Current Status of LSST High Fidelity Massive End to End Image Simulations

1. Current Status of LSST High Fidelity Massive End to End Image Simulations All Hands Meeting, May 21, 2008 John Peterson (Purdue) Garrett Jernigan (Berkeley) Andy Rasmussen (SLAC) Andy Connolly (UW) Victor Krabbendam (NOAO) Alan Meert, Suzanne Nichols, Justin Bankert, Emily Grace (Purdue)

2. Built a simulator to understand characteristics of PSF and produce realistic images based on physics of the atmosphere, telescope, and detector Use a photon Monte Carlo approach (time-dependent and wavelength-dependent effects are straight-forward) Realized that most galaxies that are detected will only produce ~1000 photons Stars & galaxies through atmosphere, complete LSST optics, and detector with complete wavelength dependent effects and does this in few hours/chip

3. Image or catalog of sub-images Sky Catalog Interface Or catalog of synthetic toy models + SED + Sample photons from these models Spectral Energy Distribution (SED)

4. Atmosphere Models & Kolmogorov turbulence Altitude Altitude From Hardy 1998 (p.81) Wind Speed Vernin et al., Gemini RPT-A0-G0094 Structure Function

5. Atmosphere Interface and Raytrace LSST Aperture Turbulence Generator by Jernigan Vector Screen: 2048 squared 0.1m/pixel can have arbitrary number with arbitrary wind velocity vectors at given altitude Photons raytraced and shifted accordingly Optics

6. Optics Fast ray trace Calculates ray intercepts Uses fast reflection and refraction algorithms Wavelength-dep index of Refractions Filter transmission curves Diffraction simulations

7. Perturbations due to thermal and mechanical distortions Each optic has 6 dof (decenter, defocus, three euler angles) Perturbations are placed on the three mirrors using a Zernike (polynomials orthogonal on a circle) expansion to simulate the possible residual control system errors each mirror can have an arbitrary amplitude code goes up to 5th order polynomials e.g. Mirror Defocus Perturbation spectrum From Claver

8. Detector model From Rasmussen Refraction for light entering the Si surface Photon interaction (wavelength and temperature dependent) Lateral diffusion due to finite electric field

9. +Detector +Mirror Perturbations Optics (aberrations) +Atmosphere Atmos+wind only +Wind

10. Ellipticity Vector diagrams Found out: Optics produce highly correlated patterns Upper layers of atmosphere remove correlation Higher correlation along wind direction Full image simulations w/ stars and galaxies

11. Simulation of stars only Used Purdue Condor Pool (1 day/189 cpus) Also tried OSG Using NOMAD (1 billion stars) catalog for bright stars (m<15) and statistical models (above) for faint stars (m>15) Meert (Purdue)

12. Dark Matter sims--> Galaxy Catalog based on Galaxy formation prescriptions --> Photon Monte Carlo sim to Images Michael Norman (UCSD), Robert Harkness (SDSC), Matt Hall and Donna Cox (NCSA) Galaxy catalog from Croton based on Millenium Sims

13. Full focal plane w/ 12 million objects every photon completely simulated! Simultaneously on 189 CPUs in condor pool at Purdue in less than a day

14. Every pixel in the previous image contains this many stars & galaxies

15. 100 images of 10-5 of focal plane or 10-7 of full Sky every photon has full end-to-end raytrace

16. Synthetic galaxy shape Monte Carlo; Meert & Nichols

17. Completed Simulations (Ready to be used!) 115 Gigabytes of Simulations at http://basov.physics.purdue.edu/lsst_sims/ Run 1: (Oct 2005) This is a simulation of a grid of stars (PSFs). This simulation was 441 stars in a 21 by 21 grid. Run 2: (Feb 2006) This is a simulation of a tiled image of the hubble ultra deep field on one chip of LSST. We did 100 realizations of this with a different atmosphere. Run 3: (Feb 2006) This is a simulation that is identical to the last one except a simulation across the entire focal plane for just one exposure. Run 4: (July 2007) This was the first simulation of the full focal plane using a star catalog based on the NOMAD catalog for bright stars and a theoretical model for the faint stars. There is one file for each chip (189). Run 5: (Sept 2007) This is the simulation of the full focal plane using stars as in #4, but using a Millenium galaxy catalog for the central 4 sq. deg. There is one file for each chip. There are catalog files in here as well. Run 6: (Oct 2007) This is the exact same as number 5, except the flux of the source was varied, so the combination of #5 and #6 can be used to find variable sources.

18. Synthetic Astro Catalog Generator Input physics parameters (Truth) Synthetic Catalogs Telescope Image Simulator Operations Simulator Observing Configuration Raw Images Images Basic Processing High Level Data Pipelines Images Output physical measurements Agree?

19. Future Simulations Full wavelength dependent effects with high fidelity novel code Have generated few full focalplanes that are available Interested in further input into the kinds of future simulations to support either science or engineering studies Will be used to support DM in DC 3&4