1. Tom Kitching
Tom Kitching

2. 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

3. The Challenge of Measuring Shapes


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

5. Cosmic Lensing
gi~0.2
Real data:
gi~0.03
5/19
Slide from S. Bridle 5

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

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

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

9. Need to measure shear to 10-3

10. Current Methods







11. STEP : Shear Testing Programme









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

13. 
 







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

16. 7 non-lensing participants
Q~1000 in some regimes

17. GREAT08 : Stacking Procedure is Important
Average Data
Individual
Object
Statistic
Ensemble
Statistic
Average
Estimators
Winning Methods (Q=1000) Stacked the Data

18. STEP
2006
2010
2008

19. 



20. Massey et al. 2008
Fu et al. 2008
Excplitily challenge the winning methods

22.   




Bonus Star Challenge:
Reconstruct the PSF at
non-star positions

23.  
Get Ready !










24.
GREAT10 Handbook, Kitching et al., 2010

27.
“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