Bob Day wrote:
Is modern distance modulus vs redshift data from type Ia supernovae
based on photon flux, so that the expansion of space would cause a
1/(z+1) decrease in the flux, or is it based on energy flux, in which case
the expansion of space would cause a 1/((z+1)^2) diminution?

Most measurements these days in the optical
and near-IR are made with detectors which count
photons, not energy.

What people do with the measurements afterwards
is very hard to follow properly.

Michael Richmond