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Today's Topics:
1. Regmaglypts ([email protected])
2. Re: Meteorite Photography (Must read!) (al mitt)
3. Re: Meteorite Photography (Must read!) (John Gwilliam)
4. Re: Updated Lorton trajectory (Mike Hankey)
5. Re: Updated Lorton trajectory ([email protected])
6. Re: Updated Lorton trajectory (Chris Peterson)
7. Re: Meteorite Photography (Must read!) (Dark Matter)
----------------------------------------------------------------------
Message: 1
Date: Wed, 27 Jan 2010 7:18:42 -0500
From: <[email protected]>
Subject: [meteorite-list] Regmaglypts
To: [email protected]
Message-ID: <20100127121842.62073.292942.r...@cdptpa-web26-z01>
Content-Type: text/plain; charset=utf-8
My Response Jan 27, 2010
Subject: Re: [meteorite-list] Regmaglypts
Jason and All,
1. My reference to ?bubbles? is to morphology, NOT voids. Another
meteoritic example of ?bubble morphology effects? is pallasitic olivines
such as Springwater and Imilac.
A thought experiment: Once again, envision a melt mass of olivine and
nickel-iron solidifying under microgravity conditions ? surface energy
dominates gravity.
On cooling, olivine begins to solidify before nickel-iron. However, since
olivine and iron-nickel share a range of temperatures where both are still
at least partially liquid (mushy stage), as cooling continues,
still-plastic olivines can be surrounded by and sometimes infiltrated and
pushed apart by liquid nickel-iron.
Cut and polished sections of Springwater and Imilac reveal this as a
relatively complex process. Observe 120 angles between some olivines,
evidence of a system governed by surface energy. Some olivine boundaries
are straight (interior polyhedral shapes); some are circular (a sphere
minimizes surface area to volume ratio); some straight and curved (perhaps
on the outer surface of the olivine mass). See my "Stepping Back in Time"
article in Meteorite magazine Nov. 2003, Vol. 9 No. 4, pp. 21-22 or see it
in the publications list on my website at http://meteormetals.com
2. There is NO WAY that the thermal history of a metal can be calculated
in reverse, despite hundreds of papers in the meteoritics literature since
the original paper of Osmond and Cartaud in 1904 and the more recent,
detailed papers on ?metallographic cooling rates!? That is more than 100
years of circular reasoning! Industrial metallurgists would be a lot
happier if this backward calculation were possible. It is NOT!
3. Speaking of industrial metallurgists, do another experiment: show a
cut section of any nickel-iron or stony iron meteorite to a modern
INDUSTRIAL metallurgist. Ask him or her to describe the microstructure,
without you giving them any ?meteorite words? or concepts. Then, Listen!
Next, give that person one of the metallic meteorite papers in the
meteoritics literature (other than mine) and see if that person can even
understand the language and concepts. Meteoritics metallurgy has sealed
itself inside an old language, not accessible to today?s busy, industrial
metallurgists. To quote one of my industrial metallurgist friends who is
a casting expert and who has become a meteorite collector, "meteorite
metallurgy is in the Stone Age."
We need a NEW METALLURGY for meteorites! Imagine what we could learn!
Phyllis Budka
http://meteormetals.com/
------------------------------
Message: 2
Date: Wed, 27 Jan 2010 08:50:27 -0500
From: "al mitt" <[email protected]>
Subject: Re: [meteorite-list] Meteorite Photography (Must read!)
To: "meteorite-list" <[email protected]>
Message-ID: <4c1498a179534fb8ad95d58999bd1...@starmanpc>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Hi Erik and all,
I'd think just the opposite would be correct. A higher f-stop (f 22, 18
etc.) would create a better depth of field and the more open your iris is
on
your camera (lower f stop, 1.8, 2.0 etc.) the less focused your items
would
be. I think you just stated it backwards. Best!
--AL Mitterling
Mitterling Meteorites
----- Original Message -----
From: "Erik Fisler" <[email protected]>
To: "meteorite-list" <[email protected]>
Sent: Tuesday, January 26, 2010 3:51 PM
Subject: [meteorite-list] Meteorite Photography (Must read!)
The third thing is auto-blending. For those of you who have SLR's you will
notice that shooting at a higher F-stop like F1.8 or F2.8 is a lot sharper
than shooting at a lower F-stop like F22. The problem is, you might have
to
drop your F-stop to make sure the whole meteorite is in focus.
------------------------------
Message: 3
Date: Wed, 27 Jan 2010 07:27:54 -0700
From: John Gwilliam <[email protected]>
Subject: Re: [meteorite-list] Meteorite Photography (Must read!)
To: "al mitt" <[email protected]>, "meteorite-list"
<[email protected]>
Message-ID:
<20100127142802.ocdn4995.fed1rmmtao101.cox....@fed1rmimpo02.cox.net>
Content-Type: text/plain; charset="us-ascii"; format=flowed
Al is right on this one. The higher the F-stop number, the greater
the depth of field is, i.e more of a three dimensional object will be
in focus. The drawback to this is less light enters the lens thus
requiring a longer shutter speed. And, if your not careful, a
background that is too close can be in focus as well. There are many
different ways to take good quality pictures of
meteorites, experimentation is the key.
Best,
John Gwilliam
At 06:50 AM 1/27/2010, al mitt wrote:
Hi Erik and all,
I'd think just the opposite would be correct. A higher f-stop (f 22,
18 etc.) would create a better depth of field and the more open your
iris is on your camera (lower f stop, 1.8, 2.0 etc.) the less
focused your items would be. I think you just stated it backwards. Best!
--AL Mitterling
Mitterling Meteorites
----- Original Message ----- From: "Erik Fisler" <[email protected]>
To: "meteorite-list" <[email protected]>
Sent: Tuesday, January 26, 2010 3:51 PM
Subject: [meteorite-list] Meteorite Photography (Must read!)
The third thing is auto-blending. For those of you who have SLR's
you will notice that shooting at a higher F-stop like F1.8 or F2.8
is a lot sharper than shooting at a lower F-stop like F22. The
problem is, you might have to drop your F-stop to make sure the
whole meteorite is in focus.
______________________________________________
Visit the Archives at
http://www.meteoritecentral.com/mailing-list-archives.html
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Regards,
John Gwilliam
Some people are born on third base
and go through life thinking they hit a triple.
[Bob Dylan]
------------------------------
Message: 4
Date: Wed, 27 Jan 2010 09:36:04 -0500
From: Mike Hankey <[email protected]>
Subject: Re: [meteorite-list] Updated Lorton trajectory
To: Rob Matson <[email protected]>
Cc: meteorite list <[email protected]>
Message-ID:
<[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
I guess this explains why it did so much damage?
On Wednesday, January 27, 2010, Rob Matson <[email protected]>
wrote:
Hi All,
I finally received a good second image of the Lorton bolide smoke
trail taken immediately after the fall (and before upper atmospheric
winds distorted it). More importantly, the two images I have were
taken from sufficiently different vantage points that a good 3D
solution could be computed. (My early, somewhat hurried "first-cut"
at the trajectory was based on only a single image, and a cobbling
together of 50+ witness reports.) That first solution wasn't bad
as far as the flight direction (NNE -> SSW); however, as steep as
I made the entry angle, I didn't make it steep enough.
The Lorton meteoroid entered at a surprisingly steep angle -- about
15 degrees from vertical! If upper atmospheric winds had been
light, this would have made for a very tight strewnfield. But
those winds were anything but light at the time of the fall. For
instance, at 11-km altitude, the jet stream was over 90 knots!
Even down at 5-km altitude, the wind was over 40 knots.
So here are my new impact predictions as a function of mass.
The distance and bearing columns are in miles and degrees,
respectively, relative to the impact coordinates of the 308-gram
mass:
Mass ? Longitude Latitude Distance Bearing
----- ?--------- -------- -------- -------
?3 g ? ?-77.1383 ?38.7130 ? 4.05 ? ?77.9
10 g ? ?-77.1635 ?38.7104 ? 2.68 ? ?75.5
30 g ? ?-77.1804 ?38.7077 ? 1.75 ? ?74.0
100 g ? -77.1976 ?38.7043 ? 0.80 ? ?71.8
300 g ? -77.2116 ?38.7007 ? -0- ? ? ?N/A
?1 kg ? -77.2282 ?38.6965 ? 0.94 ? ?252.1
?3 kg ? -77.2415 ?38.6923 ? 1.72 ? ?250.2
10 kg ? -77.2560 ?38.6874 ? 2.57 ? ?249.0
As before, these coordinates (when you connect the dots) trace
out a curve of the estimated strewn field centerline. Unfortunately,
the lightest (and presumably more numerous) fragments would have
been windblown onto Ft. Belvoir. But there is still some room ENE
of the doctor's office that is not on military land, and plenty
of real estate in the "heavy direction" (WSW) if you're feeling
lucky. ?--Rob
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------------------------------
Message: 5
Date: Wed, 27 Jan 2010 10:06:29 EST
From: [email protected]
Subject: Re: [meteorite-list] Updated Lorton trajectory
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset="US-ASCII"
guess this explains why it did so much damage?<<
Mike, I haven't been following this too hard, but am curious as to what
you mean about it explains the damage?
GeoZay
------------------------------
Message: 6
Date: Wed, 27 Jan 2010 08:30:36 -0700
From: "Chris Peterson" <[email protected]>
Subject: Re: [meteorite-list] Updated Lorton trajectory
To: "meteorite list" <[email protected]>
Message-ID: <96aa8d2f4dfa4d119fa3b2ab92563...@bellatrix>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
How so? A meteorite's impact speed is a function of its shape and mass
only,
and is unrelated to the details of its entry speed and angle. A meteorite
lands at an angle that deviates from vertical by at most a few degrees,
with
that angle entirely determined by the near-ground wind speed and
direction.
Chris
*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
----- Original Message -----
From: "Mike Hankey" <[email protected]>
To: "Rob Matson" <[email protected]>
Cc: "meteorite list" <[email protected]>
Sent: Wednesday, January 27, 2010 7:36 AM
Subject: Re: [meteorite-list] Updated Lorton trajectory
I guess this explains why it did so much damage?
------------------------------
Message: 7
Date: Wed, 27 Jan 2010 09:37:06 -0700
From: Dark Matter <[email protected]>
Subject: Re: [meteorite-list] Meteorite Photography (Must read!)
To: John Gwilliam <[email protected]>
Cc: al mitt <[email protected]>, meteorite-list
<[email protected]>
Message-ID:
<[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
Hi All,
Actually there is a further concern here. Although when a lens is
stopped down to its max it does have the greatest depth of field, but
it is also not at its sweet spot for sharpness. Usually a stop or two
less than max provides the sharpest image the lens is capable of. Here
is more about this:
http://www.bobatkins.com/photography/technical/diffraction.html
Best,
Martin
On Wed, Jan 27, 2010 at 7:27 AM, John Gwilliam <[email protected]> wrote:
Al is right on this one. ?The higher the F-stop number, the greater the
depth of field is, i.e more of a three dimensional object will be in
focus.
?The drawback to this is less light enters the lens thus requiring a
longer
shutter speed. ?And, if your not careful, a background that is too close
can
be in focus as well. ?There are many different ways to take good quality
pictures of meteorites, ?experimentation is the key.
Best,
John Gwilliam
At 06:50 AM 1/27/2010, al mitt wrote:
Hi Erik and all,
I'd think just the opposite would be correct. A higher f-stop (f 22, 18
etc.) would create a better depth of field and the more open your iris
is on
your camera (lower f stop, 1.8, 2.0 etc.) the less focused your items
would
be. I think you just stated it backwards. Best!
--AL Mitterling
Mitterling Meteorites
----- Original Message ----- From: "Erik Fisler" <[email protected]>
To: "meteorite-list" <[email protected]>
Sent: Tuesday, January 26, 2010 3:51 PM
Subject: [meteorite-list] Meteorite Photography (Must read!)
The third thing is auto-blending. For those of you who have SLR's you
will
notice that shooting at a higher F-stop like F1.8 or F2.8 is a lot
sharper
than shooting at a lower F-stop like F22. The problem is, you might have
to
drop your F-stop to make sure the whole meteorite is in focus.
______________________________________________
Visit the Archives at
http://www.meteoritecentral.com/mailing-list-archives.html
Meteorite-list mailing list
[email protected]
http://six.pairlist.net/mailman/listinfo/meteorite-list
Regards,
John Gwilliam
Some people are born on third base
and go through life thinking they hit a triple.
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? [Bob Dylan]
______________________________________________
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------------------------------
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End of Meteorite-list Digest, Vol 77, Issue 82
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