Left: spectral index map for the radio emission in NGC 1377, derived from X- and L-band observations. Values are only shown where the spectral index uncertainty Δα/α is less than 30%. Solid contours show the X-band emission and are the same as in Fig. 2. Dashed contours show the L-band continuum emission smoothed to the X-band resolution, see text for discussion. The two main emission components are labeled as A and B, as in Fig. 2. Right: map of relative uncertainty for the derived spectral index.