Estimation of radii for photometry aperture

[morcuended]

From #67

We should find a way of systematically setting the values of the radii of the annulus used for photometry aperture:

During these days I saw that for some specific sources and nights, it was behaving better. In particular for CAFOS2.2 2023-12-20 1101+384, using 3.0r made the two points inconsistent with OSN observations, and made the photometry uncertainty very large. Using 6.0r made the uncertainties sensible AND compatible with the other instruments. It also didn't affect significantly other results, as you can see, it only increases slightly the discrepancy with the test reference... but that reference comes from IOP3 and is not written in stone... so until we replace it with something more solid, we can allow a bit more of discrepancy, I think.

Anyway, we should open an issue so we don't forget to look into this. These values have changed already several times in an erratic way. We should investigate it systematically. At some point, we will definitely need to implement a way to handle several cases as in #66 for the astrometry calibration parameters.