by David Kingsley
I have long since finished the Messier List. Although I check back on some favorite Messiers nearly every observing session, it has been years since I have looked at some of the objects. I decided that last weekend would be a good time to try another Marathon, break in a new scope, and welcome the spring observing season after a long wet winter.
I brought both my 14.5 inch Starmaster and a one-month old 105 mm AP Traveler to Henry Coe on Friday night. I've had the Traveler out in the backyard a lot looking at doubles, the moon, and planets, and once to Fremont Peak, but on a night I mostly hunted objects with larger aperture. Last Friday was the first extended observing I have done with the scope on a whole range of objects from a dark sky location.
The Traveler worked great as a Marathon scope. I have it mounted on an older Vixen Custom D alt-az mount with wooden legs that I bought used on Astromart. This mount makes it possible to just grab the scope and push it around without releasing any clutches, very much like starhopping with a Dob. Once near an object,the slow motion controls on the mount make it simple to keep the scope centered on an object, and to make very fine position adjustments with almost no vibration. The counterweight on the mount means that I don't have to change balance positions of the scope as I point to different regions of the sky, or as I switch between different kinds of eyepieces. Both the scope and mount are also light enough to pick up and easily move around an observing area. I took advantage of this several times in the parking lot at Hentry Coe on Friday night. First to see around the tree that blocked part of the southern sky. Then to position myself in just the right position to pick off Omega Centauri near the horizon. Then to observe in the lee of a large truck when the wind picked up around 2 am. And finally to get the best view of the last Messier objects just rising from the eastern horizon near morning. I used an Orion 6x30 erect image finder for star hop through the entire night, based on the observing order and finder charts in the Don Machholz Messier Marathon book.
I expected I would miss M74 at dusk in the western sky, and did. This is one of the toughest setting objects for a spring marathon, and is located in the brightest portion of the sky from Henry Coe. I was more surprised at how hard both M110 and M33 turned out to be in the western sky after sunset. I was able to log both with averted vision through the Traveler after lots of looking with different eyepieces, but that's pretty sad for objects that are normally binocular eye candy when they are better placed in the sky. Once I was past the first half dozen or so objects, it was pretty easy to pick off everything else cruising through the much better placed winter and spring constellations. The pace picked up a bit again at the end of the list, but mostly because I was worried about getting everything packed up again, driving home, unloading the scopes, packing for my trip, and still having time to get to the San Francisco airport. I logged a total of 108 Messiers through the Traveler between 7:30 and 3:45 am, missing only M74 at sundown, and M30 at sunrise.
My favorite views of the night were usually pairs or trios of objects all visible in the same field of view of the Traveler with a 9 mm Nagler eyepiece. That combination gives an exit pupil of 1.5 mm, a magnification of 66x and a field of view of about 1 and a quarter degrees, a great combination for a whole range of objects in the Marathon. One of the highlight "double features" of the night was broad sparkling M35 next to the unresolved puff of the much more distant open cluster NGC2158. Other nice multiple object views were the paired open clusters M38 and NGC1907 in Auriga; the view of M105 in an arc of decreasing brightness with NGC3384 and NGC3389; the M65/M66/Ngc3628 triplet in Leo; the spectacular paired galaxies M81 and M82 in Ursa major; and the classic triangle of galaxies M84/M86/NGC4388 in Virgo, with a fourth much smaller galaxy detectable in the middle (NGC4387).
I also enjoyed two pairings of very different kinds of objects in the same field. The planetary nebula in M46 is a beautiful view against the backdrop of the rich open cluster. This pairing makes M46 of my favorite clusters on the list, and one I usually check in on several times a year during the winter. However, it has been a long time since I had looked at the Owl Nebula M97. It appeared as a large round puff with darker interior blotches last Friday. With the field of view of the Traveler, the large edge on galaxy M108 was visible as a mottled gash in the same eyepiece field. Although the dying star and island universe differ in physical diameter by nearly 50,000 times (couple of light years vs. 100,000 light years), their distance from earth also differs by a roughly similar factor (couple of thousand light years vs. 45 million light years). The enormously greater size of the island universe is balanced by its enormously greater distance, producing a "nebula" that has a similar apparent size to the Owl Nebula in our own Milky Way.
I only used the 14.5 inch scope occasionally during the night. There was plenty of time to look at things whiles waiting for summer objects to rise, so I did a little bit of comparison viewing of M objects at different aperture, looked up the Arp peculiar galaxy pair NGC3395/3396 in Leo Minor, and chased down some of the supernova reported in 2004. (SN2004A was still visible in NGC6207, but I couldn't split SN2004ab from the bright core of NGC5054). Although I always like to have a large aperture scope with me if I am going to take the time to travel to a semi-dark site, on this particular night, I would have done better to only bring the Traveler. The extra time required to set up the large Dob meant that I had no time to wander around the parking lot when I first arrived after sunset. I would have enjoyed talking with the other observers already there, but ended up rushed to set up both scopes and get started with the Marathon as soon as skies got dark. Tearing down, transporting, and unpacking both scopes back at home also increased the number of things to be be done to catch my flight, and created an unwelcome rush at the end of the night.
And for surveying eye candy objects like Messiers, the Traveler was plenty of aperture for quick, beautiful views. In fact, the bright objects seen through the Traveler were much more visually striking than the faint objects chased down with the larger aperture scope. I think most deep sky observers have a tendency to move up in aperture, but then to primarily use the increased aperture to hunt ever fainter objects.The net result is an expanded list of faint fuzzies that are within the range of the telescope, but lots of eyepiece time gets spent looking for objects on the edge of visibility, regardless of aperture. I have done much the same as I moved from a 7 inch to 14.5 inch Dob. (Hunting lots of extraglactic globular clusters in M31 is a good example of a project that requires aperture, patience, and a willingness to push the edges of what can be seen with any given scope). Howevever, an alternative use of aperture is to use the extra resolving power to see more detail in bright objects. I have found that the 14.5 inch scope has given me the best views I have ever had of many bright objects, including globular clusters, the planets, and the moon itself (see, for example, "High Moon" /reports/2003.09.13.3.htm). Last fall at LSA, I also started a project to observe all the objects in the Hubble Atlas of Galaxies with the 14.5 inch scope. That project is based largely on the brightest galaxies in the sky, but carefully examining those galaxies for morphology and structure, and comparing how much can be seen in the eyepiece compared to the beautiful photographic prints in the oversize Hubble atlas. That project has already convinced me that I should go back through all the Messier objects with the 14.5 scope as well, again focusing on detail and structure visible within the bright objects. To do that, however, I will pick times that are optimal for observing each object, and spend lots of time playing with magnifications, filters, and eyepieces as each object is as close as possible to the zenith.
Some final conclusions after finally doing most of a Messier Marathon.
1) The Messier Marathon is obviously not the best way to actually observe the Messier objects. There is not enough time to study each one in detail, or to explore all the other interesting objects nearby. By design, many of the objects are just setting or just rising, and so are only detectable rather than beautiful. We all know that objects are best observed when they are high in the sky. But there is nothing like seeing some of the best objects in the heavens reduced to dim nothings to remind you to design your observing sessions around what is actually UP, not just above the horizon.
2) The Marathon has the huge compensating virtues of providing a one-night overview and summary of the sky. It is a great way to revisit favorites you have seen before, and to compare the sizes, shapes, brightness, concentration of lots of different galaxies, open clusters, nebula, and globulars in a single session. This overview aspect of the Marathon struck me again when I arrived in New York City last Saturday, and spent Sunday afternoon going through galleries of the American Museum of Natural History with my old college roommate. There were tons of exhibit rooms at the museum that were organized around geographical area of the world, or animals of a particular type. However, one of the most striking exhibits was the much newer Hall of Biodiversity. The highlight of this exhibit was a spectacular wall nearly completely covered with all kinds of animals from a whole range of different groups. Related animals were grouped in columns, allowing you to compare the diversity of form within mammals, or birds, or insects, or crustaceans, or molluscs, etc; as well as the differences and similarities between animals in different columns (see http://www.the-scientist.com/yr1998/august/aug_art/am_mus.jpg for some idea of the juxtaposition, though the wall itself is only visible in the background). Looking at everything together in one giant display was a very different experience than the more detailed look at more focused exhibits on individual groups. But studying everything together on that wall also gave a much better overview of the overall diversity of life on earth, and relationships between different groups.
The Messier Marathon provides a similar Hall of Astrodiversity for astronomers. A great overview of both the major types of objects, and the tremendous diversity of objects within each class. And the whole night drives home again the large scale structure of our own galaxy.The early part of the Marathon is dominated by open clusters and emission nebula as we look outward into an arm of the MIlkyWay seen in the winter constellations. Then the galaxy rich regions of the sky emerge in the Spring constellations, as we look away from the dusty plane of our own galaxy. The night ends with an overwhelming number of clusters, nebula, and globular clusters as we stare towards the center of the Milky Way. The concentration of globular clusters on one side of the sky provided a key part of Shapley's original argument in 1918 that the sun and earth was located far from the center of the Milky Way. Going through the Messier Marathon forces you to think again about our position in the Galaxy, in the same way as the Hall of Biodiversity forces you to think again about our position and relationship to the long history of life on earth. I'm glad to have seen both overviews in a single weekend, despite the rush of both observing and travel.
Posted on sf-bay-tac Sat Mar 27 14:55:20 2004 PT
Converted by report.pm 1.0 Fri Jul 9 23:08:18 2004 PT
