C20, The North America Nebula in Cygnus
| Target | Type | R. A. | Dec. | Constellation | Magnitude | Size |
| C20 (NGC 7000) | Bright Nebula | 20h 58m 48s | +44° 20′ 00″ | Cygnus | +4.0 | 120×100 arcmins |
Overview
You can see from the table above what a gigantic feature the North America nebula is. Keep in mind that the full moon is about 30 arcminutes wide, and you’ll find that C20 is four times wider! Its total area is over ten times that of our planet’s neighbor.
And yet… it’s very much fainter.
This is why most people have never noticed it, despite its close proximity to one of summer’s most obvious constellations. Thankfully, pretty much any optical magnification and a dark sky reveal it to us backyard astronomers.
William Herschel first discovered this hazy glow in October 1786, but it wa Max Woolf who coined its name after taking its photograph for the first time in 1890.
We only very recently tied down the distance of this gigantic hydrogen gas cloud to 2,600 light-years away. The entire cloud, of which the North America nebula is just a part (along with the Pelican nebula), is 140 light-years across. The North America nebula is about 90 light-years wide.
The light from the nebula is due to an ionizing star which is cataloged as J205551.3+435225 (more helpfully known as the Bajamar Star) and shines at a temperature of over 40,000 Kelvin. It’s hidden from us behind a dust cloud and so is only magnitude 13. Were our view of it unobstructed, it would shine at magnitude 3.6, almost as bright as Alberio.
Finder Charts
The first sky chart, from SkySafari 6, shows the view looking south at 10 pm in the middle of July. The moon and planets are not shown and stars are only shown to magnitude 5.0.
We need to begin our search by finding Cygnus the swan. This is a bright and obvious constellation in summer evening skies, looking like a large, bright cross. It’s shown inside the large orange circle in the chart. To the left (north) is the Little Dipper, home of the Pole Star.
C20 (shown as NGC 7000) is near the bright star Deneb, at the ‘tail’ of the swan.
Pick out the star Deneb. It’s the brightest star in the constellation, shining at magnitude 1.3, and also one of the three bright stars that make up the Summer Triangle asterism.
Less bright, but still comfortably visible to the naked eye, is Xi Cygni, shining at magnitude 3.7. C20 lies between these two stars.
In this final chart, you can see more clearly how large the feature is compared to the 1° field of view circle included in blue.
Note the relative positions of Deneb and Xi Cygni.
Now you’ve found this bright nebula, what should you expect to see?
Individual Telescope Views
The following views will help you find C20 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. Black stars on a white background is often easier to use at the telescope. Each image can be clicked on for a full-screen version. Stars are shown to magnitude 10.0 and the star Xi Cygni is also shown in each image. The ring is a 1° field of view.
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
Begin with as large a field of view as you can muster to bring the full scale of this gas cloud to life. It’s a hazy but obvious glow giving the many stars contained within it a wispy curtain to hide behind.
Unless you have a very dark sky, your view should be enhanced by using an OIII or narrowband filter.
Within the gas cloud is an elliptical open cluster of stars cataloged as NGC 6997. These are very faint but a larger scope allows you to pick out a few dozen individuals. Discover this where you’d find Ohio on a map of the States.
The nebula itself is riven with brighter stripes and fainter areas. Some regions are stronger to determine while others are patchy and inconsistent. Take your time to drink in the splendor of this view and while you can use stronger magnification to tease out details, your best appreciation of the whole object will come from wider fields of view.
Once you’ve seen this object for the first time, it’s a view you’ll commit to seeing time and again when the clear summer skies beckon.
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 [C20-1], for example, click the ‘download’ button next to it below and you’ll be able to open it as a printable pdf.