[meteorite-list] Rock on the ground or not?

From: Lasse Lindh <3l_at_meteoritecentral.com>
Date: Sun, 30 Mar 2008 16:34:00 +0200
Message-ID: <47EFA4D8.2000403_at_comhem.se>

Hi Chris

Thanks for your answer. Well, this one pointed straight towards me.
While bright and when it got weaker it did not move at all. I could see
this because there were two stars just beside it. I am an amteur
astronomer, so observing is nothing new to me. It did not deviate during
the fall. I first thought it to be a GRB since it was so stationary, but
then I realized that that was out of the question, so the only thing
left was a meteorite. It showed no sign of break up. Checking the star
map, it held an angle of 76 degrees. It's brightness could be a lot
higher than -4. It's hard to tell.

Regards

Lasse


Chris Peterson skrev:
> That's a difficult question to answer. The majority of meteorites come
> from meteors that are not terribly bright. But mag -4, while
> technically a fireball, isn't much of one, and is very common. It's
> fair to say that a -4 meteor is a candidate for meteorite production,
> but I don't know how to quantify that chance.
>
> If the information you are providing is purely from your own
> observation, there's not enough information to make any estimates.
> From a single vantage point, the velocity and fall angle of the event
> are impossible to determine. It may have been heading nearly towards
> you, several hundred kilometers away, or it may have been dropping
> straight down 50 km away. There's no way to tell. Finally, from a
> single viewpoint you have no way of estimating where the actual fall
> might be. Even with many witnesses and camera views, it's usually not
> possible to narrow a fall zone to less than many square miles.
>
> The meteors that are most likely to produce meteorites have some
> common characteristics. They are slow, usually less than 20 km/s
> (which is most likely in early evening meteors). Their entry angles
> are shallow, which provides lots of time to slow down while high in
> the atmosphere, before the air becomes so thick that a fast object can
> ablate rapidly ablate away, or fragment into small pieces that burn up.
>
> Chris
>
> *****************************************
> Chris L Peterson
> Cloudbait Observatory
> http://www.cloudbait.com
>
>
> ----- Original Message ----- From: "Lasse Lindh" <3l at comhem.se>
> To: <meteorite-list at meteoritecentral.com>
> Sent: Sunday, March 30, 2008 6:44 AM
> Subject: [meteorite-list] Rock on the ground or not?
>
>
>> Hi all
>>
>> If one sees a meteor fall with a brightness of -4 or brighter, it's
>> duration is +10 sec. What is the chances of finding a small rock
>> where it suppose to have landed? Is it big enough considering the
>> brightness and length of fall. It needs to be said that the angle of
>> the fall was around 75-80 degrees, allmost straight down.
>>
>> Regards
>>
>> Lasse
>
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Received on Sun 30 Mar 2008 10:34:00 AM PDT