Recoveries of more Stubenberg meteorites fully confirmed the
predicted impact area
As we already described in detail in
the press release from 17 March 2016 (link
the press release), a very bright fireball appeared over Upper Austria
in the evening of Sunday, March 6, shortly after half past ten local
time, and was terminated by a multiple meteorite fall. The fall
area lies mostly on the German territory, to the north of Inn River,
between villages Stubenberg on the west and Ering on the east (see Fig.
3 of the PR1 or Fig 1). The instrumental records provided by the
cameras of the Czech part of the European Fireball Network were crucial
for the explanation of this rare natural event. The cameras at six
sites photographed the event at least partly. Thanks to these records,
the fireball could be rigorously described and also the fall area of
meteorites could be computed (see Fig. 3 of the PR1). In the first PR
we informed about recovery of several fragments of the total mass about
45 g, which were evidently parts of a single meteorite, which broke up
at the impact. Here we bring new information about searching activities
which resulted in several new finds in the predicted area during the
The searches for meteorites started shortly after we announced the fall
area to our German colleagues the next day after the fireball passage.
According to our prediction small fragments are expected in the eastern
and southeastern part of the fall area and fragment mass will increase
toward west and northwest. The largest fragments are expected to be
located in the forest east of Stubenberg. The effort on German side is
mostly coordinated by Dieter Heinlein, who is a long-term collaborator
of the European Fireball Network. As it was already mentioned, the
first search in larger groups was quickly successful, when several
fragments of total mass of about 45 grams were found. They were
evidently part of a single meteorite, which broke up at the impact.
Subsequently, on March 18, another piece with mass of 2.3 g was found,
so the total mass of all 14 pieces reached almost 48 g. It well
corresponds to the expected meteorite masses at given location (point
M1 in Fig 1). Two fragments were used for mineralogical analysis and
were independently classified by Prof. Addi Bischoff at the
Münster University (link to
the press release) and by Dr. Jakub
Haloda in the laboratories of the Czech Geological Survey, as an
ordinary chondrite breccia of type LL6 containing also a clast with
achondritic composition. Both orbital analysis and the composition of
the meteorite confirmed its asteroidal origin. The still unofficial
name of the meteorite is Stubenberg.
The first successful find naturally
caused great wave of interest of many meteorite hunters and it is great
that some of them were successful in their endeavour. Here we bring
short overview of all new finds and discuss the experience which
resulted from all these searching activities. Altogether, five new
meteorites have been found during last month.
Two very experienced searchers, Ralph Sporn and Martin Neuhofer, found
two meteorites on 23 March, 2016. The first small meteorite M2
(see Fig 1) with the mass of 7.66 g was found in the morning. In fact
it was broken into two fitting parts, main piece with the mass of 7.21g
was sunk practically completely into the ploughed ground layer and a
small splinter with mass of only 0.45 g was lying nearby (see Fig. 2).
Several hours later the second a bit larger meteorite (designated M3),
of mass of 19.24 g was found only 250 m westwards. This time it was a
complete individual meteorite covered by primary and secondary fusion
crust. Also this meteorite was sunk into the soil (see Fig 3).
Three days later, on March 26, fourth meteorite was found. Finder
Moritz Karl recovered it on the grassy surface on the northern bank of
the River Inn. It is a rounded complete individual meteorite with the
mass of 42.43 g, which very probably originates from the highest and
also the strongest fragmentation of the original meteoroid, which
occurred at a height of 30.5 km. Its position is slightly outside the
highlighted area (about 130 m in SW direction as can be seen on Fig 1),
which can be explained by the fact that the spread of meteorites from
higher fragmentation points can be larger than it is marked on the map.
Among others it can be caused also by side velocities which are not
included in our model. Here we have to emphasize that spread of
meteorites, especially those which are deposited from higher altitudes,
can be generally larger than it is marked on the map because the
highlighted area cover only one standard deviation stretch from the
most probable position. Therefore all this highlighted impact area
represents only the most probable territory where meteorites can be
found. This meteorite designated as M4 is shown on Figure
One week later, on April 3, next meteorite designated as M6 was found
by Dennis Harries. He found it in the forest cover near the west edge
of the marked area. It is a fragment with mass of 35.89 g, and only
smaller part of its surface is covered by a fusion crust (see Figure
5). It very probably means that this meteorite is only a small part of
much larger piece which broke up during its dark flight into several
smaller pieces. This fact corresponds with the prediction that larger
meteorites (in the order of 100 g) should be present in this part of
the strewn field.
The last and also the absolutely largest find was possible due to
admirable persistence of the same couple of searchers, which already
found one piece belonging to the first meteorite (that one used for
classification by Dr. J. Haloda) and the above mentioned meteorites M2
and M3. On Thursday, April 1, Ralf Sporn and Martin Neuhofer decided to
search the area of larger (about 1 kg) meteorites, which should
originate from the terminal part of the luminous trajectory. However,
according to the model, the number of such large meteorites is very
limited. The search was also complicated by the fact that this area is
covered by hardly searchable forest which makes this task very
difficult. However, thanks to their thoroughness and experience, after
all day searches they noticed relatively freshly broken fir branch
lying on the thick layer of beechen leaves (see Fig 6). When they
removed it, they found about a 15 cm deep hole and a black stone on its
bottom (see Fig 7). They immediately realized that this is exactly what
they intensively searched for. After 400 hours of common search they
dug up a 1320 g heavy meteorite (see Fig. 8) of the irregular and
rather flattened shape. It was completely covered by primary and partly
(bottom side) also secondary fusion crust. Smaller part of the surface
was covered by well-developed regmaglypts (see Fig 9). This find is
very important. It perfectly confirms our model and scenario which we
predicted for this fall (meteorite M5 in Fig 1). Also the meteorite
looks very interesting and we believe that its analyses will bring
We can conclude that 5 new meteorites were found during the last month
and that the recovered mass significantly increased from 48 g to 1473
g. Apart from this we also gained valuable experience which resulted
from all searching activities in the impact area. First it was found
that the search for meteorites is much more difficult than we expected.
Main reasons consist in the difficult terrain in the impact area which
means that some parts are almost unsearchable. Similarly it was found
that the surface in some parts of the impact area was very soft (like a
mud) in the time of the meteorite fall which caused that some pieces
could sink into the ground. This effect was observed for at least a
half of the recovered meteorites. We also learned that the material of
the meteorites is quite fragile which can result in somewhat smaller
number of meteorites than originally expected, especially for smaller
In any case, these new finds very convincingly confirmed correctness of
all our analyses. This is another case which fully demonstrates quality
of our instruments and also our own methods and approaches which we
used for the analysis of the all data recorded by these instruments.
All this makes this case one of the best described meteorite falls in
In Ondřejov, 14 April 2016
Dr. Pavel Spurný,
Astronomical Institute CAS
Fričova 298, 251 65 Ondřejov
Tel: +420 323 620 153
Figure 1. Schematic representation of the fall area with the plotted
positions of he recovered meteorites. Small fragments are expected in
the eastern and southeastern part and fragment mass increases toward
west and northwest according to the height in which they were
decelerated. The largest fragments are expected to be located in the
forest east of Stubenberg. Yellow arrow represents direction of the
fireball flight (from south to north) and terminates by a terminal
point in a height of 17.6 km. Systematic shift of the highlighted
impact area from the direction of flight is caused by high atmosphere
winds (photo: Google/Pavel Spurný, AI CAS).
Figure 2. Second meteorite (M2, 7.66 g) broken in two pieces in the
finding position found by R. Sporn and M. Neuhofer on 23 March (photo:
R. Sporn, M. Neuhofer).
Figure 3. Third meteorite (M3, 19.2 g) in the finding position found by
R. Sporn and M. Neuhofer on 23 March (photo: R. Sporn, M. Neuhofer).
Figure 4. Fourth meteorite with mass of 42.4 g found by M. Karl on the
northern bank of River Inn on 26 March (photo: M. Karl).
Figure 5. Sixth meteorite with mass of 35.9 g found by D.
Harries on 3 April in the western part of the impact area. Only smaller
part of its surface is covered by a fusion crust (photo: D. Harries).
Figure 6. Situation of the finding place of the largest 1320g
Stubenberg meteorite before its find. (photo: R. Sporn, M. Neuhofer).
Figure 7. The largest Stubenberg meteorite M5 in the finding position.
(photo: R. Sporn, M. Neuhofer).
Figure 8. Finders Ralph Sporn (left) and Martin Neuhofer (right) with
the largest Stubenberg meteorite just after its find. (photo: R. Sporn,
Figure 9. Detailed views of the largest 1320 g Stubenberg meteorite
(photo: P. Spurný, AI CAS).