I bought a UV flashlight with the hope of using it to find caterpillars. It's roughly 395nm, and makes it really easy to find bird poop and tennis balls. Found a few caterpillars too, as well as a number of spiders, including this one. She's nicely camouflashed on the aster in visible light, but stands out sharply in UV.
I think it's a female goldenrod crab spider (Misumena vatia) but not sure I have a good enough view to be completely sure. Jaffrey, NH, 2016/08/27.