Histograms and average trends of the MAXI/GSC dataset. Left: 2D histograms showing the unbinned MAXI/GSC dataset, depicting the flux in the 2−4 keV (soft band; top) and 4−10 keV energy range (hard band; middle), and the derived hardness ratio (bottom), calculated as explained in Sect. 3. The number of unbinned data points is colour-coded: lighter shades denote smaller values and darker shades indicate higher ones. Right: Average trends and their associated standard deviations derived from fits to the 2D histograms. Each shaded region is colour-coded, and the same code is used in Figs. 7 and B.1. For further details, we refer to the main text.