Small Wonders: Scutum 1/16 Small Wonders: Scutum A monthly sky guide for the beginning to intermediate amateur astronomer Tom Trusock 22-July-2007 Figure 1: W idefield map 22-July-2007 Tom Trusock 2/16 Small Wonders: Scutum Figure 2: W idefield image courtesy Bert Van Donkelaar For a full resolution image w/ a sky map superimposed, see ”Additional Resources‘ at the end of this article. Tom Trusock 22-July-2007 Small Wonders: Scutum 3/16 Target List Name Type Size Mag RA DEC B110 Dark Nebula 9.0’ 18h 50m 37.8s -04 45’ 31” B111,119a Dark Nebula 120.0’ 18h 51m 25.8s -04 59’ 30” B114-8 Dark Nebula 50.0’x5.0’ 18h 53m 38.2s -07 05’ 29” Basel 1 Open Cluster 9.0’ 8.9 18h 48m 38.0s -05 50’ 32” IC 1295 Planetary Nebula 1.5’ 15 18h 55m 03.6s -08 49’ 03” M 11 Open Cluster 11.0’ 5.8 18h 51m 32.0s -06 15’ 30” M 26 Open Cluster 10.0’ 8 18h 45m 44.6s -09 22’ 25” NGC 6664 Open Cluster 12.0’ 7.8 18h 36m 56.4s -08 10’ 41” NGC 6712 Globular Cluster 9.8’ 8.1 18h 53m 30.8s -08 41’ 49” R Scuti Star 5.4 18h 47m 54.9s -05 41’ 52” Challenge Objects Name Type Size Mag RA DEC PK 20-0.1 (Abell 45) Planetary Nebula 5.0’x4.7’ 12.9 18h 30m 45.0s -11 36’ 45” PK 27-3.1 (Abell 49) Planetary Nebula 35”x33” 16.1 18h 53m 56.1s -06 28’ 29” Scutum cutum, formerly Scutum Sobiescianum, is an interesting little constellation. With only one star brighter than 4th magnitude, it‘s something of a cosmic Rorschach test, then it‘s the only S political constellation still found in the night sky, and finally with it‘s location in summer Milky Way, Scutum‘s small size belies a fairly large number of interesting targets. Johannes Hevelinus introduced Scutum Sobiescianum (Sobieski‘s Shield) in 1690, to honor King Jan III Sobieski of Poland. King Sobieski‘s greatest moment came in 1683 during the battle of Vi- enna, with nothing less than European civilization at stake. At 4am on September 12, 1683 Sobi- eski found his 81,000 Polish, Austrian and German troops arrayed against 130,000 Turks. Out- numbered, they fought throughout the day, till 5pm when King John led a cavalry group against the enemy, breaking their battle line and scattering them in confusion. A mere 30 minutes later, he entered the tent of the enemy commander and the battle was over. Thereafter he was hailed by the Pope and other noteables as the —Savior of Vienna and Western European Civilization“. King John died on June 17, 1696. Contrary to the lines and drawings we see in the star atlases, I find there‘s really no easily recog- nizable figure in Scutum. Overshadowed by its neighbors Aquila, Sagittarius and Serpens, the easiest way to find it is to simply scan the Milky Way between Sagittarius and Aquila – you can use the three stars at the tip of Aquila as a guide. Scutum‘s brightest star (Alpha) rings in at a rather paltry magitude 3.85, but as mentioned above don‘t let that fool you. Because it‘s embed- ded in the summer Milky Way there are a number of interesting targets. 22-July-2007 Tom Trusock 4/16 Small Wonders: Scutum Figure 3: Scutum finder chart For example, within this small space the catalogs in SkyTools 2 list 52 planetary nebula, 21 open clusters, 91 dark nebulae, 3 diffuse nebulae, and one globular cluster. Before hauling out that telescope though, I‘d recommend a few observations using the old mark 1 eyeball and a decent set of binoculars. The first thing you‘ll notice is the great Scutum star clouds. Being on the edge of the great rift in the Milky Way helps the star clouds to stand out, but there are simply a boatload of stars in this region regardless. On those warm summer nights, I like to trace the Milky Way with my naked eye every few min- utes during late dusk. I find it interesting to watch our galaxy grow. Over the years, I‘ve at- tempted a sketch of the Milky Way, but each night I try it winds up looking just a little bit differ- ent.Watching it emerge from dusk treats me to a similar view over the course of one evening. R Scuti Speaking of stars, while you‘re in the area, you should take a gander at R Scuti. This is a member of the RV Tauri class of pulsating variable stars and ranges from magnitude 4.9 to 8.2 over its 140 day period (although the deep minimum appears only every fourth or fifth cycle). This ancient variable is located between two of our galaxy‘s spiral arms: our own Orion arm, and the Sagitta- rius-Carina arm. Dark Nebulae in Scutum Crossen, in —Binocular Astronomy“ notes that there are two great star clouds in Scutum, one in the southwest corner of the constellation, and the other in the northeast. From a dark site, these are easily visible to the naked eye, and come to life in binoculars or a rich field telescope (if you‘re using a telescope, pop in your lowest power eyepiece and be sure to look through it while moving it to scan the area to better make note of the —boundaries“ of the star clouds). My eyes are often shocked by the sheer number of stars in the area, and as I let my vision wander, I often forget to Tom Trusock 22-July-2007 Small Wonders: Scutum 5/16 use averted vision. Remember to do so, and take a few minutes to study the area carefully. You‘ll note vast regions of darkness scattered throughout the starry background. Scutum is rife with dark nebulae. These concentrations of gas and dust block the light of distant stars and create a —hole in space“ effect. To me, the largest and most noticeable of these holes (B111, 119a) lies just to the north of Messier 11 and creates the illusion of a stellar no man‘s land. Figure 4: Scutum Area Map 1 B114-8 A degree to the SE of Messier 11, we find B114-8. Eric Graff has contributed a won- derful sketch of this area. Author Steve Coe has compiled a docu- ment listing the best of these holes in space and has posted on the SAC‘s web- site. See The Best of Barnard‘s Dark Nebulae. Steve lists 5 in Scutum alone. For dark nebulae, I‘ve found I need to use low powers, wide fields and averted vision. Some are obvious, but others require a careful attention to detail. The best in- struments to see them in are probably bin- oculars or wide field refractors so as to get a good contrast with the surrounding area. Figure 5: B114/115 sketch courtesy Eric Graff 22-July-2007 Tom Trusock 6/16 Small Wonders: Scutum M11 — The Wild Duck Cluster And now, on to the —standard“ deep space targets. Let‘s start with what‘s likely the most viewed object in Scutum – Messier 11, the Wild Duck Cluster. When I asked for observations of targets in Scutum, this one object, by itself claimed over half of the total received, and talk about an overwhelming response! I want to thank everyone for submitting their images, obser- vations and sketches. Unfortunately, I‘m not able to use all of the, but there were a num- ber of excellent ones. Figure 6: M11 (DSS) Figure 7: M11 Image Courtesy Michael Fulbright Tom Trusock 22-July-2007 Small Wonders: Scutum 7/16 Figure 8: M11 Sketch Courtesy Carlos E Hernandez Just visible to the naked eye, this cluster seems to be (visually anyway) one of the densest open clusters in the night sky. With a very small telescope or binoculars it‘s easily mistaken for a globu- lar. But with moderate magnification anything above 2-3 inches or so will resolve it clear across the face. In 1844 Admiral Smyth compared it to a —Flight of Wild Ducks“ and thus it earned the name —Wild Duck Cluster“. Confused astronomers have been looking for the ducks ever since. Sue French clears up the mystery in her excellent elestial Sampler by including a copy of Smyth‘s sketch that accompanied his observation. The flight of ducks can be seen to be a long flat V off to one side. Personally I see an arrowhead or angelfish in this most populous open cluster. What do you make out? Note the one star that seems to pop out in from the cluster itself? Many people suspect it‘s actu- ally a foreground object. 22-July-2007 Tom Trusock 8/16 Small Wonders: Scutum Basel 1 While you‘re in the area, you might take a quick look just under a degree to the NW for Basel 1. Eric Graff has this to say about the region while contributing the following sketch: The Wild Duck Cluster, M11 is a truly spectacular object in an amazing field. It seems to rest on an island in a sea of dark nebulosity. Nearly a degree away to the northwest look for the scrappy little open cluster Basel 1 and its odd little ring of six faint stars. Figure 9: Basel 1 Sketch Courtesty Eric Graff Tom Trusock 22-July-2007 Small Wonders: Scutum 9/16 NGC 6712 and IC 1295 Figure 10: Scutum Area Map 2 Figure 11: NGC 6712 (DSS) Figure 12: IC 1295 (DSS) Now drop about 2.5 degrees almost directly south of M11 for a surprisingly bright globular cluster.