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Cosmic Challenge: North America Nebula (NGC 7000)


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Cosmic Challenge:

North America
Nebula (NGC 7000)

 

September 2018

Phil Harrington

This month's suggested
aperture range:

 

Target

Type

RA

DEC

Const

Mag

Size

North America
Nebula (NGC 7000)

Emission
nebula

20h
58.0m

+44°
20.0'

Cygnus

--

120'x120'

 

The North America Nebula (NGC 7000) is a large expanse of glowing hydrogen gas mixed with opaque clouds of cosmic dust just 3° east of Deneb [Alpha (α) Cygni] and 1° to the west of 4th-magnitude Xi (ξ) Cygni.  Famous as one of the most luminous blue supergiants visible in the night sky, Deneb marks the tail of Cygnus the Swan, or if you prefer, the top of the Northern Cross asterism.

 

Above: Summer star map showing the location of this month's Cosmic Challenge.

 

Credit: Map adapted from Star Watch by Phil Harrington

 

Above: Finder chart for this month's Cosmic Challenge.

 

Credit: Chart adapted from Cosmic Challenge by Phil Harrington
Click on the chart to open a printable PDF version in a new window

 

The North America Nebula epitomizes how observational astronomy has evolved over the years.  When he discovered it on October 24, 1786, Sir William Herschel (1738-1822) described the view through his 18.7-inch reflecting telescope as "very large diffused nebulosity, brighter in the middle."  Honestly, I am surprised he could see it at all because of his instrument's very narrow field of view.  That's one of the biggest challenges to seeing the North America Nebula through a telescope -- it spans an area nearly 2° in diameter.  From the sounds of Herschel's notes, the thought of trying to spot it in anything less never crossed his mind.

Five score and four years later, the German astronomer Max Wolf became the first to photograph the full span of NGC 7000.  Upon seeing his results, he christened it the North America Nebula for its eerie resemblance to that continent.  Since then, images of this vast emission nebula have appeared in nearly every introductory astronomy textbook and coffee-table astrophoto album alike.

Before the 1970s, conventional wisdom had it that, although this huge celestial continent was prominent in photographs, it was nearly invisible to the human eye because it was too large and too red.  Part of that mindset has to be attributed to the observing guides that were in print at the time.  Nearly all concentrated solely on telescopic observing.  They were so fixated on what could be seen through conventional long focal length instruments using the comparatively narrow field eyepieces of the day that they ignored other options.   And since NGC 7000 could not squeeze into a single field of view, it was nearly impossible to isolate its clouds from their surroundings.

One of the first authors to mention the North America Nebula, though not by name, was the Reverend Thomas W. Webb.  In volume 2 of his classic compendium Celestial Objects for Common Telescopes (
), Webb described the nebula as having a "sharply defined south [edge], and containing a dark opening like a cross; visible as a glow in a field glass, but brightest part scarcely visible in 17¼-in reflector."

Still, most considered seeing the North America Nebula by eye to be futile.  The winds of change began to blow, however, with the landmark work Burnham's Celestial Handbook, published originally in 1966.  Author Robert Burnham, Jr., advised "Binoculars show an irregular glow more than 1½° in diameter with the North American shape becoming unmistakable on a clear night.  Perhaps the best view of the unusual outline is obtained with a 3 or 4-inch rich-field telescope and wide-angle eyepiece."

 

Above: The North America Nebula (upper left) and surroundings.  The bright star Deneb is to its immediate right.  Photo credit: Kevin Dixon, www.magnificentheavens.com

 

 

Another pioneer who urged amateurs to look for the North America Nebula was Walter Scott Houston (1912-1993).  Throughout his nearly half century of penning the Deep-Sky Wonders column in Sky & Telescope magazine, Houston often mused about seeing this difficult object.  His evolving views captured the changing attitudes over its visibility.  For instance, in his September 1948 column, he wrote, "the North America nebula near Deneb cannot be observed readily without photography."  But then, fast forward several decades to find Scotty advising "if observing conditions are very good, and you know what size and shape to expect, the North America Nebula can be made out easily with the naked eye."

Part of that change in attitude was undoubtedly due to the advent of narrowband nebula filters in the 1970s.  As previously discussed, these filters block light at all but a few select visible wavelengths.  Narrowband filters pass only the hydrogen alpha (656nm), hydrogen beta (486nm), and oxygen III (496nm and 501nm) regions, where emission nebulae are strongest.  The net result is increased contrast between the object under observation and the filter darkened background. As a result, the North America Nebula is now a regular target at summertime star parties.

That still doesn't address the size issue, however.  For that, we turn back to Burnham and Houston, who advise using binoculars or small, rich-field telescopes.  Let's take it one step further.  Can we spot the North America Nebula without any optical aid at all, save for perhaps a narrowband filter?

To try this yourself, first, can you see the Cygnus Milky Way clearly?  A reasonably dark suburban sky should be sufficient, but be sure to look when Cygnus is nearest the zenith in order to isolate it from any errant clouds or light pollution.  Zero in on the area between Deneb and Xi (ξ) Cygni, which lies at the edge of the Northern Coalsack, a large expanse of dark nebulosity at the northern terminus of the Milky Way's Great Rift.  The Great Rift slices the galactic plane in half lengthwise, extending southward from Cygnus through Vulpecula, Sagitta, and Aquila on its way toward Sagittarius.  The brightest part of the North America Nebula, marking "Mexico" and "Florida," juts into the Northern Coalsack in much the same way as their earthly counterparts mark the Gulf of Mexico's shoreline.  The nebula's hook-shaped glow appears slightly brighter than the Milky Way immediately surrounding it, but be forewarned that, by eye alone, it is deceptively small.  If you cannot see it by eye alone, try using a narrowband filter.  It might be best to try the filter test with a friend who owns the same filter as you, since viewing through a pair of filters is preferred.  Otherwise, you will lose the two-eyed advantage by squinting through only one eye.

 

Have a favorite challenge object of your own?  I'd love to hear about it, as well as how you did with this month's test.  Contact me through my web site or post to this month's discussion forum.

 

Until next month, remember that half of the fun is the thrill of the chase.  Game on!



About the Author:

Phil Harrington writes the monthly Binocular Universe column in Astronomy magazine and is the author of 9 books on astronomy.  Visit his web site at www.philharrington.net to learn more.

Phil Harrington's Cosmic Challenge is copyright 2018 by Philip S. Harrington.  All rights reserved.  No reproduction, in whole or in part, beyond single copies for use by an individual, is permitted without written permission of the copyright holder.

 


  • okiestarman56, John O'Hara, warddl and 1 other like this


21 Comments

Photo
Astrojensen
Sep 01 2018 05:58 PM

NGC 7000 a challenge? Certainly not from dark skies, where common binoculars show it nicely, but I can see it being a challenge from light polluted areas. 

 

 

Clear skies!

Thomas, Denmark

    • TieDyeAstronomer likes this
Photo
Astro-Master
Sep 01 2018 07:16 PM

My Stellarvue 60mm finder with a Nagler 13mm plus a 1.25" O III filter gives a power of 17x and a field of 4.7.*  It frames the Neb nicely from a dark site.

    • Tyson M likes this

It’s certainly a challenge from where most observers live. I still haven’t seen it from the Connecticut suburbs.

I have yet to see this surprisingly, although in the area often in summer and at a dark site. I'll have to look closer and with a wider fov.

Photo
Astrojensen
Sep 03 2018 02:09 PM

One wonders why it took so long before it became known as a visual deep-sky object. I've seen it quite a few times through a 63mm Zeiss achromat with a 40mm huygenian eyepiece, yielding 21x and a 2° field of view. Such a scope/eyepiece combination has been available since the days of Messier...! It is rather easy in this combination, if the skies are dark. No filter is needed. It is FAR easier to see than the Veil and Rosette with this scope and eyepiece. 

 

 

Clear skies!

Thomas, Denmark

    • Sasa likes this

While I can see a lot from my backyard observatory, this remains elusive, the light pollution drowns it out. I can see it from a remote dark site though. 

One wonders why it took so long before it became known as a visual deep-sky object. I've seen it quite a few times through a 63mm Zeiss achromat with a 40mm huygenian eyepiece, yielding 21x and a 2° field of view. Such a scope/eyepiece combination has been available since the days of Messier...! It is rather easy in this combination, if the skies are dark. No filter is needed. It is FAR easier to see than the Veil and Rosette with this scope and eyepiece. 

 

 

Clear skies!

Thomas, Denmark

This is (almost) exactly how I saw it the very first night with a telescope that was given to me by a friend. For that occasion I went to my darker-site observatory. It was a telescope from his youth, with very basic OTA but with fantastic lens, C63/840. The same one as in Telementor. There was no way how to attach my 40mm Kellner other than to hold it pressed against the focuser. By far this was my best view of NGC7000, the shape was so obvious. I don't remember seeing such nice silk-like nebulosity. On the way from Deneb to NGC7000, I easily noticed another nebular patch. It took me few seconds to realize that this was the head of Pelican nebula.

 

It must have been an exceptional night. I have never saw NGC7000 that nicely, before of after. Neither in Telementor or in other of my scopes, despite looking at NGC7000 several times per season.

 

From our light polluted backyard, I feel lucky if I can sense the outlines of Mexican Gulf.

 

As for naked eye observation. I looked at NGC7000 on various  occasions. There is definitely some brightening in this region but I was never able to convince myself that what I saw was the nebula and not just some brighter patch in Milky Way.

Thanks for all of the comments!  Some are mentioning about its visibility through telescopes, which is great.  But the challenge presented here is to see it naked eye -- which personally I find to be easier than through many telescopes.

 

The trick is to know what to look for.  The NA Nebula does look like a slightly brighter patch of the Milky Way adjacent to Deneb.  The giveaway is noticing the arc of the "Gulf of Mexico."  If you see that, then congratulations, you've nabbed it.

 

Sasa also mentioned the Pelican Nebula.  That's a great binocular challenge.  Maybe I'll hold on to that one until next summer.

    • Astrojensen, Sasa, Susan H and 1 other like this
Photo
TieDyeAstronomer
Sep 05 2018 07:43 PM

I've looked for the North American Nebula with the naked eye from dark skies before, both from Texas Star Party, and from a site in the Ozarks with some of the best skies that I've seen outside of TSP (Bortle 3). I have never been able to suspect it.

 

However, I have been able to quite clearly see the shape of the North American Nebula, complete with Central America and the Gulf of Mexico-- but it's not the nebula at all, rather the rich star cloud to the northeast of Deneb. I know this for two reasons: the observed object is too large (as Phil says in the article, the nebula is deceptively small), and the "gulf" of this illusionary cloud faces east instead of south.

I mention this so that others who go looking for it with the naked eye know what to be aware of. The nebula should not appear 3-4+ degrees across! 31 and 32 Cyg, the wide double just on the other side of Deneb, should make a good yardstick. The size of the "Gulf of Mexico" of the real nebula should only be about 3/4th the distance between 31 and 32 Cyg, maximum. The best test is probably just to see if the Gulf of Mexico faces south (real) or east (star cloud). If you do observe the nebula with the naked eye, please share your observing report! I'd like to hear under what conditions the real thing is visible.

 

Here is a screenshot from the Photopic Sky Survey website (http://media.skysurv...e360/index.html) showing the false-nebula shape of the starcloud outlined:

KX7EnsC.png

Clear Skies!

Lauren Herrington

    • Dave Mitsky, paulsky, PhilH and 4 others like this

24hrs ago was some of the clearest skies I’ve had all summer. Mag 5 stars visible. Bottle 5. Milky Way bright and M31 as a smudge. As mentioned in the above post though, I’m not sure I could make out the difference between the star field and any perceived nebula. Using binoculars allowed me to convince myself that I can glimpse it in my 9x63’s, but I had to use charts and online images to confirm. Very faint, requiring averted vision. Quite a challenge for me even with binoculars! Did see numerous meteors including a very nice fireball with fragmentation! Clear and steady skies.......

    • PhilH, Sasa, Susan H and 1 other like this

I've looked for the North American Nebula with the naked eye from dark skies before, both from Texas Star Party, and from a site in the Ozarks with some of the best skies that I've seen outside of TSP (Bortle 3). I have never been able to suspect it.

 

However, I have been able to quite clearly see the shape of the North American Nebula, complete with Central America and the Gulf of Mexico-- but it's not the nebula at all, rather the rich star cloud to the northeast of Deneb. I know this for two reasons: the observed object is too large (as Phil says in the article, the nebula is deceptively small), and the "gulf" of this illusionary cloud faces east instead of south.

I mention this so that others who go looking for it with the naked eye know what to be aware of. The nebula should not appear 3-4+ degrees across! 31 and 32 Cyg, the wide double just on the other side of Deneb, should make a good yardstick. The size of the "Gulf of Mexico" of the real nebula should only be about 3/4th the distance between 31 and 32 Cyg, maximum. The best test is probably just to see if the Gulf of Mexico faces south (real) or east (star cloud). If you do observe the nebula with the naked eye, please share your observing report! I'd like to hear under what conditions the real thing is visible.

 

Here is a screenshot from the Photopic Sky Survey website (http://media.skysurv...e360/index.html) showing the false-nebula shape of the starcloud outlined:

KX7EnsC.png

Clear Skies!

Lauren Herrington

Thanks, Lauren!  Great point about the faux NA Nebula.  Honestly, I hadn't noticed it, but you're right.  It looks to be quite a bit larger than the real thing.  Plus, it's flipped!

 

BTW, when I saw your post last night, I think for a second we might be related.  (Harrington vs. Herrington)  :-)  Bet there's a common lineage somewhere way back when.

    • TieDyeAstronomer likes this
Photo
Dave Mitsky
Sep 07 2018 02:02 PM

Sasa also mentioned the Pelican Nebula.  That's a great binocular challenge.  Maybe I'll hold on to that one until next summer.

I've seen IC 5070 and IC 5067 (the Pelican Nebula) a number of times through binoculars and filtered rich-field telescopes but only from very dark sites.

https://astrobackyar...pelican-nebula/

 

Dave Mitsky

    • PhilH and Sasa like this

I've seen IC 5070 and IC 5067 (the Pelican Nebula) a number of times through binoculars and filtered rich-field telescopes but only from very dark sites.

Dave,

 

If there is a BOO program at Stellafane next year, you can bet that the Pelican will be on it.  Saw it through my Fuji 16x70s fairly distinctly this year.

    • paulsky and John O'Hara like this

My Zeiss 7x50 ( II World War Era ) is a fantastic binocular in a dark sky environements, and the NA is a beauty object, as for naked eye observation I could guess !!

thanks Phil for the interesting "challenges".

Paul

    • PhilH likes this

May be going up to my folks' place in East Texas soon. Will try to spot it from there. Thanks again, Phil!

    • PhilH likes this

I've looked for the North American Nebula with the naked eye from dark skies before, both from Texas Star Party, and from a site in the Ozarks with some of the best skies that I've seen outside of TSP (Bortle 3). I have never been able to suspect it.

 

KX7EnsC.png

Clear Skies!

Lauren Herrington

I have seen something there from Bortle 2 and 3 skies with naked eye, and absolutely no doubt of the sighting because I could see it in my image intensified monocular easily and position was the same.

 

The difference though was profound.   I did not detect a definable shape with the naked eye.  I saw only a faint patch of light at the very edge of my detection threshold, with a somewhat suggestive outline shape of the real object.  The gulf region was not at all resolved as a true shape with the naked eye (in my own case, and this is not to say at all that anyone that reports seeing it did not see it.. I tend to take people at their word, and this object has been reported enough that it is pretty credible if people say they saw more than I see, but I don't see much there.   Very poor target for naked eye.  Absolutely a threshold object for me.  Not a chance really of seeing much more than the faintest possible glow, and maybe that is simply the stars in the nebula playing a trick on me (there are a lot of Mag 7 and Mag 8 stars inside the borders). 

 

In the night vision monocular of course it is a pretty epic sight because the entire area around it is also very rich with nebula. The entire region of nebula around it and including it that I can see at 1x under dark sky is approximately 8 degrees running WSW to ESE and about 5 degrees across this axis.  It is a giant patch of nebula of which Pelican and NA simply happen to be brighter than the background of extensive glowing gas.

 

I have seens something there though but again, it really did not show much in the way of structure with naked eye, and I did not use a filter.  Just looked up.   Conditions were again Bortle 2 and Bortle 3, and in both cases, NA was very near zenith. 

 

Using NV, I can of course see it easily from my red zone sky but the stunning richness of nebula around it is greatly muted. Even with image intensifiers, there is no substitute for dark skies.

    • paulsky, PhilH and TieDyeAstronomer like this
Photo
John O'Hara
Sep 23 2018 04:47 PM

I've spied it from the dark skies of Cherry Springs State Park with the naked eye on several occasions, given top transparency.  While I know the subject of this article is observing it with the naked eye, I thought I'd mention that the night of Saturday, 9/15 I had one of the nicest views of the NA and Pelican ever.  I'd won an APM 30mm UW 80 degree eyepiece at the Black Forest Star Party.  While not a "sharp to the edge" eyepiece, even in my f/9 100mm ED, it did provide some very nice views.  I measured the eyepiece's field stop at 46.5 mm, which comes out to 88.8 deg. AFoV providing almost 3 degrees in the 100 ED.  This eyepiece, in that scope, with a 2" Lumicon OIII, provided a breathtaking view of this region

    • PhilH and Sasa like this
Photo
NorthernlatAK
Sep 24 2018 12:31 AM
I'm located in alaska and when transparency is good I can see it naked eye. Never could until I moved up here and I've tried my whole life to see it (45 now). Last week the milky way looked like lp it was so bright. N America was at zenith almost and definitely there. If transparency isn't top notch i can't see it as later that night some slight haze made it disappear.
    • PhilH and deepwoods1 like this
Photo
NorthernlatAK
Sep 24 2018 12:36 AM
On typical nights I see the star cloud, struggling to make out the nebula. The good nights the star cloud has a little "extra something"
    • PhilH likes this

Transparency has been mentioned often in ones ability to see this naked eye. Not something I’ve had a lot of this year. Skies may have been clear of clouds, but there always seem to be moisture in the air. Perhaps by Winter the skies will clear up? By then of course the will be a new set of objects to see. Clear and steady skies....

    • PhilH likes this
Photo
John O'Hara
Sep 25 2018 04:42 AM

I'm just old enough to remember the days when the NA and Veil were considered photographic objects, not visible visually in a telescope.  Of course, these were pre-light pollution filter days, and most eyepieces had 50 degree, or less AFoV.  Now we go for the NA naked eye from dark sites.

    • PhilH likes this


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