Left: source-frequency phase referenced (SFPR-ed) image of M81* on 2016 February 27 at 3.4 mm. The peak intensity is 11.0 mJy beam⁻¹. The contour levels are 2.64 × (−1, 1, 2, 4) mJy beam⁻¹. The lowest level is three times the rms of the image. The astrometric offset of the peak with respect to the phase center is −35 ± 2 μas in R.A. and −32 ± 3 μas in decl., respectively. Right: spectral index map of M81* from 43.86 GHz (7 mm) to 87.72 GHz (3.4 mm) (grayscale flux range: −2.7 to 0.1), overlaid with 7 mm total intensity contours (peak intensity 72.3 mJy beam⁻¹; lowest contour 0.69 mJy beam⁻¹).