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OWLS Pipeline Status Report

OWLS Pipeline Status Report. STEP 2007 Workshop, JPL Mon, Aug 20, 2007 MSS Gill, J.Young, P. Martini, K. Honscheid, D. Weinberg, C. Kochanek + OWLS Team ( OWLS = OSU Weak Lensing Survey). Outline. Introduction to OWLS project Description of hybrid approach

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OWLS Pipeline Status Report

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  1. OWLS Pipeline Status Report STEP 2007 Workshop, JPL Mon, Aug 20, 2007 MSS Gill, J.Young, P. Martini, K. Honscheid, D. Weinberg, C. Kochanek + OWLS Team ( OWLS = OSU Weak Lensing Survey)

  2. Outline • Introduction to OWLS project • Description of hybrid approach • Our current results from deconvolving • Cuts on various sextractor quantities and their effects on • Plans: Subaru images, LBT images

  3. OWLS Project Goals • Constraining cosmological parameters with • cluster weak lensing • Picture of Abell 611 from the LBT:

  4. LBT OWLS Projections • Projections for LBT with several clusters by next Autumn Assumes lensing using 50 richest clusters in observed 250 degree squared field with all background (lensed) galaxies at z=0.6 Colors are 1,2,3 sigma countours Here: sigma_8 vs. Omega_m (Plot: J. Yoo)

  5. Progress over the year.. • We initially started the project thinking we would be able to pretty much use the shapelets code ‘out of the can’ to extract cluster shear • But were never able to get minimal KSB estimator to give us the known shears for STEP2 fields; now know it has some instability • So we ‘cooked up’ our own method to extract shear, which seems to work…

  6. ‘Hybrid’ Approach • Seems slightly unorthodox, but we do it in 2 steps: • For sextractor, we need to make pstamp recompositions of each object from shapelets • Then separately sextract them • Deconvolve using shapelets • Extract ellipticity averages using sextractor

  7. Deconvolving with Extracted PSF • We used the STEP2 starfields for the 6 individual psfs • Extract psf in the standard way: pick stars, decompose them, fix beta and n_max, decompose again • Constant psf not assumed • We then deconvolved the galaxy field with this psf model psf

  8. Example of Deconvolved Galaxy (From STEP2 field: psfD, file shear20, object #1)

  9. From deconvolved fields to shear extraction • Use standard approach of plotting the difference of extracted shear and the input shear, vs. the input shear, for a given field • Fit this to a line, and extract output c (y-intercept) and m (slope) values • Example (psfA):

  10. Our Current Results – ADE Avg Average of PSF’s A,D,E – compared with STEP2 groups Squares = rotation-matched Triangles = original only Red square = our result

  11. Our Current Results – PSF A Squares = rotation-matched, Triangles = original only Red square = our result

  12. Our Current Results – PSF D Squares = rotation-matched, Triangles = original only Red square = our result

  13. Our Current Results – PSF E Squares = rotation-matched, Triangles = original only Red square = our result

  14. Plans • Next: go to Subaru A1689 images • Then to LBT images – currently have 2 clusters in hand

  15. BACKUP Slides

  16. Results with Known PSF • We initially used PSFs sent to us by J. Berge’ to get our technique working • Example Plot of rotation-matched averaged c, m for D compared to paper, Red = ours

  17. Cut effects on results Made cuts on several quantities (sexarea, sexflux, a*b, shapelets error) and saw results improve • Example: change in m as function of shapelets error cut:

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