Kommentarer fra Rainer Arlt i International Meteor Organisation til rapport og spørsmål fra TAF i forbindelse med ildkule observasjon 24. mai 1999.

Svar fra TAF til IMO på brevet nedenfor finner du her.

Dear Mr. Andresen,

Thank you very much indeed for the first detailed report on a fireball over Norway. It will definitely be most interesting to collect more information on this event. Would you consider writing a summarizing report on the fireball for WGN, once you have finished the source survey?

As far as I understand, the woman saw first a fireball ('something'), then heared the sound and then saw a much brighter fireball. If so, this is a peculiar event, and will be worth reporting on for a wider community. The description of the sound as being rumbling indicates it was normal sound which is heared minutes after the event, in contrast to electrophonic sound which is heared at the time as the fireball, but usually sounds different (hissing noise).

Fireballs projected on some background is a typical feature of casual eye-witness reports. Because the event is so bright, people think it must have been close. They do not see the fireball projected on the background, but judge it was closer than the background because of the brightness. Fireballs never burn as deep as one or two kilometers above ground.

'Flames' behind the head of the fireball are typical. During big events, the ablation of the meteoroid becomes visible with larger pieces of it lagging behind forming 'flame drops' or a kind of tail.

The end height of the fireball(s) should have been below 40km, otherwise no sound is audible. Maybe it penetrated as low as 30km above ground. The elevation of the end point of the fireball may have been 5-10 degrees as it seemed to vanish behind other mountains. The distance of the end point is then 200-300 km from the observer.

Pinpointing the impact site is quite difficult. Even from photographic records, a remaining uncertainty of +-1km results in a huge area of 1 square kilometer, which is hard to scan. Sometimes, a report from somebody who heared something falling coincides with the area according to the eye-witness reports. Then it is interesting to search the sourroundings of the guy who heared something. It really needs luck to get the meteorite (which is probable according to the descriptions you sent). But this should not discourage you; I would be most grateful if you can find out about as many eye-witnesses as possible, in particular a good description of the path as seen by Mrs Grongstad. I am looking forward to news about the event.

Best wishes, Rainer

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Sist oppdatert : 08. juni 1999.