[meteorite-list] Witness information that is more helpful than color

[Chris Peterson]

I seek color in submitted witness reports, not necessarily to provide 
additional scientific information (although it's data, so I wouldn't 
completely rule out that possibility), but rather, to understand how 
people see things differently, and to make for a more complete public 
report, since public education about fireball events is part of our 
function. Meteor color is as much a part of the phenomenon as 
brightness, speed, fragmentation, and everything else. The fact that we 
can't directly convert color into composition doesn't mean we shouldn't 
include this information in a complete report.

Chris

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

On 11/4/2015 4:48 PM, Matson, Rob D. via Meteorite-list wrote:
> Hi John,
>
> I think there are definitely things that can be learned by looking at the spectroscopy
> of fireball emissions, but of course such data are rare. And human eyeballs/brains
> are a poor substitute. We don't have the necessary spectral resolution, and of course
> the optical response is far from flat. It is perhaps not coincidental that green-blue
> (0.498 microns) is the peak of our scotopic response. Deep red (>0.63 microns)
> sensitivity is almost non-existent in scotopic vision, so even if a fireball had a
> significant red component, a much smaller green component would swamp it just
> due to our spectral response.
>
> Since nothing really diagnostic can be learned from a witness's perception of a
> fireball's color (as far as the meteoroid's composition is concerned), I see little
> point in asking them or encouraging them to report it. The next best thing
> that a novice witness can report (other than an accurate time and duration)
> is the slope of the meteor track relative to the horizon -- perhaps using a
> clockface analogy to avoid scary geometry. If I know the approximate fall
> zone reasonably accurately, a distant observer's slope approximation can
> greatly narrow down the true flight bearing, even without azimuth information
> (which can already be inferred from their location relative to the fall with
> greater accuracy than they can report).
>
> Mike Hankey has put together some very nice tools on the AMS site for
> amateurs to contribute useful information, concentrating on those things
> that non-technical people are reasonably good at. With enough witnesses,
> the average solution can sometimes be fairly accurate, even if the individual
> reports are all over the place.  --Rob