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