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(meteorobs) GRAND CANYON METEOR
Dear Observers,
Your assistance is requested in this matter.
Jennifer and Steve Ransdell are not subscribed to
Meteor Observers, so if you wish to reply, please be
sure to copy&paste their email address:
<jems28@attbi.com>
------------- 1st Attached Message --------------
[meteorite-list] GRAND CANYON METEOR
Jennifer and Steve Ransdell jems28@attbi.com
Mon, 19 Aug 2002 18:50:39 -0500
To whom it may concern, and sorry for the lack of
technical terminology:
On the evening of Wednesday, August 14, appx.
9:30-9:45pm Arizona time, my son and I were on a nite
"star" hike with an NPS ranger at Bright Angel
Point on Grand Canyon's North Rim. A huge meteor raced
across much of the sky, running south to north. It
lasted as long as 6-8 seconds, was bluish-white in
color, and was extremely bright. The tail was very
long, and it was very "flare-like", as the "sparks"
were very visible. We could also make out the head of
it. The 40 or so people in our group were completely
in
awe, as was the park ranger. About 10 seconds after it
disappeared, there came a loud boom that eventually
echoed down through the Canyon. I was thinking that it
was unlikely that it hit the Earth, and that the sound
was just a sonic boom, but hoping that it had made
contact somewhere just north of us. I have seen many
"shooting stars", and many good ones, but this
completely blew everything else away.
I have been trying to find information on this
occurrence on the web, but have had no luck at all. I
asked the following morning at the ranger's office if
they had heard if it landed anywhere. The ranger on
duty saw it as well, but they had not heard from the
NFS, whose territory borders the northern part of the
park. They indicated that they would be notified,
especially if a forest fire resulted from it.
A traveler came into the ranger's office while we were
speaking about this, and he said that he'd been
staying at a lodge just up the road about 20 miles,
and saw it as well.
He said that they could see debris "fly up" when it
landed. I asked at two service stations north of the
park, one directly across the road from the lodge just
metioned. The owner said she was awakened by it, but
nothing more. She also indicated that she would know
about it, had it hit and caused a fire. There is
nothing on the NPS/Grand Canyon web site, and I tried
dozens of others, to no avail. I just sent an email to
the NFS to see if they have any info as well.
Does anybody:
A. Have any information on this occurrence?
B. Have any suggestions on where I can/should
"report" this?
Thanks,
Stephen
------------ Reply to 1st Attached Message -----------
meteorite-list] GRAND CANYON METEOR
Matson, Robert ROBERT.D.MATSON@saic.com
Mon, 19 Aug 2002 18:10:48 -0700
Hi Stephen,
Thank you for sharing with the list your account of a
bright meteor over Grand Canyon NP. For clarification
and additional analysis I have a few questions for
you.
> On the evening of Wednesday, August 14, appx.
9:30-9:45pm Arizona time,
> my son and I were on a nite "star" hike with an NPS
ranger at Bright Angel
> Point on Grand Canyon's North Rim. A huge meteor
raced across much of the
> sky, running south to north. It lasted as long as
6-8 seconds, was
> bluish-white in color, and was extremely bright.
When you say it lasted 6-8 seconds, was your view
blocked from seeing the end (e.g. behind trees) or did
it just fade out? Did you notice any fragmentation?
How high up in the sky was the meteor when you first
spotted it, and was the track to the east of you, west
of you, or dead overhead as it traveled south to
north?
> About 10 seconds after it disappeared, there came a
> loud boom that eventually echoed down through the
> Canyon.
Okay, this is probably the most important piece of
information, so I'd like to pin you down on the
uncertainty if I can. Can you give me a range of time
delays that bound the uncertainty? For example,
if you're sure the sound came at least 10 seconds
later, but certainly no more than 30 seconds later,
this would be helpful. If you can narrow the
uncertainty to a smaller range (e.g. "it was between
10
and 12 seconds later") great, but pick a range that
you're confident in. The reason I ask is because a
10-second delay between seeing a meteor and hearing a
sonic boom from it is simply too short.
Even if the time of the meteor's closest approach
(highest elevation angle) was close to the beginning
of when you spotted it, that would mean a delay of
about 18 (8+10) seconds. This would correspond
to a meteor altitude of only about 5.5 km, which is
way too low:
about a quarter of the lowest altitude you could
reasonably expect.
Is there any chance it was thunder, or were your skies
completely clear?
> I was thinking that it was unlikely that it hit the
Earth, and that
> the sound was just a sonic boom, but hoping that it
had made contact
> somewhere just north of us. I have seen many
"shooting stars", and
> many good ones, but this completely blew everything
else away.
The probability that the meteoroid produced a
meteorite depends a lot on how bright it was -- was it
bright enough to cast shadows? Was it dimmer or
brighter than a full moon?
> A traveler came into the ranger's office while we
were speaking
> about this, and he said that he'd been staying at a
lodge just up
> the road about 20 miles, and saw it as well. He
said that they
> could see debris "fly up" when it landed.
I wouldn't place much stock in this traveler's
description -- it is either an embellishment of what
he saw, or an inadvertent association of two unrelated
events -- the meteor in the sky, and something else
much closer to him.
> Does anybody:
> A. Have any information on this occurrence?
Your report was the first I heard of it, but I'll now
keep an eye out for others.
> B. Have any suggestions on where I should "report"
this?
FIDAC. Here's a link:
http://www.imodot net/fireball/index.html
Click on the "Hints" link for some instructions for
filling out the online fireball report form.
Best,
Rob Matson
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