M65 is a magnitude +9.6 spiral galaxy located 35 million light years from Earth in the constellation of Leo. It was discovered by Charles Messier on March 1, 1780, the night he also discovered M66. Messier described the galaxy as a "very faint nebula without stars." Apart from M81 and M82 in Ursa Major, M65 and M66 are probably the most sought after galaxy pair for amateur astronomers. With a third galaxy, NGC 3628, lying nearby the trio forms the heart of a small group of celebrated galaxies known as "The Leo Triplet" or "M66 group". All three can be observed or photographed in the same field of view and as a result are a sought after grouping for amateur observers and astrophotographers alike.
M65 is located in the eastern section of the relatively large and bright zodiac constellation of Leo "the Lion", with the Lion's heart in western skylore marked by the constellations brightest and only first magnitude star, Regulus (α Leo – mag +1.4). Positioned approximately 16 degrees to the northeast of Regulus is the star Chertan (θ Leo - mag. +3.3). Along with the Zosma (δ Leo - mag. +2.6) to the north and Denebola (β Leo - mag. +2.1) to the east, Chertan forms a prominent right-angled triangle. Now move 2 degrees south of Chertan to arrive at magnitude +5.3 star 73 Leo. M65 lies 0.75 degrees east of 73 Leo with M66 a further 0.33 degrees southeast of M65. Located 0.5 degrees to the north of the Messier pair is the 3rd member of the famous Leo triplet, NGC 3628.
The galaxies are best seen during the months of March, April and May.
With a magnitude of +9.6 and a high surface brightness, M65 is visible in binoculars from a dark site. Although dim, 10x50 binoculars display a brighter centre surrounded by fainter edges. Also visible in the same binocular field of view is M66. In total, M65 spans 8.7 x 2.4 arc minutes of apparent sky, appearing almost side on when viewed from our perspective. A small telescope such as an 80mm (3.1-inch) refractor nicely shows the elongation as a thin slivery disk of light with a brighter core. Subtle details can be made out of the galaxy hazy structure through medium sized telescopes of the order of 200mm (8-inch) aperture with even larger amateur telescopes revealing beautiful dark lanes within the galaxy's structure.
M65 is marginally the faintest of the Leo Triplet and similar in appearance to M66. Although NGC 3628 is similar in magnitude to M66 it's also the hardest to pick out due to its larger apparent size and lower surface brightness. Once you have identified all three, it's a worthwhile taking time to compare these wonderful galaxies through the eyepiece.
M65 Data Table
|Object Type||Spiral galaxy|
|Classification||SAB (rs) a|
|RA (J2000)||11h 18m 56s|
|DEC (J2000)||13d 05m 37s|
|Apparent Size (arc mins)||8.7 x 2.4|
|Number of Stars||200 Billion|
|Notable Feature||Member of the Leo Triplet along with M66 and NGC 3628|