"on the same scales as HST COSMOS" is a bit confusing.  I think this is really correlated the same in terms of number of pixels separation.  Not the same actual scales (in arcsec).  Here is a stab at a rewrite: 

..., so that the noise among neighboring pixels is correlated at the same level as it was among neighboring pixels in HST COSMOS.  Using the original pixel scale, dx_cosmos=0.07, would leave very little correlation among our larger 0.2 arcsec pixels.  We also set the point...