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Re: Visibility at rising and setting
From: Thomas Schmidt
Date: 2000 Apr 25, 11:09 AM
From: Thomas Schmidt
Date: 2000 Apr 25, 11:09 AM
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. -- ------------------------------------------------------------------- Thomas Schmidt e-mail: schmidt@hoki.ibp.fhg.de