²⁸SiO, ²⁹SiO, and ³⁰SiO (2–1) integrated-intensity maps towards L1157-B1, obtained with a velocity resolution of ~7 km s⁻¹. The emission has been integrated between −22.95 and 6.25 km s⁻¹. The clean beam of 3.8′′ × 2.8′′ is shown in the bottom left corner of the maps, and the primary beam of 56′′ is reported as a dotted white line. The contours for ²⁸SiO start at 5σ (rms = 36 mJy beam⁻¹ km s⁻¹), then 30σ, and they then increase with steps of 20σ. The contours for ²⁹SiO start at 5σ (rms = 18 mJy beam⁻¹ km s⁻¹), and increase with steps of 5σ. The contours for ³⁰SiO start at 5σ (rms = 17 mJy beam⁻¹ km s⁻¹), and increase with steps of 5σ. B0, B1, and B2 are three shock regions along the outflow of L1157. They are composed by several subclumps marked here with circles (B0), triangles (B1), and squares (B2) (Benedettini et al. 2007). The L1157-mm protostar is located towards the north-west at Δα = −25′′ and Δδ = +63.5′′ (α₂₀₀₀ = 20^h39^m06^s.0, δ₂₀₀₀ = +68°02′14″.0). The maps are not corrected for the primary beam.