Tag: Binoculars

Jim's Corner Blog

NGC 7000 (The North America Nebula) and NGC 5070 and IC 5087 (The Pelican Nebula)

James Chen |
The North America Nebula and the Pelican Nebula (Illustration courtesy of Jon Talbot. Used with permission.)

Often referred to erroneously as the North American Nebula, the North America Nebula is an emission nebula in the Cygnus, close to the bright star Deneb. The Pelican Nebula is an emission nebula located with the North America Nebula. The NGC 7000 shape resembles that of the continent of North America, complete with a Florida peninsula and Mexico forming a prominent Gulf of Mexico shape.

NGC 7000 is visible from Spring through Summer into the Fall. As long as an observer can see the Summer Triangle of Deneb, Vega, and Altair, the North America Nebula and its companion Pelican Nebula can be seen.

The gaseous contortions of the Pelican Nebula bear a resemblance to its namesake bird. The Pelican Nebula is also located near Deneb, and is divided from its more prominent neighbor, the North America Nebula, by a dark dust cloud.

NGC 7000 was discovered by William Herschel on October 24, 1786. The Pelican Nebula, also designated by two Index Catalogue of Nebulae numbers IC 5070 and IC 5067, was discovered by the Reverend Thomas Espin in 1899, with its discovery announced in 1900. Both nebulae are part of a large Hydrogen-II emission region in Cygnus, with both the North America Nebula and the Pelican Nebula serving as a massive nursery for newly formed stars. The distance of the nebula complex is not precisely known, nor is the star responsible for ionizing the hydrogen so that it emits light. If the star inducing the ionization is Deneb, as some sources say, the nebula complex would be about 1800 light-years away, and the size of the North America Nebula would be 100 light years across. The Pelican Nebula is estimated to be 30 light years across.

Observing the North America and Pelican nebulas requires medium-to-large binoculars and the help of (UHC) filters. This is a challenging, but rewarding pair to observe. 12X60, or better yet 15×70, binoculars in a dark country sky are needed to adequately observe this Cosmic Duet. With the aid of UHC filters to enhance the viewing and allowing only Oxygen-III and Hydrogen-beta emission lines to pass, the dimmer Pelican Nebula can be detected along with details of the North America Nebula.

Without the UHC filters, a 15×70 binocular will pick up the entire Florida / Gulf of Mexico / Mexico / Central America region of NGC 7000. Just the slightest amount of ambient background light from light pollution or bright moonlight will render the nebulosity invisible.

To observe both the North America and Pelican, seek out the darkest of sky locations and use UHC filters. Use a tripod, if necessary, since 12×60 or 15×70 binoculars are difficult to handhold steadily for any length of time. Or lay back into a comfy bean bag chair!

Jim's Corner Blog

Binoculars and Backyard Astronomy

James Chen |

An important piece of equipment for observing stars and deep sky objects in the amateur astronomer’s arsenal is the binocular. Armed with star atlases, or for the more technically oriented a smartphone or tablet app, and binoculars, the stars and deep sky objects can be hunted down among the constellations, the Milky Way, and star fields. The binocular offers the widest field of view available to the backyard astronomer, with lightweight convenience and ease-of-use.

For experienced observers, the binocular is an optical tool that allows for wide-angle viewing of star fields, up-to-6º or 7º of field-of-view. An amazing amount of night sky observing can be observed with binoculars, particularly when searching and discovering stars and deep sky objects that can only be seen with the wide field-of-view that a pair of binoculars can provide. Many of deep sky objects can be easily scooped up by a binocular sweep. Seeing the stars and deep sky objects in relationship to the sky around them will put that object in its proper context in the sky.

Most backyard astronomers hand hold their binoculars for observing. To obtain the steadiest images, the preferred technique for hand holding binoculars is to hold the ends of the binocular barrels, instead of gripping them around the binocular body where the prisms are located. This technique works well for both 7×50 or 10×50 binoculars. This handheld method is especially effective with the larger 12×60, 15×70 or 16×70 binoculars.

The larger 80-mm or 100-mm binoculars require the steadier support of a tripod or parallelogram binocular mount.

Observing in a bean bag chair is a comfortable and steady way to observe the night sky with hand-held binoculars. Nestle into the bean bag with binoculars in hand, with the elbows resting on the bean bag sides as they puff up from your weight . The binocular images will be steady from the support! This is an easy and comfortable way to observe the night sky with binoculars, and cheaper than some of the parallelogram binocular mounts or other forms of binocular mounts. This technique has been used by me successfully with binoculars up to 15×70’s.

Diametrically opposite from the aforementioned 50-mm, 60-mm and larger binoculars are the new pocket-sized low power 2.1×42 binoculars. Some of our members have looked through my pair of 2.1×42 at some of our outreach star parties. The 2.1×42 binoculars are small, lightweight, and provide an extremely wide field of 25º field-of-view. Easily carried for backpacking adventures or just a quick peek at the sky in the backyard, these binoculars can be used to scan constellations and large star fields. The night sky seems to come to life with the 2.1×42, giving the user the feeling of having 42mm aperture eyeballs. Don’t let the very slight field curvature bother you, the wide-open expanse of view easily outweighs this slight aberration. stars and deep sky objects comprising of open clusters or nebula clouds appear small due to the low magnification, but are still easily seen and identifiable, and are set in their stellar surroundings. stars and deep sky objects separated by tens of degrees can be captured by this diminutive optical tool. Although slightly aperture-lite, these are fantastic for hunting down stars and deep sky objects in clear Shenandoah country skies with little or no light pollution.

On the other end of the scale are the giant binoculars with apertures of 80 to 100 mm, with the rare 125-mm behemoths. The larger apertures of these giant binoculars do enhance light-gathering ability, but at the cost of convenience, portability, and wide-field-of-view. These large prism binoculars encroach upon the territory occupied by the 80-to-102 mm telescope. With a limited field-of-view of sometimes less than 2.5˚ and needing a sturdy tripod or binocular mount, the wide-field advantage, portability, and ease-of-use of binoculars is lost by using these giant binoculars.

Also, I would be remiss in failing to mention the rare binoculars that use interchangeable 1-1/4” eyepieces. I own two of these bad boys, and will bring them out to one of outings in the future.