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Visual Deep Sky Observing: Galaxies

By Edited Sep 2, 2015 0 0

The final installment of my visual deep sky series touches on a class of celestial object that is the staple diet of most hardcore amateur astronomers. These are the hardest of the deep sky objects to observe as they are distant and their light is spread out over a large surface area, hence a very low surface brightness. Most of these astronomers use large dobsonian (altazimuth telescopes mounted on lazy susan type mounts) and seek out very dark skies to hunt down these elusive wraiths of the cosmos. Beginners usually feel discouraged when seeking them out. Although this is true for most of these island universes, there are also some very bright examples of these that are visible in scopes even as small as a 60mm refractor. I will highlight five of these, all of which are visible in 60mm departmental store variety telescopes (and even binoculars!!!!)

M31, M32 and NGC 205 Galaxies (Constellation: Andromeda)



Possibly the best and easiest to find of the great spiral galaxies, M31 is very bright and has a very intense core that is easily visible with the naked eye, even from urban observing spots. It is found in the constellation of Andromeda, hence its name the Great Andromeda Galaxy. Best viewings occur in fall where Andromeda rides high in the night sky. To locate Andromeda, firstly look straight up at about 11 pm in mid October to locate the great square of Pegasus. The constellation of Andromeda is an appendage attached to the top left star of Pegasus. The constellation itself is nondescript, composed of several stars curving upward from the great square. Not the best galaxy in terms of detail, but then again it is not fully turned face on towards us. As such its spiral structure is harder to discern. In 50  mm finderscopes and binoculars, its hazy core is easily visible. Its core is also visible in a 60 mm scope. Closer scrutiny (even from the city) reveals its bright companion M32 in the same scope. This bright elliptical galaxy appears as a bright hazy spot flanked by two stars to create a right angle triangle. The other companion NGC205 is further out and is only visible under dark skies as its light covers a bigger area of the sky. Two dark lanes are visible to astronomers with 150mm or larger scopes. Use magnifications over 50x to view this feature.

M81 and M82 Galaxies (Constellation: Ursa Major)



Another great pairing of high surface brightness city galaxies. I call them city galaxies because this pairing is visible even from within the city (although dim). Unfortunately they are not naked eye objects as M31. M81 is a spiral not unlike M31 in that it does not present its spiral arms face on towards us. As such we get a similar view of it bulging intense core. The spiral arms are all but invisible in small scopes and are hard to make out in bigger scopes. Only CCD images seems to bright them out. M82, its companion is more interesting as it is a classic example of an irregular galaxy. Some call this the cigar galaxy as it really does resemble that in scope. It has a dark lane bisecting the middle that is visible even in small 60 mm scopes. This pairing is also visible in 50mm finderscopes and binoculars. To find them, firstly find Ursa Major, the big bear. Its saucepan shape is easily recognizable. Find the dipper and draw a line  diagonally across from the star that joins the dipper to its handle down to the bottom left star. Extend this line an equal distance  between those two stars and you should have the approximate location of the galaxies.

M33 Pinwheel Galaxy (Constellation: Triangulum)


This is what every person thinks of when you mention the word galaxy. This classic face on spiral is the prettiest of its kind in the heavens. It also happens to appear as one of the largest in the sky. Unfortunely this works against it. While an easy catch with the naked eye from dark sky sites, a little amount of skyglow robs you from viewing this beauty. As it is so large, the light is spread out over a very large area of the sky. Hence an extremely low surface brightness. Still it is visible in 50 mm binoculars and finders from dark locales, and in 60mm scopes as a large fuzzy patch with a hint of brightening towards the center indicating its core. The spiral arms are very elusive and are only visible in 150 mm scopes and larger. Which such a scope, I have traced out two of its spiral arms. There is also a very curious feature in this object that is visible even in small scopes. The star cloud appears as a small fuzzy path in one of its arms. To find this object, locate the constellation of Andromeda. The galaxy is roughly midway between this constellation and the the topmost star of the elongated triangle that makes up the constellation of Triangulum.

NGC 253 Galaxy (Constellation: Sculptor)


NGC 253

This galaxy would probably get top billing right alongside the top two were it not so far south in the nondescript constellation of Sculptor. Finding this object is also not as easy as the last two as it lies in a star poor region, and the stars making up Sculptor are pretty dim. It is also not a naked eye object although its bright core punches through light pollution from the southern hemisphere (it rides high in the southern hemisphere). Nevertheless if you can get yourself to a dark enough locale (orange zone skies), you should be able to spy this flatted cigar shaped object in 50 mm finderscopes and binoculars. The 60 mm scope will probably show it better. To see detail, however, you need at least a 150 mm scope. In such a instrument, you can start to make out traces of its clumpy spiral arms. This galaxy too is not face on, appearing as an angle.

M51 Whirlpool Galaxy (Constellation: Canes Venatici)



Another textbook face on spiral like M33, this one is also relatively bright and easy to find although it is not a naked eye object. Although belonging to the constellation of Canes Venatici, it is easier to use the big dipper (Ursa Major) as a jumping off point for star hopping. This object make a shallow triangle with Alkaid, the star at the very tip of the handle of the big dipper and another star. This galaxy (and its smaller companion NGC 5195) is not hard to see at all, even from compromised skies. Under ideal conditions (dark transparent skies), it is visible as a pear shaped nebulosity even in 10x50 mm binoculars (little more magnification is required for this to be seen). Under light polluted skies more aperture is required. Its spiral arms require at least a 200 mm scope to be seen. I have seen its arms as mottling in my C8 and 250 mm dobsonian.


Astronomers like looking at galaxies because they are so varied in appearance in larger scopes. In smaller scopes, the challenge is just to detect them. While the above five are bright, they pale in comparison to the Large and Small Magellanic Clouds (LMC and SMC). These two are our home galaxy's satellites and are only visible from southern latitudes. Riddled with star clusters and nebulosities, they are visible to the naked eye even from suburban settings. Under dark skies they are glorious to sweep in small binoculars and telescopes. If you ever get the chance to travel south these two are worth the trip!



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