At approximately 0510 in December 1998 /99 I was letting my dog out in to the back yard before I went to work.
As I went outside the entire area gradually went from full dark to full day light (it was a bright white light), I looked up in to the sky and saw an inverted Y shaped smoke column and the light then faded, there was no sound of an explosion, I waited for several minutes listening,I could not see the smoke trail in the dark.
The light was like a dimmer switch being turned up full and then down again.
The arms of the inverted Y (this is just guessing)could have been several hundred to several thousand feet long and several hundred feet in diameter and the single pillar of the inverted Y was the same length as the arms of the Y. There was no way of guessing the altitude as there was nothing else in he sky.
I have looked for reports of this in the national and local press but have found nothing and I am not aware of anybody else seeing this.
I can provide a sketch if required