The author of the original study used VIIRS, which is essentially a large CCD sensor(s) on the Soumi-NPP weather satellite.

The overview for the actual data product is at: https://ladsweb.modaps.eosdis.nasa.gov/missions-and-measurem...

There are a couple of different VNP46 products, but A2 is iirc usually the one used in academic research.