Panel a: Excitation temperature, panel b: CH₃OCHO column density, panel c: H₂ column density, and panel d: [N_CH3OCHO/N_H2] ratio as a function of the radius. T_ex and N_CH3OCHO have been estimated by fitting the CH₃OCHO v = 0 and v_t = 1 emission azimuthally averaged over different rings (see Sect. 4.2), while N_H2 has been estimated from the azimuthally averaged dust emission. The CH₃OCHO column density at a radius of 0.′′22 (marked with a circle) has been calculated by extrapolating a linear fit from the R = 0.′′ 44 and 0.′′ 66 rings. The solid lines in panels a and c and the dashed one in panel b show the least square linear fits to all the points. The solid lines in panels b and d show the least square linear fits to the inner 3 points and to the outer 5 points in each panel.