Constellation Report

This weekend we move on to the constellation Ursa Major - The Great Bear. Best known as the "Big Dipper", Ursa Major is the true name of this constellation. The Big Dipper is what astronomers refer to as an asterism. An asterism is a named grouping of stars which is not officially recognized as a constellation. 

This is a well known constellation. In fact, it is probably familiar to and findable by more people than any other constellation. This is a good thing, since two of it's stars, "Merak and Dubhe" are known as the pointer stars. Pointers to Polaris, the "North-Star". Once you learn these stars, you'll always know your directions at night. To find Polaris (and hence, north) start at Merak and draw a line through Dubhe and you'll arrive at Polaris. 

Another reason for familiarity with Ursa Major is simply that Ursa Major is home to some of the most beautiful and most amazing deep sky objects known. Many of these are easily viewed in amateur telescopes and will be covered below.

This beautiful shot was taken by Jerry Lodriguss. 

Deep Sky Report

Let's start things off with an interesting treat. Take a look at the handle of the Big Dipper and you'll see that it has a kink in it. This star is called Mizar(mag2.2) Look closely and you'll notice that Mizar has a faint companion. This is Alcor(mag4). Under decent skies, Alcor is readily visible. Now, if you have access to a telescope, point it in their direction. You'll notice that Mizar is in fact a double star itself. Mizar and Alcor are one of the best known double stars in the entire sky.

Mizar, at a distance of 78 light years from the Sun, and Alcor at 81 light years - while appearing to be a double star - are actually only an optical double. An optical double star is not a true double star where the components are gravitationally bound and orbit each other, but rather a chance alignment along one's line of sight.

M81 is the large, bright galaxy in the center; M82 is the smaller galaxy towards the right edge. Low power views in most telescopes will show both galaxies.

This shot was taken on April 11th by Utah Skies own Anthony Arrigo of Park City, Utah. It was a 12 minute unguided exposure through a 10" f/4.5 reflector using ASA800 speed film. 

This is another fine image by Robert Gendler. We've used many of Robert's images in past reports. In fact, Robert is a past Utah Skies Astrophotographer of the Month. Take a moment and checkout his work - it's incredible.

When viewing this object, most people immediately see a round nebula. Averted vision is typically required for the eyes to become apparent. This is a fun object. At times, it almost appears to be blinking at you. The eyes will open when you're looking with averted vision and then close the instant you look at it directly.

To find "The Owl", move about 2° southeast of Merak.

This fine image was taken by Al Kelly.. We've also used many of Al's images in past reports. And, Al is also a past Utah Skies Astrophotographer of the Month.

This object is much harder to view than it's mag 7.2 would suggest. Spanning over 28' in diameter (almost as big as a fulll moon), this galaxy has a surface brightness of over mag14! It's bright, but that brightness is spread way out. You won't have trouble finding it; the difficulty lies in viewing the details.

To find this galaxy, envision an equilateral triangle above (northeast) of the handle of the dipper. If you're searching at low power (a good idea) this is a close enough approximation to put you on it.

This is another Robert Gendler shot.

To find this beauty, travel about 1° southeast of Phad (Gamma Ursae Majoris) in the base of the dipper.

Good Luck!

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