The Tagish Lake Fireball and Meteorite [18-Jan-2000]
The impacting meteoroid was detected by both infrared and optical sensors on board US Department Of Defense satellites, which timed the terminal flares to 16:43:42 with a two second duration at 1 micron radiation. Optical measurements showed the flash energy to be 1.1 X 1012J (1.1 terajoules). Bolides of H-chondrite composition have been found to have light energy conversions of order 10%. Given the low iron content, a more realistic value for the present case is probably in the order of 5% (Nemtchinov, pers. commun.) yielding a total energy release of ~2 X 1013 J or ~5 kilotonnes equivalent. This could possibly be the largest meteor impact ever recorded by satellite sensors over land.
The Satellites also provided information suggesting an entry velocity of ~16 km/s. This velocity and the total estimated energy released imply this object had an entry mass somewhat in excess of 150 tonnes and an entry diameter of 5 metres