Hi Sculptor,
This:
http://articles.adsabs.harvard.edu/f...BAA..100..277H
and for general info on the star:
http://www.astro.uiuc.edu/~kaler/sow/porrima.html
may be of some use. The BAA Journal indicates that the (revised) periastron should have occurred in 2005 (not 2008 as predicted long ago) with the components now rapidly widening -- according to the ephemeris, the sep should now be approx 1.1 arc seconds with PA at about 25 degrees, reducing pretty quickly (in the scheme of things).
However the 6th catalog of orbits of visual binaries indicates here:
http://ad.usno.navy.mil/wds/orb6/orb6ephem.html
a slightly different prediction for Porrima (STF 1670AB) that the separation should currently be 0.924 arc seconds in PA 41. The same catalogue indicates that by 2009 it is out to almost 1.2 arc-seconds in PA 30, and that periastron occurred in 2006 at about 0.40 arc-seconds
It seems the orbit has not been well known and so the predictions -v- observations have had a bit of scatter in them. Observations of this periastron will probably refine the elements somewhat for the future and reduce the uncertainty.
Very well done in splitting it! Your observed PA is pretty/very close to the prediction
but your estimate of the sep is a bit off according to either predictions.
I'll take a peek if I remember when the 'scope is out next (but with Sydney's weather recently ???) (but shoud I really bother trying at all:: I've only got a "light-bucket" -- woe is me!)
Sculptor wrote:
"Interestingly, the 11" Celestron SCT had no hope of resolving it. "Economical" light buckets seem good at photographing faint galaxies (see NGC 2997 attached: Mag 9.7, size 10' x 7' arc, SB 13.5 or so) not resolving doubles."
Hmmm ... can't see why a (good) C-11 wouldn't do the trick. As for "economical light buckets ... not resolving doubles" -- Pah! My old-faithful 10" F/6 on a Samson GEM mount once resolved Gamma Sextantis in 1994 which was at the time I think 0.51 arc-seconds.
Try that with your fancy-schmantsy 6" refractor!
Nice Pic BTW.
Best,
Les D
Contributing Editor
AS&T