Both MrGreyface and myself (Brian Paton) are trying to work out what this object is.
What we do know is that it's not a Satellite, or if it is, it's unlisted.
A Satellite check has been performed.
It's not a fuel dump by a Satellite, cause it's not a Satellite :)
It's not a Supernova because they have an initial explosion followed by hrs or even days of dispersion.
It's also not a Comet for the same reasons as a Supernova.
It's been suggested it could be a water droplet on the lens.
I find this highly impossible, as the water droplet would have to be minuscule. Also neighboring Stars are not effected by the droplet.
But having said that, I will be doing a water droplet and water mist test on my lens to confirm yes or no. As soon as the clouds go away and I can see Stars again.
So keep coming back for more info.