(meteorobs) Question about fireball brightness

[Jan Verfl]

Hello,

it's usually said that people overestimate the magnitude of fireballs, but I
think that the better point is to say, that they have the tendency to
"equalize" the brightness - from some brightness, it all seems like a
"really bright think". I happened to see a mag -13 or -15 (I don't rememeber
exactly) fireball (with the brigthness confirmed from a professional
fireball network camera) - the shadows were prominent, country lightened,
but I would not tell on myself, if it was -8 or -20, the eye is just too
stunend in this case  - for me, over -6, the magnitude is just
"wwwwooooowwww!!".....

Jan


> -----Original Message-----
> From: meteorobs-bounces at meteorobs.org 
> [mailto:meteorobs-bounces at meteorobs.org] On Behalf Of GeoZay at aol.com
> Sent: Saturday, June 03, 2006 10:04 PM
> To: meteorobs at meteorobs.org
> Subject: Re: (meteorobs) Question about fireball brightness
> 
> 
> >>This question is seeking a sort of rule of thumb.  I  was
> looking north, and the sky lit up behind me and I turned
> around fast  enough to see the last half of the fireball,
> which was bright green and  fragmented into a few pieces.
> The question is, how much brighter than the  local limiting
> magnitude does a fireball have to be to attract  your
> attention from behind?  That night where I was (a  suburban
> location where on the very best moonless nights the Milky
> Way  is faintly visible), the LM was probably about +4.5.
> My friend, who was not  wearing his eyeglasses, estimated
> it was -6, but I thought it had to be  brighter than that
> to attract my attention from behind.  So, is there  a rule
> of thumb about a fireball's magnitude in this type of
> situation  -- the fireball being bright enough (not to
> mention lasting long enough) to  induce you to turn around
> 180 degrees to see it?<<
>  
> I guess you'd have to consider what makes a person "sense" 
> something is  
> going on behind them. Most likely they see a combination of 
> lit up objects and  
> moving shadows that makes them want to turn around for a 
> better look. The  
> question comes to mind then, "How bright does a meteor must 
> be to light up  objects 
> and produce noticeable shadows? " I believe a meteor in the 
> neighborhood  of 
> -4 will produce shadows. So...I'd say your fireball had at 
> least  a minimum 
> magnitude of -4. I believe most people have a tendency to  
> overestimate a 
> meteors magnitude...particularly the more brighter ones. If  
> your friend estimated a 
> -6, I would think then this to be reasonable. 
> George Zay
> 
> 
> 
> 
> 
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