(meteorobs) Nice variety of Fireballs occured.

[stange34 at sbcglobal.net]

Ambiguity exists whether or not an abserver recoqnizes it or not, in 
brightness. That ambiguity is in the fact that it is estimated not 
quantitized by any scientific instrumentation. The is the nature of the 
beast in visual observing. More particularly.....

That ambiguity is in the personal perception of brightness which varies from 
individual to individual. It is not measured but compared BY personal 
opinion to another object by the observer at that moment in time.

 The distinction of brilliance differences between -8, -10 or even -12 
magnitude, (for example), or -1, -2, -3, -4, -5   is ONLY in the perception 
of the individual which is enfluenced by his own vision parameters of rod & 
cone. A momentary glance at a meteor does not establish a firm calibration 
of amplitude in lux. Just an impression based on prior observations and 
estimated. Hopefully it is consistant even though it might not match the 
impression of another seeing the same object.

My casual scale is 1 to 5. It has no meaning other than a Class 1 fireball 
is typical of the recent Albuqurque and Shingle Springs event. Class 2 is 
closer to the recent Nevada City Bolide. Class 3 is a fireball or bolide 
with a good brightness & period but not as significant as the Nevada City 
event. Class 4 is the typical meteor streak. Class 5 is a barely visible 
meteor. It is a simple concept of relative brightness & period requiring no 
measure because it is NOT INTENDED to be data entry.

I could have said it was an interesting night for meteors & fireballs. But 
instead I pointed out some interesting fireballs were seen at moderate 
brightness and it indicated promising events for tonight.

I do not attempt to quantify what can not be calibrated & cross checked 
under lab conditions. Certainly not going to assign magnitudes which are of 
my own perception.

YCSentinel

Neither does my example of classes have a pretense of being quantively 
accurate. It is a convienant way to indicate in the "conversational form" 
that I used.... that fireballs were evident and that they were not 
particulary spectacular.


----- Original Message ----- 
From: <meteoreye at comcast.net>
To: "Global Meteor Observing Forum" <meteorobs at meteorobs.org>
Sent: 2007/10/06 16:04
Subject: Re: (meteorobs) Nice variety of Fireballs occured.


> But the description was :
>
> "Ranging from what I call catagory 3 & 4."
> "Catagory 3 means medium brightness and more than 1 second duration." 
> {what is "medium?}
> "Catagory 4 means Fainter and 1 second duration." {what is fainter?}
>
> What are categories 1,2,5,6,7?????
>
> Without any definition, these could mean +1 Magnitude or -12 magnitude.
>
>
>
> -------------- Original message -------------- 
> From: "Chris Peterson" <clp at alumni.caltech.edu>
>
>> Keep in mind that there's not a lot of value in a precise definition of
>> "fireball". Meteors are meteors, and they range in brightness from
>> nearly invisible to nearly blinding. The valuable measures are apparent
>> magnitude and absolute magnitude, which are rigorously defined (although
>> in the case of meteors, very difficult to measure with much precision
>> given the rapid variation with time). I use the IAU definition and flag
>> meteors as fireballs when their apparent magnitude is brighter than -4.
>> I find that much more useful than a zenith corrected value. But whatever
>> you use, all you are really saying is that the meteor was bright.
>>
>> Chris
>>
>> *****************************************
>> Chris L Peterson
>> Cloudbait Observatory
>> http://www.cloudbait.com
>>
>>
>> ----- Original Message ----- 
>> From:
>> To: "Global Meteor Observing Forum"
>> Sent: Saturday, October 06, 2007 4:12 PM
>> Subject: Re: (meteorobs) Nice variety of Fireballs occured.
>>
>>
>> Thanx, Ed. I didn't know that the AMS had a reference for their
>> definition.
>> It's still a bit imprecise, but would suggest -4 or -5 as a cutoff.
>>
>> Appreciate you help.
>>
>> Wayne
>>
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