Here are some tips on manually locating some of the most popular galaxies in the Messier Catalog.
M31 (the Andromeda Galaxy)
M31 (NGC 224), the Andromeda Galaxy, is a large Sb spiral galaxy (apparent size=185x75 arc minutes) and a member of the Local Group, as is our home galaxy, the Milky Way. It is the brightest of the Messier galaxies (magnitude=3.4, surface brightness=13.6 magnitudes per square arc minute) and the brightest galaxy visible to most northern hemisphere observers. M31 is best seen in the fall and early winter. The Andromeda Galaxy can be seen without optical aid from reasonably dark sites. From light-polluted urban locations, only the core of the galaxy is visible when viewed through a telescope.
M31 has four dwarf galaxy companions. Two of them, M32 (NGC 221) and M110 (NGC 205) are in close proximity. M32, a cE2 compact elliptical galaxy, is due south of M31's nucleus. M110, an E5 peculiar galaxy, ls located northwest of M31. M32 and M110 are the nearest bright elliptical galaxies. Much farther away in Cassiopeia lie NGC 147 and NGC 185, types dE5 peculiar and dE3 peculiar, respectively.
It is possible to observe M31's dust lanes and other features such as globular clusters and stellar associations telescopically under very dark skies. NGC 206 is a vast star cloud similar to but larger than M24. Mayall II (M31-G1) is M31's brightest globular cluster.
Sketches of M31, M32, and M110 are posted at the following URLs:
Many novices are interested in learning how to locate M31 manually. Here are three ways to do it:
1. Star-hop "down 2" stars northeastward from Alpheratz (Alpha Andromedae) to Mirach (Beta Andromedae), then head northwestward "up 2" stars to Nu Andromedae. M31 is situated 1.3 degrees to the west of Nu Andromedae.
2. Follow the apex of the triangle formed by Schedar (Alpha Cassiopeiae), the southernmost star in Cassiopeia, and the neighboring stars Caph (Beta Cassiopeiae) and Navi (Gamma Cassiopeiae), southwestward for just over fifteen degrees.
3. Use Mirach and Alpheratz to form a near right triangle with M31. M31 lies not quite eight degrees to the northwest of Mirach and approximately fourteen degrees to the northeast of Alpheratz.
The following finder charts may prove useful:
Telrad finder charts for M31 can be found at the following sites:
Other worthwhile sites include the following:
Short videos on M31, M32, and M110 can be seen at the following URLs:
M33 (the Triangulum Galaxy)
M33 (NGC 598), the Triangulum Galaxy, is another galaxy that many amateur astronomers are interested in observing. M33 is a type Sc face-on spiral galaxy with a rather high integrated magnitude of 5.7 but a very low surface brightness of 14.2 magnitudes per square arc minute, making it sometimes rather difficult to discern through a telescope, especially if any significant light pollution or moonlight is present. However, M33 can be seen with the naked-eye from a very dark site and is a relatively easy binocular target under dark skies. The fall and winter are the best times of year to observe M33.
M33 is approximately the same distance - seven degrees - to the southeast of the second-magnitude star Beta Andromedae (Mirach) as M31 is to the northwest. The Triangulum Galaxy lies 4.3 degrees northwest of the third-magnitude star Alpha Trianguli (Mothallah). One method of locating it is to start at Alpha and go 2.5 degrees west to the sixth-magnitude star HIP 7906. The seventh-magnitude star HIP 6862 is situated 3 degrees farther west. M33 lies a bit north of a line connecting these two stars and is closer to HIP 6862, the fainter star.
The following web sites may prove useful in locating M33:
Telrad finder charts are available at these URLs:
The views of M33 can be quite amazing through a large aperture at a dark observing site. Numerous HII regions can be detected within M33, NGC 604 being the brightest. A narrowband filter such as an Orion UltraBlock or an OIII filter such as a Lumicon OIII will enhance the views of these nebulous areas. NGC 604 is over 100 times larger than M42 and can be detected with rather small apertures. I've logged this huge star-forming region rather easily with my 101mm f/5.4 Tele Vue refractor from dark sites. Charts showing M33's HII regions and star clouds are posted at http://astronomy-mal...tar.Clouds.html and http://www.skyandtel...el110320150311/
For additional information on M33, click on the following links:
M51 (the Whirlpool Galaxy)
M51 (NGC 5194, integrated magnitude=8.4, surface brightness=12.6 magnitudes per square arcminute), a type SA(s)bc pec face-on spiral galaxy, and its irregular companion M51b or NGC 5195 (magnitude 9.6, surface brightness=13.1 magnitudes per square arcminute) are perhaps the most prominent example of an interacting pair of galaxies. They are best seen in the spring.
Due to the work of Lord Rosse In 1845, M51 was the first galaxy to be recognized as having a spiral shape. Of course, M51 was merely a "nebula" at that time, which was long before galaxies were determined to be objects external to the Milky Way.
M51 and NGC 5195 may be part of the M101 group of galaxies. Three supernovae have occurred in M51: SN 1994I, SN 2005cs, and SN 2011dh.
To star-hop to the Whirlpool Galaxy, proceed southwest from Alkaid (Eta Ursae Majoris), the final star in the Big Dipper's handle, to the fifth-magnitude star 24 Canum Venaticorum. Continue southwest to an isosceles triangle of seventh-magnitude stars. M51 and NGC 5195 lie just to the south of the triangle, approximately 3.5 degrees from Alkaid and 1/4 of the way to Cor Caroli (Alpha Canum Venaticorum).
Star-hops to M51 can be found at the following sites:
Telrad finder charts for M51 are available at the following sites:
For further information on the Whirlpool Galaxy, consult these sites:
M81 (Bode's Galaxy) and M82 (the Cigar Galaxy)
M81 (NGC 3031) and M82 (NGC 3034) are two bright galaxies in the northwestern section of Ursa Major. M81, a type Sb spiral galaxy, has an integrated magnitude of 6.9 and a surface brightness of 13.0 magnitudes per square arc minute. M82, a type Ir II irregular galaxy, shines at magnitude 8.4 and has a slightly brighter surface brightness of 12.8 magnitudes per square arc minute. M81 and M82 were discovered by the German astronomer Johann Bode on December 31, 1774. Together they are sometimes known as Bode's Nebulae.
To locate this galactic pair, pan from "above" Dubhe (Alpha Ursae Majoris) towards the "front" of Ursa Major. The next fairly bright star is 23 Ursae Majoris (magnitude 3.5). To the northwest of 23 Ursae Majoris lies a moderately bright isosceles triangle of stars consisting of Sigma 1 and Sigma 2 Ursae Majoris and Rho Ursae Majoris. Northeast of the triangle is 24 Ursae Majoris, which shines at magnitude 4.5. Southeast of 24 Ursae Majoris is a magnitude 5.7 star. M81 is immediately to the southeast of that star. M82 is situated about 2° southeast of 24 Ursae Majoris and just 38 arc minutes, a bit more than the width of a Full Moon, to the north of M81. Extending a line from Phecda (Gamma Ursae Majoris) to Dubhe the same distance beyond Dubhe places one approximately one degree south of M81.
Finder charts for M81 and M82 are posted at the following URLs:
An MP3 guide to locating M81 and M82 can be found at http://ia600708.us.a...ongtheStars.mp3
Telrad finder charts for M81 and M82 are available at the following URLs:
For more on M81 and M82, see the following sites:
M81 and M82 are the major members of the M81 group, which is one of the closest galactic congregations beyond the Local Group. NGC 2976 and NGC 3077 are two other member galaxies that are good targets.
M101 (the Pinwheel Galaxy)
M101 (NGC 5457), the Pinwheel Galaxy*, is a type Sc face-on spiral galaxy with an integrated magnitude of 7.9 and a very low surface brightness of 14.8 magnitudes per square arc minute, the lowest of all the Messier galaxies. Because of this fact, M101 is often a difficult target for amateur astronomers observing from less-than-dark sites. However, from a good dark site, this "grand design" spiral galaxy is fairly easy to detect through binoculars.
One method of locating the Pinwheel Galaxy is to imagine an isosceles triangle above the handle of the Big Dipper asterism made up of the second-magnitude star Alkaid (Eta Ursae Majoris, 85 Ursae Majoris), the final star in the handle, and the second-magnitude, naked-eye double star Mizar (Zeta Ursae Majoris, 79 Ursae Majoris) and Alcor (80 Ursae Majoris)**. M101 is located at the "upper" vertex of the triangle, as can be seen at http://www.aavso.org...1fe_chart_1.png
Another method of locating M101 is to star-hop northeastward from Mizar-Alcor (the Horse and Rider) to a chain of fifth and sixth-magnitude stars beginning with 81 Ursae Majoris. Continue eastward from 81 to 83 to 84 and finally to 86 Ursae Majoris. From 86 Ursae Majoris, proceed northeastward along a crooked "cross" of fainter stars. (Alternatively, M101 forms a right triangle with the two seventh-magnitude stars HIP 68196A and HIP 68138 north of 86 Ursae Majoris.) M101 is a bit past the top of the cross, as shown at http://www.ne.jp/asa...ject_e/m101.htm
Telrad finder charts for the Pinwheel Galaxy can be found at these sites:
Like M33, M101 contains a number of HII regions that can be seen through larger amateur telescopes. An article on these regions is posted at http://www.robgendle...m/M101text.html
A number of eleventh-magnitude and fainter companion galaxies surround M101.
The M101 group is also likely to include the M51 group to the southeast and possibly the NGC 5866 group to the northwest.
M101 has been the host galaxy to four supernovae, the most recent being SN 2011fe. For more on this very bright type Ia supernova, browse http://www.rochester...1/sn2011fe.html
See the following sites for additional information on M101:
* Unfortunately, M33 and M99 are also sometimes called the Pinwheel Galaxy.
** Mizar and Alcor are actually a sextuple star system.
M104 (the Sombrero Galaxy)
M104 (NGC 4594), commonly known as the Sombrero Galaxy, is one of the easiest-to-see galaxies in the Virgo Cluster. This type SA(s)a spiral galaxy shines at magnitude 8.0 and has the highest surface brightness (11.6 magnitudes per square arc minute) of all the Messier galaxies.
How does one go about star-hopping to the Sombrero? It's actually quite simple. Approximately 2.5 degrees to the northeast of Delta Corvi (Algorab) is a triangle of fifth and sixth-magnitude stars that points to the Stargate asterism. The Stargate is also triangular in shape and, in turn, points to an asterism to the northeast known as Jaws. Jaws lies 25 arc minutes west-northwest of M104. The brighter stars in Jaws point directly at the Sombrero Galaxy.
An alternative method of locating M104 is by following a line of fifth and sixth-magnitude stars heading northeastward from Gamma Corvi (Gienah).
A Telrad finder chart for the Sombrero Galaxy can be found at the following URL:
There's more on M104 posted at these URLs:
Click on http://www.deepskyvi...ero_galaxy.html for a short video on M104.