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We report novel, high-angular resolution interferometric measurements thatimply the near-infrared nuclear emission in NGC 4151 is unexpectedly compact.We have observed the nucleus of NGC 4151 at 2.2 microns using the two 10-meterKeck telescopes as an interferometer and find a marginally resolved source ~0.1pc in diameter. Our measurements rule out models in which a majority of the Kband nuclear emission is produced on scales larger than this size. Theinterpretation of our measurement most consistent with other observations isthat the emission mainly originates directly in the central accretion disk.This implies that AGN unification models invoking hot, optically thick dust maynot be applicable to NGC 4151.Comment: 9 pages, 1 figure, accepted for publication in the Astrophysical  Journal, Letter

Interferometer Observations of Subparsec-Scale Infrared Emission in the Nucleus of NGC 4151