GalSim-developers / GalSim-Euclid-Like

Helper functions to generate simulations of Euclid-Like images.
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PSF normalization #83

Closed rmandelb closed 1 month ago

rmandelb commented 2 months ago

The PSFs are normalized to sum to 0.87, as a way of accounting for the decrease in effective collecting area due to obscuration by the secondary mirror. However, our code already accounts for that decrease elsewhere (we normalize fluxes using the effective collecting area) so this means we are double-counting the effect. We should update our code to remove this effect from the PSFs.

In particular: collecting area = 9926 cm^2, and M1 area is pi*(120/2)^2=11310 cm^2. So this obscuration is 9926/11310=0.877, and we should divide the PSF images by this. Other smaller effects that are in them can be left in.