> In the July 1986 Sky and Telescope Magazine, the Astronomical Computing
> Column topic was Astronomical Refraction. It reports a simplified
> calculation of refraction,
> R as:
>
> R = 1 / tan (h + 7.31 / (h + 4.4)),
>
> where h is the apparent altitude in degrees and R is refraction in minutes of
> arc (not minutes and minutes). Since actual refraction varies with actual
> atmospheric
> temperature profile (hard to know when constructing the dial), this provides
> a good working average. The article also has a short BASIC computer program
> to convert
> true altitude to apparent altitude. The article was written by Thorsteinn
> Saemundsson, Reykjavik, Iceland.
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Date: Wed, 17 Jun 1998 05:23:12 -0400
From: Daniel Roth <[EMAIL PROTECTED]>
Subject: Re: refraction (fwd)
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Date: Wed, 17 Jun 1998 11:22:26 +0200 (MET DST)
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Subject: Re: refraction (fwd)
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---------- Forwarded message ----------
Date: Tue, 16 Jun 1998 22:31:26 -0500
From: roger keith <[EMAIL PROTECTED]>
To: sundial list <[EMAIL PROTECTED]>
Subject: Re: refraction
In the July 1986 Sky and Telescope Magazine, the Astronomical Computing Column
topic was Astronomical Refraction. It reports a simplified calculation of
refraction,
R as:
R = 1 / tan (h + 7.31 / (h + 4.4)),
where h is the apparent altitude in degrees and R is refraction in minutes of
arc (not minutes and minutes). Since actual refraction varies with actual
atmospheric
temperature profile (hard to know when constructing the dial), this provides a
good working average. The article also has a short BASIC computer program to
convert
true altitude to apparent altitude. The article was written by Thorsteinn
Saemundsson, Reykjavik, Iceland.
