[meteorite-list] Bassikounou OCTOBER 16th

From: Mexicodoug <mexicodoug_at_meteoritecentral.com>
Date: Sun, 11 Oct 2009 19:03:32 -0400
Message-ID: <8CC18DE3019454C-307C-F020_at_webmail-d006.sysops.aol.com>

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.marmet at sunrise.ch>
To: Meteorite-list at 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 <mexicodoug at 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.marmet at sunrise.ch>
> To: Meteorite-list at 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 <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
>>>
0A>>>
>>> http://tin.er.usgs.gov/meteor/metbull.php?code=44876
>>>
>>> Jim Strope
>>> 421 Fourth Street
>>> Glen Dale, WV ?26038
>>>
>>> http://www.catchafallingstar.com/
>>> ______________________________________________
>>> http://www.meteoritecentral.com
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>>
>>
>>
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Received on Sun 11 Oct 2009 07:03:32 PM PDT