2′ × 2′ OTF maps of DCO⁺ (at 216.112 GHz), DCN (at 217.238 GHz), DNC (at 228.910 GHz), H₂CO (218.222, 218.475, 218.760 and 225.697 GHz), C₂H (at 262.004 and 262.064 GHz), HC¹⁵N (at 258.156 GHz), H¹³CN (at 259.011 GHz) and H¹³CO⁺ (at 260.255 GHz). The cross marks the IF position, the triangle marks the MP2 position, and the circle shows the MP1 position at the offset (− 15′′,15′′). The contour levels are 40% to 100%, in steps of 15% of the peak intensity; ~2 K km s^-1 for DNC; ~3 K km s^-1 for DCO⁺ and HC¹⁵N; ~4 K km s^-1 for H₂CO at ~218.00 GHz; ~5 K km s^-1 for H¹³CN and H¹³CO⁺; ~7 K km s^-1 for DCN; ~15 K km s^-1 for H₂CO and C₂H at ~262.00 GHz.