Category: Deepsky observing

Tuesday, May 09, 2006
My 20 favorite double and multiple stars, part 2: late spring – early summer
5. Polaris (Alpha Ursa Minoris, the North Star, the Pole Star, double star)
Constellation Ursa Minor, (Little Bear), magnitude 2.0 / 8.2, separation 18.4”, position angle 218°, RA 02h32m DEC +89°16’. This star is without question one of the best-known stars in the sky, but I wonder how many people know that Polaris is also a very nice double star. Through my 8-inch TAL at 133x, the primary looks yellow and the much fainter secondary looks white. Use medium to high magnification (at least 100X) to split the faint secondary from the bright primary. At low magnifications the secondary is lost in the glare of the primary. If you have an equatorial mount, you might find it difficult to get Polaris into view. You should polar align your mount exactly, or simply turn your polar axis about 90 degrees to the east or west, using your mount more or less as an alt-azimuth mount, and it shouldn’t be too difficult to get Polaris in the centre or the eyepiece. I use the exact polar align method.

Posted by Math on 05/09 at 07:25 PM | (3) Comments | filed in: Deepsky observing | Print
Sunday, April 30, 2006
My 20 favorite double and multiple stars, part 1: early spring
During the last few years I “re-discovered” a group of objects that is not as badly affected by light- and air pollution as other deepsky objects: double and multiple stars. Many hundreds if not thousands can be observed from my own suburban backyard, and almost every time I point my telescope on a double or multiple star for the first time, I am in for a big surprise. There are a lot of different factors that can turn a double or multiple star into a true celestial gem. Their components often have beautiful contrasting colors or they show a huge difference in the magnitude. But also a very close couple or group of stars of the same color and/or almost equal magnitude can look simply stunning.

There is no way to catch the telescopic views of double and multiple stars on a photograph, without destroying the aesthetic beauty of these truly sparkling stellar gems. On photographs stars turn into more or less disk-shaped blurry blobs of light. Gone are the sparkling colors, the point-like star-images and the stunning differences in magnitudes. So no matter where you live, whether in the city, somewhere in the suburbs or in a rural area, go out and observe them with your own eyes, using binoculars or a telescope. Only then you will “see” the real beauty that this often neglected group of deepsky objects has to offer.
Posted by Math on 04/30 at 10:06 AM | (5) Comments | filed in: Deepsky observing | Print
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