faint Fermi sources

After a great blackboard talk at lunch-time by Itay Yavin (NYU) about the radius of the proton (there is an anomaly brewing), I read and commented on Dmitry Malyshev's draft of our paper on very faint sources in the Fermi data. Malyshev has reinvented the classic techniques for looking at sources too faint to detect directly, invented in the early days of radio astronomy and reinvented in the early days of x-ray astronomy. The results are nice, if not revolutionary. We put a fairly strong constraint on the sources of the unresolved Fermi background.