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Binocular delights
On the night of June 18 2005, Leo and I finally had a night with good seeing conditions to test the Baader bino viewer with the TAL 250K. The nights are very short in June but we still managed to get some satisfying views, not only with the 250K but also with the 7x50 Vixen Ultima binoculars mounted on the Sky Window.

7x50 Binoculars (Moon, M 29, M 39, 61 Cygni, Omicron 1 and 2 Cygni)
Around 21.00 hrs UT we started observing the Moon with the 7x50. It's amazing to see the sharp images that are produced with this little instrument. The contrast between the Mare and Highlands is very clear. The lavas of Mare Serenetatis, Tranquillitatis and Fecunditatis look much darker than Mare Imbrium. Between Mare Frigoris and Mare Imbrium the dark lava flooded floor of the crater Plato really stands out from its surroundings. The three very bright (young) craters Tycho, Copernicus and Aristarchus really jump out at you. The crater rays of Tycho and Copernicus are a wonderful sight, even through 7x50's.

Later that night I observed a few objects in Cygnus with the Vixen 7x50. While centring the field of view on Gamma Cygni, the star that marks the "body" of the Swan, M 29 can be seen in the same field of view very easy. It looks like a small smudge of light, about 2 degrees south of Gamma Cygni.

From there I went to Omicron 1 and 2 Cygni, my favourite group of colored stars in Cygnus. Omicron 1 and 2 are both very orange colored 4th magnitude stars, that can be found 4.5 degrees southwest of Deneb (Alpha Cygni). Omicron 1 is also a visual triple. It stands together in the night sky with a very blue star (magnitude 5) about 5.5' to the northwest of the orange Omicron 1. They form a very beautiful visual pair of stars with brilliant colors. The third star of Omicron 1 is a magnitude 6.9 star about 2' to the south of the orange star.

Next on the list was the narrow double star (for binoculars) 61 Cygni. Although the two almost equally bright components are only 29" apart, they are an easy split in 7x50 binoculars, especially when the binoculars are mounted on a mirror mount. The two stars look bright orange to me.

I also visited M 39 with the 7x50. The triangle of stars is very easy to find. Just go from Deneb about 9 degrees to the east-northeast and you will come across a bright triangle of stars. This is M 39. Because the clusters stars are scattered over an area of 30' they looked better in the 7 x 50 than in the telescope.

At 23.00 hrs UT we had a tea break.

TAL 250K (M 13, the Blinking Planetary, M 27 and M 57)
After half an hour we continued with the TAL 250K. It was still around 17 degrees Celsius outside, but the air was very dry. Nothing dewed and the books that where lying around felt dry. Later that night when I got home I checked my weather station. Humidity was only 27 percent outside.

We looked at several objects both with and without the binoviewer, and boy, this piece of equipment from Baader really makes a difference with some of the objects observed. I was shocked by the different appearance of M13. In the middle of June, when the nights are very short and it doesn't get really dark, M 13 looks just like a smudge of light with very few stars resolved when I look with my 8 inch TAL 200K. With the 10-inch TAL 250K there are significantly more stars resolved, but when you put in the binoviewer, the whole cluster just stands there, with chains of stars running from the centre outwards. I wonder how M 13 will look around the end of august, when it gets a lot darker. Anyway, on this globular the binoviewer made a real difference!

The next object to visit was NGC 6826, the Blinking Planetary. On the finder chart below (click to enlarge) you can see where to find NGC 6826. Start at Sadr (Gamma Cygni) at the centre of the Cygnus. From there go about 9 degrees northwest to δ (Delta) Cygni. From delta go north to θ (Theta) Cygni, a magnitude 4.5 star. The blinking planetary lies a little less then 1.5 degrees to the east.


Image from SkyTools 2 by CapellaSoft (Click to enlarge)

We viewed the planetary at a magnification of 200x and used no filters. We immediately saw why NGC 6826 is called the blinking planetary. When you look at it with averted vision you see a nice round and bright planetary nebula without a central star. When you look at it directly, the nebula vanishes completely and the central star becomes visible. Just by moving your eye a little it pops in and out of view. A truly wonderful object!

Later that night we observed two other planetary nebulas, M 27 in Vulpecala and M 57 in Lyra. Here the different reaction to nebula filters showed really well. While M 27 got much more contrast with the OIII filter, the same filter did nothing with M 57. M 27 looked really big and M 57 was also very different from what I am used to see in my 8-inch Klevtzov. The centre of M 57 is not open but looks a little hazy white.

At 01.00 hours UT (3.00 local time) we packed up, satisfied with the first test of the TAL 250K equipped with the binoviewer. I noticed that for some objects the binoviewer showed more detail (like M 13, the Moon), for others it didn't,. However the viewing with two eyes is much more comfortable than with only one eye. It is definitely less tiring.

At 3.30 local time I dropped into bed, while the first birds where already starting their morning concert.
Posted by Math on 06/26 at 05:12 AM
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