The Hertzsprung–Russell diagram is a scatter plot of stars showing the relationship between the stars' absolute magnitudes or luminosities versus their stellar classifications or effective temperatures (Wikipedia).
These plots were created from FITS datafiles obtained from the Hubble Legacy Archive. Two filters of observational data were used, an infrared filter (F814W) and an ultraviolet filter (F275W). The two images were processed using the astronomical data analysis package photutils in Python to find linear flux data for over 120,000 stars. This was then converted into instrumental magnitude, calibrated, and plotted.
