Fireball 31-07-1999 / 20:58 UT

Slow colorful fragmenting Sporadic Fireball over the Netherlands
UPDATE (9 August 1999): Revised Trajectory

On Saturdayevening 31 July 1999 at 20h58m UT a fine sporadic meteor appeared above the Netherlands.

The following report is prepared by Marco Langbroek, DMS

Numerous reports are trickling in about a beatifull slow fragmenting fireball in the early evening twilight of July 31. Several reports from Dutch casual observers have been received by the Dutch Meteor Society and in addition several sightings are reported via the Belgian VVS newsgroup.

fireball 31 july 1999

Observers invariably report a very slow moving, fragmenting object, about 4-10 seconds duration, orange to red in color. Brightness given as in the order of -6 to -8. Several observers describe the object as 'like a piece of fireworks, quite unlike a meteor'. The general descriptions concern an object coming from the northwest traveling towards the south-southeast. This is thus a sporadic meteor, not a member of the summer southern hemisphere zodiacal streams. Time of appearance is given as near 20:58 UT by several reports, Jan van Gastel reports an accurate 20:57:40 UT. This is in early evening twilight.

A revised trajectory based on observers who give sky coordinates of start and end point indicates a long trajectory of 180 km length. The object came approximately from azimuth 325 degrees (N-NW, travelling towards S-SE) appearing first over the Dutch part of the North Sea some 50 km outside the Dutch coast (about 52d 35' N, 3d 50' E), roughly ~75 km NW from Amsterdam. There is some leeway in the true starting point since many observers presumably missed the early part of the appearation. The object entered the coastline between Leiden and The Hague just halfway on its trajectory, and ended on the Dutch-Belgian border, in the southeastern part of Dutch Brabant (about 51d 20' N, 5d 25' E) approximately 15 km south of Eindhoven.
Again, there is some leeway in this position because some observers saw the fireball disappear behind trees etc. and therefore missed the true end point. We have too little accuracy in the results for a reliable end-height determination, but it is suggested to be roughly in the order of 60-70 km altitude: this was a grazing fireball. The velocity very roughly can be determined at between 15-35 km/s. This is too large for a satellite decay (typically about 7.65 km/s), moreover no satellite decay was expected for this time and location according to Alan Pickup (UK).

Although fragmentation has been reported, I think a meteorite dropping is unlikely given the brightness and suspected end altitude of the object. Still, all reporting people are rather excited; this must have been a very spectacular appearance according to their enthousiastic descriptions.

Reports from Belgian and Dutch observers were send in from:

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dms.gif This page was last modified on August 9, 1999 by
Casper ter Kuile and Marco Langbroek