SAX J1748.9–2021 light curve during the 2015 outburst. The vertical dashed lines, indicate the ∼100 ks INTEGRAL ToO time interval. The black, green, and red vertical lines indicate the times of the detected type-I X-ray bursts with INTEGRAL, Swift and XMM-Newton, respectively. In the bottom panel the inset shows the hard ISGRI light curve zoomed in at the spectral change time interval. The count rate drops to zero within 0.5 day. The hard and soft state data points used in the spectral analysis are color coded with light blue and pink, respectively (see Sect. 4).