This set of Python-code is used to analyse the variation of VIIRS DNB nighttime imagery. The code is inline documented and the readme provides information on what is needed to run the code, and what order to run it in. These routines were used to produce the data and plots in the paper: Variation of Individual Location Radiance in VIIRS Day/Night Band Monthly Composite Images (Coesfeld et al. 2018).Monthly VIIRS DNB data can be downloaded from NOAA: https://ngdc.noaa.gov/eog/viirs/download_dnb_composites.html