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  • March Night Sky Objects: Star Clusters / Globular Gallop for Northern Hemisphere

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    March Night Sky Objects: Star Clusters / Globular Gallop for Northern Hemisphere

    As we head into spring here in the north and fall in the south, we finally start to see an uptick in the number of globulars that grace our skies. This month’s northern offerings run the range from glorious showpieces to little patches of haze that challenge experienced observers with larger apertures. So tune up your scopes and your observing skills, as the coming months will be a very busy period for pursuing these fascinating orbs of stars. Enjoy and good luck!

    Northern Celestial Hemisphere:

    Messier 3 (NGC 5272) in Canes Venatici:
    Magnitude = 6.3
    Surface Brightness = 12.3
    Angular Size = 18.0 arc mins
    Shapley-Sawyer Class = 6

    This is one of the grandest globulars for northern observers, and a spring favorite. Located a little under halfway between Arcturus (Alpha Bootis) to Cor Caroli (Alpha Canum Venaticorum). I have always found it visible in my 8x50 finderscopes, and it can achieve naked eye visibility from a truly dark site. Through the eyepiece it is a beautiful site, revealing good resolution across its face, with lines of stars arcing out from the core. This showpiece is always a satisfying target, and typically one of the first globulars that beginning observers set their sights on.

    M3 on the Astronomy Wiki

    Messier 53 (NGC 5024) in Coma Berenices:
    Magnitude = 7.7
    Surface Brightness = 13.0
    Angular Size = 13.0 arc mins
    Shapley-Sawyer Class = 5
    The hair of Queen Berenices is home to three globulars, and the 53rd entry in the catalog of Charles Messier is the best of the lot. This pretty ball of stars is bright and visible in an 8x50 finderscope under average conditions. It presents a fine view through the eyepiece, with a bright core surrounded by a fuzzy, unresolved halo. Increasing magnification will reveal some nice resolution of outlying members as well as some across the cluster’s face. Look for this treat less than a degree northeast of Alpha Comae.

    M53 on the astronomy wiki

    NGC 5053 in Coma Berenices:
    Magnitude = 9.0
    Surface Brightness = 13.9
    Angular Size = 11.0 arc mins
    Shapley-Sawyer Class = 11

    Lying just under a degree southeast of M53, this globular is quite the opposite of its brighter neighbor. As easy as M53 is to see, NGC 5053 isn’t. As a class 11 globular, it lacks central concentration, and thus its light is evenly spread across its diameter giving it a dim surface brightness. It can be a difficult object to see, appearing ghostly at best under dark skies. In areas with moderate to heavy light pollution it may simply be overcome by the brighter sky as it fades into the glow. Though it has a brighter visual magnitude than NGC 4147, I find it much more difficult to locate because of its diffuse nature and accordingly dimmer surface brightness. Give this elusive object a try.



    NGC 4147 in Coma Berenices:
    Magnitude = 10.4
    Surface Brightness = 13.1
    Angular Size = 4.0 arc mins
    Shapley-Sawyer Class = 6

    This small globular lies in the western reaches of Coma near its border with Leo, and just over 2.5 degrees west-northwest of 4th magnitude 11 Comae. This tiny orb can be passed over during sweeps unless you are purposely looking for it, and at first it might remind one of a small elliptical galaxy. Increasing the magnification will reveal a bright core that may take on a stellar appearance. With larger apertures and still higher magnification it may appear granular and even offer very slight resolution of outer members. Interestingly, William Herschel “discovered” this object twice, so it also carries the designation of NGC 4153 – another example of the many errors within the NGC catalog.

    M3 on the Astronomy Wiki


    Palomar 3 in Sextans:
    Magnitude = 13.9
    Surface Brightness = 14.9
    Angular Size = 1.6 arc mins
    Shapley-Sawyer Class = 12

    Discovered in the 1950s on the plates of the first Palomar Observatory Sky Survey (POSS), the Palomar catalog of 15 dim and distant globulars present a unique challenge for the observer. The list is dominated by low surface brightness globulars of Shapley-Sawyer class 11 and 12, only two of which are brighter than the 10th visual magnitude. Pal 3 resides in the unimpressive constellation Sextans the Sextant, and lies about 45 arc mins southeast of its brightest star, 4th magnitude Alpha Sextanis. The biggest obstacle here is being able to detect the feeble brightness of the cluster, and distinguish it from the background star field. Having serious aperture would make the task easier, but even then, don’t expect more than a subtle haze to be revealed. If you have such aperture and seek challenges, here it is.



    Palomar 4 in Ursa Major:
    Magnitude = 14.2
    Surface Brightness = 14.8
    Angular Size = 1.3 arc mins
    Shapley-Sawyer Class = 12

    What was said about Pal 3 above also relates to Pal 4 even more so. Pal 4 lies about 3.5° southeast of 4th magnitude Alula Australis (Xi Ursae Majoris). As with any of these elusive globulars, dark skies and large aperture are your best friends. Well that and excellent charts, good star hopping skills and a keen observing eye. Pal 4 is not impossible, but it really is a significant challenge.

    sketrip likes this.
    This article was originally published in blog: Globular Gallop - March 2015 (Northern) started by KT4HX
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