Spectral energy distribution of HD 93840. Upper panel: reddened ATLAS flux (solid red line) compared to various (spectro-) photometric measurements. Lower panel: difference between observed and modelled values in magnitudes. Spectrophotometric data of TUES, IUE, and Gaia are depicted as black, light gray, and dark gray lines, respectively. The photometric measurements are illustrated as follows: TD1 (diamonds), Johnson UBV (squares), 2MASS JHK (triangles) and AllWISE W1 to W4 photometric data (hexagons). The error bars in the lower panel represent the 2σ uncertainty ranges.