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.

Sunday, October 23, 2011

Summer and fall objects

While waiting for nights without a bright moon to drown out faint objects, I was observing brighter objects such as double and multiple stars, Jupiter and bright nebulae and star clusters from home. And when the night wore on, the moon too even though it's dazzling through the 15-inch. I have been looking at objects principally along the summer Milky Way from Aquila and Scutum to the south to Cassiopeia and Perseus to the north. Among them were the planetary nebulae M-57 and M-27, which are bright enough to be impressive even from my light polluted front yard in the middle of a brightly lit up suburb. I also observed other planetary nebulae such as NGC-6210, NGC-6826 and NGC-6891. Others objects I looked over were the globular clusters M-13, M-92, M-15, M-2, M-30, M-71, NGC-7006, NGC-6934 and NGC-6229. All of the NGC objects were a ghost of their normal selves but the Messier globular clusters resolved into stars at least partially.

Other star clusters I looked at included the open clusters NGC-6709, NGC-6633, the Double Cluster and M-11. However I did sketch three objects in this rich region of the sky for nebulae and star clusters. The first object is the rather small but rich open cluster NGC-7063 in Cygnus. Comprised of around ten brighter stars arranged in a crooked X, with fainter members mixed in, NGC 7063 is actually a fairly nice open cluster for light polluted areas. It stands out well from the surrounding star fields at 149X through my 10-inch Dob. It looked a little more impressive through the 15-inch, but basically the same I suspect due to the fainter stars being affected by light pollution.

Another favorite object I paid a return visit to was the small and very bright planetary nebula NGC-7027. This planetary nebula is very bluish and easy to spot in small telescopes such as my 6-inch F/8 as a small electric blue, oval shaped disk. In larger telescopes at higher magnifications the central star comes into view. Curiously, it is displaced from the apparent center of the nebula and the nebula itself is reminiscent of an oyster shell at 375X through my 10-inch telescope. At 572X through the 15-inch this object took on a bizarre appearance, the clumpiness of the nebula became very apparent and the central star shone brightly. Perhaps NGC-7027 is a bi-polar nebula like many other planetary nebulae, with one lobe pointing towards us and the other obscured by dust expelled previously by the central star while it still was a red giant. No nebula filter was needed to view it well with any of my telescopes from the driveway.

The final object is NGC-7160, a compact but rich open cluster in Cepheus unknown to me until I noted it being plotted on my Sky & Telescope Pocket Sky Atlas.  Many open clusters are drowned out by light pollution at home, but I was pleasantly surprised to find it to be a small open cluster with bright stars that enabled it to stand out from the background sky glow. It responded well to the 6.7mm Explore Scientific 82 degree eyepiece I used which gave a magnification of  196X through my 10-inch F/4.5 Dobsonian.

I've recently acquired four Explore Scientific 82 degree eyepieces with focal lengths of 14, 8.8, 6.7 and 4.7mm. With a huge 82 degree apparent field of view, peering into one is more like looking out of a visor on a space suit's helmet or a window aboard a spacecraft than looking though a telescope. The much larger true field of view makes finding and keeping objects in sight much easier as well. Sharpness, light transmission and color fidelity is excellent, without flare or filed curvature. They work very well in F/5 and below telescopes and are ideal for deep sky objects such as galaxies. If anything, the only drawback to these marvelous eyepieces is the eye relief being too short to be used while wearing eyeglasses. They come pretty close to the performance of Tele Vue Naglers, but at a much lower price. They have full multi-coatings on each surface of every element and are sealed and nitrogen purged to keep contaminants out. For the money they are an excellent buy.

Monday, October 3, 2011

The return of fall weather

The much anticipated return of cooler weather and clearer skies too has finally materialized here in Coastal Alabama, and last night was the clearest night to come along in months. I drove out to the airstrip with the 15-inch and two new eyepieces I recently acquired. There was however the annoying light from a crescent moon two days away from first quarter, but the Milky Way was plainly visible overhead as darkness fell over the airstrip I and other members observe from. Although the sky was darker than it has been, the seeing was poor and became very bad towards the end. Temperatures fell into the upper 40's F, requiring warm clothing but the dew held off until after midnight arrived. Once the moon set, the sky was dark enough for unimpeded views of my favorite objects, galaxies. Along the way I observed a number of planetary nebulae and star clusters too.

The first object I looked for was the supernova underway right now in the face-on spiral galaxy, M-101 in Ursa Major. This type 1A supernova reached a maximum magnitude of 9.9 but has faded to around 10.8 by the time I was able to finally search for it last Saturday night. Unfortunately the glare from the moon and the galaxy's being low in the sky made seeing the galaxy and the supernova harder, but the remains of the exploded star revealed themselves to the west and south of the galaxy's nuclear bulge. It's a pity the supernova didn't appear a few months earlier, it and the galaxy too would have presented a much better view for those who have smaller telescopes.

Comet C/2009PGarrad wasn't hindered at all by the moon, indeed it's tail is more apparent now than the last time I got a good look at it. Now in Hercules it's brighter than before and the tail is more side on from our perspective, making it a nice object for any telescope. A bluish color was evident and the inner coma was very bright, almost like a fuzzy star. The tail was however very diffuse and required averted vision to make out, the comet was also in front of a very star rich backdrop including three bright field stars shining through the tail.


Next I turned the telescope on the Andromeda Galaxy and several of it's companions. Seen here is a drawing I made of the inner region of the closest large spiral galaxy to our own. M-31 is actually about 5 degrees long, far too large to take in all at once through a 15-inch. At 95X the star like nucleus is surrounded by the vast nuclear bulge composed of billions of older yellow and red stars. The inner dust lane was visible plainly as a dark streak amid the intense light from the nuclear bulge and the very diffuse and faint spiral arms of M-31. The spiral arms are easily washed out by light pollution or hazy skies. Just outside the left side of the field of view in the drawing is the dwarf elliptical, M-32. M-110 was also visible on the opposite side of M-31 as a large, oval glow with a weak central brightening whereas M-32 is a small oval with an very bright, almost star like core.

After taking in M-31 and it's two nearly companions I visited two more companions to M-31, the dwarf ellipticals NGC-185 and NGC-147 in Cassiopeia. NGC-185 was bright and had a brighter center, and was easy to spot. NGC-147 was very faint, and took much more effort to spot. Both lie some 250,000 light years from M-31 and 2.7 million light years from Earth, the same distance as M-31 itself.  When I found it, it showed itself as an oval glow larger in apparent size than NGC-185, with a very slight central brightening. The next galaxy I observed in Cassiopeia was the dwarf galaxy IC-10, which is beyond our local group of galaxies. It was visible as a large fuzzy patch with a brighter zone towards one side of it. The light from the stars of the Milky Way in the foreground almost hid it from view.

The next galaxy I observed with the 15-inch was M-33, a face-on spiral galaxy that is considered to be a likely satellite of M-31. Both galaxies are some 600,000 light years apart, and M-33 is some 15 to 20 times less massive than either M-31 or the Milky Way. At 95X the small nuclear bulge is apparent and the surrounding disk is faintly visible, with patchiness and even hints of the spiral structure M-33 is well known for. The huge star forming region NGC-604 was visible, resembling a small dwarf elliptical in orbit around M-33, and a few other smaller and fainter patches where other star forming regions was seen scattered across the galaxy.

After looking at members of our Local Group of galaxies, I turned the 15-inch to Cetus and Sculptor to look at some favorite objects there. The planetary nebula NGC-246 was a large disk through my O-III filter. Despite it's overall magnitude of 8, this large planetary nebula is a difficult object for smaller telescopes, especially when skies are light polluted or hazy without nebula filters. It was very faint without the filter from the airstrip. With the filter in place, brighter zones and darker voids across its face gave the suggestion of a skull, which has led to NGG being nicknamed the "Skull Nebula."

Other objects I looked at were NGC-253, which stretched across the field at 143X and showed darker patches close to the center, and NGC-288, a foreground globular cluster that belongs to the Milky Way. It was resolved into stars to the very center. I also looked for the Cetus spiral galaxy NGC-988, which is behind a star but to no avail.

Another favorite object I looked at was the planetary nebula NGC-7662, also known as the "Blue Snowball." Through the 15-inch at 227X it was about the apparent size of Jupiter, with a very strong blue color and a dark central void visible. I was unable to see the central star due to the very poor seeing that prevailed that night, and it's faintness. Both conspired to hide it amid the glow of the surrounding nebula.

Other objects I observed include the planetary nebulae M-57 and 27, and the globular clusters M-22 in Sagittarius, M-15 in Pegasus, M-71 in Sagitta and NGC-7006 in Delphinus. The galaxies M-74 in Pisces, NGC-891 in Andromeda and the galaxy pair NGC-1160 and 1161 in Perseus were also observed. I stole a few glances at Jupiter, but the seeing was very bad and I couldn't make out much detail on the planet. For a finale, I looked at the Orion Nebula before taking the telescope down and packing up for the trip home.

Saturday, September 3, 2011

Supernovae and comets

Last Saturday night I drove out to the airstrip with the 15-inch, where I met with fellow members of the local astronomy club and a few friends. Sky conditions were not very good however, the seeing was very poor but the Milky Way was easy to see and more stars than usual were visible to the unaided eye.  Among the numerous objects observed that night, all of us looked at Comet C/2009P-Garrad, which was still in Sagitta very close to a nice double star. The tail was more noticeable while to me the coma and nuclear region became more diffuse. I'll be watching this comet for as long as possible, it's not often one stays visible for as long as this one will from the Earth.
One of Draco's many deep sky objects is the edge-on spiral galaxy NGC-6503, visible in small telescopes from a good site and an interesting object through larger ones. While it was a small oblong glow in my small 6-inch, it became a larger mottle lens shaped object through the 15-inch at 250X. NGC-6503 wasn't especially bright, either my eyes were not quite fully dark adapted or the skies increasing milkiness was attenuating the galaxy's faint light. Nevertheless, it was a object worth revisiting.

Another galaxy in Draco I visited was the multiple arm spiral galaxy NGC-6643, which shows it's spiral arms studded with star forming regions in photographs. While the spiral arms were not visible at 250X that night, the nuclear bulge was noticeable and the disk did seem somewhat patchy. This galaxy requires high magnification to make out well against the sky glow for Mobile and other nearby cities and towns.

Among the other objects I searched for was the face on spiral galaxies M-51 and M-101, both of which now have a supernova underway in them. SN2011dh has now faded from view in M-51, probably more because of the hazy skies, light pollution and the fact a dim pip of light is hard to see among the glow of the galaxy's spiral arms. SN2011fe was visible but I couldn't tell it apart from other foreground stars in our own galaxy. At the time that supernova was as 13th magnitude but now it has zoomed up to 11th magnitude, making it much more visible.

While the skies were clear at first and the Milky Way was plainly visible, sky conditions were not very good that night. The seeing was very poor, and stars remained blobs. There was surges of warm humid air mixed with cooler drier air passing through the  observing site, but strangely enough dew was minimal. Usually everything is soaking wet when I take down the telescope and put it in the car for the trip back to my house. That night everything was still mostly dry, but as I took down the telescope thin high clouds precluded observing any more deep sky objects.

Other objects I and my friends looked at are the planetary nebulae M-57 and M-27, NGC-6826, NGC-6781, NGC-7009 and NGC-7293. Those are located in Lyra, Vulpecula, Cygnus, Aquila and Aquarius respectively. I've also showed them the nebulae M-8, M-20, M-17, M-16 as well as the Veil and Crescent nebulae in Cygnus. The galaxies M-31, M-33 and NGC-7814 were among the others I examined before taking the telescope down and driving back home.

I hope to try again with SN2011fe during the next club star party to see if I can spot it against the glow from M-101's nuclear bulge, and make more drawings of my favorite deep sky objects.

Friday, August 19, 2011

Why aperture matters

When choosing a telescope, one of the most important questions that has to be addressed is the aperture, or diameter of the objective lens or primary mirror. That determines among other things, the size, weight, portability,  resolution and light gathering power a telescope has to offer. The larger the aperture, the more expensive the telescope of any given telescope will be. Furthermore, some types of telescopes are much more expensive than others of the same aperture. If observing galaxies and nebulae is what your telescope will be used for, then a telescope that offers the most aperture, and hence light gathering power is the best choice when observing capabilities alone are considered. There is no nirvana when it comes to aperture, a bigger telescope can always show dimmer objects than a smaller one from the same site. However, your muscles are only so strong, your vehicle only so big, and your bank account only so fat. Henceforth the goal when choosing a telescope is finding one large enough to show you want you want to see, yet is still affordable and isn't too heavy and bulky to transport and use easily.

With all of these factors are taken into consideration, Dobsonians are the best option for folks who want a telescope that can take them to the realm of the galaxies, and yet be affordable, portable and still have excellent optical and mechanical performance. Below are two drawings I made of the same globular star cluster from a heavily light polluted area. One was made through a 6-inch, the other through my 15-inch.

The top drawing I made with my small 6-inch Dob from a light polluted area at 60X. As you can see, it is unresolved and does not look at all like a globular cluster. From my light polluted front yard, it looks more like a comet, and even at high magnification only a few stars around the edges appear.

This is the same object from my light polluted front yard through the 15-inch telescope at 250X, which fully resolved it into stars and revealed clearly the star like inner core of thousands of stars packed into a region a few light light years across. In both cases I had the glare of thousands of streetlights lighting up the sky all around me. As you can see, a larger telescope does more even from a light polluted area, but it will be of much greater benefit from a dark site than a light polluted one.

Saturday, August 13, 2011

More drawings of deep sky objects

After my computer failed for good and I had no way to scan drawings for two months, I purchased a new computer and scanner and hence scanned the latest drawings I have made with the 15-inch telescope. While most were made from the airstrip, several were done from my driveway in the middle of heavy light pollution.

 M-15 is a compact but very bright globular star cluster in Pegasus, the only object of it's kind in fact that exists in the constellation. At 142X it was a small but very bright object that resembled a tiny pinch of salt or sand on dark fabric with the central core being a very tiny but very bright and star like. It is from this dense central region that X-rays are pouring out, possibly due to the presence of a black hole there feeding on interstellar gas and dust. At 250 and 400X the cluster becomes a swarm of glittering stars and at 572X the stars nearly fill the field of view. This 6th magnitude object is some 35,000 light years away and also possesses one of two planetary nebulae known to exist in globular star clusters. Known as Pease 1, I did not see it because it's barely non-stellar and the seeing was fair, effectively hiding it. Even so, to see it will require at least 500X to distinguish it from surrounding stars.

 M-2 is the brightest deep sky object in Aquarius and is the brightest of three globular clusters found there, the others being M-72 and the extremely faint NGC-7492. This star cluster only looks somewhat bigger than M-15, even though it is larger in reality due to the distance of more than 50,000 light years from Earth. Through the 15-inch no dense central core resembling the one in M-15 was evident, but the star cluster resolved nicely into stars at 250X.

M-51 is one of my favorite galaxies, and I look at it and it's SO companion NGC-5195 every chance I get. Through the 15-inch spiral arms are plainly apparent, along with brighter condensations that mark where star formation is underway and massive associations of O and B-type blue giants dominate the spiral arms. Recently however, M51 hosted yet another supernova, a type IIb and the third to appear in the past 15 years. The supernova occurred in the outer spiral arm and was plainly visible as a 14th magnitude start like dot the first time I looked for it. By the time this drawing was made, it brightened to a magnitude of 12.1. It is now fading and is back below 14th magnitude. In addition to the supernova and the spiral arms, hints of the "bridge" between M-51 and NGC-5195 was visible, along with NGC-5195's odd shape and structure. The nucleus of M-51 is bright and star like, with both galaxies and the supernova a splendid sight at 250X.

The pair of Messier galaxies M-59 and M-60 has always been a favorite sight for me when I had only a 6-inch telescope, and I wanted to revisit this field with the 15-inch. Two NGC-galaxies also appeared in the view and both can also be spotted with a 6-inch if the skies are reasonably clear and dark. All four of them are ellipticals with bright inner cores, resembling comets or unresolved globular star clusters instead of huge galaxies that are more massive than our own several times over. At 83X, this is a nice example of a quartet of galaxies.

M-87 is the most massive member of the Virgo cluster of galaxies and it is also the brightest radio source in Virgo as well, giving it the designation of Virgo A. This is a massive elliptical galaxy that swallowed up dozens of other galaxies over it's lifetime and also possesses over 1,000 globular clusters. In the center there is a super massive black hole that is spewing out jets of plasma at nearly the speed of light and this jet has been seen in telescopes as small as 16-inches in aperture. Through the 15-inch at the airstrip, I saw a large round object with a very bright inner core. Flanking it are two smaller elliptical galaxies, NGC-4476 and NGC-4478. This trio of galaxies makes an impressive sight at 217X through a large telescope.

The pair of bright elliptical galaxies M-84 and M-86, together with numerous other galaxies form the very heart of the Virgo Cluster of galaxies. These giant ellipticals, along with NGC-4435, NGC-4438, NGC-4387, NGC-4458, NGC-4461, NGC-4473 and a few others form "Markarian's Chain" named after an Armenian astrophysicist who found these galaxies are bound together as a small group of galaxies in the very center of the Virgo Cluster. Forming an arc two degrees long that extends into Coma Berenice's, this chain of galaxies is a marvelous assortment of elliptical and spiral galaxies for even a small telescope.

NGC-4435 and 4438 are an interesting pair of galaxies that have been interacting with M-86. Dubbed the eyes, NGC-4435 clearly shows signs of being disheveled by it's run in with the more massive elliptical, and traces of the structure seen in photos was apparent through the eyepiece. In contrast to NGC-4435, NGC-4438 has a more normal spiral form, since it has not been tugged on by M-86. The pair nicely fit in the field of an 8mm wide field eyepiece at 217X

M-80 has always been a challenging globular cluster for me even though it is very bright and easy to find. The same cannot be said for resolving it's stars, given that it's highly condensed. Through a 6-inch it looks like a comet. stars start to show up around the edges through a 10-inch on good nights, but through the 15-inch I saw it clearly as a globular cluster for the first time. It's even more concentrated than M-15, and looks very similar too, right down to the tiny, bright, star like inner core at 250X. This globular also has the distinction of being one that hosted a supernova in the center back in 1860. Probably a type 1A, the blast outshone all of the other stars put together at maximum. This object can be seen in just about any telescope, and is one of the best deep sky objects in Scorpius for owners of small telescopes who live where Scorpius does not scrape the horizon.

NGC-4458 and NGC-4461 are two more members of Markarian's Chain. Both are spiral galaxies of normal appearance and form. Fainter than NGC-4435 and 4438, they nevertheless are a nice pair of  galaxies for a 15-inch telescope at 217X.

NGC-4473 is another bright spiral galaxy that also belongs to Markarin's Chain. A single isolated galaxy, this spiral is larger and brighter than NGC-4458 and NGC-4461 with a bright core. A fine object for a 10-inch telescope, it is even better through a 15-inch at 217X.

NGC-5728 is one of a number of moderately bright and fainter galaxies in the constellation Libra, which is marked by the bright stars Zubenelgenubi and Zubeneschamali between Scorpius and Virgo. This barred spiral galaxy was small, oval shaped with a condensed, bright core. No sign of the spiral arms was apparent but the central bar gave it the appearance of an edge on galaxy. In spite of what was average sky conditions. NGC-5728 was a fairly easy and nice object through the 15-inch at 250X.

Another Libra galaxy is NGC-5812, an elliptical galaxy that is nearly round with a bright core. Easy to spot due to high surface brightness, this is probably the easiest galaxy for smaller telescopes in Libra. Resembling a comet more than anything else, it's a nice catch at 250X and can tolerate more magnification than that under good sky conditions.

NGC-5879 is one of many galaxies accessible to medium and large aperture amateur telescopes in the constellation Draco. This spiral galaxy is small in apparent size but has a reasonably high surface brightness, making it easy to find with the 15-inch. The bright inner core is distinct and the disk itself is bright enough to show up easily.

NGC-5981, 5982 and 5985 are a trio of galaxies in Draco that consists of a face-on spiral, elliptical and a edge on spiral galaxy. At 153X all three fit into the field of view nicely, with the elliptical galaxy NGC-5982 being the brightest of the three. I have always been able to see NGC-5982 and 5985,  which is the face-on spiral with a 10-inch, but the third galaxy has been elusive. Apparently the edge on spiral NGC-5981 is a lot fainter than it's apparent magnitude suggests, it was faintly visible through the 15-inch. This is a very nice trio for a medium to large aperture telescope.

One of my favorite deep sky objects has always been the Saturn Nebula or NGC-7009. Even through a 6-inch I can see the strong blue color and the distinctive outline of this planetary nebula. What I never seen clearly until now was the Saturn like ring, the ansae or the central star. The ansae did not appear because I was observing the nebula from the driveway, but the central star and ring did appear at 400X. The electric blue color was intense and oddly enough the view was not that much better through an O-II nebula filter either from home.

These are just a few of the many nebulae, star clusters and galaxies I have observed recently with the 15-inch, which has exceeded my expectations in every respect. I'm very pleased with how my handiwork has turned out, and will continue to observe and draw more deep sky objects with it in the future along with the 10-inch telescope. That telescope is much more convenient to use, but it doesn't show galaxies nearly as clearly as the 15-inch does. Even so, both telescopes as well as my original 6-inch are going to remain in active use for many years to come.