The Southern Pinwheel Galaxy also known as M83 is a barred spiral galaxy approximately 14.7 million light-years distant in the eastern section of the largest constellation of all, Hydra. It's one of the closest barred spirals, a showpiece galaxy and the finest barred spiral in the sky. With an apparent magnitude of +7.5, M83 is visible with 7x50 or 10x50 binoculars, appearing under dark skies as a patch of light with a brighter centre. It was discovered by Nicholas Louis de Lacaille at the Cape of Good Hope in South Africa on February 23, 1752 and added by Charles Messier to his catalogue on February 17, 1781.
With a declination of 30 degrees south, M83 is best seen from Southern Hemisphere or equatorial regions during the months of April, May and June. For mid-latitude northern hemisphere observers, the galaxy can be a difficult object; it's the southernmost galaxy in Messier's list and therefore never climbs particularly high above the southern horizon.
Despite being a relatively bright galaxy M83 can be tricky to locate as it's positioned in a part of the sky devoid of bright stars. It can be found by locating stars γ Hya (mag. +3.0) and π Hya (mag. +3.3). Imagine a line connecting these two stars and then move along the line until just short of the halfway mark. Located about 6 degrees south of this point is M83.
M83 is a superb telescope galaxy. A small 80mm (3.1-inch) scope reveals a bright nebula covering about 1/3 the diameter of the Moon with a brighter core. Don't be afraid to push up the magnification, this galaxy will take it. For example, through a 150mm (6-inch) telescope at high powers M83 is a splendid sight exhibiting a condensed bright nucleus, hints of the bar structure that's positioned within a large outer envelope of fainter nebulosity. Also visible on nights of good seeing are dark dust patches surrounding the nucleus. Through a larger 250mm (10-inch) scope, M83 is a stunning sight with well-formed spiral arms, numerous dust lanes and the distinct central bar nucleus visible.
M83 forms a small physical group, the M83 group, with peculiar radio galaxy Centaurus A (NGC 5128) and unusual galaxy NGC 5253 in Centaurus. In total five supernovae have been observed within M83 in the last 100 years (1923A, 1945B, 1950B, 1957D, 1968L and 1983N). Such an unusual high rate makes M83 a popular target for amateur supernovae hunters; next time you have the chance to observe M83, compare the stars around the galaxy with those on an archive photograph or image and if you observe a "new" star, you may have made a supernova discovery.
M83 Data Table
|Name||Southern Pinwheel Galaxy|
|Object Type||Barred spiral galaxy|
|Classification||SAB (s) c|
|RA (J2000)||13h 37m 00s|
|DEC (J2000)||-29d 52m 04s|
|Apparent Size (arc mins)||12.9 x 11.5|
|Number of Stars||40 Billion|
|Notable Feature||Six supernovae have been observed in M83|