2012 October 7
2012 September 21 Earth-grazing fireball
Our analysis of the fireball continues. In the light of current speculation we provide the following information based on our early results.
Currently, our first pair of images of the object are from southern Norway when the fireball was high over the North Sea. We have used an accurately timed shutter gap to determine that the velocity at this point was 12.0 km/s and the height was around 60km descending. This velocity is in excess of Earth’s escape velocity and so rules out a man-made satellite re-entry. Therefore, it is most probable that this object was natural and that atmospheric entry was well to the east of our first images.
In this regard we would be very interested to hear from observers in Denmark, north-eastern Germany, southern Sweden and northern Poland who witnessed the fireball at 23:55 CEST on Friday 21 September. Please contact us at firstname.lastname@example.org.
We have used the known exposure duration of an image from the west coast of Ireland to estimate the velocity of the two brightest components as they moved out over the Atlantic. We get velocities of 7.8 and 8.5 km/s and a height of 62 km ascending. These velocities and the track orientation and position are not at all consistent with ongoing speculation that there is a connection between this fireball and a fireball seen in south-eastern Canada/north-eastern USA 155 minutes later.
Further information will be posted as it becomes available.
John Mason & Nick James.