SNIa Results

SNIa are ultimate calibrated "flash lamps"
Observed brightness is diluted both by expansion of wavefront into space, and expansion of space.
Expectation can be calc for a given expansion history, and hence for a given cosmology
Observations are made through fixed bandpass filters at Earth but SN are at different redshifts
Filters sample different "chunks" of emission spectrum for each SN
Must correct observations to that which would have been made through notional filters custom matched to redshift of each SN using "template" spectra
Different cosmologies produce small deltas on large overall dimming so corrections must be very accurate!