NGC 3521 — Galaxy in Leo

NGC 3521 is a flocculent spiral in Leo, about 26 million light-years away. It has a brilliant, concentrated bulge and a smooth disk with tightly wound arms threaded by dust — like a smaller, more luminous version of M63. Deep imaging has revealed enormous faint stellar shells and tidal streams enveloping the entire galaxy, indicating that NGC 3521 has cannibalized one or more smaller companions in the geologically recent past. The galaxy's intrinsic brightness rivals M81's, but its lower-than-expected catalog visibility and lack of a Messier number have left it underappreciated.

An excellent and undervisited galaxy. A 4-inch at moderate power shows an elongated bright glow with a prominent stellar core; an 8-inch at 150-200x reveals a clearly inclined disk, a sharply concentrated nucleus, and hints of the dust lane along the eastern flank. A 12-inch begins to bring out the flocculent texture and the dust patchiness. Star-hop from Iota Leonis about 4 degrees southwest. Best observed February through May.

Discovered by William Herschel on 22 February 1784. NGC 3521 was relatively neglected for most of the 20th century — bright but inconvenient, lacking a popular nickname or a Messier number. Deep CCD surveys in the 2000s revealed the giant stellar shells around it, prompting renewed interest as one of the best nearby examples of a recent minor-merger remnant in a still-spiral host.