Here is the transcript for my podcast about how to see the Lozenge, globular cluster NGC 5694, and spiral galaxy NGC 3521 this week.
Check out the Astronomy.com's interactive star chart — StarDome — to see an accurate map of your sky. It'll help you locate some of this week's key targets. Astronomy magazine subscribers have access to a slew of cool functions with StarDome PLUS.
Each week, I highlight three different night-sky targets for you to see:
- One object you can find with your naked eyes or through binoculars
- One object to find with a small telescope
- One deep-sky object to find with an 8-inch or larger telescope for you avid astronomers
--Start transcript-- Easy to swallow
This week’s naked-eye object is an asterism called the Lozenge. Amateur astronomers also know it as the Head of Draco. Draco is the eighth-largest constellation. It winds between the Big and Little Dippers halfway around the North Celestial Pole.
To find the Lozenge, draw a line from brilliant Vega (Alpha [α] Lyrae) to Kochab (Beta [β] Ursae Minoris). Kochab is the second-brightest of the Little Dipper’s stars (next to Polaris), and the brightest in that asterism’s bowl. The Lozenge lies near the halfway point of this line, but a bit closer to Vega.
The four stars that form the Lozenge are Rastaban, Eltanin, Grumium, and Al Rakis. By Greek letter, that’s Beta (β), Gamma (γ), Xi (ξ) and Nu (ν) Draconis, respectively. Gamma’s the brightest, coming in at magnitude 2.2. Nu’s the best target, though. It’s a double star with equally bright, white 5th-magnitude components. The separation is wide, so you can split the pair through a finder scope or even steadily held 10-power binoculars.
Hydra hides a globular
This week’s small telescope target is globular cluster NGC 5694 in the constellation Hydra. English astronomer Sir William Herschel discovered it in 1784, but it wasn’t until 1932 that astronomers identified it as a globular cluster.
To find NGC 5694, look about 2° west-southwest of a line of three 5th-magnitude stars. The stars carry the designations 55, 56, and 57 Hydrae and lie in the far eastern end of the sky’s largest constellation. The roughly equal brightnesses and equal spacings between the stars makes me think of this grouping as a small, faint version of Orion’s Belt.
NGC 5694 glows at magnitude 9.2, so even a 2.4-inch telescope will reveal it. The cluster’s not huge, and its individual stars are faint, so it won’t resolve into points of light well.
Most of NGC 5694’s brightness comes from its compact core, which takes up more than 50 percent of this object’s diameter. At magnifications above 150, you’ll see several foreground stars superimposed on the cluster.
Catch a nice spiral in Leo
This week’s deep-sky object is spiral galaxy NGC 3521 in the constellation Leo the Lion. Because this object lies just 28 million light-years away, it appears bright and detailed.
You’ll find this galaxy 4.5° northwest of magnitude 4.5 Phi (φ) Leonis. It sits in a small region of the constellation Leo between Sextans and Virgo.
Through a 10-inch telescope, you’ll see the bright, extended core surrounded by a diffuse halo. With a 16-inch scope, NGC 3521 will appear nearly twice as long as through the smaller instrument.
That much aperture also brings out fine — almost cotton-like — spiral structure, particularly near the edge of the halo and along the minor axis near the core. If your sky’s transparency is good, also try to observe the long, dark dust lane that runs the length of the galaxy’s western side.
[Craig and Tammy Temple posted the image of NGC 3521 (above) to the Galaxies gallery of our Online Reader Gallery.]
--End transcript--
Previous podcast: Zubeneschamali, globular cluster M5, and elliptical galaxy NGC 4697