Cosmic Pursuits

Basic astronomy and night sky information

Deep Sky Observing

Articles about how to understand, find, and see celestial objects including stars, galaxies, nebulae, and star clusters with binoculars, telescopes, and the naked eye.

IC 4665, the “HI” Star Cluster

by Brian Ventrudo Filed Under: Deep Sky

The open star cluster IC 4665 in the constellation Ophiuchus.
The open star cluster IC 4665 in the constellation Ophiuchus (credit: Wikipedia)

One of the best targets for a quick stargazing session this time of year is the pretty but underappreciated open star cluster IC 4665. It’s a snap to find, beautiful to behold, and like most sky sights on Cosmic Pursuits, it’s visible from the northern and southern hemispheres.

IC 4665 is spread out over a full degree, more than twice the diameter of the full Moon, so it looks fainter than its integrated magnitude of 4.7. In dark sky, IC4665 is just barely visible to the unaided eye roughly 1° NE of the star Celebrai in the constellation Ophiuchus. Celebrai, or β (beta) Ophiuchi, is one of the stars in the distinctive asterism called Taurus Poniatowski, the “little bull”. If you’re battling light pollution, you’ll need binoculars to spot the cluster [Read more…] about IC 4665, the “HI” Star Cluster

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Hopping Galaxies in the Bear’s Den

by Joe Bergeron Filed Under: Deep Sky

The galaxies M82 (lower left) and M81 in the constellation Ursa Major. Image credit: Joe Bergeron.

So many galaxies, so little time! A good place to begin an evening of galaxy hopping on a northern spring or summer night is with the Messier galaxies M81 and M82 in the constellation Ursa Major (see above). Conveniently located by drawing a line through the Big Dipper stars Phecda and Dubhe and extending it an equal distance beyond the Big Dipper asterism, this is probably the finest galaxy pair in the sky. Separated by just 38 arc-minutes, both fit into the low power field of a small telescope. With a 22mm Panoptic eyepiece in my 8″ EdgeHD telescope, I had 93x and a field of view of 45 arc minutes, so I had to slew the mount a little from one to the other to see them both well [Read more…] about Hopping Galaxies in the Bear’s Den

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Ambling Through Auriga

by Brian Ventrudo Filed Under: Deep Sky

The carbon star UU Aurigae in the constellation Auriga.

In this month’s sky tour, we grab our optics (or our favorite smart telescope) and tour of a few of the deep-sky highlights of the constellation Auriga, the Charioteer. Auriga lies along the relatively rich path of the northern Milky Way. And while it’s not Sagittarius, to be sure, the constellation has an eclectic selection of open clusters, nebulae, and interesting stars.  Southern-hemisphere stargazers can also spot the constellation over the northern horizon in December through February [Read more…] about Ambling Through Auriga

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The Many Names of the Pleiades

by Brian Ventrudo Filed Under: Deep Sky

A wide view of the Pleiades star cluster.

The Pleiades star cluster in the constellation Taurus is one of a handful of objects in the heavens that never fail to amaze and inspire even the most experienced observers. As beautiful in an inexpensive pair of binoculars as in images from big professional telescopes, this star cluster presents visual observers an especially lovely sight with stars of an unearthly blue ensconced amid a faint frost of nebulosity. If there were more objects like it in the night sky, there would be a lot more amateur astronomers in the world [Read more…] about The Many Names of the Pleiades

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The Rosette Nebula

by Brian Ventrudo Filed Under: Deep Sky

The heart of the Rosette Nebula and the open cluster NGC 2244 that is emerging from it. Captured with a ZWO Seestar S50 telescope.

Look to the east of mighty Orion and you’ll see the constellation Monoceros, the Unicorn. While its stars are faint, Monoceros holds a small treasure chest of superb deep-sky sights for backyard stargazers. Perhaps the most striking is the Rosette Nebula, an achingly beautiful blossom of glowing gas and dust where new stars are forming.  The Rosette is an immense nebula, some three times larger than the Orion Nebula and three times farther away.  As you see in the image above, captured with a little ZWO smart telescope, the nebula overlaps the star cluster NGC 2244 which formed within the nebula and blown a bubble to give us a look inside. While can be a challenge to see the Rosette visually, even in large telescopes, the nebula is an excellent photographic target and the cluster offers a superb sight in binoculars or a telescope [Read more…] about The Rosette Nebula

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