Comparison between HST and AstroSat-measured SEDs of HIP 23309 in the FUV (1300–1700 A). The top plot shows data in linear y-scale with error bars; the bottom plot is identical to top plot except with log y-scale and omission of error bars for easier viewing. The cyan and black data correspond to the unbinned HST and UVIT data, respectively. The blue points correspond to HST data degraded to the approximate quality of the AstroSat data, to enable a closer comparison. The green points correspond to the AstroSat data binned down by a factor of 5, to improve S/N and enable better visual comparison. We assumed Gaussian uncorrelated noise when rebinning the AstroSat data.