Estimate of the electron density from QTN thermal plateau detection (see method in the text), during the first Mercury’s flyby from 22:00 to 0:30 UTC (MSB1 on top) and the second one from 9:00 to 10:30 UTC (MSB2 on bottom), respectively, using the stowed WPT antenna. In each panel, we plotted in blue the upper and lower (if any) limits of the density and the average of both. The different dashed lines correspond to some identified density drops, as explained in the text. The red dashed line indicates the closest approach (CA).