HCN (1–0) intensity maps of the Serpens filament integrated from 0.0 to 1.6 km s⁻¹ (panel a), integrated from 7.0 to 8.6 km s⁻¹ (panel b), and integrated from 11.7 to 13.6 km s⁻¹ (panel c) with respect to the frequency of the F = 2–1 hyperfine structure component. The three ranges correspond to the F = 0−1, F = 2− 1, and F = 1−1 hyperfine structure components, respectively. The color bar represents the integrated intensities in units of K km s⁻¹. In all panels, the overlaid black contours denote H₂ column densities of 6 × 10²¹ cm⁻², while the two open circles give the observed positions of sources A and B. In all panels, the (0, 0) offset corresponds to α_J2000 = 18^h28^m49.^s642, δ_J2000 = 00°50′01.′′08. The beam size is shown in the lower right of each panel.