Line profiles of the molecular ions observed in the L1157-B1 shock: HCO⁺a), HCS⁺b), SO⁺c), H¹³CO⁺d), HOCO⁺e), and N₂H⁺f). The line intensity is in mean beam temperature (T_mb). The transition, frequency in GHz, upper level energy in K, HPBW in arcsec, and 1σ rms noise in mK are indicated. The baseline and the systemic velocity (V_LSR = + 2.6 km s^-1) are indicated by the horizonthal and vertical dotted lines. For N₂H⁺f), the 15 hyperfine components of the N₂H⁺ 1–0 pattern are indicated by the vertical red lines. (Due to degeneracy only 7 of the 15 hyperfine lines do not overlap in frequency; of these, only the three main groups are resolved because of blending caused by the line broadening.)