[meteorite-list] Triangulation method for determining Norwegian bolide burst/impac t point

From: Matson, Robert <ROBERT.D.MATSON_at_meteoritecentral.com>
Date: Mon Jun 12 16:34:59 2006
Message-ID: <A8044CCD89B24B458AE36254DCA2BD07A4EB20_at_0005-its-exmp01.us.saic.com>

Hi All,

Seems like each time I take a short vacation, a bolide falls
somewhere triggering an e-mail box full of messages! ;-)

Marco wrote:

> I am curious to know whether the seismic data point to an airblast or
> a real impact (that is not yet clear to me). Not everything giving
> off strong sonic booms ends on the ground, you know.

There is an interesting variation on triangulation that may be
possible on this particular event. If I've read the message chain
right and interpreted the Norwegian links correctly, two seismic
stations detected this event. If they both measured a terminal
burst (or both measured an actual ground impact), then the locus
of points satisfying the delay in sonic arrival time between the
two stations defines a 3-D, approximately hyperbolic surface. By
itself, this surface isn't useful for determining the actual
impact point. But a visual observation (photo) defines a plane
of motion for the bolide. When you intersect this plane with the
hyperboloid, you'll get a portion of a 2-D conic: most likely
part of an ellipse, though a hyperbola, parabola or circle are
all possible depending on the geometry.

By constraining the altitude of the sonic event, you will greatly
shrink the size of this conic segment. In the limit that you
assume the burst occurred at ground level, the solution reduces
to a single point (or under some geometries, two points).

--Rob
Received on Mon 12 Jun 2006 04:23:26 PM PDT