12m23s UT screenshot of the video from southward oriented camera at Reuil-Malmaison, France (courtesy Dominique André).
Unfortunately, the astrometry has not been calculated and it is not possible to compute a trajectory from these two captures. But a study of the images allows to see the dynamics of the fireball in the atmosphere.
Time synchronization of the cameras is done with Meinberg on a ntp-server and the meteor dynamic as time match to that one on the LITIK1 video.
At 23h12m22.28s, the fireball starts, very faint, on the video of the southward pointed camera. At 23h12m24.80s, a second track (b) appears, following the more important one (a) until 23h12m28.88s.
A series of small explosions take place on the main piece (a) at 27.52s, 27.64s, 27.80s and 27.88s giving rise to a few small bright pieces disintegrating quickly, visible in the capture at 28.00s.
At 23h12m28.24s, the fireball suddenly strongly brightens, certainly corresponding to the shattering of the main object (a) and the creation of a third important piece (c). Piece (c) is clearly visible on the captures at 28.88s and 29.04s and leaving the FoV of the southwards pointed camera at 29.20s.
Figure 10 : Fireball dynamic path from southwards pointed camera at Reuil-Malmaison (courtesy Dominique André).
On the northwards pointed camera, the fireball appeared at 23h12m31.62s. According to the synchronization of both cameras, 2.4s of the path is missing and only one of the fragmented objects reappeared. From 32.904s and until the very end of the luminous trajectory at 33.86s, the object seems to break up into three pieces. It started at 23h12m22.28s on southwards pointed camera and ended at 23h12m33.86s on northwards pointed camera, corresponding to a duration of 11.58s.
Figure 11 : The dynamic path from the northwards pointed camera at Reuil-Malmaison (courtesy Dominique André).
Last very interesting capture, come from an amateur astronomer, Romain Buté, who observed and shoot the neowise comet, near Montbellet, France and report his observation on the IMO fireball report page. He was lucky to shoot the fireball with his DSLR camera in narrow field of view 12×18° and with a “dji osmo” action camera on timelapse shooting mode and 145° of field of view.
Figure 12 : Fireball and comet C/2020 F3 Neowise – Montbellet, France. Canon 750D(aps-c) + canon 70-200mm @70mm, 30s, F/2.8, ISO1600 (courtesy Romain Buté).
Figure 13 : Capture from timelapse of the fireball at Montbellet, France. Dji osmo action camera, fov ~145° (courtesy Romain Buté).
| Observer | Long. (°) | Lat. (°) | Alt. (m) | Dur. (s) | Ra. 1 (°) | Dec. 1 (°) | Az. 1 (°) | Ev. 1 (°) | Ra.2 (°) | Dec 2 (°) | Az 2 (°) | Ev 2 (°) |
| T.Gulon | 2.7810 | 46.6154 | 304 | – | 137.75 | 82.05 | 356.04 | 39.12 | 128.75 | 47.89 | 351.14 | 5.14 |
| R.Buté dslr | 4.8660 | 46.4678 | 212 | – | 192.25 | 41.42 | 390.66 | 19.90 | 166.00 | 39.67 | 324.58 | 6.25 |
| R.Buté act. | 4.8660 | 46.4678 | 212 | – | 199.00 | 41.03 | 305.6 | 23.3 | 161.65 | 38.74 | 327.1 | 3.7 |
| FR000A | 2.8161 | 46.6203 | 320 | 9.30 | 282.87 | 83.04 | 177.51 | 53.01 | 129.94 | 50.28 | 171.10 | 7.65 |
| LITIK1 | 6.2072 | 48.6446 | 220 | 6.64 | 237.80 | -3.12 | 245.67 | 15.95 | 211.98 | 8.37 | 273.38 | 8.07 |
| CHI37 | 0.2755 | 47.1692 | 105 | 2.42 | 24.99 | 31.45 | 66.22 | 21.45 | 41.26 | 37.14 | 51.94 | 15.99 |
Table 1 : Data for T. Gulon and R. Buté extracted with astronomy.net and FR000A, LITIK2 and CHI37 data from UFOsuite.
2 Trajectory
The multiple station data of the BOAM network and DSLR pictures of amateur astronomers allowed to calculate the trajectory and orbit.
Figure 14 : Groundmap of the trajectory. Yellow: BOAM cameras computation, orange: DSLR camera.
Figure 15 : 3D view of the trajectory. Yellow: BOAM cameras computation, orange : DSLR camera.
| trajectory | dur. (s) | long. b (°) | lat. b (°) | Hb (km) | long. e (°) | lat. e (°) | He (km) | dist (km) | incl. (°) | vo (m/s) | vg (m/s) |
| BOAM | 9.3 | 2.7744 | 47.2769 | 99 | 2.2560 | 48.9308 | 41 | 196 | 17.1 | 22 | 19 |
| DSLR cam | – | 2.6839 | 47.5620 | 88 | 2.1690 | 49.1806 | 33 | 192 | 16.6 | – | – |
| orbit | a (A.U.) | q (A.U.) | e | ω (°) | Ω (°) | i (°) | αg (°) | δg (°) |
| BOAM | 1.8 | 0.634 | 0.642 | 304.1 | 87.726 | 7.0 | -30.2 | 308.2 |
Table 2 and 3 : Trajectories and orbital elements – BOAM computation UFOorbit – DSLR cam computation author’s table
3 Electrophonic, photophonic sound or auditive hallucination?
At the same time of the appearance of the meteor, I heard like a “sound of blowing” or a thin “fff” made with the mouth during 2 to 3 seconds in the first part of path when the object was high in the sky.
A few persons describe the same phenomenon as Anthony J. at Dijon who heard the same sound : «Like when you immerse a very hot object in cold water and tamp out»
Jason C. at Saint-Germain-en-Laye, have heard as : «A very light breath like something burning until the fireball crumbles.»
Gregory P., amateur observer at Vitry-aux-Loges, report : «I don’t know at all how to explain it as a kind of sound in the sky as its entery. A sort of hissing.»
Normally, it is impossible to hear the fireball at the same time of appearance, because the object is far away from the observer, some 50 to 100 km or more and the sound takes several minutes to arrive. But this phenomenon had already been reported several times during a fireball event.
From the 1980s years, according to accepted knowledge, hearing sound simultaneously during the appearance of the meteor could be explained by electrophonic noise. Indeed, the disintegration of a meteor into the atmosphere generate huge energy and creates ionization of the air. This plasma produces low frequency radio emission (ELF/VLF) travelling at the speed of light and that could be transferred into acoustic waves whenever appropriated objects such as fences, hair, vegetation, glasses are in the vicinity of the observer.
In 2017, in the journal “scientific report” (https://www.nature.com/articles/srep41251), Spalding et al. propose a new way to explain this “anomalous” sounds. Intense light from a fireball could rapidly warm common dielectric materials closed nearby the observers and then produce some small oscillation in the air and create sound wave. The process is called photo-acoustic coupling.
And why not an auditory hallucination? It would be interesting that specialists in psychology or neuroscience investigate this possibility. Today, this is not fully explained, studies must continue.
Acknowledgment
The author wishes to thank Dominique André and Romaric Buté for their cooperation and their permission to include their images and BOAM members and team for providing their camera data and detection.
Wow, Tioga, you caught both comet NEOWISE and the fireball in one well exposed photo. serendipity at it’s best!
Beautiful picture and Tioga, a real once in a lifetime event!
Bonjour Tioga. Très intéréssant travail d’étude de ce bolide tonnant avec traînée persistante ! Merci. Pour les 7 témoins sur 149 qui entendent un son simultané (ce qui est impossible physiquement contrairement aux 28 autres qui entendent un son différé bien réel), il est inutile d’invoquer ici des sons electro-photo-phoniques de nature physique réelle dont les recherches n’ont jamais abouti a une quelconque preuve ou indice solide ni ne sont cohérentes avec les témoignages. Il est bien plus probable que ces 5% de témoins soient, tout bêtement, des synesthésiques visuel>sonore ! Voir un exemple ici :
https://www.lemonde.fr/blog/realitesbiomedicales/2018/05/24/synesthesie-entendre-un-son-en-regardant-un-gif-anime-silencieux/
Autre point, la météo était couverte sur la partie au Nord de Paris ce soir là après 22hTU le 26. Est-il possible que les caméras n’aient pas pu suivre la fin réelle du bolide à cause de la nébulosité ? Auquel cas l’altitude finale serait encore plus basse. Quelles sont les coordonnées du point d’impact théorique de votre trajectoire calculée SVP ?
Merci Eric pour cet article du monde très intéressant et qui peut en effet expliquer cette hallucination auditive.
Bon cette fois-ci, j’en ai été témoin. Pourtant je n’entend rien avec le gif de l’article et je ne me souviens pas avoir déjà fait cette expérience. Mais maintenant je vais faire attention.
Pour ce qui est de la trajectoire, je pense que Dominique André a la fin du bolide mais il faudrait pouvoir faire l’astrométrie sur son enregistrement. La fin à 33km d’altitude est à la position 49.1806 N, 2.1690 E
Merci Tioga pour ces infos. Deux autres questions qui vont vous paraître étonnantes : 1/ au moment où vous avez entendu ce son inhabituel , portiez vous soit une capuche, soit un bonnet, soit une écharpe, soit un col relevé ? 2/ le son a été perçu dans la partie haute de la trajectoire=> peut-il correspondre au moment où vous avez relevé la tête rapidement pour l’observer ? J’ai une seconde hypothèse pour les personnes non synesthésiques qui perçoivent tout de même ce son discret et bref. Nos oreilles ont des poils externes qui lorsqu’on les frôle font un bruit particulier _auquel on ne prête quasi jamais attention_ (sauf dans un environnement silencieux et si nos sens sont aux aguets), idem si on frôle ou frotte nos cheveux. Ce bruit pourra être décrit selon les individus comme un frôlement, un souffle ou un crépitement (selon la matière qui les frôlera-frottera). Essayez et dites moi si cela peut ressembler à ce que vous avez entendu. Il arrive aussi que lorsque l’on relève la nuque brusquement (toujours dans un environnement silencieux) on perçoive un bruit de frottement, craquements, crépitement ou “pop” _si l’on a quelques calcification des vertèbres cervicales_ (c’est mon cas). On les perçoit alors par voie de résonnance intracrânienne lors d’une rotation du crâne dans un environnement silencieux. Ces sons internes peuvent même exister juste en ouvrant grand la bouche (attitude spontanée de “bouche bée” lors de la surprise d’un bolide) avec les articulations de la ma^choire… Les frottements issus du mouvement de tête et les synesthésies expliqueraient, à mon avis, assez simplement la grande diversité des sons anormaux perçus simultanément.
Un détail m’interpelle : sur le site BOAM il est indiqué que Chinon3701 détecte un radiant BPI (NDA?) mais que Chaligny indique un radiant PAU. D’abord pourquoi cette divergence ? Autre étrangeté, aucun de ces radiants PAU ou BPI ne donne théoriquement des bolides à 22km/s mais bien plus >35km/s … Le radiant CAP correspondrait mieux à la vitesse de ce bolide du 26-07-2020 mais CAP est d’origine cométaire 45P… Que déduire des éléments orbitaux calculés en faveur ou défaveur d’un largage de météorites ?