M77 is a notable 9th magnitude face-on barred spiral galaxy in the constellation of Cetus. This galaxy contains an Active Galactic Nucleus (AGN), which although obscured by dust at visible wavelengths is detectable due to strong emissions in the infrared, ultraviolet, and X-ray regions of the electromagnetic spectrum. This type of galaxy is known as a Seyfert galaxy, named after 20th century American astronomer Carl Seyfert who first identified the class in 1943 of which M77 is the brightest example. They are believed to be home to supermassive black holes of between 10 and 100 million solar masses.
M77 was discovered by Pierre Méchain on October 29, 1780. He described the object as a nebula and subsequently reported it to Charles Messier who then added it to his catalogue. Messier and later William Herschel both described M77 incorrectly as a star cluster.
The galaxy is located about a degree southeast of delta Ceti (δ Cet - mag. +4.1) and a few degrees northeast of the famous long period variable star, Mira. The constellation Cetus in Greek mythology represented a Sea Monster, although today it's often referred to as the Whale or the Shark. It's the fourth largest constellation in the sky covering 1231 square degrees and is bordered by Aries, Pisces, Aquarius, Sculptor, Fornax, Eridanus and Taurus.
M77 is best seen during the months of September, October and November.
Although it shines at magnitude +9.1, M77 is a compact galaxy with a bright center and therefore a relatively easy target for large binoculars (15x70s or 20x80s) and small telescopes. It can be spotted with 10x50 binoculars from dark sites with ideally good seeing conditions. An 80mm (3.1-inch) scope shows the galaxy as a condensed ball of fuzzy light with a slightly brighter central core. A 100mm (4-inch) telescope enhances the view with the galaxy displaying an oval shaped halo surrounding a bright center. When viewed through 200mm (8-inch) reflectors the details are more pronounced with the central core evident and almost stellar like. The large surrounding diffuse halo is prominent. Just east of M77 is a notable star.
M77 is a magnificent galaxy and one of the largest in Messier's catalogue. It's estimated to be at least 47 Million light-years distant. With an apparent size of 7.1 x 6.0 arc minutes this corresponds to an actual diameter of 100,000 light-years. Images of the outer spiral extensions suggest that the galaxy is probably even larger than this. The stars in the inner region of M77 are young, while those away from the centre tend to be older.
This was one of the first recognized spiral galaxies and was listed by Lord Rosse as one of 14 "spiral nebulae" discovered to 1850. When Vesto Slipher was working on galaxy spectra, M77 was one of two galaxies in which he detected large redshifts (the other being the Sombrero (M104)).
M77 Data Table
|Object Type||Barred spiral galaxy|
|Distance (light-years)||47 Million|
|RA (J2000)||02h 42m 41s|
|DEC (J2000)||-00d 00m 47s|
|Apparent Size (arc mins)||7.1 x 6.0|
|Number of Stars||>300 Billion|
|Other Name||Arp 37|
|Notable Features||Brightest Seyfert galaxy and one of the largest Messier galaxies.|