So, let me try to understand this. While reviewing my research for this post, I discovered that the constellation Canes Venatici came about through quite a bit of uncertainty. According to a few sources, the stars of Canes Venatici were considered part of the constellation Boötes and were taken as Boötes’ cudgel or better known as a club, or baton, truncheon, nightstick, or bludgeon, you get the idea. One source mentioned that The Greek astronomer Ptolemy included the stars of Canes Venatici in the constellation Ursa Major as informes (unformed). Keeping that entire thought in mind, next I discover that the association with Boötes’ dogs is a direct result of someone’s mistranslation of the Greek word for cudgel. In Ptolemy’s original text, Almagest, the Greek word for cudgel was translated to Arabic to mean “the spear shaft having a hook,” and later when it was translated to Latin, the translator mistook the word “al-kullab” for “kilab.” I’m not really sure how those two words could be mixed up but there it is. Anyway, the “spear shaft having a hook” becomes “spear shaft having dogs” which makes no sense at all and sometime during the 17th century the Polish astronomer Johannes Hevelius steps up and says, “Ya know what, why don’t we just call it Canes Venatici, which means “hunting dogs” and we’ll call the dogs Asterion (little star) and Chara (joy) and be done with it”. Probably not in those exact words but it’s my guess that’s how the constellation came into being.
Canes Venatici – the hunting dogs of the Herdsman Boötes. Image by StarryNights
So then, constellation Canes Venatici (CANE-eez ve-NAT-iss-eye) represents the hunting dogs of the Herdsman Boötes and is located just beneath the tail of Ursa Major, The Great Bear. The constellation is rather faint consisting of just two stars, magnitude 2.8 α Canum Venaticorum and magnitude 4.2 β Canum Venaticorum. Both of these stars are fascinating indeed. α CVn, also known as Asterion or even better known as Cor Caroli, is a double star separated by 19.5” (arc-seconds). The brighter of the two stars is α-2 CVn, which is a chemically peculiar star of spectral class A0 and shows an overabundance of certain elements, such as mercury, silicon and europium in its spectrum. The star is also a prototype of a class of variable star, the α-2 Canum Venaticorum variables. These stars are notable for strong magnetic fields which are believed to produce vary large sunspots which cause the luminosity to vary during the stars’ rotation. The companion star, α-1 CVn is an F-type main sequence star of magnitude 5.6. In the 90mm refractor at 40x the pair is an easy split and the colors appear blue-white for the primary and white for the secondary. What colors do you see? The star was named “Cor Caroli” which means “Charles Heart”, by Sir Charles Scarborough, mathematician and physician to Charles II, in honor of Charles I, the king executed after the English Civil War, whose son was restored to the throne shortly after his death.
Chara (β CVn) is the second brightest star in the constellation and is a G-type main sequence star very similar to our Sun. In 2006, astrobiologist Margaret Turnbull (Global Science Institute – New Worlds Observer Science Team Lead) labeled Chara (β CVn) as the top stellar system candidate to search for extraterrestrial life forms. Due to its solar-type properties, astrobiologists have listed it among the most astrobiologically interesting stars within 10 parsecs of the Sun. I could not however, find any real data confirming any planets associated with the star.[1]
Canes Venatici chart by IAU and Sky & Telescope magazine. Click to download.
Canes Venatici is home to five Messier objects four of which are galaxies and one globular cluster. All of these objects are visible in small backyard telescopes but I want to remind you that they are faint and require pristine skies when viewing under light polluted conditions. The best time to go out and track down these “island universes” is late at night when light pollution is at a minimum. If you can, I encourage you to take the time to travel to a dark sky location to fully appreciate the splendor these galaxies offer.
M51/NGC 5194 Whirlpool Galaxy
One of the best and most observed galaxies in the night sky is M51, the Whirlpool Galaxy. Glowing brightly at magnitude 8.1 with a surface brightness of 12.5, M51 was discovered by Charles Messier on 13 October 1773, it was not recognized as a spiral until Lord Rosse observed it using his 72-inch reflector. M51 is easy to locate by centering the easternmost star of the Big Dipper, η Ursae Majoris, and moving 3.5° southeast. This is one of those two-for-one deep sky targets as the other object in the field-of-view is NGC 5195, discovered by Pierre Méchain in 1781. Recent research reveals that M51’s somewhat distorted spiral structure was caused by NGC 5195 passing through the main disk of M51, about 500 million years ago. In the 90mm refractor at 71x here at the light polluted observatory, both M51 and NGC 5195 are visible. M51 shows a fuzzy stellar like core surrounded by a faint uneven glow while NGC 5195 is a faint even glow. Using the 120mm refractor at a dark sky sight at 83x, M51 shows a bright core with faint wispy extensions revealing its spiral nature and a very faint bridge touching the edge of NGC 5195 which exhibits a large bright core.
M63/NGC 5055
From M51, move your telescope six degrees south-west to locate M63, the Sunflower Galaxy. I’m not sure why M63 is called the Sunflower Galaxy but somewhere in time someone coined the name and it stuck. M63 is the second brightest galaxy in Canes Venatici glowing at magnitude 8.5 but, with a surface brightness of only 13.2, which places this galaxy at the threshold of many small telescopes. In the 90mm Megrez refractor at 50x, M63 is easy to spot as a dim smudge of light without any detail. Increasing the power to 71x gives better contrast but still no detail. I found an observing record from April 18, 2010 when we still had the 150mm refractor which reads, “Averted vision is required at 38x to see this faint fuzzy. The view is a little better at 54x, no detail. At 76x I can tell it’s a spiral galaxy. Bright core, no detail. 108x gives the best view. Using the averted vision/moving eye technique reveals some detail but very little”.
M94/NGC 4736
Move your telescope five degrees west from M63 and you’ll encounter M94. As you may suspect this galaxy was first observed by Pierre Méchain (March 22, 1781) and then cataloged by Charles Messier a few days later (March 24, 1781). A notable feature of this galaxy is its two ring structure which is more evident in long exposure photographs then it is with a small telescope. M94 boosts an 8.1 magnitude but it 10.8’ x 12.3’ (arc-minute) size reduces the surface brightness to a dim 13.2 magnitude. With the 90mm refractor at 37x, the galaxy is visible with direct vision displaying a bright core with a very faint halo surrounding it. At 71x the core is a little fainter but the halo surrounding it is slightly more pronounced.
M106/NGC 4258
To locate our last galaxy, move your telescope eight degrees north-west and you’ll find one of the more overlooked Messier objects, M106. This is one of Pierre Méchain’s findings which were later added to Messier’s catalog along with M105 and M107 by Helen Sawyer Hogg in 1947. M106 glows at magnitude 8.3 with a surface brightness of magnitude 13.2 but it’s still an easy target for small backyard telescopes. In the 90mm Megrez refractor at 23x M106 requires averted vision to see well. Only the bright core is noted. Increasing the power to 51x, reveals the galaxy core and a fainter halo of light. Using the same telescope, I submitted an observation of M106 that I made from a dark sky site to Galaxy Log for their May 2013 video which you can view on YouTube.
M3/NGC 5272
Our next target is one of the few objects that was actually discovered by Charles Messier and in fact, was the first object he discovered and recorded on 3 May, 1764. M3 of course is not a galaxy but I wanted to include it here since it is within the boundaries of Canes Venatici. This globular cluster shines at an impressive magnitude 6.2 and is an easy target for any telescope and can be seen with the naked eye from a dark sky location. In the 90mm refractor at 33x M3 appears as a large gray hazy disk of concentrated light. With the 120mm refractor at 52x the outer most edges of the cluster are resolved into a sprinkling of tiny diamonds. M3 is about 33,900 light-years distant which is a little further away then the center of our galaxy. If you don’t observe anything else this season, don’t miss this one.
Well, I have to wrap it up here but there are other galaxies and interesting stars to view in the constellation of the Hunting Dogs. I know this post is a long one but for the backyard astronomer, Canes Venatici holds some of the brighter Messier objects and its high position in the night sky for mid-northern latitude observers makes it prime hunting grounds. Please do stop back and tell what you see in your telescope. We love to hear from our readers.
Clear Skies!
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