(meteorobs) On the connection between nearby NEAs and the recent increase in fireballs...

Robert Lunsford lunro.imo.usa at cox.net
Tue Jan 18 14:48:14 EST 2011


Mike and All,

Yes, you understood the main point of my post.

Fireball colors are subjective and witnesses at the same location can see different colors in the same object. It's difficult to 
perceive colors with something that lasts so short a time.

In the new AMS fireball table, we have decided not to list colors due to column constraints plus it is one of the least important 
aspects of a fireball's characteristics. I have looked through the emailed reports for January (that contain all of the information 
provided by eyewitnesses) and most of the reports have white for a primary color. Green is mentioned in approximately 25% of the 
reports. Off the top of my head (which means I don't have time to research these figures) 25% for green fireballs is higher than 
normal. I can tell you from my personal observing experience that only the brightest fireballs (> magnitude -10) have produced a 
green color for me.

Finally, as a member of the IMO council, the IMO still accept fireball reports but does not currently publish the results. They may 
be available for research purposes, but I am not certain of this fact at this time.

Clear Skies!

Bob Lunsford


-----Original Message----- 
From: Mike Hankey
Sent: Tuesday, January 18, 2011 10:55 AM
To: Global Meteor Observing Forum
Subject: Re: (meteorobs) On the connection between nearby NEAs and the recent increase in fireballs...

Carl,

Excellent information and explanation. Thanks for sending out such a
detailed analysis.

To summarize in laymans terms without putting words in your mouth, I
think what you are saying is:

There is no correlation to witnessed fireball activity on Earth and
NEOs that are reported in close approach to Earth, because, these
reported NEOs are only a small subset of the actual NEOs flying by
everyday anyway.

My understanding of what Chris is saying is -- sometimes fireball
rates are going to go up and sometimes they are going to go down and
that is just the way it is. Rates will ebb and flow, and correlating a
perceived increase in fireball rates for a certain time with
approaching NEOs in that same time frame is a fallacy. It would be
like saying, fireball rates went up right after christmas, that must
be why those dead birds are falling from the sky.

And I think what Bob is saying is -- an increase in reported fireballs
does not correlate to an increase in actual fireball rates. It just
means more people are seeing them and reporting them. This is a trend
he has seen with the AMS reports since they were started. Explanations
for this can include: more people with computers and internet access,
increased interested in meteors and fireballs, better news coverage
and better promotion of the AMS reporting form.

Wayne, to your point, yes the ams fireball reporting form was broken
from approximately Nov 2009 - Jan 28 2010. While reports were still
coming in via email, this would certainly impact the number of total
reports as well as the number of events. Good call.

I think it would be interesting to review the fireball reports from
the IMO for the last 12-16 months to see how they correlate. Did IMO
rates in Jan 2011 seem to go up like they 'seemed' to with US rates? I
checked the IMO site and don't see where I can view a fireball log
like I can on the AMS site.

Lastly, shouldn't there be some metric collected by the camera based
fireball networks, like ASGARD that would quantify the fireball rates
in a consistent manner year over year, so that we could get a real
number vs a perceived number? Using counts from a fixed network would
compensate for fluctuations caused by the human factor. I think this
sort of data would be the only thing that could 'prove' a rate
increase theory, one way or the other.

Thanks,

Mike Hankey 




More information about the Meteorobs mailing list