Radial velocity of star HD40307 for order 116, which is contaminated by H₂O. The result with the standard binary mask BM1 before telluric correction is shown in red; the result with our new binary mask BM2 after telluric correction is shown in black. The average radial velocities of 31 386.4 and 31 388 m s⁻¹ were subtracted from the series before and after correction, respectively.