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Planetary nebula M27, known as The Dumbbell Nebula, is a staple of Summer observing. It's easy to find it using the arrow shape of the constellation Sagitta as your guide. You'll find Sagitta's tail feat~ers about a quarter of the way from Altair to Albireo. Follow the arrow to its tip, then take a 90° turn to the north to reach a sprawling capital M of mag 5-6 stars, 5° across and 4° above the arrow: M27 is a half degree south of the middle star of the 11M" (mag 5.7 whitish dwarf 14 VUlpeculae).

With a diameter of 6 • Vega arcminutes, M27 is quite large • for a planetary nebula, but its • high surface brightness makes it fairly easy to spot. Start out at low power, but then take • advantage of the nebula's • brightness to ramp the power • up over 100x to see its A/bireo distinctive shape in greater • • detail. The Dumbbell's name derives from its dual-lobed structure, giving it an almost • rectangular. hourglass or apple­ M27 ' • core shape. Its mag 13.9 o central sta(is a hot blue (type ~. Coa/hanger • 07) subdwarf with a surface temperature of 85,0000K. Sagitta

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While you're in the neighborhood, wander back to Sagitta and hunt down the often-elusive globular cluster M71, hiding between Gamma and Delta Sagittae, and just a shade south of a line between them. A distinctive line of three stars of decreasing brightness (anchored by mag 6.2 hot blue supergiant 9 Sagittae) will bring you right to the cluster, which surrounds a mag 8.1 star lying a quarter degree east of the line of three. It can be seen as a round or slightly triangular haze in small scopes, and begins to resolve in 4" scopes at higher power (try lOOx). M71 is exceptionally loose for a globular, and has sometimes been classified as a dense open cluster.

Eyepiece Charts (M71): 1 0 field, stars to mag 9.5, North at top, magnitudes shown decimals omitted Erect image (left), mirror-reversed (right) l ~------~----- J • •

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I l____---"-__-======_ ___J Before packing up for the night, take a minute to scan 4 0 NW of Sagitta's tail feathers - a third of the way from Altair to Vega - to find the open cluster Collinder 399, also known as Brocchi's Cluster but most commonly referred to as The Coathanger: a perfectly straight line of six mag 6-7 stars couples with a hook­ shaped group of four slightly brighter stars to serve up the image of a coat hanger floating upside-down in space. Just over 10 wide, The Coathanger is a good target for binoculars - and a good reason to have a wide-field eyepiece in your collection.

Rick Gering / September 2019