Discover the Alpha Persei Cluster: The Ultimate Binocular Stargazing Target

Continuing our series on low-powered astronomy following our look at the Double Cluster in Perseus, we are turning our sights to another remarkable target in the same region: the Alpha Persei Cluster. While the famous Pleiades (M45) will appear in an upcoming episode, this massive open cluster is an incredible deep-sky gem that deserves just as much attention.

What can you see through binoculars

What is the Alpha Persei Cluster?

Also cataloged as Melotte 20 and Collinder 39, the Alpha Persei Cluster surrounds Alpha Persei, the brightest star in the constellation Perseus. While modern astronomy often relies on brightness designations, this prominent anchor star is traditionally known as Mirfak. Centered around Mirfak's luminous glow, the cluster presents a loose, glittering cascade of dozens of bright, blue-white stars scattered across the dark backdrop of space.

How to Find It

Click to enlarge Sky Map

Finding the cluster is straightforward by using neighboring constellations as a guide:

• Locate Cassiopeia, easily identifiable in the sky by its distinct giant "W" shape.
• Find the two bright stars Navi and Ruchbah within Cassiopeia.
• Trace a line downward from those stars toward the constellation Perseus.
• Hop down to the third and brightest star in Perseus, Alpha Persei (Mirfak), which sits directly in the center of the cluster.

The optimal time to observe this region in the Northern Hemisphere is during the autumn and winter months.

Why Binoculars Beat Telescopes for This Target

Alpha Persei Cluster Size

While the Double Cluster contains a significantly larger amount of solar mass, it spans only about 1 degree—roughly the width of two full moons. In contrast, the Alpha Persei Cluster covers an impressive 5 to 6 degrees across the sky, spanning the equivalent of 10 to 12 full moons.

Because telescopes and high-magnification setups offer narrow fields of view, they can easily cause this cluster to spill outside the frame. A standard pair of binoculars (such as 10x50mm) provides a circular field of view of roughly 5 to 6 degrees, framing the entire cluster perfectly in a single view.

Tips for Steady Binocular Viewing

Holding binoculars steady by hand can sometimes lead to shaky views. To stabilize your image while observing, try these simple techniques:

• Lean firmly against an exterior wall for body support.
• Pull your binocular neck strap taut against your neck to create stabilizing tension.
• Observe while seated in a comfortable reclining lawn chair.

Have you had a chance to view the Alpha Persei Cluster through your binoculars yet, or do you have another favorite winter target? Leave your thoughts in the comments below, and clear skies!

Check out the video below to see the full visual walk-through! Be sure to follow along for upcoming episodes and guides as we explore the best targets for low-magnification observing.

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