Gordon: Many thanks for your report on this fireball, the fourth I've received on it. Unfortunately, the details available haven't allowed me to estimate a particularly accurate trajectory for it, but my best-guess is it was likely high above southern Wales, which seems consistent with your sighting too.
CliffM: There's little doubt that all four observers saw the same meteor; the timing and rough directions all point to this, assuming typical meteoric heights of around 80-100 km. If not, there would have to have been more than one bright meteor in a similar part of the atmosphere within a couple of minutes, while only one was seen at each of the separate locations. That's not impossible of course, but it is stretching coincidence rather.
Colours are too subjective to be used to confirm or deny the point, and occasionally meteors don't seem to show the same colours to witnesses at different angles to the track anyway.
The apparent magnitude discrepancy too could be down to a number of causes, not just those in McKinley's text David drew attention to. Fireball brightness estimates are notoriously difficult to make for visual observers. Potential variations result from differences in visual perception and sky clarity, distance to the object, and how much attention the observer was paying to recording this aspect of the event, as well as how familiar the observer was with reference targets like the brighter planets and phases of the Moon. One of the other December 1-2 event's witnesses suggested it was about magnitude -10/-11, while another noted it lit up the ground nearby, which suggests a brightness probably in excess of magnitude -7/-8, for instance. Though you may have been the most distant of the four observers to the trail if my "southern Wales" guesstimate is right, it's likely some tropospheric murk quite low in your sky - or between you and the meteor at least - had more to do with it than anything else. McKinley's formulae rely on a "clean" atmosphere, and as David mentioned, only give a guide to what the extinction may have been once reality intervenes.
Further sightings of this fireball or any others - meteors of magnitude -3 and brighter - made from the British Isles or nearby would be welcomed by the Meteor Section. See the "Fireball Observing" webpage for details of what to send me, at: http://www.popastro.com/sections/meteor/fireball.htm
Meteor Director, Society for Popular Astronomy.
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