8
Feb
2012

Update on TX 2012-02-01 Fireball

We just got this email from Bill Cooke, the directory of the NASA Meteoroid Environment Office. Great work Bill!

We have spent the last few days analyzing the Sandia camera videos kindly provided by James Beauchamp and Kevin Palivec (also thanks to Esko Lyytinen for his insight and comments). These have enabled us to determine a decent trajectory for the meteor; unfortunately the meteor entered at a shallow angle and its path/duration was so long (18.5 seconds) that the linear approximation used in our trajectory codes is not valid, resulting in a possible error of several (~5) kilometers in the final position. Consequently, we did not attempt the dark flight calculations needed to determine the impact zone, as an error of 5 kilometers in position at 30-40 km altitude would translate to over a hundred square kilometers of uncertainty in the meteorite fall area. I can say that a solution using the first hundred frames of video (meteor is above 65 km altitude) yields a trajectory consistent with the Edgewood doppler returns; all other solutions put the meteor path about 20 km to the north of the radar signature.

Here are the beginning and end coordinates of the meteor, based on a solution involving all 976 points (frames) from the 3 videos:

Meteor beginning point: 99.176 W, 32.108 N at an altitude of 92 km
Meteor end point: 96.357 W, 32.745 N at an altitude of 43 km

Mean residuals in trajectory fit (residuals show systematic trends due to breakdown of linear path approximation)

Coleman: -0.045 km vertical, 0.703 km horizontal
Hawley: -1.889 km vertical, -1.711 km horizontal
OKC: +1.302 km vertical, -0.123 km horizontal

Again, the end point is NOT the impact location; it represents meteor position in the last frame in the OKC all sky camera video.

Average speed is 16.3 +/- 1.4 km/s
Initial meteor speed: ~18 +/- 1 km/s
End meteor speed: 9.8 +/- 4 km/s

I am confident this meteor produced meteorites. It was very bright, with peak absolute magnitude around -14 (lower limit). Mass estimates from the light curve range from about 20 kg all the way to just over a metric ton (1017 kg), depending on whose equations/technique you use. I consider a few hundred kg likely. How much mass made it to the ground is anyone’s guess, but be assured that this was a BIG rock that blazed across the Texas sky.

The gory details are in this pdf file: http://www.billcooke.org/events/20120202_0157.pdf
The complete meteor trajectory is here: http://www.billcooke.org/events/smets.txt

Update 2012-02-09 – Dark Flight Model

From Bill Cooke:

This morning I reversed my earlier position and decided to ask my team to perform the necessary calculations to compute an impact zone. This is a 2 step process – first, each observed fragment of the meteor (only 1 piece in this case) has to have its trajectory extrapolated via a single body ablation code from the last observed position to the point where it is no longer ablating, i.e., when the speed drops below 4 km/s. This position is then used as the start point for the darkflight calculations, which take the meteor all the way to the ground.

3 sets of calculations were performed – two of the sets were done by my team here at MSFC, with densities of 2.3 (carbonaceous chondrite) and 3.7 g/cc (ordinary chondrite). We did not take into account the winds, as our code is a work in development (we can only handle winds in an average sense). However, I also asked the Meteor Physics Group at the University of Western Ontario to do a 3rd set of calculations; their numbers do account for the wind data and assume a density of 3.7 g/cc.
The results are given in the purple, yellow, and orange columns of this table:
They are plotted here:
The masses are not your usual 1g, 10g, 100g, 1 kg sizes. I just took whatever came out of the ablation code and ran them through the darkflight. Normally we would iterate on the ablation until we got a starting mass at the last observed position which would ablate down to one of the standard sizes I just mentioned. However, I feel that these adequately characterize the lengthy fall area, caused by the shallowness of the meteor trajectory. As I expected, this is a lot of territory to cover, and it is quite possible meteorite fragments could have landed in the area lakes.
I believe that Mark Fries and Rob Matson have identified some doppler signatures that may help the hunters out there. Hopefully something will be found soon.
Regards,


Bill Cooke
NASA Meteoroid Environment Office
Marshall Space Flight Center
Email:william.j.cooke@nasa.gov

Office: 256 544-9136

Regards,

Bill Cooke
NASA Meteoroid Environment Office
Marshall Space Flight Center
Email:william.j.cooke@nasa.gov
Office: 256 544-9136

About Mike Hankey

Mike Hankey is a software developer, entrepreneur, amateur astronomer, astrophotographer, meteor observer and meteorite hunter. Mike's enthusiasm for meteors led him to the American Meteor Society where he volunteered his time and the services of his software development company to redesign the AMS website and fireball reporting tool. In 2011 Mike was awarded the society's C.P. Olivier award for his work. In 2012 Mike was promoted to the role of Operations Manager. Mike and his company continue to maintain and enhance the AMS website and fireball reporting tools. You can see Mike's photography work and read more of his posts on his astronomy blog: MikesAstroPhotos.com. Mike can be contacted at mike.hankey [AT] gmail.com
7 Responses
  1. Dustin George says: February 8, 2012 at 10:23 pm

    Hi there! I just saw a very bright shooting star up here in Whitehorse, Yukon Territory in the western sky (towards Alaska). The time was 6:17 pm (Pacific time). I’ve never seen one so bright!

    Any details?

    Cheers!


  2. Pat Beaugrand says: February 10, 2012 at 8:09 pm

    Is this the meteorite that was forecast to fly between the earth and the moon?


    • Pat, I believe you are confused between meteorites and asteroids. Many thousands of meteoroids (meteors in space) strike the Earth every day. These are mostly the size of tiny pebbles. Asteroids are much larger, in the range of one meter in size and up. No, this fireball was not an asteroid and had nothing to do with any asteroid predicted to pass between the Earth and the moon.

      I hope this helps!

      Robert Lunsford
      American Meteor Society


  3. noel hollyfield says: February 13, 2012 at 4:54 pm

    I saw what I assume to be a meteor on Sunday night, February 12, 2012 at approximately 8:30 PM Mississippi time. I was in a rural area of Hinds County, about 12 miles Southwest of Jackson, Mississippi. The meteor had a white trail that turned bright green just before the object disappeared from my view.It was 3 times larger than “shooting stars” I’ve seen and observablly slower than those “bullet like white streaks”. The green trail at the end was quite beautiful, I’ve never seen that before.


  4. Ray Rochelle says: February 20, 2012 at 11:49 am

    Noel,
    I am from Jackson, but reside in Chico, Ca. now and I believe we may have observed something very similar if not the same thing. On the 12th I was outside with my grandson and we observed the exact same thing you described so nicely in your note. It was traveling from the West to the East toward you. However we had scattered light clouds and it moved in and out of the clouds well beyond them. We have a lot of Jet traffic from SFO to Seattle and this was at a right angle. We seldom see any contrails from the west. The contrail did not persist like a jet contrail it was in fact very short but quite thick like you described……I wonder if it was the same thing….WoW!!!!


  5. Noel Hollyfield says: July 31, 2012 at 7:02 pm

    Hi Ray, I was driving on Highway between Jackson and Raymond, not too far past where Spring Ridge Road intersects.It is still pretty undeveloped out there, and I had a great view of the sky. I watched the “fireball” ( I’ll call it ) travel quite a distance across the sky. The “trail” was wider than any shooting star I have ever seen. The “apparent size” of the object was also larger than “shooting stars”, I assume because it was closer that most shoooting stars get. That thick, “neon green” trail at the end was new too me. It was sort of like the “payoff” for watching the thing go all the way across the sky. I’m betting that we saw the same thing.


  6. In the morning of 8-12-2012 at 6:49 Berlin time (corrected systemtime, systemtime 6:51) my ToUCam longexposurecamera registred a bright short flash low above the east-south-eastern horizon in Nijmegen, Netherlands 51.48.40-05.52. 89. This flash is a single dot in only one image of a series. It appears as a bright dot in the image in contrast with the small streaks from the moving stars.
    Camera field approx. 18 degrees.


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