Interesting paper.
Fourier Analysis can be a minefield by filtering out good data but the methodology looks OK.
Comparing the paper to the time dilation of Type IA supernovae in galaxies, there are fewer variables to contend with in the supernova data.
http://users.westconnect.com.au/~sja...n_redshift.pdf
In this case "all" that has to be done is calculate the light curve of the supernova in the galaxy's (supernova) rest frame.
This is done using the SNID algorithm.
The authors of the algorithm go to great pains in defining SNID.
"What does SNID stand for?
Super
nova
Identification. It does
not stand for any of the following:
Scandinavian Network for Infectious Diseases
Smart Network Interface Device
Studies in National and International Development
Subscriber Network Interface Device
Sud Nivernais Imphy Decize"
Steven