Posted 02 November 2013 - 03:58 PM
Posted 02 November 2013 - 05:26 PM
Posted 02 November 2013 - 07:45 PM
It could be possible with a good 8-inch (200mm) - the secondary star on the outside edge of the first diffraction ring. For a 7-inch the secondary will sit on the diffraction ring, making it hard to see. Hmmm. Think I'll try it with my C9.25 when it gets into my midnight sky, a month from now. With that aperture the secondary should be nicely outside the first diffraction ring, with Rayleigh being ~0.6" for that aperture.
Doubles like this one need both sufficient aperture, and preferably an aperture that avoids putting the secondary star on the first diffraction ring.
An historical note - SW Burnham discovered Omicron Per (BU 535) as a double in 1878 with the 18.5-inch refractor in Chicago (though it had been measured by another observer the previous year). The separation has been pretty constant since then, but the angle has gradually changed.
Posted 02 November 2013 - 07:57 PM
Well your finds top the scale the other way then.
Posted 02 November 2013 - 09:08 PM
I agree with Fred, and Pete, at ~ 3 mag difference inside the first ring things get interesting. It might be doable, though difficult.
Posted 03 November 2013 - 11:03 AM