Tom Kitching Coordination Team THOMAS KITCHING ADAM AMARA

Coordination Team: THOMAS KITCHING, ADAM AMARA, SARAH BRIDLE, MANDEEP GILL, CATHERINE HEYMANS, RICHARD MASSEY,

Typical galaxy used for cosmic shear analysis Typical star Used for finding Convolution kernel

Cosmic Lensing gi~0. 2 Real data: gi~0. 03 5/19 Slide from S. Bridle

Atmosphere and Telescope Convolution with kernel Real data: Kernel size ~ Galaxy size 6/19

Pixelisation Sum light in each square Real data: Pixel size ~ Kernel size /2

Noise Mostly Poisson. Some Gaussian and bad pixels. Uncertainty on total light ~ 5

Heymans et al. , 2006; Massey et al. , 2007 & Kitching et al.

Quality Factor Kitching et al. , 2008 (form filling functions); Amara & Refregier (2007)

7 non-lensing participants Q~1000 in some regimes

GREAT 08 : Stacking Procedure is Important Average Data Individual Object Statistic Ensemble Statistic

§ § Bonus Star Challenge: Reconstruct the PSF at non-star positions §

http: //www. greatchallenges. info/ GREAT 10 Handbook, Kitching et al. , 2010

http: //www. greatchallenges. info/ “Every time the amount of data increases by a factor

Slides: 27

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Tom Kitching

Coordination Team: THOMAS KITCHING, ADAM AMARA, SARAH BRIDLE, MANDEEP GILL, CATHERINE HEYMANS, RICHARD MASSEY, BARNABY ROWE, LISA VOIGT Advisory Team: SREE BALAN, GARY BERNSTEIN, MATTHIAS BETHGE, FREDERIC COURBIN, MARC GENTILE, STEFAN HARMELING, ALAN HEAVENS, MICHAEL HIRSCH, RESHAD HOSSEINI, DONNACHA KIRK, KONRAD KUIJKEN, RACHEL MANDELBAUM, BABACK MOGHADDAM, GULDARIYA NURBAEVA, STEPHANE PAULIN-HENRIKSSON, ANAIS RASSAT, JASON RHODES, BERNHARD SCHOLKOPF, TIM SCHRABBACK, JOHN SHAWE-TAYLOR, MARINA SHMAKOVA, ANDY TAYLOR, MALIN VELANDER, LUDOVIC VAN WAERBEKE, DUGAN WITHERICK, DAVID WITTMAN

The Challenge of Measuring Shapes §

Typical galaxy used for cosmic shear analysis Typical star Used for finding Convolution kernel Slide from S. Bridl

Cosmic Lensing gi~0. 2 Real data: gi~0. 03 5/19 Slide from S. Bridle

Atmosphere and Telescope Convolution with kernel Real data: Kernel size ~ Galaxy size 6/19 Slide from S. Bridle

Pixelisation Sum light in each square Real data: Pixel size ~ Kernel size /2 7/19 Slide from S. Bridle

Noise Mostly Poisson. Some Gaussian and bad pixels. Uncertainty on total light ~ 5 per cent 8/19 Slide from S. Bridle

Need to measure shear to 10 -3

Current Methods §

STEP : Shear Testing Programme § §

Heymans et al. , 2006; Massey et al. , 2007 & Kitching et al. , 2008 KSB

Quality Factor Kitching et al. , 2008 (form filling functions); Amara & Refregier (2007)

7 non-lensing participants Q~1000 in some regimes

GREAT 08 : Stacking Procedure is Important Average Data Individual Object Statistic Ensemble Statistic Average Estimators Winning Methods (Q=1000) Stacked the Data

STEP 2006 2008 2010

Massey et al. 2008 Fu et al. 2008

§ § Bonus Star Challenge: Reconstruct the PSF at non-star positions §

Get Ready ! § § §

http: //www. greatchallenges. info/ GREAT 10 Handbook, Kitching et al. , 2010

http: //www. greatchallenges. info/ “Every time the amount of data increases by a factor of ten we should totally rethink the way we analyze it” Jerome Freidman, Data Mining and Statistics, 1997