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18 April 2003: Algieba, Xi Bootes, M3, Delta Corvi, Stargate, Jaws and M104



Instrument used: TAL 200K and Bresser 7x50 Binocular. Eyepieces 32mm Televue Plossl, 25mm Tal plossl, 20, 15, 12, 10, 9, 7mm Vixen Lanthanums. TAL Barlow 2x. Deep sky Filter Lumicon. Location: My own backyard, 50.55N 06.03E. Time 20.00 hours UT until 22.45 UT. Seeing: bad, 6 out of 10 (1 is best). Transparency: very good: 3 out of 10 (1 is best). Visual magnitude: 5 (little Dipper).

I started with Gamma Leonis (Algieba), the brightest star in the curve of the Sickle of Leo. Because it was not completely dark at the moment of observing, both components (Gamma A of the second magnitude and Gamma B of a magnitude of 3.5) did not shine as brightly as they normally seem to do in a real dark sky. It made it easier to split at lower magnifications.
A beautiful pair, both yellow with a hint of orange.
Then I went to another very nice double, Xi Bootis. This pair lies about 8.5 degrees west of Arcturus, the constellations brightest star. William Herschel discovered xi Bootis in 1780. The primary star is of the 5th magnitude, its companion is of the 7th magnitude. According to Harrington it is one of the closest binary star systems to earth, lying at a distance of 22 light-years. The orbital period is 149.9 years. The true separation of the two components is about 33 AU (average). The apparent separation varies. (1.8" in 1912 to 7.3" in 1984). At 62.5x a hint of a split could be detected. At 80x there was a definite split of the double. To me the A component appeared white and the B component yellow-orange.

After the two doubles I visited one of my favourite globulars, M3. It was easy to detect in my 8x50 finder and 7x50 binoculars. At high power (282x) it could be resolved to the middle. The best view however was with the 15mm (133x). Next on the list were a few galaxies, M51 in Canes Venatici and M65/66 in Leo. Due to the heavy light pollution I could not detect any detail. I tried the Lumicon Deep sky filter, to gain some contrast (darker sky around the galaxies). It helped very little. I also tried different magnifications but I had no success in detecting any detail. They remained fuzzy patches of light. Averted vision improved the image only a little.
Then I went further to the southern horizon. I wanted to see a few objects in the Corvus area. Luckily my neighbour cut down some of his shrubs, so I could see Corvus just above the garden fence. I started with Delta Corvi (Algorab), the double star marking the northeast corner of Corvus. In 1823 John Herschel and James South discovered that Delta Corvi was a double star. It is a beauty, even at low powers. The primary star is of 3rd magnitude. The 9th magnitude companion lies about 24" away at a position angle of 214 degrees. I could not detect any colours.
From there I went for an object called "Star 20" by Phil Harrington in his book "The Deep Sky, an Introduction". Star 20 is also known under several other names like "Stargate" and "Delta-Wing Starship". You can find it easily if you start at Delta Corvi, using the finder chart below (North is up and West is to the left). The red circle represents the 7-degree field of view of my 8x50 finder. From Delta Corvi, go to the east to Eta Corvi. If you move north from Eta Corvi about 3 degrees, you will see a triangle of stars. The triangle points in the direction of a faint pair of stars, barely visible in the finder scope. Centre your finder on these stars. They are the brightest stars of Star 20.


Finderchart Stargate

Finder chart Star 20 (Harrington)
Copyright and Credits: TheSky for Macintosh by Software Bisque.



Stargate


And this is what I saw using a 12mm Lanthanum, magnification 166x (North is up, west is to the left):
A triangle within a triangle. Great sight

Jaws

From there I went looking for Harrington's Star 21, just 1 degree Northeast of the Stargate. Star 21 lies in Virgo, and using my 32mm Televue plossl (field of view 46.5', magnification 62.5x) this is what it looks like: (North is up, west is to the left):

An easy to recognize eleven star asterism. Harrington describes it like a southward swimming shark, the two brightest stars at the bottom of the field of view marking the mouth, the rest of the stars, forming the body. The lonely star to the west marks the tip of the dorsal fin. Because of this, Harrington named the asterism "Jaws". Between the three stars on the East, M104 (the Sombrero Galaxy) could be seen as a very faint "smudge". Again, because of the heavy light pollution in the southern direction, I could not detect any detail. At 22.30 UT I ended the session. It was a satisfying evening with some beautiful deep sky-objects.







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