Photon Simulator (PhoSim) – Official Site

Most Recent News: (5/1/20) PhoSim v5.2.7 is available (3/27/20) PhoSim LSST Simulated Survey #1 (1/9/20) PhoSim iPoster-- See the detailed announcements.

Welcome to the official Photon Simulator (PhoSim) site! PhoSim is a set of extremely fast photon Monte Carlo codes that calculate the ab initio physics of the atmosphere and a telescope & camera in order to simulate realistic optical/UV/IR astronomical images. It does this using modern numerical techniques applied to the physical response of photons (and electrons) to comprehensive physical descriptions of the atmosphere, telescope, and camera. After these detailed physics calculations, PhoSim simply generates images by collecting electrons into pixels. This photon simulation [left] shows the photon Monte Carlo method where photons and electrons are physically propagated through the system using appropriate approximations. The physics of the site/telescope/camera includes: hydrodynamic-based descriptions [middle left] of the atmosphere, elasticity theory calculations [middle right] of optics deformations, and electrostatic simulations [right] of sensors. Since PhoSim is a physics-based code, it is written independent of the telescope/camera/site system, so there are a number of present, past, and future observatories implemented as different input configuration files.

Despite the physics detail, PhoSim is quite fast due to both novel numerical techniques and efficient multithreading. Individual astrophysical objects can be simulated in milliseconds, and large fields of objects in minutes to hours depending on the size and depth. PhoSim is easy to install and has a tiered set of commands designed for both simple or complex applications. PhoSim has both a graphical user interface and a standard command line/file input interface. PhoSim can run on either your desktop or laptop as well as high performance computing systems (HPC).

There are a variety of uses of PhoSim. Some of the more common applications include: 1) detailed simulation of a telescope while it is being designed, constructed, or commissioned in order to understand scientific performance and unexpected behavior, 2) planning of future observations with straight-forward realistic image simulations, and 3) simulation of realistic training sets with perfect input knowledge for a variety of machine learning/AI and any advanced image processing algorithms.

PhoSim is currently being improved by: 1) asymptotically improving the ab initio physics implementation, 2) pursuing a number of validation studies, 3) enhancing computational performance, and 4) refining interfaces based on user feedback. Many additional large telescopes are currently being implemented. Besides large professional astronomical telescopes, PhoSim potentially has applications in remote sensing/earth-facing satellites, photography & cameras, and various optical instruments (amateur telescopes/binoculars/microscopes).

The links below describe how to use PhoSim, document detailed technical information about PhoSim, and show several example images.

PhoSim User Information:

• Basic PhoSim Tutorials (Last Updated 12/12/19)

• Detailed User Documentation (Last Updated 5/1/20)

• PhoSim Announcement Page (Last Updated 5/1/20)

• PhoSim Code Download Page (Last Updated 5/1/20)

PhoSim Detailed Technical Documentation:

• PhoSim First Reference Paper (General): Peterson, J. R., Jernigan, J. G., Kahn, S. M., Rasmussen, A. P., Peng, E., Ahmad, Z., Bankert, J., Chang, C., Claver, C., Gilmore, D. K., Grace, E., Hannel, M., Hodge, M., Lorenz, S., Lupu, A., Meert, A., Nagarajan, S., Todd, N., Winans, A., Young, M. 2015, ApJS 218, 14.

• PhoSim Second Reference Paper (Optics Deformations): Peterson, J. R., Peng, E., Burke, C. J., Sembroski, G., Cheng, J. 2019, ApJ 873, 98.

• PhoSim Third Reference Paper (Additional Physics for Space Telescopes): Burke, C. J., Peterson, J. R., Egami, E., Leisenring, J. M., Sembroski, G., Rieke, M. J. 2019, SPIE JATIS 5(3), 038002.

• PhoSim Fourth Reference Paper (Sensor Distortions): Peterson, J. R., O'Connor, P., Nomerotski, A., Magnier, E., Jernigan, J. G., Cheng, J., Cui, W., Peng, E., Rasmussen, A., Sembroski, G. 2020, ApJ 889, 2.

• PhoSim Reference Document (pre-2013 work)

• PhoSim Internal Notes (24 documents)

• Publications That Use PhoSim (22 publications)

PhoSim Examples:

• A visualization of the photons through the optical designs for various telescopes that have been implemented is shown below.

• An uncalibrated uiy 13'x6' PhoSim image is below. An explanation for what you are looking at is here.

• Below are series of exposures of the image above: a sequence of 100 exposures of a 13' x 13' field [left] similar to the example image above, a cumulative sequence of these exposures [middle left], a sequence of a smaller 2.5' x 2.5' field [middle right], and the cumulative sequence of the smaller field [right].

• A guider simulation [left] shows the changes in the image quality due to the atmosphere. A mirror control simulation [right] shows the distortion of the mirror shape and the corresponding actuator correction of the control system.

• Hubble galaxy sequence

• PhoSim Rubin LSST Simulated Survey #1

• Sample images to download.

• Very large-scale PhoSim images

• An example of stars, cosmic rays, and background using a generic telescope is shown to the left below, and an example of galaxies is shown to the right below:

• On-axis (left) and off-axis (right) examples of chromatic point-spread-functions with various physics:

• Large star and galaxy fields with real stars-- Orion (left) and the Big Dipper (right):

PhoSim Contact Information:

• About PhoSim

• Email questions or capability ideas to: John Peterson

• Report bugs on: the issue page

• Current Official Support: Purdue University and JWST (NASA)

• Email us to collaborate on adding other telescopes (professional or amateur) and other projects

• Add your email to the mailing list to receive PhoSim release announcements

• PhoSim Suggestion Box for anonymous new capability requests

• Please link to https://bitbucket.org/phosim/phosim_release/wiki/Home to help expand PhoSim