Sunday, November 13, 2011

2011 Deep South Regional Star Gaze

The last week of October was the occasion I was long looking forward to, the chance to try out my 15-inch truss-tube Dobsonian under some dark skies at the annual 29th Deep South Regional Stargaze held near Norwood Louisiana at a site called the Feliciana Retreat Center. While the weather forecast looked doubtful at first, it turned out weather conditions were better than expected and I was able to observe during all three nights I was there before returning home. I also took along my 10-inch F/4.5 Dob as well, because it has digital setting circles and itself is a powerful telescope when the skies are dark.
 Along with numerous well known objects such as the Ring Nebula and the Andromeda Galaxy, I went in search of galaxies and nebulae I have not seen before too. During the daytime I spent time looking at the telescopes other folks brought, attended a few presentations and even bought another coma corrector so I have one for both of the larger Dobs I currently have. 
I've also walked about the retreat where the stargaze was held, which is a sprawling facility in the Louisiana countryside that has a lodge, cottages, a log cabin home, a pavilion, a large lake, a huge field where attendees set up and used their telescopes, a pond and numerous hiking trails. The lodge also had a dining hall where breakfast and dinner were served, and on Saturday some of the attendees cooked gumbo for everyone. It was very good gumbo indeed.  At night when I wasn't observing I retired to the cottage where I reserved a bunk and slept there when fatigue or clouds made it time to call it a night. The retreat where the DSRSG was held was the nicest place so far where I have attended a stargaze, and I hope to be able to return there next year,  hopefully with all three of my telescopes instead of just two. Aside from myself, only one other member of the Mobile Astronomical Society was able to make it out there this year.

 We set our telescopes up in adjacent spots on the north side of the observing fields so we could gain the best possible view of the sky. While my 15-inch was among the biggest telescopes on the field, only a 20-inch 18-inch and a 16-inch were larger than mine, he brought his 8-inch Schmidt Cassegrain and 4.5-inch Newtonian. While I mostly observed by myself, I did show him and some University students next door objects such as the Andromeda and Triangulum galaxies, the Veil Nebula and Stephan's Quintet along with the planets Jupiter and Uranus. 
The galaxy NGC-784 in Triangulum has been a frustratingly elusive object for me, until I finally located it with the 15-inch from the DSRSG. It was much larger than I expected, and hence had a very low surface brightness that made it invisible from the airstrip due to haze and light pollution. It was large and ghostly, with little sign of any structure other than it's elongated cigar like shape.
NGC-877 in Aries was much easier to spot through the 10-inch than NGC-784 was through the 15-inch. Fairly small but fairly bright, it's highly elongated with a brighter core. This galaxy is one of six in Aries that an 8 or 10-inch telescope can reveal to someone who has good skies to observe under.
The quartet of elliptical galaxies in Pisces was one target I have found hard to see from the usual site I observe from due to light pollution and the faintness of it's members. From the airstrip I've seen "lumpy darkness" whereas from the Feliciana Retreat all three galaxies plus a fourth were evident through the 10-inch. All were small and faint round, oval or egg shaped featureless objects that like most elliptical galaxies have a brighter center. Three more galaxies exist in the vicinity, but I was not aware of them and hence I didn't search for them. That will have to wait until I can get to a dark site in the near future.
Also in Pisces I located the pair of galaxies NGC-507 and 508. NGC-507 is the larger and brighter of the two, both have bright cores and round or nearly so shapes. While the NGC-507 is an 11th magnitude object that forms the core of a small group of galaxies, NGC-508 is much fainter at nearly 13th magnitude. Both galaxies are interacting with each other and are thus listed at Arp 229 with NGC-507 classifies as an Sa type spiral whereas NGC-508 is an E0 elliptical. The galaxies NGC-503, NGC-504, and IC-1687 along with MCG+05-04-048 are other members of the NGC-507 galaxy group that I did not see through the 10-inch due to their extreme faintness.  I will be able to see NGC-503 through the 15-inch, but the others are 15th magnitude and fainter, requiring either a much larger telescope or a CCD camera to see.
Another Pisces galaxy I located was the round and bright NGC-524, which is a face-on Sa spiral galaxy with a very large nuclear bulge and a small disk. It could be confused with an elliptical galaxy and was easy to spot at low power. At 170X it showed it's bright core but was otherwise rather featureless, and it remains so even in long exposure photos. Like NGC-507, it too forms the nucleus of a small galaxy group, whose other members are 14th magnitude and fainter. I will return to this galaxy with the 15-inch since three of them should be doable objects when the skies are dark enough.

The galaxy NGC-1156 in Aries was an interesting find through the 15-inch. This irregular galaxy showed clear evidence of it's lumpy structure at 227X. Although it's faint and diffuse, subtle brighter patches mark where star formation is underway, making this object similar to the Large Magellanic Cloud.
The edge-on galaxy NGC-1184 in Cepheus was quickly located with the 10-inch, after eluding repeated searches from my usual observing site. With an apparent magnitude of 12.6 and a size of 2.8 by .7 arc minutes, NGC-1184 is both small and very faint. It appeared as a dim slash of light with a somewhat brighter center. This lenticular galaxy is only ten degrees from the north celestial pole and thus is a circumpolar object from most of the northern hemisphere.
The galaxies NGC-6906 and IC-5006 are a challenging pair to see from less really dark locations, but they revealed themselves to the penetrating gaze of the 15-inch. NGC-6906 is the larger and brighter of the two was was quickly spotted as an oval glow with a brighter center. The 12.7 magnitude Sb spiral galaxy has repeatedly gone unseen from the airstrip because of it's low surface brightness. IC-5006 is an even tougher nut to crack, being visible as a very small glow with a weak central brightening at 298X. Both formed a nice galaxy pair embedded in the dense star fields of eastern Aquila the eagle.
Another galaxy in Aquila I observed was the much brighter NGC-6915, arguably the best galaxy in Aquila for medium sized amateur telescopes. This 12th magnitude spiral galaxy is fairly bright with a bright inner core and has an oval outline. Otherwise featureless, it is observable even from less than pristine sites with an 8 or 10-inch telescope.
NGC-6926 is another galaxy in Aquila, but unlike NGC-6906 and NGC-6915, this object is both an irregular and barred-spiral galaxy. It looked lumpy through the 10-inch, but I did not see the jumbled spiral arms so clearly seen in photographs. Clearly it has been disturbed by or even merged with another galaxy recently. NGC-6929 also lies in the field but was unseen due to it's magnitude of nearly 14 and the galaxy's low elevation in the sky. I will definitely re-visit this object next spring or summer with the 15-inch.
 NGC-7172, 7173, 7174 and 7176 form a quartet of galaxies in the southern constellation Pisces Australis, the southern fishes. The brightest of them is NGC-7173, an elliptical galaxy with an apparent magnitude of 11.2. NGC-7172 is an lenticular galaxy that is bisected by a dark dust lane, which did not show up through the 10inch. However this galaxy was larger and more elongated than NGC-7173. NGC-7174 and 7176 are amalgamating into a single galaxy, and appear as such at 196X through the 10-inch. NGC-7174 is a spiral galaxy whereas NGC-7176 is an elliptical in close proximity to it both in space and in the field of view. All belong to a galaxy group centered around NGC-7172. This is definitely a worthy subject of close study by owners of medium and large telescopes for here the ongoing merger of two galaxies can be see plus another one that apparently has just finished swallowing up another galaxy.
NGC-7221 is another galaxy in Pisces Australis, but it is not associated with the NGC-7172 galaxy group. At an apparent magnitude of 12.5, this nearly round spiral galaxy is rather faint for a 10-inch and shows it's bright core. Small in apparent size, it does bear magnification well and the spiral arms and disk appear as a haze that surrounds the nuclear bulge. Although classified as an Sb spiral galaxy, it looks like a barred spiral galaxy in photos that is a rather good match for the Milky Way in structure and appearance.
The pair of galaxies NGC-7541 and 7537 in Pisces made an interesting find though the 10-inch. With an apparent magnitude of 11.9 and double the apparent size of NGC-7537, NGC-7541 is an easy object from a dark site with an 8 or 10-inch telescope. It's sliver like shape and fairly high brightness made it easy to spot. NGC-7537 took a little more effort to see, but it quickly showed itself with averted vision despite it's faintness due to an apparent magnitude of 13.1. It brightens rapidly towards the center where NGC-7541's brightness is more even. Both galaxies are canted with respect to each other. Because of it's location within the circlet of western Pisces, it is in a good position to observe through the fall and early winter from the northern hemisphere and is a striking sight.
The last object is the incredibly difficult emission nebula NGC-7635 in Cassiopeia, also known as the Bubble Nebula. I have only once caught a mere glimpse of it with a 10-inch from a remote and very dark forest in southern Alabama, and that required averted vision and an O-III filter. From the Feliciana Retreat Center it was easier to see through the 15-inch, but not by much even with an O-III filter in place. I made out the arc of nebulosity and soon found the fan of dimmer nebulosity that extended from the concave side of the brighter arc. Then I spotted hints of nebulosity around a nearby star. Once I located it, I was able to see it with direct vision through the 15-inch with a 6.7mm and 8.8mm Explore Scientific 82 degree eyepiece, with the 8.8mm providing the best view. This emission nebula can be spotted in smaller telescopes, but you will need very dark and clear skies far from cities, it is very faint. Apparently, a star has ejected it's outer envelope, creating both the bubble and the fans of very dim nebulosity so evident in long exposure photographs.

I enjoyed immensely the opportunity to try out the 15-inch at a very dark area on both familiar objects as well as objects I have not seen before. The extra five inches of aperture had a huge effect on how objects looked through the telescope, and others I never would be able to see with a 10-inch are now visible. Even so I was locating scores of objects with the 10-inch thanks to the digital setting circles it is equipped with. It's also a blessing to be able to look just about anywhere in the sky and remain seated in a chair. I plan to take both telescope to star parties in the future where I can observe an ever growing number of galaxies and nebulae impossible to see from my local area.

Sunday, November 6, 2011

Latest objects observed from the airstrip

Before heading off to the Deep South Regional Stargaze at the end of October this year, I loaded the 15-inch into my car and drove to the usual observing site the local club uses at the airstrip. Once there I began looking for a list of objects I found in my star atlas and planetarium software, and as soon as it became dark they began to turn up one after the other in the eyepiece. Sky conditions started off as excellent, and the Milky Way was plainly visible overhead with the dark rift from Cygnus to Sagittarius evident. As the night wore on they declined somewhat, until the impending moonrise and heavy dewing arrived and it became too moonlit and damp to be worth staying any longer.
I first located the large and bright open cluster NGC-1342 in Perseus from my heavily light polluted front yard, where it showed itself to be an impressive open cluster. From the airstrip it was even more so, with stars grouped into patches with an apparent void that divides it in two. A nice winter star cluster that rivals others in the area such as NGC-1664, NGC-1528 and NGC-1545 in neighboring Auriga in size, richness and brightness.
In contrast to the sprawling and splashy NGC-1342, NGC-7044 in Cygnus the swan is a much less conspicuous object. Both immerse deep in the star clouds and interstellar dust that pervades Cygnus, it is also very remote and thus faint. This small open cluster is visible as a dim patch of light  peppered with very faint stars. Completely out of reach from my home, it is quite small and faint through the 15-inch.
In the constellation Cepheus the king I came across NGC-7139, a fairly large and very faint planetary nebula. Nearly invisible without an oxygen III nebula filter, it became plainly visible with the filter in place. This round planetary nebula was nearly featureless except for a slight brightening around the rim. I was unable to find the central star with or without the filter, and with an integrated magnitude dimmer than 13th magnitude NGC-7139 is impossible for small telescopes.
In Cygnus I turned the telescope on the proto-planetary nebula PK80-6.1, also known as "The Egg Nebula." Imaged by the Hubble space telescope, this nebula shows it's successive shells of gas and dust, which are nestled within each other much like a Russian matryoshka doll. The nebula which shines by relfected light from the central star instead of flouresecence as true planetary nebulae do also has peculiar beams of light emerging from it in the shape of an "X." When first found in photographic surveys, it was dubbed the Egg Nebula in reference to it's shape. I was not able to make out the X shaped beams or jets, but I was able to make out the two illuminated lobes, which were white in color and looked much like the jet spat out of a plasma-cutting torch. Small and bright, this object is quite detailed at 425X. The challenge this object posed for me was not seeing, but finding it. The Egg Nebula is very small, and yet even a good small telescope at 200X and above will reveal it.
In the constellation Triangulum most stargazers concentrate on M-33, the Triangulum galaxy and it's features such as it's reverse S-shaped spiral arms and it's star forming regions. However, other background galaxies do exist there which are much more distant than M-33, but still visible in amateur telescopes. One such galaxy is the nearly round elliptical galaxy NGC-777. This 11th magnitude object is small but quite bright, and thus observable even when skies are somewhat light polluted. Only a central brightening was noticeable, in all other respects like most E2 elliptical galaxies NGC-777 is what amounts to a huge and featureless globular star cluster of old yellow and red stars.
NGC-7419 in Cepheus is another faint open cluster next to a pair of bright field stars. It's very faint with the stars being arranged in an ellipse with one of the bright field stars at one end which almost hides it. It took boosting the magnification to 298X to clearly distinguish the star cluster from the numberless field stars visible at the same time.
The galaxies NGC-1160 and 1161 I located with the 15-inch, with NGC-1160 being the fainter of the two. Previously that galaxy eluded me while searching for it with the 10-inch, whereas NGC-1161 was quickly located. Both are oval shaped galaxies but NGC-1161 is an SO lenticular galaxy while NGC-1160 is a Sc spiral galaxy. Both are canted to each other in the field of view. This is a nice duo of galaxies for those who have a medium or large aperture telescope and access to at least a reasonably dark site.
NGC-7429 is another open cluster in Cepheus, but brighter, larger and more conspicuous than NGC-7419. One group of stars forms the outline of a teardrop with the rest of the members scattered across the vicinity. A quite attractive open cluster for larger telescopes. Other objects I observed included the spiral galaxies M-31 and M-33, which showed their spiral arms, dust lanes, star formation regions and star clouds and in the case of M-31 it's star like nucleus. The Veil Nebula actually resembled a bridal veil drifting among the stars, while the Crescent Nebula or NGC-6888 showed it's full oval outline around the Wolf-Rayet star that expelled it into space along with the brighter arcs along one side. The face on spiral galaxy M-74 and the edge on galaxy NGC-891 in Andromeda were beautiful sights as well, with the dust lane along NGC-891's length apparent at 227X. Before I started to disassemble the telescope and load it into my car for the trip home, I spent a few minutes scanning the Orion Nebula, which showed details rivaling those seen in photographs, Dark clouds were everywhere among the brightly glowing ionized gasses that dominate M-42. It was a very nice night of observing and when I was not peering through the telescope, looking up at the stars.