The (hopefully!?) useful info above was (slowly) assembled over the years in large part
thanks to the following folks:
Jacopo "Scensiato" Antichi for his advice on the Airy Disk figures, reminding me about
the "holy" Born & Wolf and giving me a privileged perspective on the daily life of a
designer of future astronomical instruments and his dreamy world;
Lucia "Stordita" Marchetti for the many questions we asked ourselves about AB and Vega
magnitudes while she was in the no less fancy limbo of her Thesis writing;
Gabriele "Subcomandante" Mainetti for our lengthy and slightly unprofessional investigations
of the Airy function and assorted Bessel functions;
Russ "Haggis" Johnston who never seemed to want to brush up on his magnitudes,
Emmanuel "Crane" Ocran for our multi-wavelength studies of the faint radio sky.