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Visual Deep Sky Observing: Nebulae

By Edited Oct 30, 2014 0 0

One of the most popular classes of objects, nebulae can be both a blessing and a curse. The are some examples of this class of objects that are so bright, they are visible with the unaided eye. Then there are those obscure little nebulae that are only visible with the largest of telescopes. My aim is to give you an idea of what you can realistically expect to see in a beginners telescope, even one as small as the ubiquitous 60mm and 70mm Christmas Trash Telescopes (CTT), which are usable by the way and can be improved. The description I give of the views in binoculars and small telescopes are what you can hope to see in 60mm to 70mm scopes and 7x50 and 10x50mm garden variety binoculars. So without further ado here are the 5 best and brightest nebulae visible from both the northern and southern hemispheres.

NGC 3372 Eta Carina Nebula (Magnitude 1.0, Constellation Carina)

Eta Carina

Coming from the equator in Malaysia, and living in Australia for 11 years, this great sprawling complex known as the Eta Carina Nebula has been nothing but an awe inspiring sight for me. Clearly visible to the naked eye as a fuzzy patch between the southern cross (Crux) and the false cross, even under suburban skies, the Eta Carina Nebula is a truly glorious sight in binoculars and small telescopes. Through my 10x50mm binoculars the nebula is found in a very rich part of the sky, flanked by open clusters NGC 3532 and IC2602. This nebula reveals the extent of its nebulosity through small and medium sized scopes. I have observed this extensively in my small 76mm newtonian reflector, a 80mm Orion ST, a 150mm newtonian reflector and even in my 250mm dobsonian telescope. Its three leaf clover shape is greatly enhanced by narrowband nebula filters and reveals extensive mottling and dark nebulae crisscrossing its brightest portions. The most prominent dark nebula projected against the bright emission component is a feature known as the keyhole. this feature is easily seen even in small scopes. Another very interesting sight within this huge complex is a bulbous nebulosity surrounding Eta Carina, known as the homunculus. Unfortunately to see this well you need a telescope 150mm or larger.

M42 Orion Nebula (Magnitude 4.0, Size 65.0' x 60.0', Constellation Orion)

M42 sketch

The best nebula complex visible from the northern and southern hemispheres, this is probably one of the most well known of all the great and bright nebulae as well. It is also very easy to locate, plus it is visible as a faint smudge to the naked eye from darker skies. To locate this, simply look for the constellation of Orion. After finding the three stars that make up Orion's belt, look for Orion's scabbard, another grouping of three stars in a row. The nebula lies in the middle of the three stars that make up the sword holder. Photographs show vivid reds and pinks, while the telescopic views show shades of grey and green (and in larger scopes, rusty hues). The shape is immediately obvious even in the smallest of scopes (i.e. 60mm scopes). The main body of the nebula looks like a partially opened flower. A step up in aperture shows markedly more detail. The outer nebulosity of course becomes more obvious, as is the cirrus cloud effect at magnifications in excess of 100x. This nebula responds very well to narrowband nebula filters. The stars embedded at the heart of the nebulosity is also very intriguing. Due to the arrangement of the component stars, this grouping is called the trapezium. There are four main stars that are easily visible, even in scopes as small as 40mm. In addition, there are two fainter components (E and F) that should be visible in scopes as small as 80mm. M42 also has a smaller component M42, which is a comma shaped nebula at the base of the larger complex.

M8 The Lagoon Nebula (Magnitude 4.6, Size 45.0' x 30.0, Constellation Sagittarius)

M8 and 20 sketch

Also ranked as one of the brightest nebulae in the night sky, this is mainly a summertime object. This is also very easy to locate, is a naked eye object (from dark skies) and is found at the sprout of the teapot shaped constellation known as Sagittarius. The nebula also happens to sit close to the center of our galaxy (the milky way). Photos show vivid reds and pinks, interspersed with dark nebulae twisting its way through the main body of the nebula. This dark lane is what gives the object its name, and this feature is visible even in binoculars. The nebula is a glorious sight in small telescopes. Its best to use a wide field scope, or lower magnification as this object occupies quite a bit of celestial real estate. Things to look out for include the hourglass nebula, found at the heart of the brightest region of the nebula and the embedded open cluster NGC 6530. This object greatly benefits from the use of a narrowband filter, although a broadband filter frames it nicely as the open cluster embedded in the nebula shines through.

M17 The Swan Nebula (Magnitude 6.0, Size 11.0' x 11.0', Constellation Sagittarius)

M17 sketch

Yet another bright nebula located close to the heart of our galaxy, and in the constellation of Sagittarius, this object can be found slightly north of the tip of the teapots cover. This object is bright, but unfortunately is not visible to the naked eye. Also this one really resembles its moniker. In binoculars and small telescopes, the nebula looks more like a grey checkmark amidst a crowded star field (remember this is at the heart of our home galaxy). Through larger telescopes, the swan shape becomes more apparent and the dark nebulosity appears more obvious around the neck region of the swan. The main body of the swan takes on a feathery texture at high magnification. A very pretty sight visually for sure.

M27 The Dumbbell Nebula (Magnitude 7.30, Size 8.0' x 5.7', Constellation Vulpecula)

M27 sketch

The last object on this list is not an emission nebula but rather a planetary nebula. It is the brightest of its kind and has very high surface brightness, and therefore is also very easy to see. Unfortunately, its harder to spot as it is not a naked eye object and lies in a rather desolate part of the sky, in the constellation of Vulpecula, the fox. The easiest way to spot this celestial puffball is to locate the constellation of Sagitta, the arrow. Sagitta is composed of three stars in a row, with the first two being double stars. These stars can serve as a jumping off points to Vulpecula, which is made up of rather dim stars forming the letter W. M27 lies at the tip of the W. Due to its compact nature M27 has a very high surface brightness. As such it can be seen even from very bright locales with small binoculars and telescopes. In these instruments, it appears more like a hollowed out apple core than a dumbbell. In larger scopes, the hollow ends fill out with fainter nebulosity (especially if you use a narrowband filter) and the nebula looks more like a football. Another summertime must see.

Next stop star clusters.....

 

 

 

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