Tom, very good...you have the right genus. I'm not sure that it's not Hieracium gronovii, which is more likely than H. venosum to be blooming right now. Do you have a photo of the leaves?
It should have yes, but lets not rule Venosum out completely just yet. You don't exactly have a close up view there. But, its does look like gronovii from where I'm sitting. But if you asked me to put $100 on it, I'd want to see it up close.
That looks like Aster patens Tom, though I have never met its aquaintence. Were there others around? Do you have a shot of how the leaves attach to the stem?