[time-nuts] Local Solar Time Clock

[Max Robinson]

Many years ago I saw some pictures in Sky and Telescope where some people 
had mounted a camera in such a way as to not be disturbed from day to day 
and taken an exposure of the sun at 12 noon local mean time every day of the 
year all on the same photographic plate.  At the end of the year upon 
development of the plate they had a nice infinity sign.  I don't see how 
such a feet could be pulled off with digital photography.

Regards.

Max.  K 4 O DS.

Email: max at maxsmusicplace.com

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----- Original Message ----- 
From: "Brian Lloyd" <brian at lloyd.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Sunday, January 19, 2014 7:35 AM
Subject: Re: [time-nuts] Local Solar Time Clock


> On Sat, Jan 18, 2014 at 10:09 PM, David J Taylor <
> david-taylor at blueyonder.co.uk> wrote:
>
>> I am looking for a physical clock (not software) that will indicate local
>> solar time. IOW when the sun is at its highest point, the clock would
>> reliably read 12:00 throughout the year.
>>
>> Is there a commercial product or kit available for this?
>>
>
> For a mechanical clock, probably not. The problem is demonstrated by what 
> I
> suggested that you do with a stick and pebbles. By marking the position of
> the sun to locate the point where the sun is highest in the sky you
> identify local solar noon. By marking the position of the sundial's shadow
> at a fixed time every day relative to GMT you will find that, over the
> course of a year, your shadow will inscribe an analemma, whose lateral
> displacement represents the correction factor between sidereal (GMT) noon
> and local solar noon. This is all caused by the tilt of the rotational 
> axis
> of the earth which causes the poles to be displaced either advanced or
> retarded relative to the centroid at the equinoxes. (Equinoxae?) So your
> mechanical clock would need to speed up and slow down in a smooth fashion
> twice over the course of a year. Pretty hard to do with a mechanical 
> clock.
> Definitely a job for a uP.
>
> BUT a really cool thing would be to interface a camera to find the point 
> in
> time where YOUR local noon actually occurs and corrects the clock.
> Automatic meridian circle anyone?
>
> -- 
> Brian Lloyd, WB6RQN/J79BPL
> 706 Flightline Drive
> Spring Branch, TX 78070
> brian at lloyd.com
> +1.916.877.5067
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