Messier 2 is a globular cluster lying 55,000 light-years from Earth in the constellation Aquarius. It is a remarkable globular for several reasons. First, it is one of the largest known globulars with a diameter of 150 light-years. Second, it is a Shapley-Sawyer Class II globular, which means it has an extremely dense and bright core. How dense? Photometric measurements indicate that a 1'x1' area at its core contributes 37% of its light output. At 5' from the core, an equivalent area contributes only 0.02%. Lastly, it has interesting dark lanes arching and branching across its southwest quadrant (bottom edge in this image) that are not present in the other three quadrants. These dark lanes can be glimpsed visually through amateur telescopes.

Exposures: L:R:G:B=75:55:30:35 minutes=2 hours, 15 minutes total exposure at f/7.5.

This image was published in the August, 2024 issue of Astronomy magazine.

M10 is a Shapley-Sawyer class VII globular cluster in the constellation Ophiuchus. It is one of the nearest globular clusters in the Messier catalog, lying only 14,300 light-years from Earth.

Exposures: L:R:G:B=55:30:30:25=2 hours, 10 minutes total exposure at f7.2.

Poor globular cluster M56 in Lyra is frequently overlooked because of its tiny little neighbor M57, the Ring Nebula, grabbing all the attention of observers. Few bother to shift their scope a short distance and gaze on this gem. That is a shame because most globulars are visible in portions of the sky rather devoid of stars and it is spectacular to see M56 shining amidst a field filled with countless colorful stars of the summer Milky Way. M56 appears small among Messier globulars, largely because it is farther than the commonly viewed globulars at 32,600 light-years from Earth.

Exposures: L:R:G:B=160:50:50:50 = 5 hours, 10 minutes total exposure at f/7.5.

This image was published in the April, 2021 and the August, 2024 issues of Astronomy magazine.

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M5 is a globular cluster in the constellation Serpens. It is Shapley-Sawyer class V which gives it a readily resolvable core lending it the classic snowball of stars appearance. M5 lies 24,460 light-years from Earth and is located in a part of the sky quite devoid of Milky Way foreground stars. The lack of foreground stars gives this image the illusion of not being very deep. However, it is actually a very deep image, with nearly 12 hours of exposure time and as evidenced by the very distant galaxy, IC 4537 to the lower left of M5, lying perhaps 500 million light-years away. This gives this image an incredible depth of field.

Exposures: L:R:G:B= = 180:180:170:170= 11 hours, 40 minutes total exposure. at f/8.3.

This is a new image of globular cluster M15 in Pegasus. It is different from the other image of M15 displayed in Star Clusters in that this image was taken with the Starizona Large Field reducer/corrector. The core of M15 is very bright and difficult to resolve into individual stars. The goal of this image was to resolve the cluster down to the core. It also shows more peripheral stars than the other image. M15 lies 32,000 light-years from Earth.

Exposures: L:R:G:B=120:60:60:60 minutes= 5 hours total exposure.

This image was published in the July, 2020 issue of Astronomy magazine.

M12 is a globular cluster in the constellation Ophiuchus that lies 15,700 light-years from Earth. It is a Shapley-Sawyer Class IX globular, which means that the core is not very dense and fairly easy to resolve.

Exposures=L:R:G:B=100:60:60:50 minutes=2 hours 40 minutes total exposure at f/7.2.

M13 is a Sawyer-Shapley Class V globular cluster that lies 25,000 light-years from Earth. Class V implies that the concentration of the cluster is low enough that stars can easily be resolved within its core. A curious feature of M13 is a Y-shaped dark lane in its southeast portion (upper left). William Parsons, the 3rd Earl Rosse first noticed this in the 1850s through his leviathan telescope. Amateurs today have dubbed it "the propeller". Exposures: L:R:G:B=230:50:50:50 minutes = 6 hours 20 minutes total exposure at f/7.2.

This image was published in the July, 2018, November, 2018, and October 2019 issues of Astronomy Magazine.

M71 is a globular cluster in the constellation Sagitta. It a very unusual globular cluster in that it lies very close to the plane of the Milky Way galaxy, as indicated by the innumerable stars in the field. In contrast, most other globular clusters are visible away from the Milky Way because the Milky Way obscures our view of such distant objects. Because it is visible within a densely packed region of the Milky Way, for a long time M71 was thought to be a tightly packed open star cluster within the Milky Way. Recent research shows it is a globular cluster well outside the galaxy, but it is still one of the closest Messier globular clusters at a distance of only 13,050 light-years.

Exposures: L:R:G:B=290:30:30:30= 6 hours, 15 minutes total exposure at f/7.2.

M15 is a globular cluster located in a star-poor field off the tip of Pegasus' nose (the star Enif). It lies 33,600 light-years from Earth. It is a Shapley-Sawyer Class IV globular cluster, which have considerable scattering of peripheral stars, but their hallmark is that they still retain a small dense core of stars that cannot be resolved. In the case of M15, the dense core is intensely bright, and has distinctly triangular shape outlined by dark lanes, one of which is remarkably linear.  LRBG=100:100:100:100=6 hours 40 minutes total exposure.

This image was published in the January, 2014 issue of Astronomy Magazine. 

M92 is a Shapley-Sawyer class IV globular cluster in Hercules, not far from and nearly as beautiful as the famous M13 globular cluster in Hercules. Sadly, because of it’s proximity to M13, this globular cluster is frequently ignored by observers. If it were in a different constellation, it would probably be viewed as showpiece of that constellation. This image shows an unusual feature of M92, a dark “?” shaped globule at the right edge of the cluster that obscures cluster stars. Additional dark globules obscure stars near the bottom edge of the cluster. M92 lies 24,740 light-years from Earth. The distant galaxy in the upper right is MCG7-35-58, which is probably about 500 million light-year away.

Exposures: L:R:G:B=530:50:50:50=11 hours 15 minutes total exposure at f/7.2.

This image was published in the March, 2019 issue of Astronomy magazine.