A 12.5" Dob, 2 EDs and a GM-8.
Quote:Tonight I observed eta Crb & gamma Crb with my 8" OOUK Newt. Etas airy disks were kind of "kissin & touching" at 576X but no black space between them. So neg. clear split. To my eyes both components appeared yellowish.Gamma was neg., I could not detect any hint of two airydisks. Maybe `cause they differ somewhat 1,5 mag.Anyone who knows the sep. at the moment?Magnus
Quote:Eta CrB AB: 4.98+6.02 mag, STF1937, ADS 9617, B=STF1937BDefinitive Orbit: P=41.6 yr, a=0.87"PA 174° Sep 0.61" (2010.3)
Quote:Gamma Crb AB: 3.85+5.62 mag, STF1967, ADS 9757Good Orbit: P=92.9 yr, a=0.74"PA 112° Sep 0.69" (2010.3)
"You're not afraid of the dark, are you?" - Riddick "The best scientists are humble. They seek to understand, not to ensure their legacy, but merely to understand." - Mori
Quote: Some years ago, Luis Arguelles and another observer used a 4" f/10 Vixen achromat to split/detect a 0.35" unequal double.
A few telescopes of dubious value. Understanding wife and two curious cats. "Semper ubi sub ubi"
Quote:Hi MagnusSissy Haas had an article about a mathematical formula invented by Chris Lord several years ago in S&T. Does the limit mentioned in her book come from that formula? If so, I can tell you it's flawed.
Quote:Hi MagnusSissy Haas had an article about a mathematical formula invented by Chris Lord several years ago in S&T. Does the limit mentioned in her book come from that formula? If so, I can tell you it's flawed. I have tested it and can best it by quite a large margin....Thomas, Denmark
Used acronyms: NEML=Naked Eye Magnitude Limit, SQM=Sky Quality Meter, TML=Telescope Magnitude Limit, CO=Central Obstruction, delta_m=difference in magnitudes between double star components, RoT=Rule of Thumb, pD_mm=proposed D_mm for resolving a binary (ident with earlier used pA=proposed Aperture), D_mm=Diameter (of scope) in mm, UCAC4=USNO CCD Astrograph Catalog 4th edition
Quote:...I'm impressed that you can see a clean split on Eta CrB at only 200x - with the current separation, ~0.67", that indicates good eyesight, as well as good optics and air steadiness. ...As well, I'll remark again that not taking CO effects into account with uneven pairs is unhelpful. ... 215mm would have a harder time getting a neat DL split on Gamma than 176mm on Eta. ...
Quote:... also inclined to think the effect of CO on Airy disc size is not of much significance with most telescopes, having CO in the 25% to 36% range...
Quote:... I'll experiment with some Dawes Limit pairs...
Quote:I spent at least half an hour looking and looking again at that beautiful image.