Integrated-intensity maps towards IRAS4B1 (yellow star) for SiO 2-1 (E_u = 31 K; colour) and CH₃OH 4₂−3₁ and DCN 3-2 (E_u = 45 K and 21 K, respectively; contours). The SiO maps are integrated from −25 to 6 kms⁻¹ and 6.8 to 47 kms⁻¹ and show emission above 10σ with σ_blue = 0.42 K km s⁻¹ and σ_red = 0.49 K km s⁻¹. Contours are at −30σ, −15σ, 15σ, and 30σ and then increase by a factor of 3 for CH₃OH (σ_blue = 0.25 K kms⁻¹ and σ_red = 0.23 K km s⁻¹) and at −10σ, −5σ, 5σ, and 10σ and then increase by a factor of 3 for DCN (σ_blue = 0.17 K kms⁻¹ and σ_red = 0.24 K km s⁻¹). The velocity ranges (in km s⁻¹) used for the integration of CH₃OH and DCN emission are indicated in the top left corner. The half-power beam width (HPBW) is shown in the bottom left corner. Positions R1 and B1 were selected for further spectral line analysis (Sect. 3.3). The black crosses indicate H₂ knots (Choi & Lee 2011).