[meteorite-list] Witness information that is more helpful than color
From: Chris Peterson <clp_at_meteoritecentral.com>
Date: Thu, 05 Nov 2015 07:02:52 -0700 Message-ID: <563B618C.3010706_at_alumni.caltech.edu> 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 ******************************* 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 Received on Thu 05 Nov 2015 09:02:52 AM PST |
StumbleUpon del.icio.us Yahoo MyWeb |