An article published in the journal “Science” describes a precise measurement of the magnetic field of the corona of the black hole V404 Cygni. A team of researchers used the data collected in 2015 during a violent outburst of energy connected to the emission of jets from the black hole detected at many wavelengths using various space and ground-based telescopes. The result of this measurement was very surprising, being about 400 times lower than previous estimates.