NGC 3370 (also known as UGC 5887 or Silverado Galaxy^[2]) is a spiral galaxy about 82.2 ± 5.9 million light-years (25.2 ± 1.8 megaparsecs) away in the constellation Leo. It is nearly comparable to our Milky Way both in diameter with a D₂₅ isophotal size about 77,300 ly (23.69 kpc) comparing to the Milky Way Galaxy's 87,400 ly (26.8 kpc) diameter, and as well as in mass (10¹¹ M_☉).^{[citation needed]} NGC 3370 exhibits an intricate spiral arm structure surrounding a poorly defined nucleus. It is a member of the NGC 3370 Group of galaxies, which is a member of the Leo II Groups, a series of galaxies and galaxy clusters strung out from the right edge of the Virgo Supercluster.^[3]

NGC 3370 was likely discovered by William Herschel, who provided it with the designation II 81.^[4] His son John later designated it 750. William Herschel cataloged I 80 to NGC 3348^[4] before and II 82 to NGC 3455 after NGC 3370.^[4]

The object has a surface brightness of 13 and a position angle (PA) of 140°.

On November 14, 1994, S. Van Dyk and the Leuschner Observatory Supernova Search discovered a supernova in NGC 3370 at 10^h 44^m 21.52^s +17° 32′ 20.7″, designated SN 1994ae.^[5] SN 1994ae was a type Ia supernova, and one of the nearest and best observed since the advent of modern digital detectors.^[6] The maximal light of the supernova was estimated to have occurred between November 30 and December 1^{[citation needed]}, peaking at visual magnitude 13.^[5]

• NGC 1365, spiral galaxy