In color, the C¹⁸O 2−1 integrated intensity in the range [5−15] km s^-1 (Pilleri et al. 2012). Squares indicate the positions of the OH⁺ 1−0 (971 GHz) observations, and the white circles show the HPBW of Herschel at this frequency. White dashed contours show the H(42α) integrated intensity from 1 to 11 K km s^-1 in linear steps of 2 K km s^-1. Black contours represent the relative variation of the continuum emission at 971 GHz from SPIRE-FTS in 20% intervals of the peak, 0.6 K.