[meteorite-list] Bassikounou OCTOBER 16th

[Mexicodoug]

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 or 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.marmet at sunrise.ch>
To: Meteorite-list at meteoritecentral.com
Sent: Sun, Oct 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 <webbth1 at 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 <nwa482 at comcast.net> wrote:
>
>> From: Jim Strope <nwa482 at comcast.net>
>> Subject: [meteorite-list] Bassikounou OCTOBER 16th
>> To: "Meteorite Central" <meteorite-list at meteoritecentral.com>
>> Date: Sunday, October 11, 2009, 10:29 AM
>>
>>
>> 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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