First observation-based SDM-disambiguated vector magnetogram. The SO/PHI-HRT vector magnetogram is disambiguated using SDO/HMI information from the (ambiguous) hmi.ME_720s_fd10 data series and Eq. (5). Panel a: background image representing B_los on the SO/PHI-HRT image plane, saturated at ±1500 G in grayscale; red and blue arrows represent the transverse field at positive and negative B_los, respectively. The 400 G isoline of |B_los| is drawn as a solid yellow line. Panel b: same as panel a but in remapped Stonyhurst coordinates, with the magnetic field re-projected in radial, poloidal, and toroidal components. In this panel, the background image represents the radial component B_r saturated at ±1500 G in grayscale, and red and blue arrows represent the horizontal field at positive and negative B_r, respectively. The 400 G isoline of |B_r| is drawn as a solid yellow line.