Drones over Novato?

I don't know where else to inquire, we don't have a local radio station any more. I live in South Novato, and for the past hour and a half or so, there has been the sound of what seems to be a small helicopter with jets circling around here! It is small, makes a sort of buzzing prop sound and a whining jet sound at the same time. So small it is practically invisible, I've only been able to catch extremely short glimpses of a flash reflection or a spindly mosquito-like white thing.

It was making slow circles, never dropping out of earshot, as it circled wide in a counterclockwise fashion.
Started around 11AM and continued until just a few minutes ago, around 12:35.
How could I find out more about it? Anybody else hear or see it?