2007-04-17

SDSS mosaic images

Pizagno got me back to thinking about our mosaic images of SDSS galaxies, because he is making stellar mass maps. He requires correct inverse variance maps, and we were creating pretty good, but not perfect, maps. (We record our uncertainties in images in units of inverse variance, not traditional root-variance; this is because the inverse variance is what you use for weighted means, and also because then badly measured pixels get values in the uncertainty map of zero, not infinity.) I made them much closer to correct today.

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