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Date: 09 Aug 2006 01:08:23
From: canopus56
Subject: Further notes on resolving limit for unequal binaries
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Based on a discussion in sci.astro.amateur late July regarding
resolving unequal binaries, I threw together some notes I have on this
topic going back to 2003.
http://members.csolutions.net/fisherka/astronote/astromath/ueb/Unequalbinaries.html
Simple rules for the resolving limit for unequal binaries where the
secondary is brighter than magnitude 11.5 are discussed. Resolving
tables and a javascript calculator based on Peterson's 1954 model are
provided for doubles where the secondary is fainter than 8.5 magnitudes
and brighter than 11.5 magnitudes.
Early literature is reviewed including Peterson (1954) and Treanor
(1947). These are earlier studies that led to Lord's algorithm in the
late 1990s. Haas (2006) resolving limit table is discussed in the
context of these studies.
A table of high precision binaries for telescope testing is provided
after Argyle (2004).
A table of double split nomenclature after Haas (2006) is provided,
supplemented with proposed physical criteria.
Corrections to any errors found are welcome and appreciated.
In reviewing this matter further, it appears what is really needed is a
javascript calculator that implements Chris Lord's algorithm. See page
11 of his paper at:
Lord, Chris. Undated. A Report on the Analysis of the Telescopic
Resolution of Unequal Binaries. Brayebrook Observatory.
http://www.brayebrookobservatory.org/BrayObsWebSite/BOOKS/TELESCOPIC%20RESOLUTION.pdf
I stopped short of writing this calculator due my inability to
understand some of the logarithm symbols. I wanted to invite anyone
here to take a shot at it.
Hope this webpage is of interest and help.
- Canopus56
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Date: 09 Aug 2006 10:01:12
From: Brian Tung
Subject: Re: Further notes on resolving limit for unequal binaries
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canopus56 wrote:
> Based on a discussion in sci.astro.amateur late July regarding
> resolving unequal binaries, I threw together some notes I have on this
> topic going back to 2003.
Send me e-mail. I will send you the current draft of my paper, which
contains within it all you need to compute Lord's criterion.
--
Brian Tung <brian@isi.edu >
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.html
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Date: 09 Aug 2006 12:42:56
From: canopus56
Subject: Re: Further notes on resolving limit for unequal binaries
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X-No-archive: yes
Brian Tung wrote:
<snip >
> Send me e-mail. I will send you the current draft of my paper, which
> contains within it all you need to compute Lord's criterion.
Will do. Thanks. - Kurt
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Date: 09 Aug 2006 12:41:49
From: canopus56
Subject: Re: Further notes on resolving limit for unequal binaries
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canopus56 wrote:
<snip all >
I was able to get a functioning javascript calculator functioning that
implements Lord's double star split algorithm:
http://members.csolutions.net/fisherka/astronote/astromath/ueb/html/LordSplitCalc.html
Based on a plot of Lord's algorithm results against Peterson's
empricial data:
http://members.csolutions.net/fisherka/astronote/astromath/ueb/img/LordCalcTest.jpg
- it appears that Lord's model might not capture the effect of photopic
vision on the ability of human eye to split doubles where the secondary
is fainter than magnitude 9.0. Lord's model is an improved Treanor-like
telescopic performance-based model for scotopic (daylight) vision where
the secondary is brighter than magnitude 9.0.
The main paper was updated accordingly.
http://members.csolutions.net/fisherka/astronote/astromath/ueb/Unequalbinaries.html
Corrections and comments on the above are welcomed appreciated.
- Canopus56
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Date: 10 Aug 2006 10:50:59
From: canopus56
Subject: Re: Further notes on resolving limit for unequal binaries
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Brian Tung wrote:
<snip all >
It appears in my literature review, I overlooked another Chris Lord
paper that has a discussion of the resolution of unequal binaries using
a contrast model. May be worth reading.
Lord, Chris. 1979 (Rev. ____). Contrast & Definition. Brayebrook
Observatory.http://www.brayebrookobservatory.org/BrayObsWebSite/BOOKS/contrast%26definition.pdf
- Canopus56
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Date: 11 Aug 2006 14:51:35
From: canopus56
Subject: Re: Further notes on resolving limit for unequal binaries
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canopus56 wrote:
<snip all >
This webnote was substantially revised this note in light of:
Lord, Chris. 1979 (Rev. ____). Contrast & Definition. Brayebrook
Observatory.
http://www.brayebrookobservatory.org/BrayObsWebSite/BOOKS/contrast%26definition.pdf
Summary of this webnote now is:
This note discusses an amateur astronomy rule-of-thumb for resolving
unequal binaries where the secondary is brighter than magnitude 11.
Equal binaries are also discussed. Historical and current major models
to predict the splitting of doubles are reviewed.
In the tetraology of the observing act - eye, telescope, atmosphere and
object - modern models tend to focus telescopic resolution performance,
seeing and object intensity. By their nature, these models do not
include human visual acuity. Beginning double-star observers should be
aware that many modern models do not provide practical predictions for
about one-half of the double stars that beginners are likely to
encounter. One-half of common double star observing lists involve
secondaries that are fainter than magnitude 9.0. Most modern double
star split calculators do not accurately predict binary resolution
where the secondary is below magnitude 9.0.
Double star resolution algorithms could be most improved by focusing
future work on adding a visual acuity factor to existing telescopic
performance models. If the goal is providing amateurs with practical
useable information, further improvement to the accuracy of telescope
performance models is of secondary importance.
- Canopus56
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