SN 1940B was a supernova discovered on 5 May 1940 in the galaxy NGC 4725 in Coma Berenices.

[1] It had a magnitude of 12.8[2] and became the first observed type II supernova.

[3][clarification needed] SN 1940B is one of the five supernovae discovered in 1940, the other being SN 1940A, SN 1940C, SN 1940D and SN 1940E.

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