Velocity calibration: The black line represents the average v_los of the QS area of Scan 3_05 along part of the slit used to correct the trend produced by an instrumentation problem. The red line is a second-degree polynomial that fits the black line. The pink line corresponds to the value obtained by averaging the velocity of the UM after correcting the instrumental trend. Finally, the blue line corresponds to the final result of the averaged QS v_los after applying the previous corrections. The green line marks the 0 value.