Hi Peter,
While the fall is officially listed as October 16 in the database, the
only thing you posted and which I responded to was:
"Recalculated to 12 October 2006 22Na was 38.0±2.2 and 26Al 31.5±2.1
(both dpm/kg), the activity ratio of 1.21 is fully consistent with a
fall on that date."
Of couse the 16th is in the online Met Bulletin as the official fall
date, and it seemed you thought the date was the 12th by posting the
above. Most definitely, though the Meteoritical bulletin database is
only as good as the information that it receives. And most definitely I
agree with you now that you say you were only referencing the fall date
in the link, rather than the Oct 12 info you posted to the list.
The question I answered which is interesting, to me at least, was
whether something as short as 4 days difference could be determined
scientifically by the radionuclides mentioned. The answer in this case
was most certainly: No. Something that could be nice to know ...
It might be a good idea that the online database clears up the apparent
inconsistency a little better regarding the October 12 date it lists in
relation to the gamma measurements. Also the clear error that it states
that the measurements were taken in December - January 2006 should be
updated to January 2007, if in fact that is the date. It would seem
they received that typo from Svend whose website says the same=2
0thing at
the moment, on page 5 of his superb article when discussing the support
between the two different fall dates (4 days apart):
http://www.niger-meteorite-recon.de/en/Bassikounou_Meteorite_5.htm
Typographically yours
Doug
-----Original Message-----
From: Peter Marmet <p.mar...@sunrise.ch>
To: Meteorite-list@meteoritecentral.com
Sent: Sun, Oct 11, 2009 4:37 pm
Subject: Re: [meteorite-list] Bassikounou OCTOBER 16th
Hi Doug
the analysis was done by P. Weber, PPGUN.
The results are from the Meteoritical Bulletin Database.
In the Meteoritical Bulletin Database the fall date is still Oct. 16 -
so officially it's Oct. 16, isn't it!
I only found a hint why some sources mention Oct. 12 for the fall date!
Cheers, Peter
2009/10/11 Mexicodoug <mexicod...@aim.com>:
Hi List, Peter,
Could you give a little more detail, as 22Na has a half life of about
950
days and the experimental uncertainty of that particular measurement
apparently used to calculate the ratio was 11.6%, not to mention worse
uncertainties with the 26Al. It says the measurement was between
December
and January of 2006.
So for starters, did they measure the meteorite 9 months before it
fell?
OK, so maybe it is a typo in the link you gave (source or on line
Meteoritical Bulletin, but the same January 2006 date is currently on
Svend´s website) and say they are both typos which may o
r may not say
something about precision: and should read January 2007.
If we assume the measurements were taken about 75 days after the fall
and we
throw around a ten percent order of magnitude as the possible
measurement
error, would not the difference of 4 days (October 12 vs. Oct. 16) be
totally lost in the error?
It is more likely the measurements were just to prove it was a fresh
fall,
but the ability to distinguish four days based on a bunch of
assumptions of
the original composition seems far-fetched to me. That must be what
the
scientists set out to prove.
So, maybe the gamma spectroscopist had received the October 12 date
and only
set out to prove it was reasonable. Surely if they had received the
October
16 date, they would have allowed it as consistent as well - after
all, over
99.7% of the 22Na would still be there (did I do that right?), and
this is
dwarfed by the experimental error.
As Jim mentioned I think a real witness needs to speak up ... the
press, as
reported by Svend Buhl, has October 16 as the fall date. So at the
moment,
it would seem the press is preferable to insignificant digits being
extended...
Best wishes,
Doug
-----Original Message-----
From: Peter Marmet <p.mar...@sunrise.ch>
To: Meteorite-list@meteoritecentral.com
Sent: Sun,20Oct 11, 2009 3:28 pm
Subject: Re: [meteorite-list] Bassikounou OCTOBER 16th
Hello Thomas,
Cosmogenic radionuclides:
(P. Weber, PPGUN) Gamma-spectroscopy performed in December-January
2006 showed the presence of the following radionuclides: 48V, 46Sc,
56Co, 54Mn, 58Co, 7Be, 51Cr, 57Co, 22Na, 26Al and 60Co.
Recalculated to 12 October 2006 22Na was 38.0±2.2 and 26Al 31.5±2.1
(both dpm/kg), the activity ratio of 1.21 is fully consistent with a
fall on that date.
More info here: http://kuerzer.de/1u0Y557jF
Cheers,
Peter
2009/10/11 Thomas Webb <webb...@yahoo.com>:
Jim and List,
The bulletin shows a discrepancy concerning the fall date. In the
data table
it gives October 12, 2006 but in the writeup it is October 16. I
belive I
was
the first to offer any on ebay and at that time I gave the fall date
as Oct.
12
and still have that date in my
database. However, perhaps a corrected date was
offered later.
Can someone give us confirmation of the actual date that it fell?
Thanks,
Thomas
--- On Sun, 10/11/09, Jim Strope <nwa...@comcast.net> wrote:
From: Jim Strope <nwa...@comcast.net>
Subject: [meteorite-list] Bassikounou OCTOBER 16th
To: "Meteorite Central" <meteorite-list@meteoritecentral.com>
Date: Sunday, October 11, 2009, 10:29 AM
0A>>>
http://tin.er.usgs.gov/meteor/metbull.php?code=44876
Jim Strope
421 Fourth Street
Glen Dale, WV 26038
http://www.catchafallingstar.com/
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