Best-fit value of the energy of the Fe XXV line in region A for the observations considered in this work (red data points). The energy is the best-fit value obtained for a power-law and Gaussian line model. The error bars refer to the associated 68% confidence interval. MJD refers to the start of the observation date. The black data points are the centroids of the Fe XXV triplet measured in the outer region and displayed in Fig. 4.