The Bunburra Rockhole meteorite fall in SW Australia: fireball trajectory,luminosity, dynamics,orbit, and impact position from photographic and photoelectric records |
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| Authors: | Pavel SPURNÝ Philip A BLAND Lukáš SHRBENÝ Jiří BOROVIČKA Zdeněk CEPLECHA Andrew SINGELTON Alex W R BEVAN David VAUGHAN Martin C TOWNER Terence P McCLAFFERTY Ralf TOUMI Geoff DEACON |
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| Institution: | 1. Astronomical Institute, Academy of Sciences CR, Fri?ova 298, 25165 Ond?ejov Observatory, Czech Republic;2. Impacts & Astromaterials Research Centre (IARC), Department of Earth Science & Engineering, Imperial College London, London SW7 2AZ, UK;3. IARC, Department of Mineralogy, Natural History Museum, London SW7 5BD, UK;4. Department of Applied Geology, Curtin University, G.P.O. Box U1987, Perth, Western Australia 6845, Australia;5. Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2AZ, UK;6. Department of Earth and Planetary Sciences, Western Australian Museum, Locked Bag 49, Welshpool DC, Western Australia 6986, Australia;7. P.O. Box 187, Subiaco, Perth, Western Australia 6000, Australia;8. Office of Research and Development, Curtin University, G.P.O. Box U1987, Perth, Western Australia 6845, Australia |
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| Abstract: | Abstract– We report an analysis of the first instrumentally observed meteorite fall in Australia, which was recorded photographically and photoelectrically by two eastern stations of the Desert Fireball Network (DFN) on July 20, 2007. The meteoroid with an initial mass of 22 kg entered the atmosphere with a low speed of 13.36 km s?1 and began a luminous trajectory at an altitude of 62.83 km. In maximum, it reached ?9.6 absolute magnitude and terminated after a 5.7 s and 64.7 km long flight at an altitude of 29.59 km with a speed of 5.8 km s?1. The angle of the atmospheric trajectory to the Earth’s surface was 30.9°. The first organized search took place in October 2008 and the first meteorite (150 g) was found 97 m southward from the predicted central line at the end of the first day of searching (October 3, 2008). The second stone (174 g) was recovered 39 m northward from the central line, both exactly in the predicted mass limits. During the second expedition in February 2009, a third fragment of 14.9 g was found again very close (～100 m) from the predicted position. Total recovered mass is 339 g. The meteorite was designated Bunburra Rockhole (BR) after a nearby landscape structure. This first DFN sample is an igneous achondrite. Initial petrography indicated that BR was a brecciated eucrite but detailed analyses proved that BR is not a typical eucrite, but an anomalous basaltic meteorite ( Bland et al. 2009 ). BR was delivered from an unusual, Aten type orbit (a < 1 AU) where virtually the entire orbit was contained within Earth’s orbit. BR is the first achondrite fall with a known orbit and it is one of the most precise orbits ever calculated for a meteorite dropping fireball. |
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