Estimating rotational broadening of the broad-lined Be star. The disentangled spectrum of the broad-lined companion star around the He I 4026 Å line is shown in grey. Shaded regions indicate estimated uncertainties, calculated as the standard deviation of the flux residuals between the observed spectra and the disentangled spectrum. Overplotted are simulated spectra from the TLUSTY library with T_eff = 17 kK and logg = 4.0. The model spectra have been broadened using a fixed macroturbulent velocity of 50 km/s and differing rotation velocities; the best-fit value of v_rot, Be = 270 ± 70 km/s and ±2 − σ uncertainties.