From: Dennis Persyk (dpersyk_at_antispamdomain.not)
Date: Sat Jul 05 2003 - 17:33:07 EDT
The refraction angle in arc seconds is given by
Arc seconds = 58 x [tan (Z) – 0.067 x tan(Z)^3],
where Z is the zenith angle; Z = 90 degrees at horizon and 0 at
zenith.
The refracted pole can be calculated by this approximation: The
amount of error in arcminutes is Tan(90-Latitude); this is used to
determine where the NCP really is for purposes of polar alignment.
Clear skies,
Dennis Persyk
Igloo Observatory Home Page http://dpersyk.home.att.net
Hampshire, IL
--- In digital_astro_.at._yahoogroups.com, "siebren klein"
<s.s.klein_.at._t...> wrote:
> Hi Dennis, Johnny,
>
> An astronomer I know told me that the difference in refraction in
arcseconds equals the refraction in arcminutes.
> The only number I'm sure of is that refraction AT THE HORIZON is
about 30 arcminutes, so mars images that low would not even overlap
at red and blue. If somebody now comes up with refraction as a
function of height, we will know exactly how much the images are
shifted.
> Clear skies,
> Siebren Klein
> s.s.klein_.at._t...
> http://www.geocities.com/siebren2001/index.html
>
> ----- Original Message -----
> From: "Dennis Persyk" <dpersyk_.at._a...>
> To: <digital_astro_.at._yahoogroups.com>
> Sent: Friday, July 04, 2003 10:41 PM
> Subject: [digital_astro] Re: Mars morning of July 4th
>
>
> Hi Johnny,
>
> The effect to which you refer is differential atmospheric
refraction,
> a/k/a messed up Mars images.
>
> Picture a prism. It is wide at the base, skinny at the top. It
> breaks up white light into color and spreads it out.
>
> Now picture the atmosphere. It is wide at the base (horizon) and
> skinny at the top) zenith. It beaks up the white light from Mars
and
> spreads it out.
>
> Clear skies,
>
> Dennis
> Igloo Observatory Home Page http://dpersyk.home.att.net
> Hampshire, IL
>
> ! Terms of Service.
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