Weight maps, SExtractor and Qphot ?

[hbouy]

This is not an issue but rather a question and a suggestion: it seems that Lemon is using SExtractor to extract the sources in the coadded mosaic image, but IRAF qphot that to perform the photometric measurements.
Is there a specific reason why you do not use SExtractor for both?
One important advantage I see for SExtractor is that it can use weight maps, which can significantly improve the results. See for example E. Bertin's nice discussion about weights.
I am not so familiar with qphot but from the man page it seems it cannot use weight maps.

Additionally, SExtractor combined with PSFex can also measure PSF photometry, which can be superior to aperture photometry specially at low signal-to-noise ratio.

cheers :-)

[vterron]

That's a very good suggestion indeed. The (rather disappointing) answer is that... that's the way it was done by hand when the development of our pipeline started. The astronomers at our research group had been doing exactly this for a long time: sources detection with SExtractor, and then photometry with IRAF. This started as a series of scattered scripts to automate some of these tasks, and eventually became a full piece of software — using SExtractor + IRAF... because of inertia.

SExtractor is clearly much more sophisticated than IRAF, which in my opinion failed to keep up with the times. However, a SExtractor-based photometric solution would still have the disadvantage (although definitely to a much lesser extent) of requiring a separate binary as part of the installation process. My goal is to nuke IRAF from orbit and replace it with photutils, moving towards a fully Python-based pipeline.

[hbouy]

Having a 100% python pipeline would indeed be even better!!!
Hope you can implement that soon :-)
Thanks!