What is PhoSim?

PhoSim (Photon Simulator) is an image simulator originally developed for the Large Synoptic Survey Telescope (LSST) by John Peterson and his group at Purdue University.  PhoSim is different from typical image simulators in astronomy in that it replicates the whole telescope and instrument system in the code (as well as the atmosphere in the case of LSST) and follows the propagation of photons using a Monte Carlo approach.  PhoSim, therefore, is a full end-to-end simulator, capable of creating highly realistic images that contain all the characteristics of the actual telescope + instrument system.  Furthermore, since PhoSim allows direct control of any element in the system, it can be used to diagnose real data, helping to identify the origin of any unexpected features and characteristics that may appear in the real system.

PhoSim-NIRCam

Although developed primarily for LSST, PhoSim itself is a physics-based code that can simulatie any optical/IR observing system when used with appropriately constructed configuration files. PhoSim-NIRCam has been developed by taking advantage of this feature, and is essentially PhoSim that comes with a particular set of configuration files constructed for JWST + NIRCam. Despite its complex inner working, PhoSim-NIRCam is easy to use, and is typically run as a one-line command with a CatalogFile and a CommandsFile.

Disclaimer: PhoSim-NIRCam is still in the early phase of develpment, and has not been tested extensively. So, please report to us any problem you might encounter! The "Known Issues/Development Plan" document (available from the "Quick Guide" menu at the top) lists the current limitations and develepment plans.

Information

LSST PhoSim

• PhoSim Reference Paper:
  Peterson, J. R. et al. 2015, ApJS, 218, 14
• PhoSim Reference Document:
  The Photon Simulator (PhoSim)
• PhoSim SED library (star/galaxy SEDs):
  SEDs (6 GB)
• Websites: PhoSim, PhoSim@LSST

JWST PhoSim-NIRCam

• PhoSim-NIRCam Reference Document:
  Implementation of the JWST/NIRCam in PhoSim
• PhoSim Diffraction Algorithm:
  Modification to the Diffraction Algorithm in PhoSim for Space Telescopes
• Quick Guide (up-to-date instruction):
  Full Guide (also downloadable from the top menu)
• Examples of PhoSim-NIRCam output files:
  mkimage.tar.gz (6.7 MB)