I recently tried flux calibration of an Alpy spectrum using David Boyd’s method. I had acquired my own photometry for the target with a view to bring the two data sets together in this way…
I started to read a bit more about flux and magnitudes etc and disappeared down a rabbit hole… 🙂 Flux can be a counting concept (photons, electrons, ADU) or energy-based. The relation between the two is given by the Planck–Einstein relation (E = h c / lambda) and so they are not directly comparable….
However, in obtaining the instrument response using a MILES star, it seems we come good in the end.
I attach a brief analysis that I hope sheds some light!