All Figures

	Figure 1: Low-lying rotational levels of the CH2 molecule showing the wavelength of the strongest fine structure component for each transition.
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In the text

Figure 2: Upper panel: fit of the CH line towards Sgr B2 with the data binned at a quarter of the resolution element. Lower panels: in the lower three panels, a model based on the CH line shape has been fitted to the data around the three lowest energy transitions of CH2. The relative contribution of each velocity component in these fits was fixed to the CH values in Table 3, except for the 94 m (313-202) transition in the bottom plot which only includes the velocity component due to Sgr B2 itself (see text). The fit was carried out to the strongest fine structure component in each case. Other (sometimes undetected) components are included in the model using their expected relative line strengths from Table 1. The data are binned at half of the resolution element and the errors reflect both statistical noise and systematic error due to the dark current subtraction and continuum fit. The extra absorption feature seen at -250 km s-1 relative to the 127 m (1 11-000) transition appears to be real but is not identified.

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In the text

	Figure 3: Data around the J=2-1 (127.6 m) and J=1-1 (127.8 m) fine structure components of the 111-000 CH2 transition toward W49 N. The solid line shows a model derived from a fit to the J=2-1 component and the expected relative line strength of the J=1-1 component.
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In the text

	Figure 4: The CH J=3/2-1/2 transition observed towards Sgr A showing two resolved -doublet components.
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In the text