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As first appeared in the June/July 2010 edition of the Syracuse Astronomical Society newsletter The Astronomical Chronicle (PDF).

Constellation Map generated with Starry Night Pro 6.

Those in the vicinity of Manlius, NY are no doubt aware of the presence of Sno-Top (home of the best soft black raspberry in the area, IMHO) and the duck pond at town center(-ish). Those continuing just a tad further along Fayette Street (92, DeWitt-to-Cazenovia direction) also know that the swan population is localized to the higher pond near the Saucy Swan Restaurant (they do make for loquacious patrons). These facts, combined with the oppressive CNY heat of early July, made the choice of Cygnus the Swan obvious for this month's constellation. Fittingly, Cygnus is an astronomical feast for naked eye, binocular, and telescope observers alike and, as it is half-way between horizon and zenith in early July in the early evening, it is strategically placed for accessibility with all manner of optics.

Cygnus is surrounded by several dangerous Constellations. The animal Constellations Draco, Velpecula, and Lacerta might enjoy freshly killed what the king Cepheus would otherwise enjoy glazed. The massive Constellation Pegasus is a problem in its own right. Trampled by horse is bad enough on the ground, but to have to avoid trampling by a flying one is another matter altogether. Lyra may be the only reminder to Cygnus of its terrestrial past, having been the instrument of choice for one of Cygnus' human attributions (that man being Orpheus. See below). For those using only their free pair of 1×7 binoculars (that is, your pair of eyes), the cross that makes up the body and elbows of the wings of Cygnus are most obvious. The bright stars Deneb, Sadr, and Gienah (and the nearby Vega in Lyra, the easiest of the stars in this part of the sky to find starting at sunset) are perhaps most obvious, but the rest of the body is pronounced. As the evening progresses (and on reasonably clear nights), the most striking feature of Cygnus is the river of stars and interstellar dust that is our view of the Milky Way (as if Cygnus is flying above it).

As a collection of prominent stars within the body of the Milky Way, you can guess that the Constellation we know as Cygnus has a long and distinguished history. The Greeks ("Give me a Constellation, any Constellation, and I show you that the history of that Constellation is Greek") have many swans in their mythology, from Zeus (who fathered Gemini and Helen of Troy disguised as a swan, or so the story goes) to Orpheus (turned into a swan upon his death and placed next to his lyre (Lyra) to characters in Ovid's Metamorphoses. Cygnus is a member of the "Famed 48," the 48 original Constellations contained within Ptolemy's Almagest.

Alberio. From wikipedia.org.

At the head of Cygnus is the star Alberio which, upon inspection with even low-magnification optics, resolves into two stars that make up quite possibly the best color contrast in the northern hemisphere (above, from wikipedia). Alberio A (the orange-ish one), is actually itself a true binary, meaning its two stars are gravitationally bound to one another. It is possible, with scopes larger than 20" and under excellent conditions, to resolve the two stars, Alberio B (the blue-ish one), is a single star that is not gravitationally bound to Alberio A, making this most famous binary an "optical binary," one where the two stars look very close but only because of our perspective from Earth. If Cygnus is out, this star always makes its way into the eyepiece of the 16" scope at Darling Hill. Further, for those who like to get their scopes perfectly focused (especially large binoculars), this combination is an excellent test.

M29. From wikipedia.org.

As is the case with all of the Constellations within the band of the Milky Way, Cygnus is host to several binocular and telescope objects. The two pronounced Messier Objects are M29 and M39, both open clusters. M29 (above, from wikipedia) is famous (to me) for being the one Messier Object that does NOT appear in the index of the Peterson Field Guide To Stars And Planets. Believe me, I have tried several times to find it (just assuming the dark conditions kept me from seeing it. It does appear in the Constellation map, though). This object appears within the binocular field of view of Sadr and is small but worth scanning in dark skies. M39 (below, from seds.org) is similarly nondescript, residing between Deneb and the stars of Lacerta.

M39. from seds.org.

Cygnus becomes quite interesting for its wealth of interesting New General Catalogue (NGC) Objects. The four most prominent objects are the North America Nebula (NGC 7000), the Pelican Nebula (IC 5070), the Veil Nebula (NGC 6960, 6962, 6979, 6992, and 6995), and the Crescent Nebula (NGC 6888). The North America (not American) Nebula (below, with the Pelican Nebula to its right, from wikipedia) is a testament to the only mild imagination of the working observational astronomer. Like many nebulae, details can be pulled out of this object with the use of filters. Depending on the conditions, the best way to confirm this structure exists in your scope is, frankly, to move the scope ever so slightly in the field of view of nearby stars and confirm for yourself that some slightly darkened patch of sky is staying put with respect to the background of stars. This approach, combined with averted vision, is definitely my method of choice for finding the locations of objects I may otherwise miss completely (and we've all had the experience of NOT seeing something in a scope that another person can even make detail out of). The very low surface brightness of the nebula makes it an at-least binocular object to observe, but it is noteworthy that this entire North America Nebula is reportedly four times the size of the full Moon. The Pelican Nebula (lower right of the image above) looks more like a Teradactyl to me, but there is some similarity in both (in case you do not see it, the pair of eyes are at upper left (with a bright star in each marking the pupils), the beak extends to the left (and is narrower than a typical pelican), and the body extends to some less structured arrangement down to the lower right).

The North America and Pelican Nebulae, photo by Jason Ware. From wikipedia.org.

The Veil Nebula is a collection of nebulae that make for haunting photos. I am very pleased to have a greyscale image of the Eastern Veil provided by our own Stu Forster (below and in the member gallery). This object is very difficult to observe without an OIII filter, but even an 8" scope will resolve the detail of this nebula with the filter (it is reported that in excellent sky locations, simply holding this filter to one's eye will make the Veil Nebula stand out). The Veil Nebula has also been the focus of some considerable Hubble imaging time and a web search for these images is definitely worth one's time.

The Crescent Nebula. Photo by Stu Forster.

Finally, the Crescent Nebula has also been the focus of some astrophotography time by the good Dr. Forster (below (The Crescent, not Dr. Forster)), appearing to me more like a floating brain than a boring crescent. The Nebula is formed by a Wolf-Rayet star, a type of very hot, massive star with a strong stellar wind. This nebula is actually a double-whammy, as the fast-moving stellar wind from this WR star is colliding with the slower stellar wind from this same star when it was a red giant some 400,000 years earlier.

The Crescent Nebula. Photo by Stu Forster.

Clear skies, Damian

As first appeared in the March 2010 edition of the Syracuse Astronomical Society newsletter The Astronomical Chronicle (PDF).

Constellation Map generated with Starry Night Pro 6.

It often seems to me that the night is much more alive and richly colored than the day.
Vincent van Gogh to his brother Theo, 1888

If the Hubble Ultra Deep Field image has taught us nothing else, it is that every piece of the sky, regardless of how diminutive it may be in the two-dimensional view of the universe through our eyes, holds a wealth of astronomical treasures. We begin the 2010 Constellation presentations with one such small, but by no means insignificant, piece of the sky. Canes Venatici ("Now that's Italian(-sounding)!") is a young constellation, one of the many additions formalized by Johannes Hevelius in the 17th century and the result of some rather troublesome bookkeeping over the course of written history. As the story goes, several of the stars within the modern borders of Canes Venatici were originally part of Bootes' staff (or club. Some herdsmen take the protection aspect of their job very seriously). A poor translation of Ptolemy's Almagest from Greek to Arabic to Latin resulted in the "hook" of the staff being turned into "dogs" (accordingly to the translation history provided at wikipedia, the translation went from "the spearshaft having a hook" in Arabic to "spearshaft having dogs" in Latin. Perhaps the Arabic-to-Latin translation occurred on a late Friday afternoon before a much-anticipated Public Viewing session?). Befitting a new constellation of hunting dogs now accompanying Bootes in his nighttime watch, Hevelius, er, ran with it and gave the mythological canines Chara and Asterion a small but astronomically busy place next to their master.

The two dogs Chara (represented by the star "Chara") and Asterion (represented by "Cor Caroli") are identified by only their two brightest stars, which are themselves joined by a short leash in the modern line representation. The many dimmer stars in this constellation that jump out even with low-power binoculars add multiple "spots" to the imagined bodies of these two dogs. As they rush ahead of their master Bootes, they point straight towards the hindmost of Ursa Major (or appear to be running past the Big Dipper). If celestial real estate is any measure of actual size in the ancient illustrations, the giant Ursa Major is right in aligning his gaze away from the two diminutive playful pups. I'm sure there's some imagined connection between Canes Venatici and its final bordering constellation Coma Berenices, but I was once told that the explanation can get a little hairy (if you did not recognize that as a poor pun, do read the wikipedia entry for Coma Berenices, which may find its way to a feature in upcoming newsletters).

If we let lying dogs rest for a moment, we find Chara and Asterion in possession of five Messier Objects, including a phenomenal telescope sight that is otherwise most often found by chasing Ursa Major's tail. The distance between M3 and M106 marks the total width of this constellation. M3 (below) is an 8 billion-year-old globular cluster composed of 500,000 stars that rests roughly 1/3 the width of our galaxy from us (33,900 light years).

M3, from Robert J. Vanderbei.

M106 (below, from NASA/CXC/University of Maryland) is one of those distant (well, 25 million light years) galaxies that NASA astronomers have a field day with as they overlay various wavelengths to make visually stunning images. The strong X-ray lines in its spectrum indicate that a supermassive black hole resides in this galaxy that is in the process of devouring large swaths of stellar and gaseous matter.

M106, from NASA/CXC/University of Maryland.

M94 (below), also known as the Cat's Eye Galaxy, is a remarkable structure, as it contains two distinct spiral regions in one galaxy (providing the bright central pupil and the darker edges of the eye). Speaking of two significant features in one, its discovery is attributed to Pierre Mechain and its cataloging by Charles Messier, occurring just two days later (pairs come in three's?). M94 is itself the most prominent member of the so-called M94 Group of Galaxies, a closely associated group of (up-to 24) galaxies within the much larger Virgo Supercluster. Fourteen of these galaxies lie between 9.0 (M94) and 14.2 magnitude, making the search possible with available gear but only under most ideal viewing conditions.

M94, from Spitzer, GALEX and R. Jay GaBany.

The Sunflower Galaxy (M63, below) was one of the first galaxies to have a distinctive spiral quality associated with it (this by Lord Rosse in the mid-19th century). The short and tightly spiraled arms pack considerable spectral density into a seemingly small space, providing the stem-free sunflower view that, as it contains tens of thousands of suns, might better be called The Galaxyflower. M63 is a member of the M51 Group, another cluster of galaxies within the Virgo Supercluster that feature, as their crown jewel…

M63, from NASA and WikiSky.

The Whirlpool Galaxy (M51, below) is, perhaps, the third best view of any galaxy to be found at Darling Hill (the second-best being the Andromeda Galaxy (M31) and the first being, you guessed it, our own Milky Way). We view the Pinwheel Galaxy looking straight down the rotation axis of the pinwheel, providing us with what can be a very clear view of the spiral structure of the galaxy through our scopes (and providing those with big scopes a very clear view of this structure). I suspect not a single member with a non-GOTO scope has ever said "It's over in Canes Venatici." Instead, I suspect the standard manner of location involves some instruction stating "Look at the last star in the handle of the Big Dipper and go at a right angle about half the distance of the last two stars in the handle." If you can see the famous pair Alcor and Mizar in the Big Dipper, you're almost at M51 in a pair of binoculars. The bright bulge at the end of one spiral arm is a true companion galaxy. Computer models indicate that the distortions of the M51 arm at this companion position are a result of the companion galaxy passing through the plane of the M51 some 550 million years ago, as if M51 were in the process of throwing its companion out into the void to be retrieved by our two dogs.

M51, from NASA and ESA.

Lord Rosse, who also identified the spiral structure in M63, observed and sketched the clear spiral structure of M51 in 1845 (shown below). The sketch he made reminds me of the center swirl within Vincent Van Gogh's "Starry Night" (shown below). And speaking of fine art, the Hubble image of M51 (provided as a massive download here) is one of those views that might well make the final cut in the first intergalactic exhibition.

The proverbial "Cat's Meow" of nighttime viewing from a small pair of stars that mark a small pair of dogs that were spared from the celestial kennel thanks to a mistranslated description of a cudgel.

Clear skies, Damian

Tag: almagest

Some Light Science Reading. The Constellations: Cygnus

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