Comparison of OH maser emission and our NOEMA observations. The colour maps show moment-0 maps of CO J = 2 - 1 (top) and SO₂ JK_a,K_c = 11_1,11 - 10_0,10 (bottom) line emission (colour maps) constructed for the velocity ranges specified in each panel's lower right corner, in accordance with the ranges covered by the maser emission. Contours show the NOEMA continuum emission (white) and the OH maser emission from Etoka & Diamond (2004) in cyan. These are, from left to right: red-shifted OH 1612 MHz, blue-shifted OH 1612 MHz, and blue-shifted OH 1665 MHz. The beams of the line emission measured with NOEMA are given in the bottom-left corner of each panel as white ellipses.