M96 is an intermediate spiral galaxy 35 million light-years distant in the constellation of Leo. At magnitude +9.6, it's the brightest member of the Leo I or M96 group of galaxies, which also contains M95, M105 and at least another 21 fainter galaxies. The grouping is one of many that lie within the Virgo Supercluster. Although these three galaxies are among the faintest in the Messier catalogue, all are visible as faint smudges of light with large 15x70 or 20x80 binoculars from a dark site.
M96 is an unusual galaxy in that it contains asymmetric arms and a displaced core, which were probably caused by gravitational pulling from other nearby galaxies. It was discovered, along with M95, by Pierre Méchain on March 20, 1781 and Charles Messier included both items in his catalogue four days later. M105 was not in the original Messier catalogue but added much later by Helen Sawyer Hogg in 1947.
The galaxies are located in the southern middle section of the relatively large and bright constellation of Leo, which lies east of Cancer west of Virgo. Leo contains one first magnitude star, Regulus (α Leo - mag. +1.4), which happens to be the brightest star in the surrounding region of sky. About 24 degrees east and two degrees north of Regulus is the constellation's third brightest star, Denebola (β Leo - mag. +2.1). Less than half the way along a line connecting these two stars are M95, M96 and M105. The northernmost member of the trio is M105 with M96 located 50 arc minutes south of M105 and M95 positioned 40 arc minutes west of M96.
They are best seen during the months of March, April and May.
It's difficult to notice much detail in M96 through small 80mm (3.1-inch) scopes but it's possible, on nights of good seeing, to make out the oval shaped core. Larger apertures of 200mm (8-inch) or greater bring out more detail, including wispy nebulosity that hints at the spiral nature of the galaxy. In total, M96 spans 7.8 x 5.2 arc minutes of apparent sky.
In the same field of view as M96 is M95, which appears as an oval patch of diffuse light with a bright core. The third galaxy, M105, is the least impressive of the trio and appears only as a small faint fuzz of light. Since each galaxy is of a different type, it's interesting to compare them through the eyepiece (M95 is a barred spiral galaxy, M96 an intermediate spiral galaxy, M105 an elliptical galaxy).
M96 spans 80,000 light-years in diameter. For comparison, M95 and M105 measure 46,000 and 55,000 light-years respectively. On May 9, 1998 a type Ia supernova (SN 1998bu) was discovered in M96, which peaked at magnitude +11.8.
M96 Data Table
|Object Type||Intermediate Spiral galaxy|
|Distance (light-years)||35 Million|
|RA (J2000)||10h 46m 46s|
|DEC (J2000)||+11d 49m 25s|
|Apparent Size (arc mins)||7.8 x 5.2|
|Number of Stars||100 Billion|
|Notable Feature||M96 is a member of the Leo I or M96 group of galaxies|