Update to End to End LSST Science Simulation

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Update to End to End LSST Science Simulation
Garrett Jernigan and John Peterson December, 2004
Status of the Science End-to-End Simulator 1.
Sky Models (two modes) Grids of stars / FITS
interface for arbitrary image 2. Atmospheric
Model Kolmogorov refractive layer models 3.
Optics and Deformations Geometric ray trace
with perturbations 4. Detector
Model Conversion depth/Diffusion (Andy
Rasmussen) Telescope diffraction
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Three Types of Simulators
1. Component Design, Modeling, and Simulation
(a required routine
engineering activity)
2. Science End-to-End Simulator (early
informs design 10 accuracy) 3. Engineering
End-to-End simulator (late follows design in
detail, lt1 accuracy)
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Atmospheric Models Raytrace Code - Monte
Carlo of photons through Atm. (also optics and
detector end-to-end) - Multi-layer Atmospheric
Model (each layer a frozen screen) - Modified
Kolmogorov Model for each layer (Random Gaussian
with outer scale) - Now Each Layer contains
256x256x256 cube (3D Kolmogorov Model) - Soon
Each layer 2048x2048x16 (also 3D Kolmogorov
Model) - Refractive Approximation for Raytrace
with Phase Screen - Modeling ground/dome
effects (not currently included) Validation
Code - PSF determined from multiple phase
screen with full diffraction (FFTs required) -
Non-Kolmogorov Models (atmospheric wedge, wind
sheer driven flows) - Time Dependent Kolmogorov
Models (drop frozen screen assumption) -
Numerical Hydrodynamic Simulations
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Near Term Goals (Science Applications) -
Results on PSF atmosphere only (raytrace and
validation code results) - Distribution of
seeing and ellipticity of PSF - Semi-analytic
form for e1 and e2 de-correlation versus angle
for stars - Numerical simulation to verify
semi-analytic model - Determine the effects of
LSST optics (Zernike perturbations only) -
Simple examples of the shear of ideal galaxies
(PSF corrected) - Some simple tests to estimate
effects of non-Kolmogorov models - Validate
with real data (Guide stars ? large aperture
telescopes ?)
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3-D atmospheric density
Density Slice
Kolmogorov Model
Numerical simulation (Porter)
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Single layer phase screen based on Kolmogorov
spectrum Refraction raytraced
Phase Map
Vector Perturbations
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Multilayer Models
Altitude
Structure Function
Wind Speed
Vernin et al., Gemini RPT-A0-G0094 from Sebag
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Atmospheric Diffraction
Telescope Diffraction
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Detector Model (Rasmussen) Refraction for light
entering the Si surface reduces the cone angle of
the incident beam (cf. Radeka) Finite electric
field at point of interaction leads to a lateral
diffusion during drift time to the channel.
Electric field function is dependent on doping
density profile in the Si and bias
voltage. Interaction length into Si is strongly
wavelength dependent, and also temperature
dependent, particularly at long
wavelength. Photon detection by CCD alters the
position of best focus and also the PSF.
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Telescope Raytrace Perturbations
Fast Geometric Optics code Finds ray intercept /
refraction or reflection Handles
non-sequential straylight Has arbitrary
rotations, translations, and perturbations
Perturbations Residual wavefront Zernike
coefficients as deformations and vary as function
of time
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Telescope (No perturbations)
PSFs separated by 10 arcseconds centered at (
1.5, 0) degrees Dotted grid is 10 microns
PSFs separated by 0.6 degrees centered at (0,0)
Dotted grid is 10 microns
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OpticsPerturbations on Primary
PSFs separated by 10 arcseconds centered at (
1.5, 0) degrees Dotted grid is 10 microns
PSFs separated by 0.6 degrees centered at (0,0)
Dotted grid is 10 microns
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OpticsPerturbations on Secondary
PSFs separated by 10 arcseconds centered at (
1.5, 0) degrees Dotted grid is 10 microns
PSFs separated by 0.6 degrees centered at (0,0)
Dotted grid is 10 microns
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OpticsPerturbations on Tertiary
PSFs separated by 10 arcseconds centered at (
1.5, 0) degrees Dotted grid is 10 microns
PSFs separated by 0.6 degrees centered at (0,0)
Dotted grid is 10 microns
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Telescope Optics 10 realizations of zernike
perturbations (all mirrors)
PSFs separated by 10 arcseconds centered at (
1.5, 0) degrees Dotted grid is 10 microns
PSFs separated by 0.6 degrees centered at (0,0)
Dotted grid is 10 microns
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Telescope (w/ Perturbations)Atmosphere
PSFs separated by 10 arcseconds centered at (
1.5, 0) degrees Dotted grid is 10 microns
PSFs separated by 0.6 degrees centered at (0,0)
Dotted grid is 10 microns
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TelescopePerturbationsAtmosphereWind
PSFs separated by 10 arcseconds centered at (
1.5, 0) degrees Dotted grid is 10 microns
PSFs separated by 0.6 degrees centered at (0,0)
Dotted grid is 10 microns
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Sky Image Simulations
HDF galaxies
Image raytraced perturbations atmospherewind
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Ellipticity Residual Studies
Zernike Pert. on all mirrors
Perfect telescope
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Ellipticity Vectors computed from weighted
Qij moments ellipticity shot noise 1/sqrt(N)
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Ellipticity Residuals as a function of separation
Preliminary
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Many investigations continuing to understand
ellipticity changes Telescope (current sims
give e0.3 for perfect telescope e0.1 for 10
realizations of up to 5th order
pert. decorrelateda degree for all mirrors)
of Zernikes (more reduces corr.) amplitude of
Zernikes (affects rel. importance) which mirror
(should be less correlated w/ tertiary, but
not so obvious?) rate of changes of Zernikes
(affect corr.) Atmosphere (current sims give
e0.05, decorrelated40) seeing/structure
function (affect rel. importance) outer
Kolmogorov scale (increase e) wind (reduces
e) layer height (reduces correlation) non-Kolmog
orov effects (ellip?)
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