May 18, 2000

About an hour before dark, I looked outside and there was only a wisp or two of high-level clouds. At this time of year, you need to take advantage of any observing opportunities that present themselves, so I dusted off my eyepieces and headed outside.

I decided to continue my quest to observe the double stars listed in the "Double Stars off Mizar" article in the May, 2000 issue of Sky & Telescope. If you haven't had a chance to purview this article yet, I strongly recommend it. Sissy Haas deals with both the art and science of double star observing, and even includes eyepiece sketches of what the doubles look like through various scopes and various magnifications. And since one of the scopes used is a 60mm refractor similar to mine, it gives me a chance to compare notes and see if my equipment is up to the task.

This has become my favorite spring/summer double to test my scope's focus on. The two stars are bright enough to produce a single diffraction ring. When viewing both Mizar AB and Alcor in the same field of view, it's hard to believe the difference in separation is so large. Alcor is obviously a lot farther away from Mizar A than Mizar B is, but to me, it doesn't look like its 48 times farther away... (709" / 14.7")

After viewing this binary for the first time the other night, I marked it as a favorite. While not as impressive as Albireo or g Leonis, it has a beauty all its own. I think the companion star is the first one I've viewed in my telescope that has a distinctly brownish tinge to it. At 35x, I can just barely make out the companion star through the glare of the primary. At higher powers, the companion becomes more obvious, but dims significantly.

At the lower powers, it's impossible to view k Boötes without also getting at least one of the members of i Boötes in the same field of view. While the wide separation of i Boötes makes this a mediocre object by itself, seeing two completely separate binary star systems in the same field of view is something you don't soon forget.

The separation of this pair is given at 3.8", and the two stars are 2 magnitudes apart in brightness, making this a difficult object for a 60mm telescope. However, the author of the article was able to view the binary system with a 5" scope and using 83x. 83x is certainly achievable with my telescope, so I thought I'd give it a try. Besides, this pair is supposed to have a nice color contrast.

I'm reasonably certain I found the proper star, but after about five minutes of trying different eyepieces and adjusting the focusing knob in and out, I was unable to detect a companion. Not really surprising, but kind of disappointing, nonetheless. I'll try again, but will prepare a better star-chart to make absolutely certain that I'm staring at the right star(s).

The clouds had almost reached zenith now, and the nearly-full moon was starting to peek above the horizon. I abandoned my quest for S1695 and decided to take a stab at another binary system I'd not looked at yet. O.S138 is described in the article as "bright, esy but too wide; both yellowish khaki white" at 25x in a 60mm scope.

Being in unfamiliar territory for me, it took me a few minutes of star-hopping to verify that I was looking at the right pair of stars. I had no sooner verified that I had found them, than the clouds started to haze up the view through the eyepiece, causing the stars to flicker in and out of visibility. In the moments when they were both visible, they appeared to be almost identical stars.