Last Sunday, Jimi Lowrey, Jim Chandler and I took a look at NGC 3239. I had completely forgotten about SN 2012, discovered early last month, but picked it in the observation --
48" (2/19/12): NGC 3239 = Arp 263 is a large, disrupted Irregular dominated by numerous HII regions and a fascinating sight at 488x. A mag 10 star is superimposed on the SW side of the galaxy with the patchy, highly irregular surface brightness glow of the galaxy extending mainly north and east of the star.
Most prominent is a very bright, round knot of ~15" diameter on the SE side of the galaxy, which is catalogued as VV 95B in NED and in Hodge-Kennicutt's 1983 "An Atlas of HII Regions in 125 Galaxies" as #6 and #10. A faint star or knot is attached on the north side. A "star" recorded just off the west side of this knot turns out to be supernova SN 2012A, discovered on 7 Jan 2012, still currently around 14th magnitude. Very faint haze extends SE of the knot, but a "tail" structure was not seen.
Along the north side of the galaxy (elongated east-west) are several additional knots. About 30" due north of VV 95B is HK[83] #3 and #4. This close pair of knots appeared as a faint, small, irregular glow, ~6" diameter. Patchy haze is just west, but with no condensed spots. Further west, and 40" due north of the mag 10 star, is a moderately bright, small, round knot, ~10" diameter that has several HK[83] entries (#28/29/31/34). To the west of this knot, the glow of the galaxy ends near HK[83] #57/58, a faint low surface brightness knot that is elongated N-S.
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