Herschel dust temperature map of Serpens South (Könyves et al. 2015) overlaid with H₂ column density contours that start at 2 × 10²² cm⁻² and increase in steps of 2×10²² cm⁻². The beam size is shown in the lower-right corner of the central panel. The (0, 0) offset corresponds to α_J2000 = 18^h30^m04.19, δ_J2000 = −02°03′05″.5. The region mapped in HCNH⁺ (2−1) is indicated by the red boundary. The positions toward which pointed observations of HCNH⁺ (3−2) were carried out are indicated by the black plus signs in Serpens South. Observed HCNH⁺ (3−2) spectra are displayed in black, while Gaussian fits to the line profiles are shown in red. The source name is indicated in the upper-right corner of each panel.