High‐Resolution Mid‐Infrared Images of the Nucleus of M81

We observed two nearby galaxies with potential or weak indications of nuclearactivity, M32 and M81, with the MIRLIN mid-IR camera at N band (10.79 microns).M32 is not detected, but we give detailed measurements of the nucleus of M81.Our observations of M81 show a bright nuclear point source at N, and comparisonto measurements made in the early 1970's gives an increase in nuclear flux ofnearly a factor of two. If the comparison is accurate, the nuclear mid-IRemission must ultimately be powered by a variable, compact source, similar tothat in Seyferts and quasars. M81 has been classified in the literature as alow-luminosity LINER, not a pure Seyfert galaxy. Further, it has been suggestedthat this and other low-luminosity AGN may have intrinsically different spectrathan Seyferts and quasars. However, we find that the relative fluxes in theX-ray, MIR, and radio bands, all essentially unaffected by extinction andgalaxy pollution, show a nuclear continuum remarkably like that of a bona fideSeyfert or quasar.