Survey Simulation


  • Javier Sanchez (UC Irvine)
  • Alex Drlica-Wagner (Fermilab)

A significant fraction of all dark energy measurement systematics with LSST will come from the complex physical effects of the atmosphere, telescope, and camera that distort the light from astrophysical objects. This distortion is imprinted in the images, and therefore the most direct and robust way of mitigating and understanding these systematics is through high-fidelity image simulations.  We are studying these effects through producing millions images in 7 large major data challenges in the next 3 years.  The Survey Simulation Group enables these data challenges by performing the test runs, defines the configuration for the image simulations, validates the simulations, and works with groups to meet the analysis group’s requirements for the data challenges.

To transform the catalogs of astrophysical objects into images, the DESC uses a high fidelity simulator called the photon simulator (PhoSim; Peterson, J. R. et al. 2015, ApJS 218, 14.). The photon simulator does this using a photon Monte Carlo approach. A Monte Carlo approach produces simulated images efficiently and encodes an arbitrary complexity of atmosphere and instrument physics in terms of photon manipulations.  More details about PhoSim can be found at