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Solar Position / Sunrise Sunset calculator.



 
 
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  #11  
Old September 21st 05, 01:48 PM
MS
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M Holmes emailed this:
My brother is a cinematographer and needs a Solar Position and Sunrise
Sunset calculator for his Apple computer. You enter long/lat, timezone +
daylight savings, altitude, etc. and it gives you the figures.



Shouldn't be too hard to do on a calculator:

The angle between the southern meridian and sunset/sunrise on a flat
horizon is given by:

Cosine (angle) = minus Tangent (Latitude) multiplied by Tangent
(Declination of Sun)

So what you need is some tables of the Sun's declination for the year
and you can get the angle. Then you need the difference between Noon and
the Sun's transit of the southern meridian at your longitude, which can
be calculated from the longitudinal difference from your location and
the longitudinal meridian for your time zone. I have vague memories that
you may need to apply an Equation of Time correction (someone here will
probably know?) and so you may need EoT tables. Don't forget to correct
for British Summer Time too...


Very funny. What fun that would be working out the sunrise, sunset,
daylight hours, etc. for a two month shoot in ten different locations.

Thanks anyway,

MS
  #12  
Old September 21st 05, 02:34 PM
M Holmes
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In uk.sci.astronomy MS wrote:
M Holmes emailed this:


Very funny. What fun that would be working out the sunrise, sunset,
daylight hours, etc. for a two month shoot in ten different locations.


Well, some folks prefer to understand what they're calculating rather
than just take the numbers from the magic box. YMMV.

Thanks anyway,


No probs.

FoFP

--
Then the Gods of the Market tumbled, and their smooth-tongued wizards withdrew
And the hearts of the meanest were humbled and began to believe it was true
That All is not Gold that Glitters, and Two and Two make Four
And the Gods of the Copybook Headings limped up to explain it once more.
  #13  
Old September 21st 05, 02:40 PM
Twittering One
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seen Ashworth?

  #14  
Old September 21st 05, 02:51 PM
Twittering One
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~ * Music for Torching ...

As A.M. Homes's incendiary novel unfolds,
The Kodacolor hues of the good life become nearly hallucinogenic.

http://www.powells.com/biblio?isbn=068817762x

  #15  
Old September 21st 05, 02:57 PM
Twittering One
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.... although
A Country of Mothers
I prefer ...

  #16  
Old September 22nd 05, 05:23 AM
Odysseus
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MS wrote:

Many, many thanks, it is perfect!

One question, what's EOT?

EG. The display looks like this:
Sunrise 0610
Sunset 1831
Transit 1220
EOT 6:48 min:sec


"Equation of Time". It's explained at the Analemma site:

http://www.analemma.com/Pages/Summation/SummationEffect/Summation.html

(and elsewhere!) but in a nutshell it's how long before or after mean
solar noon the Sun transits the meridian, due to the ellipticity of
the Earth's orbit and the inclination of its axis. It never amounts
to more than about a quarter of an hour's difference, whether early
or late.

--
Odysseus
  #17  
Old September 22nd 05, 11:58 AM
MS
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Thanks for the explaination.

Odysseus emailed this:
MS wrote:

Many, many thanks, it is perfect!

One question, what's EOT?

EG. The display looks like this:
Sunrise 0610
Sunset 1831
Transit 1220
EOT 6:48 min:sec



"Equation of Time". It's explained at the Analemma site:

http://www.analemma.com/Pages/Summation/SummationEffect/Summation.html

(and elsewhere!) but in a nutshell it's how long before or after mean
solar noon the Sun transits the meridian, due to the ellipticity of
the Earth's orbit and the inclination of its axis. It never amounts
to more than about a quarter of an hour's difference, whether early
or late.

  #18  
Old September 22nd 05, 12:04 PM
MS
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Very funny. What fun that would be working out the sunrise, sunset,
daylight hours, etc. for a two month shoot in ten different locations.


Well, some folks prefer to understand what they're calculating rather
than just take the numbers from the magic box. YMMV.


Don't get me wrong, I shouldn't have been sarcastic (I meant it to be
humerous), it's good to understand these things. One of the beauties of
computers is they can take the tedium out of what would be a very time
consuming set of calculations, which if done manually may result in the
occasional error and when shooting a film an hour lost sunlight could be a
costly mistake.

Thanks,

MS
  #19  
Old September 22nd 05, 11:46 PM
Llanzlan Klazmon
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MS wrote in
.uk:

Very funny. What fun that would be working out the sunrise, sunset,
daylight hours, etc. for a two month shoot in ten different locations.


Well, some folks prefer to understand what they're calculating rather
than just take the numbers from the magic box. YMMV.


Don't get me wrong, I shouldn't have been sarcastic (I meant it to be
humerous), it's good to understand these things. One of the beauties of
computers is they can take the tedium out of what would be a very time
consuming set of calculations, which if done manually may result in the
occasional error and when shooting a film an hour lost sunlight could be
a costly mistake.


If Johannes Kepler had known about electronic calculators he would have
killed for one (well not really). Imagine doing the calculations required
to produce the Rudolphine tables by hand. He thought he was really lucky
that Napier had come up with the idea of logarithms being used to speed up
multiplication and division via a set of tables.

Klazmon.






Thanks,

MS


 




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