Challenge #3 – C65, Sculptor Galaxy in Sculptor
| Target | Type | R. A. | Dec. | Constellation | Magnitude | Size |
| C65 (NGC 253) | Spiral Galaxy | 00h 47m 33s | -25° 17′ 18″ | Sculptor | +7.0 | 27×4.6 arcmin |
Overview
You’ll find the name William Herschel many, many times throughout the hundreds of guides inside the VAC, but rarely do I have the opportunity to mention his sister, Caroline, an astronomer in her own right. She discovered NGC 253, Sculptor Galaxy, in September 1783, which Sir Patrick Moore included as the 65th object in the Caldwell Catalog.
This is one of the brightest galaxies in the night sky, only just out of reach of naked eye visibility, and it contains some of the densest patches of stars that we’ve ever discovered. It’s the name-giver and brightest of the Sculptor Group of galaxies, which is the closest one to our local group at just under ten million light-years away. Its other members also appear as Caldwell objects: C62, C70, and C72 are all gravitationally bound to this galaxy.
It’s an intermediate spiral, midway between a barred and unbarred variety. It’s also a starburst galaxy, a name given to galaxies rich with active star formation. At its heart is believed to be a supermassive black hole five million times more massive than the sun. The whole galaxy is about 120,000 light-years from edge to edge.
Finder Charts
The first sky chart, from SkySafari 6, shows the view looking south at 10 pm in the middle of November.
We’re looking for Cetus, the whale constellation, to begin our hunt for this galaxy. To find the right part of the sky, use the obvious signposts of the Great Square of Pegasus and Orion, both circled orange below. Cetus swims to the south of the Great Square.
This first chart shows stars to magnitude 5.0, and the moon and planets are not shown.
The second chart still only shows stars to magnitude five. We can see the bright star Deneb Kaitos (Beta Ceti) shining at magnitude 2.0 on the southern edge of Cetus. South of that, not the brightest star of Sculptor, Alpha Sculptoris, which is a much fainter magnitude 4.3.
The Sculptor Galaxy is a little southwest of the midpoint of the imaginary line that connects these two stars, shown in orange in the chart below.
Stars are shown to magnitude seven in this final finder chart and you can see Alpha Sculptoris just visible at the base of the chart. Our galaxy is inside the same 1.5° field of view as the magnitude 5.9 star HR 228. This is about 5° away from Alpha Sculptoris.
Although this looks like it could still be a tough spot, there are two things that make it easier. Firstly, the galaxy is very bright – rivalling Andromeda. This makes it easy to pick up in binoculars or a magnifying finderscope. Secondly, there is very little in its immediate surroundings bright enough to confuse us. In essence, if you think you’ve found it, you probably have!
In the last section, you’ll discover what you should expect to see of this excellent galaxy once it’s in your eyepiece.
Individual Telescope Views
The following views will help you find C65 in different telescope types by presenting the images as your telescope will show them. The first image is with a black sky and white stars, the second picture is the same image but presented in inverse monochrome. Stars are shown to magnitude 10.0 and the star HR 228 is the brightest one near to the N marker at the edge of the 1.5° field of view.
Each image can be clicked on for a full-screen version.
Upright View – This is what your eyes see unaided and through a reflex or red-dot finderscope
Upside-down view – This is what reflectors and magnifying finders show, and refractors / Cassegrains without a star diagonal
Mirrored View – Refractors and Cassegrain models with a star diagonal show this view
Observation
This is a true joy of a galaxy to observe, rivalling the mighty Andromeda Galaxy in the eyepiece!
With a dark sky as your backdrop, a modest 4″ telescope reveals structure in this distant object. Note that the galaxy’s orientation is northeast to southwest and that we’re seeing it compressed into a spindle shape because it’s more edge-on than face-on to us.
We can see the mottling texture of these billions of stars interacting with each other and dust clouds to form different densities of light. At these low magnifications, we can immediately see the core is brighter than its surroundings, and swapping to a higher power only improves the distinction. It also better clarifies where the edges of the galaxy reach to.
If you’re fortunate enough to own a larger telescope, this bright galaxy will treat you at higher magnifications. We can see better detail in the mottling, more complexity at the heart of huge star pool, and you might even glimpse the dust lanes that run north of its core.
PDFs for Printing
Each of the star maps above is reproduced as a pdf below. Each star map has a number in [square brackets] beneath it which corresponds to the file number below. If you want image [C65-1], for example, click the ‘download’ button next to it below and you’ll be able to open it as a printable pdf.