Express galaxy locations by interpolating the PSF

[rgiordan]

Currently, we first render the galaxy at the location given by the variational parameters and then convolve with the pixelated PSF. For the same reason that we cannot get sub-pixel locations of stars without interpolating the PSF, this will make small galaxies will be difficult to locate accurately.

A better way would be to render the pre-convolution galaxy image at a fixed location and then convolve with a PSF that has been interpolated to the location given by the variational parameters.

[rgiordan]

It might be interesting to compare this to Dustin's idea of expressing the FFT of the pre-convolution MOG in closed form. My intuition is that this will work better, but the proof will be in the pudding.