Distribution of the HCO⁺ (1–0) (gray scale and solid contours) and ¹²CO (1–0) (dotted contours) velocity-integrated emission in OH 231.8 from previous interferometric observations; adapted from Fig. 2 of Sánchez Contreras et al. (2000). The smallest and largest HPBW of the IRAM 30 m (long dashed) and Herschel (dotted) telescopes in these observations are represented by the circumferences. We labeled the different regions/clumps in the molecular outflow as I1 to I7, as in Alcolea et al. (2001). Clump I2d corresponds to the region where the HCO⁺ emission peaks. The V_LSR range (in km s^-1) of each clump is I1) [−80:−30], I2) [−30:+10], I2d) [−20:+60], I3) [+10:+55], I4) [+55:+80], I5) [+80:+150], I6a) [+150:+205], I6b) [+205:+230], and I7) [+230:+285]; see Table 2 in Alcolea et al. (2001), and also Sánchez Contreras et al. (1997, 2000), for more detail on the physical properties of the clumps.