Deep-Sky Images
Deep-Sky Images
| Group Name | dso |
| Reference | NOAO, see dso.speck file for image credits |
| Prepared by | Nate Greenstein, Matt Everhart, Ryan Wyatt, Brian Abbott (AMNH/Hayden) |
| Labels | Yes |
| Files | dso.speck, dso.label |
| Dependencies | Various images |
| Census | 65 images |
“Deep-sky” is a term familiar to avid sky watchers as an object in the sky that is not a star or planet. These include open and globular star clusters, nebulae, supernova remnants, and even galaxies. Often invisible to the unaided eye, they require binoculars or a telescope to view them.
The first list of such objects was compiled by Charles Messier (1730-1817), a French astronomer who was searching for comets. Comets resemble diffuse, fuzzy objects, and with the low-power optics of the day, star clusters, nebulae, and galaxies looked like diffuse comets too. In order to distinguish these static nebulae, clusters, and galaxies from the comets that move in the sky, Messier created a list of the stationary diffuse objects so he would not confuse them with the comets he was searching for. The resulting list contains 110 objects beginning with Messier object 1, or M1, also known as the Crab Nebula, and ending with M110, a small satellite galaxy of the Andromeda Galaxy, which itself is called M31.
The dso data are 2-D images of Messier objects placed in 3-D space. Not only do we place our images at the proper location and give them the correct orientation, we also size them accurately so that you can fly to the globular cluster M13, for example, and see just how small the cluster of hundreds of thousands of stars is relative to the rest of the Galaxy.
The group consists mainly of open star clusters, globular clusters, diffuse nebulae, and planetary nebulae. All together, sixty-seven of the Messier objects are represented in 65 images (M32 and M110 appear in the image for M31). We do not include galaxies outside the Local Group or objects for which we have 3-D data, which is often superior to a 2-D image. For example, you will not see the Orion Nebula (M42 and M43) because we have a 3-D Orion Nebula model in the atlas. Similarly, we have 3-D stars in place for M45 (Pleiades), M44, and a few other open star clusters. Below we list the Messier objects included in the dso group.
| Object type | Messier objects included |
| Open star clusters | 6, 7, 11, 16, 18, 21, 23-26, 29, 34-39, 41, 46-48, 50, 52, 67, 93, 103 |
| Globular star clusters | 2-5, 9, 10, 12-15, 19, 22, 28, 30, 53-56, 68-72, 75, 79, 80, 92, 107 |
| Planetary nebulae | 27, 57, 76, 97 |
| Diffuse nebulae | 8, 17, 20, 78 |
| Supernova remnants | 1 |
| Galaxies | 31, 32, 33, 110 |
You may know some of these objects by their common names:
| M1 | Crab Nebula |
| M8 | Lagoon Nebula |
| M16 | Open cluster (in the Eagle Nebula) |
| M17 | Omega Nebula |
| M20 | Trifid Nebula |
| M27 | Dumbbell Nebula |
| M31 | Andromeda Galaxy |
| M57 | Ring Nebula |
| M97 | Owl Nebula |
I Don't See Any Images!
By default, the dso data group is on when you launch the Milky Way Atlas, but you are not likely to notice them just as you don't typically see these objects in the night sky. This is due to their size, which in most cases is quite small. One way to pick them out is to turn on the labels for the group. To see the image, you can either zoom in from your current location on Earth, or fly out to the object.
To view the images from Earth's position, you can use Partiview to simulate how we see these objects in the night sky when looking through binoculars or a telescope. Center one of the objects in your view and select fov from the Slider Menu. The default value for the Digital Universe is 60o. To zoom in, decrease the field of view by moving the slider to the left. You may need to center the object as you zoom in. The value to the left of the slider is the field of view of your window in the up-down direction in degrees. A value of 5-10 degrees might simulate a pair of binoculars while a value less than 0.5 replicates a telescopic view.
Of course, you can also exaggerate the size of the images by changing the polygon size of the data group, but we don't recommend this as a means of seeing the images since it grossly misrepresents these data. However, if you do increase the polygon size by choosing polysize from the Slider Menu, a polygon size of 1.0 will bring them back to their actual size.
Image Credits
For information such as credits, place your mouse over an image and hit the p key. This picks an object in your view, which will be challenging if you have a lot of data in your view. For example, if you zoom in on M27, the Dumbbell Nebula, and hit the p key while your mouse is over the image, you will see the following one-line report in the Console Window:
[g28]Picked -121.574 -217.853 -16.117 (w121.574 217.853 -16.117)The first numbers describe the location of the object selected, followed by the object name and image credit in quotes, followed by other metadata values associated with the data point.
"M27 (Joe and Gail Metcalf/Adam Block/NOAO/AURA/NSF)"
@250 (of 2); texture 27 radius 0.2568
© 2002-2005 American Museum of Natural History
Last Modified: 2007-12-19 by Brian Abbott