NGC 3746

Lore & Background

NGC 3746 was discovered by Ralph Copeland on 9 February 1874, with subsequent observations made by Hermann Kobold, Lawrence Parsons, and John Louis Emil Dreyer. It has a luminosity class of II and features a broad H II region with a recessed core (RET). The galaxy is a member of the Copeland Septet, which comprises seven galaxies: NGC 3745, NGC 3746, NGC 3748, NGC 3750, NGC 3751, NGC 3753, and NGC 3754. This grouping is also known as Hickson 57 and Arp 320.

Two supernovae have been discovered in NGC 3746. SN 2002ar (Type Ia, magnitude 16.5) was discovered by Dr W. D. Li from the University of California, Berkeley via unfiltered CCD images taken by the 0.8-m Katzman Automatic Imaging Telescope on 3 and 4 February 2002, located 3.3 arcseconds east and 0.5 arcseconds south of the nucleus. SN 2005ba (Type II, magnitude 17.5) was discovered on 1 April 2005 by Norwegian scientists Arne Danielsen, Mikkel Steine, and Stale Kildahl via unfiltered images taken from a Celestron 14 reflector at Veggli, Norway, located 14.6 arcseconds west and 4.0 arcseconds north of the nucleus.

Reader's Guide

NGC 3746 is notable as a large barred spiral galaxy with a ring structure, situated 449 million light-years away in Leo. Its membership in the Copeland Septet—a compact group of seven galaxies discovered by Ralph Copeland in 1874—places it within a system also cataloged as Hickson 57 and Arp 320, making it a subject of interest for studies of galaxy interactions and group dynamics. The galaxy's luminosity class II and broad H II region with a recessed core indicate ongoing star formation and structural complexity. The two recorded supernovae, SN 2002ar (Type Ia) and SN 2005ba (Type II), provide data on stellar explosions within this distant system, with the latter discovered by amateur astronomers in Norway. The galaxy's discovery history, involving multiple 19th-century astronomers, and its inclusion in multiple catalogs underscore its enduring significance in extragalactic astronomy.