PhoSim: a code to simulate telescopes one photon at a time

In this work, we summarize the progress on a code to simulate optical survey telescopes one photon at a time as presented at a workshop on November 18th & 19th, 2013 at Brookhaven National Laboratory. The photon simulator (PhoSim) uses a novel photon Monte Carlo approach to simulate astronomical images from optical survey telescopes. The simulator uses a physics-based approach to follow the propagation of photons through the atmosphere, telescope, and camera. Individual converted electrons are followed into the Silicon to produce pixelized images. The code has been applied to produce simulations of the Large Synoptic Survey Telescope (LSST), and can be used with other telescopes as well. PhoSim is publically available.