[meteorite-list] Fireball rattles the east coast(2001).

From: Elton Jones <jonee_at_meteoritecentral.com>
Date: Thu May 4 12:07:27 2006
Message-ID: <445983ED.9050403_at_epix.net>

Don Merchant wrote:

> Hi List. I was organizing some old papers and came across an article
> that brought back memories of something I will never forget. On July
> 23rd, 2001 (almost 6 years ago) ...

Yes, quiet the excitement for a few weeks in a particularly warm summer
for Pennsylvania. Several list members worked on this for a while,
tracking down witnesses, conducting interviews, collecting photos,
coordinating with the State Emergency Action Center, etc. We had a
good handle on what needed to be done but lacked the resources to do get
it done. While it was widely seen, few people submitted fireball
reports. The media was all over "impact sites"-- sensationalizing crop
damage but down right hostile about informing the public where to send
eyewitness reports or what to be on the look out for.

This east to west, daytime fireball was viewed as far south as Virgina
where it was photographed by a car passenger. It was sboth seen and
photographed in Ontario. Other than smoke trails no fireball photos
surfaced any place closer to the ground track. Satellite tracking info
provided by the US Air Force was analyzed and the terminal point was
projected over a very rugged steep wooded terrain vicinity of Tioga
County/Wellsboro PA--around 8-12 sq miles centered on the Pine Creek
Gorge, aka The Grand Canyon of Pennsylvania
<http://www.visittiogapa.com/grandcanyon.html>. A less trekable area of
PA doesn't exist!

The meteoroid is believed to have "bolided" somewhere below 20
miles(32km). Some math whiz can do the math: it dropped 50km over a
140km track. I can't locate the velocity estimates, sorry. Keep in
mind this was a snapshot measurement by the satellite, not including the
detection time, lock on nor the time after the on board sensors ceased
tracking. I presume the stated yield of 3000 kiloton was also only the
portion of the total output that was measured during the tracking
segment. In other words 1.3 BILLION joules were expended in the
atmosphere over 88 miles (140 km). So the yield could have been 3-5
times higher than published. Incidentally, this fireball criss-crossed
the Peekskill ground track which was west to east.

You perceived the fireball headed south. Because in Rochester you were
near to a perpendicular (90-100?horizonal angle) to the flight azimuth
(line of flight) and seeing it at the termination point , I surmise that
you saw it in its steepest vertical down-angle drifting right to left.
Be it remembered: On the line of flight, if you are behind the fireball
trajectory, it will appear to be rising in the sky. If you are in
front/beyond the trajectory it can appear headed down and/or away
drifting slightly. It you are in the vicinity of ground zero, it can
appear as an almost steady point in the sky. At your vewing location,
it could have looked like it was going away--not sure, but it is nice to
get another eyewitness account. I saw the flash which lit up a darkened
room and many seconds later heard --what then I assumed, was a
transformer blowing up.

Elton

Archives: via Sky& Telescope/ Ron

NORTHEAST FIREBALL PINPOINTED

It now appears that July 23rd's dazzling daylight fireball punched
through the atmosphere over central Pennsylvania and may have
scattered meteorites over the rugged woodlands of Sproul State Forest.
Defense Department satellites tracked the meteoroid's flare for
several seconds beginning at 6:19:11 Eastern Daylight Time. The path
began over Scranton (75.6 deg. W, 41.5 deg. N) and ended 140
kilometers to the west over the town of Williamsport (77.3 deg. W,
41.3 deg. N), during which it dropped in altitude from 82 to 32 km.
Despite occurring in daylight, the meteor was bright enough to be
spotted by eyewitnesses from Canada to Virginia.

In its final moments the fireball created a deafening sonic boom that
shook the ground. Meteor expert Peter Brown (Los Alamos National
Laboratory), who is analyzing the satellite records, told Sky &
Telescope, "I can almost guarantee that this object broke up." He says
that reconstructing the object's orbit and flight path are proving
difficult because the entry velocity is uncertain, though it's
probably in the "asteroidal" range of 17 to 20 km per second. Brown
believes that whatever remains of the incoming object probably fell in
an elongated pattern up to 30 km long.

The meteoroid's size is also still a guess. The satellites' visible
and infrared sensors recorded 1.3 billion joules of luminous energy,
which corresponds to a kinetic-energy wallop equivalent to 3,000 tons
of TNT (one-fifth that of the Hiroshima bomb). Meteoroids in this
energy range strike Earth roughly 10 times each year. If it was stony,
as most meteorites are, such an object would have weighed 30 to 90
tons and been the size of a car. However, Brown says acoustic and
seismic data argue for much less kinetic energy and, in turn, a much
smaller object. "I'd hoped to have had some meteorites recovered by
now," Brown concludes, but the many uncertainties diminish that
possibility. "That's why I'm here in New Mexico instead of heading for
Pennsylvania."
Received on Thu 04 May 2006 12:32:45 AM PDT