Another interesting article, by one of the EHT team, which delves more deeply into the scientific analysis of the images of the black hole.
https://astrobites.org/2019/04/11/th...-a-black-hole/
Amongst other fascinating items, it hints at variability of the black hole environment over the period of a week that the data was gathered.
Figure 2 (Figure 11 in Paper IV): Fiducial images on each day of observations from each imaging pipeline. A consistent asymmetric ring feature is recovered by all pipelines on all days, with hints of time variability along the brighter southern edge.