PhoSim v3.7 completed

Dear DM-

The thirteenth major release of the Photon Simulator (PhoSim) is completed, tagged, and validated. Its called PhoSim v3.7. PhoSim is the ab initio photon/electron physics simulation tool for optical survey telescopes. It is capable of running on your laptop as well as on high throughput computing platforms and grids.

There have been a number of changes that speed up PhoSim more than an order of magnitude (increased multi-threading efficiency (40% to 100%), a bright star unoptimization bug, and a faster background option (examples/quickbackground). All the issues in the open tickets should be resolved. PhoSim also has more refined physics detail in the sky background, clouds, detector, and optical perturbations. PhoSim now can simulate the correct time correlations of various aspects of the turbulence, clouds, and sky background from two or more different PhoSim runs. PhoSim is also continuing to expand the functionality for simulating systems other than LSST: LSST ComCam is fully implemented, DES is fully implemented (see PIN-24), and JWST and WIYN are mostly completed. The documentation on the website has been redone again and should be much more user-friendly with an updated walkthrough and lots more examples.

You can download the new version and get all the documentation here:

Specific new items in the v3.7 release follow:

More accurate accumulated charge e-field
Various architectural & software standard improvements
Physical separation of lunar scattered components
ComCam implementation
Additional oxide layer for fringing
Allowing >2 bounces inside sensor
Deltara & Deltadec parameters in degrees
Cloud structure simplification
Corrected focal plane layout according to drawing
Made all perturbation commands as additive allowing both pre-defined & custom perturbations
Time correlation of clouds, turbulence, opacity in independent phosim runs
Corrected extra commands to the readout modules
Enabled multi-threading for OPD calculations
Additional validation of sky background
Added eye ISC
Added MCT detector physics
Additional capability for near diffraction-limited calculations
Additional capability for tilted-foresight telescopes
Better zodiacal SED in IR
Pupil screen capability
JWST NirCam ISC files
Cluster Submit script
Updates to speed test validations related to multithreading
Various fixes related to rare bright star optimization bugs
Fixes for WCS keywords
Source ID changed to string
Cleanup and more examples related to cleaner interfaces
Expansion of 1C validation (PSF properties)
Numerous efficiency improvements to multithreading

As always, please file tickets for bugs at the phosim site. Feel free to email me more complicated questions as well.

Best Regards,


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v3.7.1 is out at usual place:

fixes two bugs related to very bright stars

v3.7.2 is done at:

fixes a bug related to the new source ID as a string feature

v3.7.3 is tagged. it fixes a bug in the optimization of photons near the chip edge for extended sources

at usual place:

v3.7.6 is done. it fixes a bug in the bright star optimization that was compiler-dependent.

v3.7.8 is completed. it fixes a bug with bright extended galaxies triggering the optimizer which results in spurious photons per pixel in some situations.

v.3.7.10 is posted: significantly improves performance for large numbers of threads and fixes rare random number sequencing bug.

v3.7.11 is out and fixes v3.7.10

v3.7.12 gives greater multithreading performance

v3.7.13 works even better.

and v3.7.14 is even better than the last one.

Please follow PhoSim Version 3.7 Completed for updates and discussion.