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
C-11 SCT, XT10i Dob, C-6 SCT, ETX125PE Mak-Cass, TV102, & AT66
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Quote:Don't be concerned about being a "fool" if you didn't see it.
Quote:Just a thought, try to estimate the position angle. That alone will rule out a bright spot on the defriction ring that is not the companion star.
Quote:...but the main question remains: Are the diffraction pattern formulas of use for estimating close separations?
Quote:Quote:Just a thought, try to estimate the position angle. That alone will rule out a bright spot on the defriction ring that is not the companion star. This is a procedure I meanwhile use on a regular base as tool to verify my observations - but the main question remains: Are the diffraction pattern formulas of use for estimating close separations? In my coming observation sessions I will give this aspect special attention.Wilfried
Quote:... Does not a stars predominate color change a little with a stars spectral type? ...That means you must know the spectral type of each star observed and do the math for each target object, correct? ...
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Astronomical Files from Black Oak Observatory
David Cotterell Toronto, Ontario "If an observer actually sees an object, there is no point in referring to a formula to find out whether he ought to see it; and if he fails to detect it, no formula will ensure his success." - W.H. Steavenson 8" f/15.5 TEC Maksutov - 16" f/5 Teeter/Zambuto Dob - TEC 140 - AT 65EDQ APO Refractor - Astro-Physics Mach 1 GTO Mount - iOptron ZEQ25 mount - Discmount DM6 - Canon 60Da
Quote:"the gaussian formula says all airy disks are exactly the same diameter in the same aperture, independent of stellar magnitude: there is no formula to estimate by how much the disk of a 2knd and 6th magnitude star will differ in apparent diameter. "
To be clear, the gaussian formula says that the radius to the first minimum in the diffraction pattern is the same at a given aperture. This is the so-called Airy disc. the radius of the visible portion of the Airy disc changes with magnitude at a given aperture and is often referred to as the central spurious disc.
Quote:...there is no formula for relating magnitude and the radius of the spurious disc ...Dave
Quote:... Still,23 Aql is a much more difficult double star than Delta Cyg...Mircea
Quote:You and I both agree that there is no formula for relating magnitude and the radius of the spurious disc as defined above. There most certainly is a 'formula' relating magnitude and the radius of the Airy Disc - specifically, the Airy disc size is constant for a given aperture without regard to magnitude or telescope type.
Quote:Thus the radius of the spurious disk of a faint star, where light of less than half the intensity of the central light makes no impression on the eye, is determined by [s = 1.17/a], whereas the radius of the spurious disk of a bright star, where light of 1/10 the intensity of the central light is sensible, is determined by [s=1.97/a]."
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Quote:i haven't even read any of the books you mention. All those authorities, though, throw these terms arond in a very mixed up manner as you have pointed out with the difference between 'modern' and older experts. ... and don't call me 'dear'.
Quote:The issue, I think, relates to how one connects what is seen with Airy and others' understanding of diffraction. That one does not see exactly what theory suggests does not in itself indicate a problem with theory. It may well be that perception (the eye/brain combination) isn't up to the job of fully perceiving the exact form of the image.