Maps of the H¹³CN (1–0) integrated intensity between velocity range −21, 12 km s⁻¹ (left panel) and of HC¹⁵N (1–0) integrated intensity between velocity range −14, 6 km s⁻¹ (right panel). The synthesized beam, 3. ′′8 × 2. ′′8 (PA = −168°), is shown in the bottom right corner. First level is equivalent to 3σ, corresponding to 0.06 and 0.04 Jy beam⁻¹ km s⁻¹ for H¹³CN (1–0) and HC¹⁵N (1–0), respectively. Level steps are 0.1 and 0.02 Jy beam⁻¹ km s⁻¹ for H¹³CN (1–0) and HC¹⁵N (1–0), respectively. The central position of several clumps (B0d, B0e, B1a, B1b, B1c, B1d, B1e, B1f, and B2a), previously identified with other molecular tracers (Benedettini et al. 2007; Codella et al. 2015), is indicated by a cross and the arrow indicates the direction towards the driving source L1157-mm.