NGC 3239 is an irregular galaxy in the constellation of Leo.[2] The galaxy was discovered in 1784 by William Herschel[3] and is part of the New General Catalogue. It harbors a large and relatively bright H II region in its southeastern section that was first cataloged by Russian astronomer Boris Vorontsov-Velyaminov as VV95b.[4] It's believed that NGC 3239 is the result of a galactic merger with a low-mass galaxy.[5]
Supernova
One supernova has been observed in NGC 3239. SN 2012A (Type II-P, mag. 14.6) was discovered by Bob Moore, Jack Newton, and Tim Puckett on 7 January 2012.[6][7] It reached a peak visual magnitude of +13.6.[8][9] Later analysis concluded that the progenitor was a red supergiant with 10 to 15 times the mass of the sun.[10]
