Monthly Messier Star-Hop; Septemeber #1
By Art Russell

Anticipating September's arrival, we hope for cooler weather and clearer skies when the first breezes of Autumn will finally dispatch the Southeastern summer’s impenetrable haze. No more evenings lost peering into skies that for all intents and purposes have the limiting magnitude of skim milk!

This month’s star-hops take us directly overhead and into "Dobson’s Hole." "Dobson’s Hole," or more properly, the "zenith," is that area of the sky in which it is most difficult to maneuver alt-azimuth, or dobsonian style, telescopes. This month "Dobson’s Hole" frames the area of the constellation Cygnus and the nearby constellations of Lyra, Vulpecula, and Sagitta. Here, we’ll star-hop to two of the northern hemisphere’s finest planetary nebula, M57, the "Ring Nebula," and M27, the "Dumbbell Nebula." We’ll also take in several double stars, Albireo, and Epsilon Lyrae; two open clusters, M29 and M39; and two globular clusters, M56 and M71, as well. That gives us a pretty full agenda for this month, so let’s head outside under dark skies and get started!

Star-Hop #1; M29, NGC 6913. Directly overhead this month is the constellation Cygnus, the "Swan," also known as the "Northern Cross." As we look directly overhead we’ll find the zenith about 2 degrees, or about the width of two fingers held at arms length against the sky, away from Eta Cygni, the middle star in the neck of the "Swan," which itself points to the southwest. Moving back to the northeast in Cygnus to its central star, Gamma Cygni, our first star-hop this evening is to the open cluster M29. This open cluster is a little less than 2 degrees to the south-southeast of Gamma Cygni, and is really best seen in binoculars as it sometimes becomes almost indistinguishable from neighboring background stars in larger telescopes. Take your time to look over the field and properly identify M29. This is important as Cygnus is astride the northern Summer Milky Way with its myriad stars and seemingly countless clusters. In binoculars, M29 is very easily seen as a very small open cluster with perhaps 6 stars visible in averted vision. Its remaining stars were not visible in direct vision, but rather appeared as an embedded nebula. In a moderate sized telescope at low power, the cluster was unimpressive with no concentration of stars. Moreover, there may appear to be a distinct "H" pattern present.

Star-Hop #2; M39, NGC 7092. Locating M39, takes a bit of work on our part. First locate the stars Delta Cygni, and Deneb, Alpha Cygni, and then extend an imaginary line between them. Extend this line past Deneb for a distance a little less than that between Delta Cygni, and Deneb, and you arrive at the much less brighter 4th magnitude star, Rho Cygni. As an aid, the distance between Deneb and Rho Cygni is about 9 degrees or a little less than that spanned by your fist. From Rho Cygni, M39 is located a little more than 2 1/2 degrees to the north-northwest. Although M39 is the brightest open cluster in the area, you’ll find that it may a bit disappointing through the telescope where it appears as a poor cluster with only a few stars, most of which seem to be of the same apparent magnitude.

Star-Hop #3; Albireo, Beta Cygni. The next star-hop is so simple that its really more of a star identification. Albireo marks the foot of the "Northern Cross" formed by the stars Deneb, Gamma Cygni, Delta Cygni, Epsilon Cygni, and Albireo. It is also known as the "Hen’s Beak" and marks the southern end of the constellation Cygnus. However, more importantly, Albireo is also one of the most beautiful double stars for small telescope users. Take a look. Can you see its beautiful blue and yellow-gold component stars? A high power set of binoculars may split this star, but try to use a telescope at low to moderate power if you have it available. Also importantly, don’t forget Albireo’s location. We’ll use it as the jumping off point for our following star-hops.

Star-Hop #4; Epsilon Lyrae, the "Double-Double." Our next star-hop starts at Albireo and takes us to the constellation Lyra, the "Lyre," or harp. Locating Lyra from Albireo is relatively easy because its most prominent star Vega, Alpha Lyrae, is the second brightest star in the northern skies. From Albireo, Vega is 15 degrees, or the distance spanned by your hand’s first and last fingers, along an imaginary line to the northwest. Once there, you can’t help notice Vega. Once you’ve located Vega, you’re just a short hop away from Epsilon Lyrae, one of the most famous double stars in the sky, as well as being one of the finest. In fact Epsilon   Lyrae is not a double star at all. Rather, it is a quadruple star. Epsilon Lyrae is a little more than 1 1/2 degrees (a little more than the width of your forefinger) northeast of Vega. Alternatively, Epsilon  Lyrae also forms the northern most apex of an equilateral triangle consisting not only of itself, but Vega and the star Zeta Lyrae as well. Take your time here. You don’t need a telescope to "split" or resolve the separate components of the "Double-Double;" a set of binoculars will do the job nicely. Once you arrive, you’ll be rewarded with one of the most interesting double stars in the sky.

Star-Hop #5; M57, NGC 6720, the "Ring Nebula." Once you’ve found Vega, you are also very close to the planetary nebula, M57. From Vega, within the constellation Lyra, head southeast toward the two northern "pointing stars" for M57, Zeta Lyrae and Delta Lyrae. From Zeta Lyrae, head south-southeast to the two southern "pointing stars" for M57, Beta Lyrae and Gamma  Lyrae. M57 is located almost exactly between Beta Lyrae and Gamma Lyrae. M57 is not a good object for viewing with normal sized binoculars because of its relatively small size and the fact that normal binoculars will not provide enough magnification. However, large astronomical binoculars (11X80 and larger) under dark skies and ideal conditions may show M57 as a pale, soft appearing disk, whose edges gradually fade into the background sky. M57 maintains its disk like appearance in a telescope and takes on an annular, or ring like, appearance under higher powers. Take time to find M57. You’ll be well rewarded. Moreover, since its position is so well known and well marked in the sky, finding M57 is often one of the first objects a beginner seeks when learning how to use a telescope.

Star-hop #6, M56, NGC 6779. Located along the same imaginary we used when locating Vega from Albireo, the globular cluster M56 is located about 3 degrees, or 1/5 the total distance, from Albireo to Vega. In binoculars, M56 is easily found and appears as a disk shaped soft edged glow which brightens toward its center. Since this cluster is so easy to find, don’t miss it enroute to Vega!

Star-Hop #7, M27, NGC 6852, the "Dumbbell Nebula." The star hop to the planetary nebula, M27, in the 4th magnitude constellation Vulpecula, is a natural continuation of a star-hop from Albireo to Vega, except in the opposite direction. In fact, it uses the same imaginary line, with Vega and Albireo as pointer stars! Using this imaginary line, M27 is located only about 8 degrees, or a bit less than the distance spanned by your fist, away from Albireo, except, in this case, to the southeast. Alternatively, you can also locate M27 by first locating Vulpecula and then proceeding to M27. Starting at Albireo, Alpha Vulpeculae is only a little more than 3 degrees to the south-southwest. From there, hop over to 13 Vulpeculae which is a little more than 5 degrees, or three fingers width, to the east-southeast. From 13 Vulpeculae, M27 is only about 2 degrees to the southeast. M27 is visible in binoculars as a soft, roughly square glowing cloud. However, using a telescope quickly tells you that this is a spectacular object. In fact, M27 is the second largest and brightest of all planetary nebula. At high power, M27 takes on a distinctly oblate or foot ball shape with the area of greatest brightness confined to a rectangular area near its core and areas of lesser brightness extending along either end of its longitudinal axis.

Star-Hop #8, M71, NGC 6838. Our last star-hop for the evening takes us to the relatively small constellation Sagitta and its moderately bright globular cluster, M71. There are several ways to locate M71. From the constellation Vulpecula, start at the star 13 Vulpeculae. M71 is about 5 degrees directly south on a line from 13 Vulpeculae. Alternatively, starting in the constellation Sagitta proper, M71 is located about midway and south of the line between Gamma Sagittae and Delta Sagittae. In a moderate power telescope M71 is clearly seen with the possibility of dark lanes within the globular cluster. Can you find them?