Posted 26 May 2013 - 04:08 AM
Posted 26 May 2013 - 06:59 AM
Posted 26 May 2013 - 09:43 AM
From the WDS:
11037+6145BU 1077AB 1889 2010 73 326 18 0.9 0.6 2.02 4.95
That's 0.6" and a delta mag of 3! I would think a scope of 12 inches and a night of perfect seeing might have a chance.
The AC pair has a separation of 308". It is undoubtedly this pair you are reporting.
Posted 26 May 2013 - 06:41 PM
Posted 27 May 2013 - 07:05 AM
Posted 27 May 2013 - 01:30 PM
Ummm.. are you sure you were looking at Dubhe (Alpha UMa)?? - as Cotts has pointed out, the AB pair is very (very) close and has a large brightness difference. His suggestion of at least a 12-inch scope seems to me not at all pessimistic - I'd be inclined to think 16-inches a better chance. So your description of stars with discs touching, with a 5-inch scope, suggests a double at twice Dubhe's separation, and with less unequal stars.
Definitely Dubhe. My scope has a Dawes limit of 0.9 arcsec, so with doubles around 0.7 arcsec sep, I usually get a "figure of eight", although I agree here with a mag difference of 2.8 that's more difficult.
Posted 27 May 2013 - 04:55 PM
Posted 27 May 2013 - 11:31 PM
I've looked at Dubhe several times with my six inch f/10 at magnifications up to 608x and only had the slightest inkling of an elongation. The 2.93 magnitude difference adds a huge degree of difficulty because of the tight separation.
On the other hand, Dubhe has a beautiful yellow-orange color that more than makes up for all the time I've spent on it.