Tuesday, April 28, 2009

Seeing Double: Splits with scopes.

You can say astronomy is as difficult as you want it to be. That is true. Many spend the night just looking while other set up elaborate equipment and imaging systems and gather as much light as they can in the short hours we do this.

Double Stars are sort of in between all that. It's observing, fun but also challenging to the eye. Some doubles are easy splits, obvious, and often times beautiful in contrasting colours (Albireo for example). Some require more attention, more power, better optics, sturdy mounts. Castor and Algeiba are more challenging but certainly well within the grasp of today's instruments. Epsilon Bootis is more of an example of a challenge for smaller scopes given the contrast in stellar magnitude (brightness). Some seem almost impossible.

Then there is Porrima or Gamma VirginisWith an orbital period of 168.93 years, it was at it's closest in 2008 at around 0.4 arc seconds the distance is beginning to open up to 0.9 arc seconds in 2010. It will be *observable* in small scopes in 2020 (whatever that means). Here's what I do know. Both my scopes won't spilt it cleanly. This is no surprise. But what can be said is that the Pronto does show this as an elongated single star, meaning it is starting to see the companion. It's tough to tell. I can say that I think I saw what I saw in the Pronto. But that little scope was pushed off the deep end of it's power range, around 300X. If the Pronto could talk, it would probably apologize for "just being a 70mm" which is too bad because the optical quality is more than up to the task. The aging SP-C1o2, a classic achromat that dates back to an era of extremely good quality, shows more of a companion. But the problem with this scope is the mount is just too wobbly and the focuser being a bit too stiff to confirm a sharp image, never mind the atmosphere acting up. This old scope is pushing 25 years old, needs new legs and heftier mount. I'm almost positive I can see the beginning of a companion, but really, I can't totally confirm it.

Did I see it? I don't know. I don't have an answer this time. I'd like to think I did, but that sounds wishful. Maybe I should wait till 2020. But why? Why miss out on pushing the outer limits of the scopes. I mean, how boring it would be to wait.

I just don't know for sure....


1 comment:

  1. Hello Marc,

    I was fortunate to see Castor split with its companion, last Saturday night (May 2). I was viewing through a friend's scope, a Maksutov, at the Ont. Science Centre event. The smaller companion star seemed slightly behind and to the left. No colours noticed. But a thrill!

    Your photography gives a great deal of pleasure. Thanks for making it available.

    -- Judith Adam (new member, NYAA)