It doesn't seem to be remotely accurate as to the impact energy. A 1/2 mile asteroid impact energy will be vastly more than 1000 tonnes of TNT. One calculator shows ~150,000 MegaTon.

I am not sure about their devastation area calculations.

Nevertheless, it is an amazing find if the object is from 700BC!! I hope so.

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Lighten up! This is a stellar board! Author: duh.

"The mean of five measures each of which is not worth a dang (sinc), has a maximum value of only five dangs (sinc)". Heber Curtis

"(sinc)" - spelling is not correct (in its orginal form) :)