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George Huxtable wrote:
...
> What I'm asking is whether any of you enjoys clear enough skies that they
> can observe stars or planets, even Venus at its brightest, right down to
> being able to time a sudden moment of extinction as it sets below the
> horizon.
...

The right person to ask this is probably Prof. Brad Schaefer of Yale,

schaefer@grb2.physics.yale.edu

who has devised detailed models of atmospheric extinction, drawing on
a large database of observations. See for example this abstract:

http://www.aas.org/publications/baas/v30n4/aas193/354.htm ,

> [23.02] Celestial Visibility for Astronomy History
>
> B. E. Schaefer (Yale)
>
> The application of astronomy to history often requires detailed calculations
> of the visibility of celestial objects. Recent advances have greatly improved
> the accuracy, scope, and ease for making celestial visibility calculations.
> I will detail my recent results for heliacal rise dates and directions,
> extinction angles for rising stars, the dates of lunar crescent visibility,
> and the size of the ubiquitous refraction variations low on the horizon. Some
> simple resulting statistics will also be mentioned. Since the theory is complex
> and the observations are many, the results will be presented in a handout as
> graphs that cover most cases, references to the original articles, and complete
> computer programs. I hope to provide workers with the tools required to support
> their research.

--
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  Thomas Schmidt                  e-mail:     schmidt@hoki.ibp.fhg.de

   

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