From the August 2005 issue

Glenn Chaple’s observing basics: Summer sledding

August 2005: The summer Milky Way dominates the evening sky in August.
By | Published: August 1, 2005
The summer Milky Way dominates the evening sky in August. What a grand sight it is — a bright band of light arching high overhead to the north from Cassiopeia, then southward to Sagittarius.

Well, at least that’s how I remember it.

When I moved to rural Massachusetts 30 years ago, the summer Milky Way from my backyard truly was awe-inspiring. But as the surrounding community grew, so did the light pollution. A town-wide lighting ordinance passed a few years ago came too late to save the once-pristine skies. Like many of you unfortunate souls, I have to trek to remote sites to get my Milky Way “fix.”

Fortunately, the local light pollution isn’t so severe that I can’t sail along the Milky Way with binoculars or a telescope. One of my favorite Milky Way ports-of-call is an asterism — a small grouping of stars in the night sky — I call the “Sleigh.” Located on the boundary between Aquila and Scutum (see finder chart below), it’s visible to the unaided eye from dark-sky locales.

The Sleigh’s front centers on the star Lambda (λ) Aquilae, while the back pokes into Scutum. If you scan the Sleigh with binoculars, you can spot a small misty glow. This is the Wild Duck Cluster (M11), so named because its telescopic appearance reminds some viewers of migrating ducks.

A spellbinding sight in any telescope, the Wild Duck Cluster contains more than 100 stars glowing at magnitudes 11 to 14 in an area 15 arcminutes (1/2 Moon diameter) across. An 8th-magnitude star near the cluster’s center most likely is a foreground object.

Also sprucing up the view is a wide double star just off the cluster’s southeast edge. I visit this sight again and again.

Nestled nearby is the variable star R Scuti. It’s a sentimental favorite, because it was the first variable star for which I reported magnitude estimates to the American Association of Variable Star Observers (AAVSO). R Scuti is an RV Tauri-type star — a variable class that undergoes alternating bright and faint minima.

During its 5-month cycle, R Scuti varies from magnitude 4.5 at maximum brightness to 6 during a shallow minimum, and 8th magnitude or fainter during a deep minimum — a range within the reach of most binoculars. A chart for R Scuti appears on this page, along with the magnitudes of nearby comparison stars (magnitudes are shown without decimal points; so, magnitude 5.6 appears as 56). An observation every 5 to 7 days will suffice.

The Ring Nebula
A year ago, I featured the Ring Nebula, M57, in Lyra (“A ring and a triangle,” August 2004). Large and bright, M57 is a fine example of a planetary nebula.

Some of you questioned my opinion that to see the Ring and not just a uniformly hazy oval, you’ll need a telescope of at least 6 inches in aperture.

With a 4-inch reflector, I barely perceive a hint of darkening near the center, but never enough to convince me it’s the real deal. Maybe I’m being too picky. As I’ve said in the past, I describe objects based on what a beginner, using ordinary equipment under average sky conditions, might expect to see. When you peer into the eyepiece, always see what your eyes truly see, not what someone else suggests you should.

Special thanks to David Guibert, who spent time observing M57 with his telescope and forwarding observing reports to me. Dave, you’ve become an M57 expert.

Next month: Swimming with the Dolphin, and a cheapskate’s guide to observing Mars. Clear skies.