a nested double double?

[neural]

On Sunday night I found zeta CrB and STF 1964 for the first time. This is a really nice pair of easy doubles, zeta brighter and closer, 1964 wider, dimmer and set at a jaunty angle. The two can be seen and split in the same field with a judicious choice of eyepiece, which is my criterion for a double double (a fairly relaxed one - I'm not too bothered whether doubles are physically related or not).

However, it gets better. Cranking up the magnification I was able to split STF 1964 CD, given in WDS as 1.5", mags 8.1 and 9.0. I didn't hold out much hope of splitting AB (1.2", 8.1/9.9) and indeed I couldn't even elongate it. Still this must be unique as a double double within a double double. 

I would love to hear if anyone out there has split STF 1964 AB and therefore seen 1964 as a d-d. A challenge to those with bigger apertures, darker skies and better-honed double-splitting eyes! 

[Stu]

Not tried that one, sounds very interesting so will give it a go!

Thanks for posting this up

Stu

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[alan potts]

One to have a look at, thanks for posting

[neural]

After I posted this it occurred to me that the Star-Splitters might have something to say about it - and indeed they do:

http://bestdoubles.wordpress.com/2013/07/29/star-hopping-in-the-northern-marches-of-corona-borealis-part-two-kappa-%CE%BA-and-%CF%83-1983-zeta-%CE%B6-and-%CF%83-1964-and-lambda-%CE%BB/#attachment_5772

Although John N doesn't claim the AB prize, a bit of googling shows it can be done, at least by the redoubtable Wilfried from CN:

http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/6062262/Main/5348277

Steady seeing to you!

[chiltonstar]

A nice group this - I had a look this evening. As you say, another double-double!

First impressions of STF 1964 AB was that it was an out of focus star. However, as the scope cooled and the seeing improved a bit, it resolved itself nicely into a close pair. IMO it is not that difficult, although clearly very seeing dependent. 5" Mak at x200 and x250.

Chris

[cotterless45]

Neat, from my good book,

[neural]

Great stuff. I think I should have another go at AB. Sometimes things become easier when you believe you can do them...