(meteorobs) Determining physical dimensions of a largefireballin the sky?

[Chris Peterson]

Mike-

The dark flight details are only loosely tied to the ground track during the 
luminous part of the flight. Within a few seconds of retardation, any 
surviving meteoroid components have lost virtually all of their original 
velocity, and are falling vertically with respect to the local wind field. 
That's why there are two key components to connecting meteors with strewn 
fields: first, using instrument data or witnesses to locate the ground 
position of the terminal explosion or disruptions near the end of the event, 
and second, determining where an object of a given mass dropped from that 
location will land, based on upper level wind conditions.

Working with accidental video is always a challenge. It can be fun, though; 
we once reconstructed a meteor path using the reflection in a car fender 
caught by a security camera. For that event we not only have meteorites, but 
this video record and numerous witness reports.

Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com


----- Original Message ----- 
From: "Mike Hankey" <mike.hankey at gmail.com>
To: "Global Meteor Observing Forum" <meteorobs at meteorobs.org>
Sent: Tuesday, October 13, 2009 10:38 AM
Subject: Re: (meteorobs) Determining physical dimensions of a 
largefireballin the sky?


Chris,

Thanks for the reply and info. I understand about the dark flight, but
its also my understanding that the dark flight model is tied to the
trajectory / ground track. I also understand the ground track can only
be as good as the field research that is done on the original videos.
So at this point my strategy is improving the ground readings so we
can improve the trajectory and then the dark flight model. I believe
for this fall the radiosonde data has been collected and is being used
in the current projections. (problem is we've searched the heck out of
the current area and are still coming up with nada).

Unfortunately we do not have video from the all sky meteor cams but
rather security tape and amateur footage. It sure would be nice if the
whole country or world was covered with these all sky cams (i'm
planning on adding one at my house for next time).

For the fall I'm working we have a total of 10 recordings: 2 direct
video recordings, 3 use-able shadow recordings, 4 flash of light
recordings and 1 photograph. Up to this point the direct sighting
recordings were not calibrated / they were more eyeballed with low
quality copies of the videos. And none of the work to measure the
shadows was ever done. (that's next on my list after completing the
stellar calibrations.) My thoughts were, if I could put in the time to
properly do the field work it would improve the trajectory and dark
flight model (probably a pipe dream, but I'm running out of options
and time).

Thanks,

Mike