NGC 4651 is a nearly face-on spiral galaxy that is easily visible in a 10-inch telescope as an elongated halo surrounding a bright but defuse nucleus. It is probably a part of the Coma/Virgo galaxy cluster. It has a distance of about 40 million light years, with a diameter of 50,000 light years.
Giuricin et al. (1990) includes NGC 4651 in their class of galaxies with active nuclei known as LINERs (Low-Ionization Nuclear Emission-line Regions). At least some LINERs are less energetic versions of Seyfert galaxies. Many astronomers believe that active galactic nuclei are powered by giant black holes lurking in the centers of many galaxies. (see also M-77).
NGC 4651 is also known as Arp 189, and is Arp's class of "galaxies with narrow filaments". De Vaucouleurs noted that the galaxy includes a "Faint spur and blob attached", as seen in the Kopernik image above.
Quote from The Deep Sky Field Guide to Uranometria 2000:
Very bright defuse nucleus in bright lens 1.0 x 0.6 arc minutes; several filamentary, knotty branching arms.
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George Normandin, KAS
August 17th, 2000