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Abstract: We investigate data compression schemes for proposed all-skydiffraction-limited visible-NIR sky surveys aimed at the dark energy problem.We show that lossy square-root compression to 1 bit of noise per pixel,followed by standard lossless compression algorithms, reduces the images to2.5-4 bits per pixel, depending primarily upon the level of cosmic-raycontamination of the images. Compression to this level adds noise equivalent to<10% penalty in observing time. We derive an analytic correction to flux biasesinherent to the square-root compression scheme. Numerical tests on simplegalaxy models confirm that galaxy fluxes and shapes are measured withsystematic biases <~10^{-4} induced by the compression scheme, well below therequirements of supernova and weak gravitational lensing dark-energyexperiments. An accompanying paper Vanderveld 2009 bounds the shape biasesusing realistic simulated images of the high-Galactic-latitude sky. Thesquare-root preprocessing step has advantages over simple linear decimationwhen there are many bright objects or cosmic rays in the field, or when thebackground level will vary.



Autor: Gary M. Bernstein, Chris Bebek, Jason Rhodes, Chris Stoughton, R. Ali Vanderveld, Penshu Yeh

Fuente: https://arxiv.org/



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