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Great Fireball of 21st September 2012 UK and Ireland

 
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Robert J Cobain



登録日: 2006.04.25
記事: 77

記事日時: Sat Sep 22, 2012 11:14 am    記事の件名: Great Fireball of 21st September 2012 UK and Ireland 引用付きで返信

Hi All, Tonight I captured the 'biggest' meteor I have so far recorded in the almost 8 years operation of my meteor camera Very Happy I have sent an email to the other meteor recording station in Armagh to see if they have also recorded it, but it is late at night now and they probably wont check till the morning.

http://www.youtube.com/watch?v=-aZE8rEGR8k

http://www.bbc.co.uk/news/uk-19683687
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登録日: 2004.08.07
記事: 9976
所在地: 139.67E 35.65N

記事日時: Sat Sep 22, 2012 1:56 pm    記事の件名: Re: Great Fireball of 21st September 2012 UK and Ireland 引用付きで返信

Great!!
I've also never caught such a slow and diffused fireball. It is truly amazing.
It is like a satellite re-entry. Isn't it too slow for meteor?

I wait continued report, with expectation.
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Robert J Cobain



登録日: 2006.04.25
記事: 77

記事日時: Sat Sep 22, 2012 7:46 pm    記事の件名: 引用付きで返信

Hi SonotaCo, Yes space debris is a suspect but because the fireball travelled east to west, it is unusual. I am sure we will know more later today. I have found a report on this web page here (Armagh observatory). I am not sure whether it is a serious report or not though.

"Date:
2012-Sep-21
Time:
22.56pm till 22.59pm
Location:
NEWTOWNABBEY, COUNTY ANTRIM, N.I.
Report:
An amazing WHITE HOT set of meteors in a line, perhaps only 20 to 40 metres above us. The largest was about 2m across. We live quite high up in the COUNTY ANTRIM hills. My boyfriend and I heard the sounds of many small meteors fall to the earth near us, around DERRYMORE ROAD, and BURNEY'S LANE, NEWTOWNABBEY, then we heard a large THUD as 1 much large meteor landed near us. We have just collected 16 possible meteor fragments. 13 are dark black, like basalt. 1 is dark black and looks volcanic like obsidian. 1 is grey. 1 is like black volcanic pumice."
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登録日: 2004.08.07
記事: 9976
所在地: 139.67E 35.65N

記事日時: Sat Sep 22, 2012 8:08 pm    記事の件名: 引用付きで返信

http://www.youtube.com/watch?v=-aZE8rEGR8k Robert's one
http://www.youtube.com/watch?v=0wDkFZuuuck
http://www.youtube.com/watch?v=V7BFGb9DEN8
http://www.youtube.com/watch?v=b8LDL5Ri_84
http://www.youtube.com/watch?v=4_1CRN-v2qs
http://www.youtube.com/watch?v=VvK5JVTczIY
http://www.youtube.com/watch?v=5niWgqiwgGI
http://www.youtube.com/watch?v=XebASHxBTds

So far, several clips are uploaded about 21:55 21/Sep/2012 FireBall over UK.
....but it seems Robert's one is the only one scientific record.
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Robert J Cobain



登録日: 2006.04.25
記事: 77

記事日時: Sun Sep 23, 2012 4:57 am    記事の件名: 引用付きで返信

Hi SonotaCo,

Unfortunately the other station in Armagh says they did not capture the 'meteor' because it was 'too low'. Our stations are only about 50 miles apart so we have our (6mm) cameras pointed up at quite a steep angle of about 65 degrees, so low meteors are missed. They have 2 other cameras which are also pointed up at fairly steep angles of elevation, so it must have slipped under those too! Sad

Based on some rough single station analysis and observer reports I have made a map showing the ground track I reckon it took. I think fragments must have been scattered along this track over Ireland along the border between Northern and Southern Ireland, with the largest fragments ending up out in the Atlantic off the west coast.

I hope that it will be possible to make a better map soon since there are so many reports and videos, so it is just a case of combining them all to get the best fit path!

Regarding the observation of a meteorite being found in Newtownabbey, I think it is unlikely, although they have posted another message on the armagh fireball report webpage saying, http://arpc65.arm.ac.uk/cgi-bin/fireballs/search.pl?txtDate=2012-09-21

Location:
ANTRIM ROAD, NEWTOWNABBEY
Report:
Further to my previous report, when we collected a total of 16 possible meteorite rock fragments:- We have tested the rocks with a magnet, and the magnet is definitely attracted to 2 of them.

If the find is a hoax it will be found out soon enough!



21stSeptemberTrailMapGuess.jpg
 説明:
21st September UK and Ireland Fireball ground track guess.
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21stSeptemberTrailMapGuess.jpg


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登録日: 2004.08.07
記事: 9976
所在地: 139.67E 35.65N

記事日時: Sun Sep 23, 2012 8:46 am    記事の件名: 引用付きで返信

just a thinking....
Robert J Cobain wrote:
the fireball travelled east to west, it is unusual.

This point can be a hint.
"East to west at midnight" means it came from apex side (orbit moving direction of the earth).
So if the object came from heliocentric orbit, it should have more than earth's orbit speed plus escape velocity of the earth.
It will be 40km/s or so.
And it is said that it was "low altitude".
So from a impression of videos, it seems very slow... around 10km/s or lower.
If so it means it came from geocentric orbit and was re-entry of something.
or it was the final stage of meteor that was enough decelerated by atmosphere.
But latter possibility is not likely because it had still very long duration time, more than 30 seconds.

We'd better to make inquiries to satellite monitoring agent who has all TLEs including military ones.
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Robert J Cobain



登録日: 2006.04.25
記事: 77

記事日時: Sun Sep 23, 2012 11:02 pm    記事の件名: 引用付きで返信

Hi SonotaCo,

I have been making some 'back of fag packet' calculations based on written reports and my own video and I did arrive at a speed of around 10km/s for the object as you say. The height when it entered the frame must have been at most 70km because it was not visible to the Armagh camera. The height when exiting the frame was probably still about 60km. A report of sonic booms from the west of Northern Ireland and their timings gave a height of about 30km there. I think landfall was probably in the sea just off the coast of County Mayo, Ireland, but some fragments could have landed in North County Mayo.

Robert.
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Robert J Cobain



登録日: 2006.04.25
記事: 77

記事日時: Tue Sep 25, 2012 5:07 am    記事の件名: 引用付きで返信

Hi SonotaCo,

I have attached the files needed for analyzing the fireball. I am not sure how best to use the UFOAnalyzer in this case because there are so many objects. I think it will have to be a manual method using the 'clicks' functionality. I used the clicks to measure the path of the leading fireball because when I analyzed the whole file it wasn't clear from the objects list and 'hit mark' red line which of the objects had been measured. When I did the manual analysis I got 7.4 deg/s AV for the leading fireball. Then I made the assumption that the meteor stayed a constant 70km level path and got a figure of 9km/s Please excuse my math if this is badly wrong Smile



21stSeptemberFireball.zip
 説明:

ダウンロード
 ファイル名:  21stSeptemberFireball.zip
 ファイルサイズ:  561.79 KB
 ダウンロード回数:  339 回


M20120921_215551_Ivyhill_WS.avi
 説明:

ダウンロード
 ファイル名:  M20120921_215551_Ivyhill_WS.avi
 ファイルサイズ:  3.95 MB
 ダウンロード回数:  328 回

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登録日: 2004.08.07
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記事日時: Tue Sep 25, 2012 2:27 pm    記事の件名: 引用付きで返信

Robert J Cobain wrote:
Then I made the assumption that the meteor stayed a constant 70km level path and got a figure of 9km/s

It is not so far, my resut is 10.4 km/s as below. ( I used the longest object that was got by auto analyze, and set its height)
------------------
Altitude can be lower, means velocity can be slower
East to west very slowly..... amaging Exclamation



WS000000.JPG
 説明:
Profile for this clip
0.02deg accuracy for 15 refstars
 ファイルサイズ:  133.22 KB
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WS000000.JPG



WS000002.JPG
 説明:
measured object
 ファイルサイズ:  191.96 KB
 閲覧数:  9739 回

WS000002.JPG



WS000001.JPG
 説明:
ground plot using 70km assumption
 ファイルサイズ:  247.18 KB
 閲覧数:  9738 回

WS000001.JPG


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Robert J Cobain



登録日: 2006.04.25
記事: 77

記事日時: Tue Sep 25, 2012 4:33 pm    記事の件名: 引用付きで返信

Hi SonotaCo, Thanks for your screenshots showing this operation of UFOA Smile I think the differences in our calculations comes from the fact I used the main object at the lead of the train and when I measured its time of flight I got 6.2 seconds?? I will go back and check things again, thanks, Robert.
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Robert J Cobain



登録日: 2006.04.25
記事: 77

記事日時: Tue Sep 25, 2012 4:41 pm    記事の件名: 引用付きで返信

O I think the problem might lie with the fact I used the time-stamp on the video frame, rather than counting the number for frames between the two points? Since counting frames would give a more accurate value of the time span?? (As long as any dropped frames are known)
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登録日: 2004.08.07
記事: 9976
所在地: 139.67E 35.65N

記事日時: Tue Sep 25, 2012 4:52 pm    記事の件名: 引用付きで返信

my object may be a part of all, the bold red arrow in the image was the measured part.
So it is shorter. It is not the cause.
It begins on #140 field and ends on #413 field, so UA2 computes its duration (413-140)/50 = 5.460 sec
--------
Anyway the assumption of 70km may be the biggest ambiguity now.
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Robert J Cobain



登録日: 2006.04.25
記事: 77

記事日時: Tue Sep 25, 2012 6:26 pm    記事の件名: 引用付きで返信

Thanks for your help on this, I don't normally do any of these calculations myself as I leave it for the experts in Armagh! I have emailed them again to see what sort of range of heights the object could have had in order for it to be seen in my camera but not in any of theirs. After that I think we can get some good altitude estimates from eyewitness accounts and photos.
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Robert J Cobain



登録日: 2006.04.25
記事: 77

記事日時: Wed Oct 03, 2012 2:59 am    記事の件名: 引用付きで返信

Hi SonotaCo,

Just to give you an update on the latest findings on the 'object' (maybe you have seen this already). It appears the object must have been briefly captured in orbit around the Earth before descending into the atmosphere :-O

http://sattrackcam.blogspot.nl/

http://lunarmeteoritehunters.blogspot.fi/2012/09/breaking-news-uk-earth-hugging-asteroid.html
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