A new supernova has exploded in the famous Whirlpool Galaxy, M51. Discovered independently by French amateur astronomer A Riou and the Palomar Transient Factory on 31 May, the supernova has been designated SN 2011dh and tentaively classed as a type II-L based on the amount of hydrogen in its spectrum, meaning the collapse and destruction of a massive star. At the time of discovery the supernova was magnitude +13.5.

Messier 51 in Canes Venatici is located 23 million light years away from Earth and is one of the most observed galaxies in the sky – it can be seen towards the west with the onset of darkness. SN 2011dh is the second supernova seen in M51 in the last six years.

If you imaged the supernova please send your images for consideration in our monthly Picture Gallery to gallery2011(at)astronomynow(dot)com. All images submitted will be posted online.