Oxygen analysis for HD 36512 (O9.7 V) (#1). Upper panel: iso-contours in the ϵ_O–v_mic plane. Middle panel: compares the observed and theoretical equivalent widths including error bars (see text), and visualizes the quality of the best-fitting model. In this case, major discrepancies are only found for O III 5592, which indicates a larger value of ϵ_O. Lower panels: χ² distribution projected onto the ϵ_O (left panel) and the v_mic (right panel) axis (see text).