Was looking at sky NE over Belfast last night seen a light brighten up (quite bright) then dim for about 5 to 10 seconds. It stayed in the same section of the sky although it may well have been coming toward or moving away from the atmosphere relative to me as its dimming could be caused by its change in distance or lunminance. Can meteors appear like this if coming at a particular angle towards the observer? Can satellites have this brightening and dimming effect? I was tempted to think of a supernova but I suspect it would remain visible for a lot longer!
Most likely an Iridium flare, these have a gradual start & fade with slow movement across the sky and at their brightest can outshine Venus by a considerable margin. If you have the exact time & your location accurate to 100 metres or so you will be able to identify the "culprit" using a satellite prediction website such as Heavens Above or Calsky.