Chasing doubles with a 55 mm fluorite

1998 Apr 12

The full Moon mocks most observing programs, and cirrus and ratty seeing make things worse, but even so, I hauled my new Vixen 55 mm f/8 fluorite refractor out in front of my Palo Alto, California home in the small hours of 12 April, 1998, to look at double stars. High cloud cast glare across the sky, and low-level scud came and went.

The seeing was bad enough to require patience to separate close pairs, but not so terrible to make focusing uncertain. The rings of the diffraction pattern were usually visible, but always moving. In these conditions, you stare at close doubles for minutes before getting a glimpse of separation, yet when it comes, it is convincing.

Gamma Leonis took no waiting. It was wide open at 88x, and quite encouraging for tougher prospects. I tried Polaris next, but it had lost a couple of magnitudes due to intervening cloud, and I suspect the companion was just too faint to see.

Bootes was near the meridian. Hmn, epsilon is nice, but can I get my altazimuth mount to point that high? I splayed the legs asymmetrically to keep the focus knob from colliding with the tripod head, but it was worth it -- a clear split at 176x -- the first diffraction ring of the primary ran through the secondary. The white and blue colors were lovely. 176x was too much for the seeing, but I had only brought one eyepiece and a Barlow out -- a Celestron 5 mm Orthoscopic and a Celestron 2x Ultima Barlow -- and I was too lazy to go fetch another. I didn't think to try epsilon Boo at 88x.

Vega caught my eye through a thin patch in the clouds to the east. I lined it up in the finder, then set the crosshair on epsilon Lyrae, the double-double. The seeing had deteriorated, but at 176x I caught periodic glimpses of thin dark lines separating both epsilon-1 and epsilon-2 -- the little fluorite showed all four stars.

I wanted to try Gamma Virginis, but between Moon and cirrus, the sky was too bright even to see Spica. Fortunately, my car was handy, and I keep a 7x35 binocular under the front seat. It is a Tasco I bought at Sears -- an entirely decent small binocular, and a wonderful value at $29.95. With its aid, a little scanning revealed both Spica and my target, and I soon had gamma in the 176x field. The seeing had gone far enough that I could no longer see diffraction rings at all, but even so, now and then I got a glimpse of the separation. Not bad at all for 55 mm.

I continue to be impressed with this little Vixen -- high optical quality and high portability make for a lot of fun. In an earlier posting, I referred to it as the "Fox Cub", but I think it needs a rather more powerful name, and I have one in mind. But I can't tell you what it is till I change the color scheme appropriately.

Jay Reynolds Freeman; 1998 Apr 12