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At 11 Dec. 2004, 15h36m UT (11d23h36m LT), a brilliant fireball appeared over LanZhou, China sky.
Around lighted up like as day time.
After some minute, the sonic boom big sound reached around.
Dr. Wang SiChao and another research team went to LanZhou to survey this phenomenon.
They concluded the phenomenon originated from the meteorite fell.
Mr. Kou Wen(Beiqing Planetarium) and Dr.Lin YangTing(Chinese Academy of Sciences)
team collected security camera images on the toll gate on the highway.
These images recorded flashed ground but not recorded any fireball images.
About after one month, many research teams and meteorite hunters visit Lanzhou but not successed recovering any meteorites.
Dr. Rong DaiLu(Earthquake Institute of Lanzhou) et al published an analyzed results of eight sites' seismographs record.
They concluded the LanZhou fireball trajectory by sonic boom recordes.
Mr. Zhang Xu and his team continued to research however meteorites didn't succeed to recover.
I have carried out recalculation of the fireball trajectory from (2007 Dr.Rong) seismograph data.
The result was compared with (2007 Rong), the trajectory direction was different(below figure) but the elevation angle was equal to 60 degree.
The reason for the different results was caused by the calculation method that
I had considered the upper atmosphere wind and temperature effect but not on (2007 Dr.Rong).
Well, the large trajectory elevation angle easy to make an error that the impact point error west-northwest to east- southeast direction.
However, the trajectory direction and elevation angle error were estimated small about 1 degree.
Well, the fragmented particles' impact area was estimated narrow district
because of the relation of trajectory direction and upper atmosphere wind.
I agree with Dr. Rong's prediction that this meteoroid produced a meteorite shower of some hundred or more.
Predicted Strewn Field
The red arrow is the trajectory, The blue oval is predicted Strewn field.
DingYuan toll gate
GanCaoDian toll gate____The security camera on top of the pillar
Collecting witness reports
Strewn field ____smooth tail head but steep gradient
Looked down from the top of the hill. The line is Goat road.
Looked up the hill from drained valley. Small white spots are Goats.