Sensitivity of the λ15273 DIB to the radiative environment: ratios of λ15273 EWs with five optical DIBs are shown as a function of the radiation-sensitive ratio EW(5797) /EW(5780). The right scale range is chosen from zero to three times the average ratio. An ODR linear fit provides the relative slopes indicated in the figure along with the correlation coefficients. The largest slope is found for λ5797 band and the smallest for the λ6283 DIB. Here, we show (red line) an exponential fit to the whole dataset and a linear fit (black dashed line).