Result of Saha’s equation analysis for the lines with disk-like profiles and low transition probabilities for the observationstaken during the outburst phase (upper panels) and for the same lines as observed during quiescence (lower row). The panels show the data corresponding to individual days in chronological order; last panel: result of fitting the average spectrum. The color scheme reveals the relative variations in the line intensity ratio for each combination of temperature and electron density (such that 0.1 would correspond to 10% average deviations). The white contour indicates the regions for which the relative variations of the line ratio are up to 3 times the minimum value observed, which is considered as our best-fit region; a white star denotes the best fit.