N₂H⁺(3−2) spectra measured from the pre- and protostellar cores in Orion B9. Spectra are overlaid with the 38 component hyperfine structure fits. Hyperfine fits to the second velocity components are indicated by red lines. Note that only the second velocity component is detected towards SMM 4. The relative velocity of each individual hyperfine component is labelled with a short bar on the spectrum towards IRAS 05399-0121 (top left panel). The temperature scale is in T_MB.