Do PSF photometry

[NCastro-Segura]

I was thinking we could add PSF photometry to the pipeline as this would be more appropriate for galaxies.

Probably the easiest way to implement this would be by using sextractor as this software is already part of the code.

This may require to use the cross matching of the sources in the images in another method besides photometry.
So, I would create a separate method for the cross match and save these matches in an intermediate file that could be useful for future new features.

[Alymantara]

It all depends on how bright the AGN is in comparison to galaxy. I would argue that in this case, Difference Imaging is a better course, but more computationally expensive. We have made tests on NGC 4395 using both PSF, aperture photometry, DI and made little difference to the lag detection (albeit not with OPTICAM).

The intermediary source file is a good idea anyway. This could be used in other applications downstream