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Copeland's Septet (Hickson 57)




Copeland's Septet
A close grouping of seven major galaxies that lies about 480 million light-years away in the constellation Leo, about 8° NW of Denebola. It was discovered by Ralph Copeland (1837-1905) in 1874 while he was employed as an observer under Lord Rosse. Copeland probably first observed the group while using the 72-inch "Leviathan of Parsonstown" at Birr Castle.

The galaxies have NGC numbers of 3745, 3746, 3748, 3750, 3751, 3753, and 3754, apparent magnitudes between 13.6 and 15.2, and angular sizes between 0.4' × 0.3' and 1.7' × 0.5'. The entire group spans about 5 arc-minutes and is centered around RA 11h 38m, Dec. 22° 00'. The barred spiral NGC 3746 (Hickson 57b) was the host galaxy for Supernova 2005ba and also Supernova 2002ar, a Type Ia supernova that reached a maximum magnitude of 16.5.


Related category

   • GALAXIES