A new method of positional reduction of all-sky photographs taking into account the difference of zenith and the centre of projection is presented. The importance of the exact knowledge of the exposure. time for the evaluation of meteor photographs is demonstrated.
On February 15, 2013, an asteroid entered Earth's atmosphere over Russia. With an estimated speed 18 km per second the meteor became a supetolide over the southern Ural region. It exploded in an air burst over Chelyabinsk Oblast creating small fragmentary meteorites and a shock wave. The Interplanetary Matter Department of the Astronomical Institute of the ASCR published a study that calculated the meteor's trajectory in the Solar System and in the Earth's atmosphere. and Pavel Spurný, Jiří Borovička a Petr Pravec.
The meteorite fall at Glanerbrug, at 18:32:38 UT on April 7, 1990, is described on the basis of 200 eye witness accounts of the associated meteor. Due to a favourable distribution of observing locations, the atmospheric trajectory can be reconstructed from several different approaches to the data. The orbit found has a relatively high inclination of 23 ± 5 degrees, adding weight to the high inclination tail of the population distribution of meteorite dropping events. The pre-entry mass of Glanerbrug was of the order of 100 kg, of which some 5-10 kg arrived at the Earth’s surface. One fragment of approximately 1.2 kg fell through the roof of a house, resulting in a catastrophic fragmentation with a logN/logM = 1.15±0.12 size distribution. 855 grams of fragments could be recovered on the floor of the attic. The largest piece weighs 135 gram, from which an impact velocity of 80 ± 30 m/s is estimated.