C₂H and c-C₃H₂ integrated line-intensity maps (white contours) of the Orion Bar. Upper panels: C₂H a) N = 3 → 2 at 262.0 GHz; and b)N = 1 → 0 at 87.3 GHz. Lower panels: c-C₃H₂c) 6_1,6 → 5_0,5 at 217.8 GHz; and d) 2_1,2 → 1_0,1 at 85.3 GHz. The Spitzer 8 μm extended emission due to PAHs and very small grains is in colour scale. Black contours are the Hν = 1 → 0 emission (Walmsley et al. 2000). Stars represent the positions of denser clumps/condensations detected in H¹³CN J = 1 → 0 (Lis & Schilke 2003). The IRAM 30 m beams at 1 mm and 3 mm are plotted in the bottom left corner (white striped circle). The target position of the Orion Bar survey, close to the dissociation front, and the molecular peak position beyond the PDR (clump No. 10 of Lis & Schilke 2003; see text for discussion) are indicated with a red and a black circle, respectively. The emission of all lines from C₂H and c-C₃H₂ is integrated in the 10–12 km s^-1 velocity interval in which the Orion Bar shows prominent emission.