The master plot of all experimental data in the width–intensity representation. The solid lines connect data points (circles) measured at fixed temperatures for various angles. The displacement of solid lines from the bottom-left to top-right corners corresponds to decreasing of the angular position θ. The envelope (blue dashed line) shows the maximum available intensity at specified effective width of the source. The squares connected by the red dash-dot line show the data points measured for θ = 0 angular position at indicated temperatures. The red solid vertical line shows the natural width Γ0.