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Brilliant bolide over UK, January 9, 2000

A total of 19 sightings of this object were made from Banff in northern Scotland to Portmarnock near Dublin in Ireland, Cardiff in Wales and near Mansfield in England at the southern limit. Just three of these reports arrived from sites north of the track however, and unfortunately very few witnesses managed to give useful sky positions for the visible trail. The imprecise nature of many sightings means the details given here remain regrettably tentative. Two reports of acoustic sounds heard at roughly the correct time, but where no meteor was seen, were also received.

The bolide occurred at around 01:56 UT on 2000 January 9. Assuming a start height of about 90 km and an end height of ~ 30 km not inconsistent with several reports of acoustic sounds, the fireball's visible track probably started above or not far from Appleby in Cumbria (54 degrees 35' N, 2 degrees 30' W), and ended roughly 10+ km offshore due east of Seaton Sluice, Northumberland (55 degrees 05' N, 1 degree 15' W). The trajectory probably passed directly over part of the conurbations of Newcastle and Gateshead. It was seen as "almost overhead" from a site on the western outskirts of Sunderland, probably only ~ 12 km south of the proposed ground track, for instance. The trajectory would have passed at an elevation of ~ 73 degrees (range ~ 70-75 degrees) for the observers here, a reasonable lay-estimate for "almost overhead". The ends of this track could be extended west/south-west (start), or east/north-east (end) of these places, plus the track could be shifted somewhat north or south of this current one, but all the sightings received can be fitted to this pattern. The ground track (including the part over the North Sea) would thus have been around 90 km, trending south-west to north-east. Splashdown for any meteorites would have been well out into the North Sea, maybe 40-60+ km from land. The map here shows the area the object most probably passed over. Black dots show where observers near the trail were.

Adobe ImageReady

The atmospheric trajectory of the object based on the above track gives an angle of descent from the horizontal of about 33 degrees (uncertainty ~ 30-35 degrees), and an atmospheric path length of about 110 km. Assuming this was completed in ~ 5 seconds (in-line with the more accurate reports), this equates to a mean atmospheric velocity, not allowing for deceleration, of 22 km/sec (range perhaps ~ 20-25 km/sec). Distinct late deceleration was a factor mentioned in a couple of reports that were almost perpendicular to the trail, but in the absence of photos or videos, this was not sensibly determinable.

Acoustic reports were received from several locations, which have been further used to support the line of the track above, based on the usual values for sound in air at mean sea level. Two reports from Morpeth in Northumberland were from people who were awoken shortly before 02:00 UT by loud noises like an explosion or nearby thunder. Morpeth would have been about 30 km north-west of the proposed end-point. The fact that the night was clear and still, and the hour far too late for low-level military or civilian jet aircraft flights was commented upon in both instances. An additional acoustic sound report came from the Banff observer, who would have been about 280 km from the meteor's end point. The sound should have taken around 13-15 minutes to arrive, but no estimate of the time delay could be given. This might seem a long distance for sound to persist, but it would have passed largely over water on a night noted by several observers as being very calm.

A single report of possible electrophonic sounds simultaneous with the meteor's flight were received from Eston Nab (54 degrees 33.5' N, 1 degree 07' W), a hill perhaps ~60 km south-east of the ground track at its closest. These were described as "Whoosh, then rustling".

A persistent train lasting for several seconds occurred, and the meteor seems to have been fragmenting along part of its later stages at least. The colours were generally given as green-yellow or green-white, with red or orange-red sparks/fragments. Three main fragments were reported by several witnesses as falling near the end of the visible flight.

As for its brightness, this was perhaps between magnitudes -15 to -20 or so. "Brighter than full Moon" was the most accurate measure any witness suggested, but the event lit up the sky and cast clear, moving shadows for some observers at least.

I am very grateful to Ray Worthy of Cleveland & Darlington AS (who rounded up reports from south of the River Tyne), John Lambert of Newcastle AS (who endeavoured to do the same north of the Tyne) and Mike Dale of Royal Observatory Edinburgh, for all their assistance in tracking down and forwarding most of the reports on this object, and to all the observers who contributed information.

Alastair McBeath,
SPA Meteor Section Director.
E-mail: vice_president@imo.net

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