Deep Sky Objects
In simple terms, any celestial object or a group of celestial objects that is / are not a part of the solar system or individual star is known as a Deep Sky Object (DSO). They’re objects of interest among the astronomy community and are treated differently, one of the reasons being that while tracking the object using an equatorial mount, you only need to move the mount in the RA axis to make sure that the object is always in frame. The list of DSOs includes but not limited to:
- Star Clusters
- Nebulae
- Galaxies
In order to know what is what, astronomers have come up with catalogues, “cataloguing” DSOs. Many widely used catalogues include the Messier Objects Catalogue and NGC Objects Catalogue.
Messier Objects
Initially containing only 45 DSOs, the yet unnumbered Messier Catalogue was made by the French Astronomer, Charles Messier in 1774. Most of the objects were visible from the northern hemisphere, owing to Messier’s place of origin and observation. Subsequently, the list was expanded and numbered by various astronomers and now included 110 objects.
Charles Messier initially wanted to hunt down coments. But due to the relatively rare occurence of comets visible from the naked eye and the abundancec of DSOs, the frustrated Messier created a list of objects that were causing a problem for his hunt of comets.
A list of the most famous Messier Objects, their number and the constellation in which they’re found is given below:
| Number | Name | Constellation |
|---|---|---|
| M45 | Pleiades | Taurus |
| M31 | Andromeda Galaxy | Andromeda |
| M42 | Orion Nebula | Orion |
| M22 | Sagittarius Cluster | Sagittarius |
| M33 | Triangulum Galaxy | Triangulum |
| M20 | Trifid Nebula | Sagittarius |
| M16 | Eagle Nebula | Serpens |
| M27 | Dumbbell Nebula | Vulpecula |
| M101 | Pinwheel Galaxy | Ursa Major |
| M104 | Sombrero Galaxy | Virgo |
| M1 | Crab Nebula | Taurus |
| M51 | Whirpool Galaxy | Canes Venatici |
| M57 | Ring Nebula | Lyra |
You can download the complete list of messier objects from here
NGC Objects
The New General Catalogu of Nebulae and Clusters of Stars (NGC) is the most widely used astronomy catalogue published in 1888 by John Louis Email Dreyer. It contains 7,840 objects and supplements to it, known as Index Catalogies (ICs) contain an additional 5,386 objects, making it one of the, if not the most exhaustive catalogues of DSOs. Some of the most stunning images of the universe you see or will see ever are the images of one or multiple of these objects.