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Bolide sighting near Geislingen (Germany) on Jan. 8th, 2011
A report of an effort to find the extra-terrestrial visitor, by members of the German Meteorite Forum.



(c) Hermann Koberger, Fornach (Austria)


On Jan. 8th, 2011, at 17:51h local time, a bolide stroke across the evening sky in southern Germany. The bolide was witnessed by many, and captured by at least two cameras in Switzerland and Austria. Also roaring sounds and thunder were reported. Especially the reports of sound being heard made (potential) meteorite hunter hearts beat faster...

One of the two known photographs of the bolide was made in Switzerland by one of Mark Vornhusen's meteor-camera-network cameras. Being a member of the German Meteorite Forum, Mark posted his photo on the Forum, and soon after other reports were shared, including a beautiful second photograph, made by Hermann Koberger in Fornach (Austria).

As both photographs captured the bolide at angles almost perpendicular to each other, this yielded a perfect opportunity to determine the location of the track across the sky, and it's projection on the earth's surface. The exact location of both cameras was known, and because stars were visible in both photographs, combined with the know time of exposure, directions could be determined fairly precise. Track ends in both photos could be calculated at about the same high above the earth's surface (28 km). Track beginnings showed a difference. The Swiss photo seemed to have captured the bolide somewhat earlier in its flight. This could be explained by the larger distance to the track in the Austrian photo, and the lower sensitivity of this camera. The Austrian track was extrapolated to the Swiss photo's high at the beginning.

From the two photographs, Mark Vornhusen calculated the location of the bolide's start and end point and their highs above the earth's surface. He also collected wind speed information for different highs, and came up with a first prediction of a possible fall area. It was situated near the German city Geislingen an der Steige.

Forum members became excited about the idea to go out, and try to find meteorites that might have reached the ground.
With a calculated bolide end high of 28 km (17.4 miles), there was expected to be little chance of material being found however.
On the other hand, this looked to be an ideal opportunity to meet fellow Forum members, and have a great time "talking meteorite" with the equal minded.


134 km (83 miles) to end of bolide track
(c) Mark Vornhusen
282 km (175 miles) to end of bolide track
(c) Hermann Koberger, Fornach (Austria)

A video of the bolide can be found here (2MB): VIDEO (c) Mark Vornhusen



Wind data showed that the wind had been blowing almost exactly in the direction of the track. Many variables were still unknown, and had to estimated. Fourteen Forum members agreed to meet on Friday evening, the weekend after the Bolide sighting.
Mark produced his final estimate for the strewn field shown below, and the hunt was on!

 
(c) Mark Vornhusen


The day of the bolide, the possible fall area had been covered with snow. Thaw removed the snow the week after, and conditions were ideal for a hunt. Grass and leaves in the mostly farm land covered area were flattened by the snow, and possible meteorites could be expected lying on top of this flattened surface.

When we arrived at the hotel, we appeared to have booked about the whole hotel! The bolide appeared to have boosted tourism. Next to our team, also others were active in the area. For instance "team Svend Buhl", a French team and solo hunter Thomas Grau.
I counted people from five different European countries, and from all over Germany. A local newspaper posted an article about the tourism boost.



click to enlarge


We had planned a first meeting for Friday evening at 22:00h.

In the hotel we had a room for ourselves, that was used for discussions and planning. The ones who arrived late were having their diner simultaneously.

Although most Forum members had never met, it was as if we had known each other for years. Great camaraderie!

Forum member Martin had coordinated the
preparations in the days before the trip. Hanno provided a large detailed map, three teams were formed and search areas were agreed upon.

The aim for the next day was to search the beginning, the mid and the end of Mark's predicted strewn field.

We had a lot of meteorite talks, laughs, beer, and it was much too late when I finally went to bed...

(c) Hanno Strufe


(c) Hanno Strufe

The next day, a quick group photo in front of the hotel, and off we went to the fields.



We arrived in farmland with endless meadows.

As we "only" had one and a half day for our search, we decided to concentrated on the easier meadows, and ignore the ploughed fields and small patches of woodland.

Our GPS device was very convenient, to help us walk straight parallel tracks across the meadows.
The author on his first ever meteorite hunt.
A stick came in handy, to distinguish soft animal droppings from possible meteorites, without the need to bend over and feel...




Mice had made numerous corridors and holes underneath the - disappeared - snow blanket.

Not to be confused with impact holes...
Typical landscape to the south west of Geislingen



A large area was searched that first day.
We didn't find any meteorites, but the evening of that first day in the fields, we had a great time of togetherness again.

"Team Svend Buhl" paid us a visit, and information was being exchanged. Later that evening also solo hunter Thomas Grau came in to say hello.

Of course there were sore muscles and a little disappointment of not finding meteorites. But we had a lot of fun, admiring and discussing meteorites that had been brought by several Forum members, and were being passed around.
It was great to be able to discuss meteorites with equal minded.
For me - as a foreigner - it was also a great opportunity to practice my German :-)
The next day, based on a theory of small fragments, and a larger drift by wind, we decided to search another area, at a larger distance from the bolides track end, near Schalkstetten.

We were looking for 1 to 10 gram pieces this time. It was a beautiful sunny day, but sunshine and shadows made it harder to distinguish possible meteorites.




Where did this hole come from???
Again no meteorites were found that day.
Soon after noon, the search was ended, and we had to start diving home again. For me this meant driving for eight and a half hour.
Fortunately, I had a Forum member that needed a lift as a companion.
Time flew, and when I arrived home that evening, that was the end of a great experience of companionship with equal minded, that surely made the trip worthwhile, even without finding any travellers from space.

A special Thank You goes to Mark Vornhusen who made this all possible, by sharing his photograph of the bolide and his calculations on the German Meteorite Forum.




Thomas Grau and others planned to continue the search. A few days later however, snow returned, and futher search efforts had to be canceled/postponed.

After the weekend, at the Forum, trajectory calculations were discussed. Influence of size and shape of fragments, air density and windspeed as a function of heigh, specific mass, drag coefficient as a function of Mach number, etc. Also placing of additional meteor cameras was concidered. This surely will result in a Forum, that will be even better prepared in case of future bolide sightings and subsequent search efforts.

I'm looking forward to the next big one!

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