model should be larger than the entire psf

[benmontet]

We were missing the dumb (right) way to calculate the total expected flux from a star in each cadence:

pred_flux = [np.sum(np.exp(model(*results[i], gds))) for i in range(len(tpf)]

Duh. Just calculate the model explicitly and sum over all pixels.

Anyway, when we do this (see the old notebook) we still get too much noise. I think this might be in part because the model region is smaller than the entire PSF and so the movement carries it out of the model region. The residuals look like noise (which is good!) but there is too much of it.

The good news is that we can see the sinusoidal pattern in the data. The residuals aren't quite centered around 0, but I believe this is a background issue and will be fixed when we fix #1.