Detection of cis-HCOOH towards the FUV-illuminated edge of the Orion Bar. Left: ¹³CO J = 3 → 2 integrated emission image with a HPBW of 8′′ obtained with the IRAM-30 m telescope (Cuadrado et al., in prep.). The cyan contour marks the position of neutral cloud boundary traced by the O i  1.317 μm fluorescent line emission (in contours from 3 to 7 by 2 × 10^-4 erg s^-1 cm^-2 sr^-1; Walmsley et al. 2000). Right: Cis- and trans-HCOOH stacked spectra towards the observed positions.