Fireball? 7.4.10

[Breakintheclouds]

Just as I was setting up tonight, at 2008 UTC, I glanced up and saw an incredibly bright light just next to Alioth, in Ursa Major. It must have been magnitude -5 or so, as best I can guess. It was moving more-or-less in the direction of Kocab, at a fair old pace (2-3 degrees/sec??). It quickly dimmed, to about the brightness of a typical satellite, and was visible for maybe 15 seconds in total, moving in a straight line, before I lost it. The fact it went from being very bright to looking like a satellite made me wonder if it was an Iridium flare, but I've just checked Heaven's Above and the only flare anywhere close to that time was due about 30 minutes later, at 2040 UTC (I've just missed it coming indoors to type this!).

So any ideas what it might have been? It certainly livened up a night that otherwise has been marred by terrible seeing.

[Cassiopeia]

Maybe it was a comet? I saw something that sounded quiet familiar to your experience but last Friday (the 16th) around 10pm and it was near Ursa Major too.. :S But im not sure, sorry