[meteorite-list] OFF LIST Fwd: First cut at wind-shifted, predicted impact coordinates

From: Mike Hankey <mike.hankey_at_meteoritecentral.com>
Date: Sun, 24 Jan 2010 14:32:00 -0500
Message-ID: <f0a794131001241132x30da6f6w1fbbed61da55a4ea_at_mail.gmail.com>

Hi,

A correction to this email was pointed out to me off-list:

"Marc Fries was the first to use this strategy and has been as willing
as anyone else to share his information within the meteorite
community."

I chose some words poorly and didn't mean to insinuate that there were
not other people out there who could plot strewnfields and meant no
disrespect to Marc or others who have helped plot fields that led to
discoveries or helped with searches in the past. Marc was very helpful
with the PA fall and provided a great deal of information. I'm sure if
he wasn't in Antartica now he would be all over this too.

Thanks,

Mike


>
> -----Original Message-----
> From: meteorite-list-bounces at meteoritecentral.com
> [mailto:meteorite-list-bounces at meteoritecentral.com] On Behalf Of Mike
> Hankey
> Sent: Sunday, January 24, 2010 1:38 PM
> To: meteoritelist
> Subject: [meteorite-list] Fwd: First cut at wind-shifted,predicted impact
> coordinates
>
> Hi,
>
> Meteor wizard Rob Matson has taken a first crack at estimating a strewnfield
> for the Lorton Meteorite.
>
> I have plotted the points in Google Earth. You can see some maps and
> download the KMZ file here:
>
> http://www.mikesastrophotos.com/astro-photos/lorton-meteorite-estimated-stre
> wnfield-version-1/
>
> Its looking like the Fort Belvoir Golf Course could be prime hunting
> grounds.
>
> Rob is the only person I know of who is qualified to do this type of work
> and willing to share it with the meteorite community. Rob's work has been
> instrumental in numerous meteorite discoveries and we all owe him a debt of
> gratitude.
>
> Thanks Rob!
>
> Mike
>
>
>
>
> Hi Guys,
>
> I've done some serious data-gathering and number-crunching today to come up
> with a hunting corridor for you. Here are my current best assumptions based
> on witness observations, images of the dust cloud, the impact location, and
> upper atmospheric radiosonde data for the balloon launched from Sterling,
> VA, about an hour after the fall:
>
> Entry angle: ~55-60 degrees from horizontal (i.e. steep) Flight direction:
> Azimuth +191 (11 degrees west of south) Average wind velocity from 5-16 km
> altitude:? 70 knots Average wind direction from 5-16 km altitude:? Az 90
> (east)
>
> Using an example break-up altitude of 25 km at an initial velocity of 15
> km/sec, the rotation of the strewn field relative to flight direction ends
> up being 40-50 deg clockwise, which is quite significant. Here are where
> masses of various sizes end up, both in Lat/Long and distance/bearing from
> the
> 308 g find:
>
> ?Mass??? Longitude? Latitude? Dist (mi) Bearing
> -------? ---------? --------? --------- -------
> ? 3 g??? -77.12929? 38.73888???? 5.2????? 59.3
> ? 5 g??? -77.14419? 38.73268???? 4.3????? 58.7
> ?15 g??? -77.16179? 38.72688???? 3.2????? 56.0
> ?40 g??? -77.18079? 38.71908???? 2.1????? 52.6 120 g??? -77.19569
> 38.71088???? 1.1????? 50.6
> (308 g)? -77.21159? 38.70068???? -0-????? N/A 1150 g?? -77.22609
> 38.69048???? 1.1???? 228.0 3750 g?? -77.24249? 38.67848???? 2.3???? 227.4
>
> The reason the masses aren't round numbers is that my program includes
> ablation, so while the simulated stones started off with nice round numbers
> like 100 g and 1 kg at altitude, the ablated masses are a fraction of the
> original.
>
> So where are these locations? The 120-gram mass ends up near Rhondda Drive,
> a couple hundred meters NW of Richmond Highway and Telegraph Rd. The 40-gram
> mass ends up on the north end of Ft. Belvoir. The simulated 15-grammer ends
> up on the Ft.
> Belvoir golf course. But 5-gram stones would be off the base to its north,
> north of John J. Kingman Rd. And 3-gram stones end up in the southwest
> corner of Huntley Meadows Park.
>
> Going in the other direction (heavier masses), the ~1.1 kilo simulated mass
> above ends up very close to I-95, a little west of Morris Ginsberg & Co.
> And the largest mass I ran crosses over to the other side of I-95 on
> Landfill Drive. ;-)
>
> If you connect all these dots, you should find quite a bit of searchable
> real estate.? My advice is on a map to draw a
> 45 degree angle southwest of the doctor's office for heavier stones, and a
> ~55-degree angle NE of the 308-g find for the lighter stuff (that's
> 55-degrees clockwise from north).
>
> I'll continue to search for better observations that can yield a more
> accurate entry angle.? We really need a good observer who had a side view of
> the event and can tell us what the slope was like relative to the horizon.
> --Rob ______________________________________________
> Visit the Archives at
> http://www.meteoritecentral.com/mailing-list-archives.html
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list
>
>
Received on Sun 24 Jan 2010 02:32:00 PM PST