Spectral observations along the main horizontal cuts at ΔDec = −12′′ (IRAM/GBT) or −16′′ (JCMT) compared to our best-fit radiative transfer model. The blue spectra show the observational data, and the red spectra show the models. Each column corresponds to different horizontal offsets from the center of L 1512 according to Fig. 1. Each row shows a spectral line, except that the N₂ H⁺ (1–0), N₂D⁺ (1–0) and (2–1) lines are split into three rows corresponding to their different F₁ -transition groups. For C¹⁸O (2–1), our data are supplemented with OTF spectra from previous works at large offsets. The green dashed lines indicate the three σ noise level.