Re: Sun's Altitude from Sun's Azimuth

[John Goodman via sundial]

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Thank you Alfonso. Your reply is right on time.

I've been surprised by how many different ways there are to solve this problem! 
I'm drawn back to Morrison's approach. His figures of spherical triangles have 
a foundation in observable orientations.

I'm working on programming Morrison's equations and, once I account for the 
quadrants with the proper additions, subtractions, and inversions, I think I 
may have a solution that works for me.

Thanks to all the mathematically astute members of this list who've given me 
their detailed explanations. 

John

> On Jul 22, 2024, at 5:13 AM, Alfonso Pastor-Moreno  
> wrote:
> 
> To John Goodman.
> Hello John.
> Sorry for the delay in my answer.
> I think that the solution to clarify your question is in the Morrison's book.
> Here you have the solution that Morrison gave to you in 2015, interleaved 
> with the explanation that Morrison gives in his book.
> And if you continue reading in the page 264 is the complementary explanation, 
> that Morrison gives.
> Here are the notes I wrote, paraphrasing Morrison's text.
> For the figures of the two spherical triangles to which I make reference in 
> my text, I recommend to you to look to the figures of the Morrison's book of 
> the pages 264 and 265, because it is not possible to send here the figures to 
> you due to the rules of the SUNDIAL MAILING LIST, that allow only to send 
> text.
> I hope this will help.
> Have my best regards.
> Alfonso Pastor-Moreno
> galvag...@gmail.com
> 
> From Morrison:Pages 262 and following
> 
> It is not possible to calculate the Sun's Altitude directly, but  Gunter 
> solved the problem in a clever way (see belowfor an outline of the proof).
> 
> 1.- For a given Azimuth, calculate the Sun's Altitude when the Sun's 
> declination δ is zero;
> 1. Calculate the Sun's Altitude (h0)  when the Sun's declination (δ) is 
> zero:(i.e. the Sun is on the equator) from: tan ho = cos A / tan φ
> 
> 2.- Then calculate an auxiliary angle, x from: sin x = (cos ho sin δ) / sin φ
> 2. Calculate an auxiliary angle (x) from: sin x = (cos h0 sin δ) / sin φ 
> 3.- Calculate the Sun's altitude, h, for the azimuth and declination:
> If A < 90°, h = x + ho
> If A > 90°, h = x - ho
> 3. Calculate sun's altitude, h, for the azimuth and declination from:
> 
>  If A < 90, h = x + h0
>  If A > 90, h = x - h0
> Once again, a significant number of calculations are required but this is not 
> difficult with a spreadsheet program or a simple computer program. 
> 
> I assume that the azimuth at noon is 180 degrees which would make 90 degrees 
> due east. 
> Why would there be mathematical symmetry around a 90° azimuth?  
> 
> I would expect symmetry around noon when A is 180° degree
> Can anyone explain the logic here for me?
> Thank you all very much, John
> 
> Here is what Hervé Guillemet wrote: Hi John, 
> If I understand your point, I think that the confusion comes from the fact 
> that for the gnomonists,  the origin of azimuth is South , and not North like 
> it is for navigators (sail men , pilots ). In such case East is -90°, West is 
> +90°, North is +/- 180°. 
> 
> With this origin ( South = 0°), there is a symmetry in the trigonometric 
> circle  : 
> sin (π - A) = sin A. As an example:
> sin 120° = sin 60° = 0,866... 
> For the same sine value, you have 2 angles. 
> This is why you need to determine whether 
> Az is > 90° or < 90° 
> 
> I hope that it answers your point. Best regards
> 
> (Now back to Morrison:)
> 
> The problem to be solved is to calculate h given δ, φ and A.
> There is a standard equation from spherical trigonometry that at first glance 
> appears to solve the problem:   sin δ = (sin φ sin h) - (cos φ cos h cos A)
> However, this equation cannot be solved directly for h, although it can be 
> solved by successive approximations.
> Gunter needed a way to solve directly for h, and he solved the problem by 
> breaking it into two parts that can be solved. 
> 
> 1.- First. Gunter solved the Sun's altitude when it's declination is zero. 
> (i.e. when in the Equator)
> 2.- Second. Gunter found  the additional altitude of the Sun when the 
> declination is not zero, and the two  components are added. 
>  
> 
> 
> In the first part (Triangle  of the page 264 ) it is found the Sun's altitude 
> when the Sun is on the equator and when it is above the horizon, and with an 
> azimuth less than 90°.
> 
> The construction is a right spherical triangle than can b

Re: Azimuth Calculation

[John Goodman via sundial]

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Thank you for reworking your equations for me. I have to confess that I'm weak 
at math and matrices make me a little queasy. The spherical trigonometry of 
Morrison's solution is territory I feel safer exploring, once I get my 
quadrants under control.

> On Jul 20, 2024, at 5:44 PM, Steve Lelievre  
> wrote:
> 
> John,
> 
> Here's my second attempt.
> 
> Steve
> 
> >>>>>>
> 
> 
> 
> Sun position vector S is   where ω is hour angle, φ is latitude, and δ is 
> solar declination.
> 
> Azimuth (from south) obeys  so 
> Dividing right hand side by –cos δ and then rearranging  
> 

> Setting a = , b = 1, c =  gives
> 
> a cos ω – b sin ω = c
> 
> Use trig identity 
> 
> a cos ω – b sin ω ≡ R cos(ω + x) where R =  and 
> which converts our case to
> 
> R cos(ω + x) = c
> 
> which rearranges as
> 
> ω =  
> 
> or
> 
> ω = 
>  
> 
> To force correct quadrant
> 
> if γ > 90, use ω =360 − Term 1 – Term 2
> 
> if γ < −90, use ω = −Term 1 – Term 2
> 
> if γ = 0, use ω = 0
> 
> 
> 
> These rules are for latitudes north of Tropic of Cancer. I'll leave you to 
> figure out quadrant adjustments for other cases if you need them. 
> 
> 
> 
> 
> 
> 
> On 2024-07-20 9:13 a.m., John Goodman wrote:
>> No rush; thank you. I appreciate you applying your brain to my concerns!
>> 
>>> On Jul 20, 2024, at 12:11 PM, Steve Lelievre 
>>>  <mailto:steve.lelievre.can...@gmail.com> 
>>> wrote:
>>> Oh, no! I think I may have my initial term for tan gamma inverted, so my 
>>> result would be an angle relative to EW.
>>> 
>>> I have to go out for the day now, but will check my calculation when I get 
>>> home.
>>> 
>>> Steve
>>> 

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Re: Azimuth Calculation

[John Goodman via sundial]

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I look forward to seeing this article and the design of your volvelle!

What I would be ideal for me would be a portable device that would align with 
the sun (azimuth) and read off the time for the date at that location. If the 
altitude is measured too, I believe the date would be inferred too. Finding the 
orientation of the meridian is a problem if this device is frequently moved.

Have you seen this? http://www.dickkoolish.com/rmk_page/suncalc.html

> On Jul 20, 2024, at 4:43 PM, Fred Sawyer  wrote:
> 
> At the recent NASS conference in Vancouver I introduced a new variety of 
> azimuthal volvelle sundial based on the solution to this very question. At 
> some point it will appear in an article in The Compendium.
> 
> Fred Sawyer
> 
> 
> 
> On Sat, Jul 20, 2024 at 10:02 AM John Goodman via sundial 
> mailto:sundial@uni-koeln.de>> wrote:
>> Diese Nachricht wurde eingewickelt um DMARC-kompatibel zu sein. Die
>> eigentliche Nachricht steht dadurch in einem Anhang.
>> 
>> This message was wrapped to be DMARC compliant. The actual message
>> text is therefore in an attachment.
>> 
>> 
>> -- Forwarded message --
>> From: John Goodman mailto:johngood...@mac.com>>
>> To: Alfred Galvagnon mailto:galvag...@gmail.com>>
>> Cc: Sundial List mailto:sundial@uni-koeln.de>>
>> Bcc: 
>> Date: Sat, 20 Jul 2024 10:01:38 -0400
>> Subject: Re: Azimuth Calculation
>> Thanks for the reference. My ultimate objective is to find the sun's hour 
>> angle on a given day, in a given location, when it reaches a selected 
>> azimuth. 
>> 
>> If I understand this paper, it's starting with equatorial coordinates and 
>> calculating an azimuth, which is sort of flipping my problem around.
>> 
>> > On Jul 19, 2024, at 2:56 AM, Alfred Galvagnon > > <mailto:galvag...@gmail.com>> wrote:
>> > 
>> > Maybe this article will help.
>> > 
>> > https://www.academia.edu/32880342/Non_current_ephemeris_for_approximated_calculations?source=swp_share
>> > 
>> > Alfonso Pastor Moreno
>> > galvag...@gmail.com <mailto:galvag...@gmail.com>
>> > ---
>> > https://lists.uni-koeln.de/mailman/listinfo/sundial
>> > 
>> 
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>> 

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Re: Azimuth Calculation

[John Goodman via sundial]

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No rush; thank you. I appreciate you applying your brain to my concerns!

> On Jul 20, 2024, at 12:11 PM, Steve Lelievre 
>  wrote:
> Oh, no! I think I may have my initial term for tan gamma inverted, so my 
> result would be an angle relative to EW.
> 
> I have to go out for the day now, but will check my calculation when I get 
> home.
> 
> Steve
> 
> 
> 
> On 2024-07-20 8:50 a.m., Steve Lelievre wrote:
>> 
>> On 2024-07-20 7:01 a.m., John Goodman via sundial wrote:
>>> My ultimate objective is to find the sun's hour angle on a given day, in a 
>>> given location, when it reaches a selected azimuth.
>> John, here's my attempt. I've never used this result so my calculation needs 
>> checking.
>> 
>> Cheers,
>> 
>> Steve
>> 
>> 
>> 
>> δ is solar declination
>> 
>> φ is latitude
>> 
>> ω is hour angle
>> 
>> γ is azimuth
>> 
>>  
>> Solar position vector S is
>> 

>> so
>> 

>> Rearrange:
>> 

>> Above equation is of form:
>> 

>> Using trig identities:
>> 
 where  and 
>> in which case
>> 

>> or
>> 

>> or
>> 

>>  
>> We have to watch out for quadrant in inverse functions.
>> 
> -- 
> https://www.gnomoni.ca <https://www.gnomoni.ca/>
> https://www.youtube.com/@gnomonica
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
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Re: Azimuth Calculation

[John Goodman via sundial]

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This is a lot of math for me to digest at once! 

One sanity check I like to use is setting the azimuth to due south (whether 
180° or 0°).  In this case, latitude, and declination don't make any difference 
and the hour angle should be zero.

Having written these equations, can you readily see if this sanity check holds 
true?

> On Jul 20, 2024, at 11:50 AM, Steve Lelievre 
>  wrote:
> 
> 
> On 2024-07-20 7:01 a.m., John Goodman via sundial wrote:
>> My ultimate objective is to find the sun's hour angle on a given day, in a 
>> given location, when it reaches a selected azimuth.
> John, here's my attempt. I've never used this result so my calculation needs 
> checking.
> 
> Cheers,
> 
> Steve
> 
> 
> 
> δ is solar declination
> 
> φ is latitude
> 
> ω is hour angle
> 
> γ is azimuth
> 
>  
> Solar position vector S is
> 

> so
> 

> Rearrange:
> 

> Above equation is of form:
> 

> Using trig identities:
> 
 where  and 
> in which case 
> 

> or
> 

> or
> 

>  
> We have to watch out for quadrant in inverse functions.
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial

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Re: Azimuth Calculation

[John Goodman via sundial]

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Thanks for the reference. My ultimate objective is to find the sun's hour angle 
on a given day, in a given location, when it reaches a selected azimuth. 

If I understand this paper, it's starting with equatorial coordinates and 
calculating an azimuth, which is sort of flipping my problem around.

> On Jul 19, 2024, at 2:56 AM, Alfred Galvagnon  wrote:
> 
> Maybe this article will help.
> 
> https://www.academia.edu/32880342/Non_current_ephemeris_for_approximated_calculations?source=swp_share
> 
> Alfonso Pastor Moreno
> galvag...@gmail.com
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
> 

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Re: Azimuth and altitude

[John Goodman via sundial]

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Thank you Geoff! I can clearly see the significance of the 90° threshold for 
azimuth in connection with the cosine function of the first equation. 

I also want to thank Hervé for pointing out that, when south is 0°, azimuth can 
be measured as - to the east and + to the west. I typically think in terms of 
360 positive degrees.

I'll have to program these equations now and see if I can calculate results 
that match others' values. Now that I understand the instructions, I'm ready to 
move forward.

Thanks for everyone's help,
John

> On Jul 18, 2024, at 12:03 PM, Geoff Thurston  wrote:
> 
> Here is a small amendment to my previous message.
> 
> Although h0 becomes negative x does not so I should have written:
> 
> if the absolute value of A exceeds 90 degrees, then h0 and thus x becomes 
> negative. This is the reason for:
>   If A < 90, h = x + h0
>   If A > 90, h = x - h0
> 
> Geoff
> 
> On Thu, 18 Jul 2024 at 11:33, Geoff Thurston  <mailto:thurs...@hornbeams.com>> wrote:
>> Hi John,
>> 
>> I have just been studying Jim's book and I have to admit that I was 
>> initially confused by the diagrams. However, after redrawing them for 
>> myself, I am convinced by Jim's argument and equations provided that azimuth 
>> is measured from the southern meridian. Referring to his equations:
>> 
>> tan h0  = cos A / tan ϕ
>> sin x = cos h0. sin d / sin ϕ
>> 
>> From the first equation, we can see that h0 takes the same value for 
>> positive and negative azimuths which is what we would expect. However, if 
>> the absolute value of A exceeds 90 degrees, then h0 and thus x become 
>> negative. This is the reason for:
>>   If A < 90, h = x + h0
>>   If A > 90, h = x - h0
>> 
>> Best wishes,
>> 
>> Geoff
>> 
>> On Wed, 17 Jul 2024 at 19:11, John Goodman via sundial > <mailto:sundial@uni-koeln.de>> wrote:
>>> Diese Nachricht wurde eingewickelt um DMARC-kompatibel zu sein. Die
>>> eigentliche Nachricht steht dadurch in einem Anhang.
>>> 
>>> This message was wrapped to be DMARC compliant. The actual message
>>> text is therefore in an attachment.
>>> 
>>> 
>>> -- Forwarded message --
>>> From: John Goodman mailto:johngood...@mac.com>>
>>> To: Sundial List mailto:sundial@uni-koeln.de>>
>>> Cc: 
>>> Bcc: 
>>> Date: Wed, 17 Jul 2024 15:11:55 -0400
>>> Subject: Re: Azimuth and altitude
>>> Thank you for explaining. I can see how sine functions are symmetric around 
>>> 90 degrees but I still don't see how 90 degrees is an axis of symmetry for 
>>> measuring azimuth.
>>> 
>>> If South is treated as 0 degrees instead of 180 degrees, then, as you 
>>> describe it, East could be -90 degrees and West would be +90 degrees. The 
>>> symmetry around South would then be Az < 0° or > 0° but still not the Az < 
>>> 90° or > 90° that was specified in Morrison's equations.
>>> 
>>> 1. Calculate the sun's altitude when the declination is zero:  tan h0 = cos 
>>> A / tan phi
>>> 
>>> 2. Calculate an auxiliary angle x from:  sin x = (cos h0 sin d) / sin phi 
>>> 
>>> 3. Calculate sun's altitude, h, for the azimuth and declination from:
>>> 
>>> If A < 90, h = x + h0
>>> If A > 90, h = x - h0
>>> 
>>> NOTE: 
>>> 
>>> h = altitude
>>> A = azimuth
>>> d = solar declination
>>> phi = latitude
>>> 
>>>> On Jul 12, 2024, at 4:40 AM, Hervé Guillemet >>> <mailto:guillemet.he...@free.fr>> wrote:
>>>> 
>>>> Hi John,
>>>> 
>>>> If I understand your point, I think that the confusion comes from the fact 
>>>> that for gnomonistthe origin of azimuth is South, and not North like it is 
>>>> for navigators (salesmen, pilots). In such case East is -90°, West is 
>>>> +90°, North is +/- 180°.
>>>> With this origin (South = 0°), there is a symetry in the trigonometric 
>>>> circle : sin (pi - A) = sinA.  As an example sin 120° = sin 60° = 0,866... 
>>>> For the same sine value, you have 2 angles. This is why you need to 
>>>> determine whether Az is > 90° or < 90°
>>>> 
>>>> I hope that it answers your point.
&g

Re: Azimuth and altitude

[John Goodman via sundial]

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Thank you for explaining. I can see how sine functions are symmetric around 90 
degrees but I still don't see how 90 degrees is an axis of symmetry for 
measuring azimuth.

If South is treated as 0 degrees instead of 180 degrees, then, as you describe 
it, East could be -90 degrees and West would be +90 degrees. The symmetry 
around South would then be Az < 0° or > 0° but still not the Az < 90° or > 90° 
that was specified in Morrison's equations.

1. Calculate the sun's altitude when the declination is zero:  tan h0 = cos A / 
tan phi

2. Calculate an auxiliary angle x from:  sin x = (cos h0 sin d) / sin phi 

3. Calculate sun's altitude, h, for the azimuth and declination from:

If A < 90, h = x + h0
If A > 90, h = x - h0

NOTE: 

h = altitude
A = azimuth
d = solar declination
phi = latitude

> On Jul 12, 2024, at 4:40 AM, Hervé Guillemet  wrote:
> 
> Hi John,
> 
> If I understand your point, I think that the confusion comes from the fact 
> that for gnomonistthe origin of azimuth is South, and not North like it is 
> for navigators (salesmen, pilots). In such case East is -90°, West is +90°, 
> North is +/- 180°.
> With this origin (South = 0°), there is a symetry in the trigonometric circle 
> : sin (pi - A) = sinA.  As an example sin 120° = sin 60° = 0,866... For the 
> same sine value, you have 2 angles. This is why you need to determine whether 
> Az is > 90° or < 90°
> 
> I hope that it answers your point.
> Best regards Hervé Guillemet
> 
> De: "John Goodman via sundial"  <mailto:sundial@uni-koeln.de>@uni-koeln.de <mailto:sundial@uni-koeln.de>>
> À: "Sundial List" mailto:sundial@uni-koeln.de>@uni-koeln.de 
> <mailto:sundial@uni-koeln.de>>
> Envoyé: Jeudi 11 Juillet 2024 20:03:10
> Objet: Azimuth and altitude
> 
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Azimuth and altitude

[John Goodman via sundial]

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Early in 2015, James Morrison helped me with some formulae for calculating the 
sun's altitude when given the azimuth, declination, and latitude. I'm stuck at 
the last step. Here's what he wrote: 

The procedure is:  

1. Calculate the sun's altitude when the declination is zero:  tan h0 = cos A / 
tan phi

2. Calculate an auxiliary angle x from:  sin x = (cos h0 sin d) / sin phi 

3. Calculate sun's altitude, h, for the azimuth and declination from:

 If A < 90, h = x + h0
 If A > 90, h = x - h0

NOTE: 

h = altitude
A = azimuth
d = solar declination
phi = latitude

The same procedures are described in his astrolabe book on pages 262-263, where 
he also includes a proof.

I'm puzzled by step #3. 

I assume that the azimuth at noon is 180 degrees which would make 90 degrees 
due east. Why would there be mathematical symmetry around a 90 degree azimuth?  
I would expect symmetry around noon when A is 180 degrees.

Can anyone explain the logic here for me?

Thank you all very much,
John 






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Re: No more leap seconds!

[John Goodman via sundial]

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It’s hard to conclude that ‘“nothing will change” for the public’, when there’s 
a proposal for ‘a “kind of smear”, in which the last minute of the day takes 
two minutes.’

> Date: Sun, 20 Nov 2022 19:56:23 -0800
> From: Steve Lelievre 
> To: Sundial List 
> Subject: No more leap seconds!
> 
> Apparently the Powers That Be have officially decided that Clock Time is 
> right and Solar Time is wrong.
> 
> Or to put it another way, the International Bureau of Weights and 
> Measures has voted to stop using Leap Seconds by by 2035.
> 
> However, an IBWM representative said "the connection between UTC and the 
> rotation of the Earth is not lost [...] Nothing will change [for the public]" 
> which apparently means we'll have less frequent adjustments instead (leap 
> minutes?).
> 
> https://phys.org/news/2022-11-global-timekeepers-vote-scrap.html
> 
> Steve
> 
> --
> Date: Mon, 21 Nov 2022 18:59:44 +1100
> From: John Pickard 
> 
> Good evening,
> 
> I doubt it will affect dials very much, especially the EoT, ...
> 
> https://www.theguardian.com/world/2022/nov/18/do-not-adjust-your-clock-scientists-call-time-on-the-leap-second
> 
> -- 
> Cheers, John.
> 
> Dr John Pickard.
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[no subject]

[John Goodman via sundial]

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> Date: Tue, 19 May 2020 14:05:55 +0200
> From: Willy Leenders 
> To: Sundial sundiallist 
> Subject: combination of vertical sundial and a noon sundial
> 
> This sundial (see picture) is a successful combination of a regular vertical 
> sundial and a noon sundial with analemma. I found the photo somewhere on the 
> internet. Does anyone know where it can be seen in reality?
> 
> Willy Leenders
> Hasselt in Flanders (Belgium)
> 

This looks like the same dial:

https://commons.wikimedia.org/wiki/Category:Sundials_with_analemmatic_noon_marks#/media/File:AixProv3.jpg
 


Aix-en-Provence: Place Richelme, Sonnenuhr an der Rückwand des Postamtes

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[no subject]

[John Goodman via sundial]

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This story from the Hoover Dam should find interest from some of the 
subscribers to this mailing list:

"The earth’s axial precession is a rather obscure piece of astronomy, and our 
understanding of it through history has been spotty at best. That this major 
engineering feat was celebrated through this monument to the axial precession 
still held great interest to me, and I wanted to understand it better. […]

[T]he angle of Polaris was depicted as precisely as possible to show where it 
would have been on the date of the dam’s opening. Hansen used the rest of the 
plaza floor to show the location of the planets visible that evening, and many 
of the bright stars that appear in the night sky at that location.

By combining planet locations with the angle of precession, we are able to 
pinpoint the time of the dam’s completion down to within a day."

https://medium.com/the-long-now-foundation/the-26-000-year-astronomical-monument-hidden-in-plain-sight-9ec13c9d29b5--- End Message ---
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[no subject]

[John Goodman via sundial]

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eigentliche Nachricht steht dadurch in einem Anhang.

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Hi Kevin,

Your site is an awe-inspiring collection of research and personal creation. 
There’s no end to what I can learn from what you’ve generously shared. I’ll be 
spending many happy days reviewing your comprehensive perspective on a 
fascinating subject.

Thank you for this record of your accomplishments,
John

> On Sep 9, 2018, at 6:00 AM, sundial-requ...@uni-koeln.de wrote:
> 
> Message: 1
> Date: Sun, 09 Sep 2018 00:38:22 +0100
> From: Kevin Karney mailto:kar...@me.com>>
> To: tonylindisun--- via sundial  >
> Subject: A new website : Equation-of-Time.info 
> Message-ID:  >
> Content-Type: text/plain; charset="utf-8"
> 
> Dear colleagues and friends
> 
> I have spent a lot of time over the last few years in front of my computer 
> thinking about the Equation of Time. Recently my son asked where all the 
> output of my studies resided. At first, I thought I should write a book. But 
> instead I acquired a new domain and found that Adobe had a simple package 
> that allows one to make a nice looking website with little technical effort.
> 
> You can find the website at https://Equation-of-Time.info 
> 
> 
> It contains three main sections, all copiously illustrated...
> The Equation of Time - 8 pages. Here,  see the videos on why the Equation of 
> Time looks as it does (under the page ?The components of the Equation of 
> Time?). I am particularly proud of these!
> Sundials that are (or can be) Equation corrected - 8 pages
> Mechanical Means to Simulate the EoT - 6 pages.
> 
> I have been harvesting images of EoT related things for many years, often 
> without recording where they came from. So if I have included an image of 
> yours and have not attributed it to you, please let me know.
> 
> Please do have a look and send comments/additions/corrections/improvements
> 
> Best wishes
> Kevin Karney - from Wales
> -- next part --
> An HTML attachment was scrubbed...
> URL: 
>   
> >

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Re: Missing an opportunity

[John Goodman]

According to the report, "Retired mechanical engineer and Friends of Berkeley 
Castle member Bob Hunt designed the sun dial according to the castle’s latitude 
and longitude.” Maybe Kevin can track him down? 

> On Jun 30, 2018, at 7:48 AM, John Davis  wrote:
> 
> Hi all,
> 
> I wonder who designed it? They incorporated a gapped gnomon as seen on the 
> Spot-On sundials of Piers Nicholson (Piers, you should have patented the 
> idea!) but it looks as though they used the wrong delineation origins for the 
> ‘back hours’.
> 
> Regards,
> 
> John
> ——
> Dr J Davis
> Flowton Dials http://www.flowton-dials.co.uk/ 
> <http://www.flowton-dials.co.uk/>
> BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/ 
> <http://sundialsoc.org.uk/publications/the-bss-bulletin/>
> 
> 
> On 30 Jun 2018, at 11:53, Kevin Karney mailto:kar...@me.com>> 
> wrote:
> 
>> John
>> Not very beautiful, as you say,  by pretty impressive technology - I'll try 
>> to get to see it. Berkeley Castle is not too far from my home. I'll post 
>> some photos if I get there.
>> Kevin
>> 
>> 
>>> On 28 Jun 2018, at 16:03, John Goodman >> <mailto:johngood...@mac.com>> wrote:
>>> 
>>> The sundial shown at this link looks completely conventional but it was 
>>> made out of stainless steel using a 3D printer. Someone at the Renishaw 
>>> company should have contacted this list to commission a more interesting 
>>> design!
>>> 
>>> http://trends.directindustry.com/project-181814.html 
>>> <http://trends.directindustry.com/project-181814.html> 
>>> ---
>>> https://lists.uni-koeln.de/mailman/listinfo/sundial 
>>> <https://lists.uni-koeln.de/mailman/listinfo/sundial>
>>> 
>> 
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial 
>> <https://lists.uni-koeln.de/mailman/listinfo/sundial>
>> 

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Missing an opportunity

[John Goodman]

The sundial shown at this link looks completely conventional but it was made 
out of stainless steel using a 3D printer. Someone at the Renishaw company 
should have contacted this list to commission a more interesting design!

http://trends.directindustry.com/project-181814.html 
---
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Re: Kepler

[John Goodman]

Hello Fabio,

This is a beautiful animation and clever mechanical design! I can’t say that I 
completely understand either. What software did you use to compose and animate 
the gears?

Thank you for sharing your work. It was definitely a worthwhile use of two 
week. I wish I could say I’ve accomplished as much in that time.

Best wishes,
John

> On Jul 7, 2017, at 5:54 AM, fabio.sav...@nonvedolora.it wrote:
> 
> Hi, I just finished  a work that has engaged me in the last two weeks.
> 
> For those are interested about the 
> Kepler's laws, it is an orrery to show the true anomaly starting from the 
> mean anomaly.
> 
> The mathematical formula expresses the mean anomaly as a function of the 
> eccentric anomaly, function of the true anomaly (the true anomaly is the 
> angle of the vector ray that sweeps out equals areas during equal intervals 
> of time)
> The problem is that the first formula is not reversible. There are some 
> iterative mathematical methods to get the eccentricity anomaly from the mean 
> one, with several steps up to the desidered approximation, or it is possible 
> the resolution into an infinite series of terms but not a direct formula.
> 
> Here math limps. But what can not be achieved with a formal language can be 
> at hand by changing the language, so suggests Godel.
> So I designed a gear structure to get the mean anomaly from the eccentric 
> one, like the formula, ma the movement of the gears, unlike the formula, can 
> work contrariwise.
> I attached an image of an orrery, for the moment it is virtual, where turning 
> a knob with a costant angular velocity, the mean anomaly, you get the 
> movement of a planet on an elliptical orbit, following the Kepler's laws.
> The turquoise planet follows the true anomaly and the one outside the zodiac 
> follows the mean anomaly.
> This orrery is setted with an eccentricity of 0.7216, far higher than he 
> Earth's one (0.0167086), to point out the gear's dinamic and the elliptical 
> movement.
> I also upload a video on youtube: https://youtu.be/Y5eSOfd5Imk
> 
> This work is the entrance door to calculate the eot with gears instead to use 
> the customary cam, this is the target for some future gnomonic projects.
> 
> ciao Fabio
> 
> Fabio Savian
> fabio.sav...@nonvedolora.it

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Solstice to solstice photo

[John Goodman]

"Six-month solargraphy - showing the sun’s high path in summer to low path in 
winter – taken over one of the sunniest cities in Canada."

http://earthsky.org/todays-image/suns-path-over-medicine-hat-alberta-canada
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Bringing the sun indoors

[John Goodman]

Not a sundial, but another tool sensitive to solar movement.

> The first of her kind, Caia illuminates your home with real sunlight. She’s a 
> smart robot that finds and redirects natural light for you. Caia remembers 
> where to send the sunlight and keeps it there all day as the sun moves. You 
> can place Caia anywhere with no installation and she will brighten up your 
> home or office with sunshine.

https://www.indiegogo.com/projects/caia-a-robot-that-fills-your-home-with-sunshine-solar#/
 
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Re: Unusual bi-annual sundial

[John Goodman]

On Jan 20, 2017, at 7:40 AM, Frank King  wrote:

> If I had been consulted, I would have suggested that the Great Seal should be 
> a little smaller so that it will always be wholly illuminated at the crucial 
> instant!

That would have been a clever and elegant solution! 

---
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Re: Unusual bi-annual sundial

[John Goodman]

Thank you, Patrick. The link you sent shows that the designer clearly 
considered the time-variation problem. His comments sound like a fair enough 
conclusion to me:

"I would say that it is perfect if you recognize the plus or minus 12 time 
second difference for 11:11:11 a.m."

> On Jan 19, 2017, at 1:05 PM, sundial-requ...@uni-koeln.de wrote:
> 
> Date: Thu, 19 Jan 2017 17:59:21 -
> From: "Patrick Powers" <patrick_pow...@compuserve.com 
> <mailto:patrick_pow...@compuserve.com>>
> To: "Sundial List" <sundial@uni-koeln.de <mailto:sundial@uni-koeln.de>>
> Subject: Re: Unusual bi-annual sundial
> 
> John,
> 
> There is also this that describes (a little) the thinking that was behind the 
> way they attempted to accommodate the small changes that still occur year to 
> year.
> 
> http://www.onlineatanthem.com/news/memorial-science 
> <http://www.onlineatanthem.com/news/memorial-science>
> 
> Patrick
> 
> 
> From: John Goodman 
> Sent: Thursday, January 19, 2017 5:01 PM
> To: Frank King ; Sundial List 
> Subject: Re: Unusual bi-annual sundial
> 
> Thank you, Frank. You?ve sharpened my vague suspicions with mathematical 
> clarity.
> 
>> On Jan 19, 2017, at 11:33 AM, Frank King <f...@cl.cam.ac.uk 
>> <mailto:f...@cl.cam.ac.uk>> wrote:
>> 
>> OK, take a deep breath and see what we are up against...
> 

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Re: Unusual bi-annual sundial

[John Goodman]

Thank you, Frank. You’ve sharpened my vague suspicions with mathematical 
clarity.

> On Jan 19, 2017, at 11:33 AM, Frank King  wrote:
> 
> OK, take a deep breath and see what we are up against...

---
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Re: Unusual bi-annual sundial

[John Goodman]

Won’t the factors that necessitate the addition of a leap day prevent this 
alignment from happening at exactly 11/11 11:11 every year? From year to year, 
that calendar date occurs at a slightly different fraction of the year’s days.

November 11 is the day 316 of 366 in 2016 and 315 of 365 in 2017. Will the sun 
have precisely the same alignment to this sculpture at a time that’s 316/366 of 
the year vs. 315/365? Close enough for the difference to be imperceptible?

The dates and times of the solstices and equinoxes vary from year to year. If 
these events shift relative to our timekeeping, how can the angle of sunlight 
required by this sculpture occurs at 11/11 11:11 every year? 

The beauty of math and the beauty of symbolism may not align here.

> Date: Wed, 18 Jan 2017 22:41:15 +
> From: Art Krenzel >
> To: "sundial@uni-koeln.de " 
> >
> Subject: Unusual bi-annual sundial
> 
> I have been to Arizona many times but never saw this "working sundial" of 
> sorts.  It is on my bucket list now.
> 
> 
> I thought you might enjoy watching the beauty of math, the sun and time all 
> coming together.  There is a 30 second video of the solar display near the 
> bottom of the opening page at this URL.
> 
> 
> http://www.onlineatanthem.com/anthem-veterans-memorial 
> 
> 
> Anthem Veterans Memorial | Online At 
> Anthem >
> www.onlineatanthem.com 
> Reserve the Anthem Veterans Memorial area for a special ceremony or event. 
> Please refer to the ACC Board Policy Manual for a complete list of facility 
> rules and ...
> 
> 
> Enjoy!
> 
> 
> Art Krenzel

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Re: Photo-etching

[John Goodman]

You can find Tony's BSS photo-etching video on YouTube - 
www.youtube.com/watch?v=HkpCCA-hgrc

The same video was posted in two parts back in 2010:

Part 1 - www.youtube.com/watch?v=ML37yRmAsOA
Part 2 - www.youtube.com/watch?v=PAW0q6i7aqg


> On Aug 31, 2016, at 12:34 AM, Wojtek Galinski wrote:
> 
> Hi Tony,
> 
> Thank you for your reference to some old but cheap technologies of
> importance for our sundial community. I think we would have much more fun
> (?) had you provided us a link to the film (preferably a link that would
> be accessible also for those who are not yet members of  the British
> Sundial Society).
> 
> Best regards,
> 
> Wojtek

---
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Re: Tropic of Capricorn sundial

[John Goodman]

Hi Roger,

Your analysis makes sense but I suspect that the explanation for the anomalies 
is the sundial was just badly designed. I don't think it's ancient; it looks to 
have been built within the last few decades. 

It may have been modeled after a traditional monument but perhaps by someone 
not familiar with the functional requirements of a sundial. It wouldn't be the 
first example of bungled execution.

Thanks for giving your attention to my question,
John


> On Apr 24, 2016, at 4:42 PM, Roger Bailey <rtbai...@telus.net> wrote:
> 
> Hello John,
>  
> Yes, this is a puzzle. The sun on the solstice, 21 June, is at its lowest 
> altitude in the southern hemisphere. The noon altitude would be 47°. The sun 
> would rise and set on that day farthest to the north. This is an appropriate 
> new years day in the southern hemisphere to celebrate the return of the sun 
> as our new year in the north starting at the winter solstice. None of these 
> 21 June observations seem to relate to the "sundial".
>  
> However other seasonal markers would be obvious with this sundial. One is the 
> winter solstice 21 Dec. On that date at the Tropic of Capricorn the sun at 
> noon would be directly above this sundial, casting no visible shadow. This 
> would explain the vertical orientation of the gnomon as the shadow could be 
> seen getting shorter as noon approaches and longer in the afternoon.
>  
> The sloping east west gnomon could be used to note an approximate midway 
> point between the equinox and the solstice. When does the sun line up due 
> east and west at an altitude of 23.5°? The equation for the prime vertical, 
> the east west meridian, Sin Alt = Sin Dec / Sin Lat. This resolves to Sin Dec 
> = Sin23.5 x sin 23.5 and gives the declination as -9.15°. The east west sun 
> along the line of the sloping gnomon occurs around 17 Oct and 25 Feb. Perhaps 
> these were significant dates for the ancient culture in the area. 
> Pre-Christian cultures in Europe had such mid-season markers, Samhain 1 Nov 
> and Imbolc 2 Feb. were a couple of the names. A residual in Christian 
> cultures is Michaelmas and Candlemas  
>  
> The gnomon could also indicate the equinoxes as the sun rises due east and 
> sets due west in line with the gnomon. For early cultures marking the 
> calendar with seasonal markers was much more important than measuring the 
> time of day.
>  
> Regards,
> Roger Bailey
>  
>  
> From: John Goodman <mailto:johngood...@mac.com>
> Sent: Sunday, April 24, 2016 8:31 AM
> To: Sundial List <mailto:sundial@uni-koeln.de>
> Subject: Tropic of Capricorn sundial
> 
> I was recently in northern Argentina at the Tropic of Capricorn. I saw a 
> structure there that has been described as a sundial but I have trouble 
> understanding how it could work. I'm attaching a small photo of the gnomon, 
> which is angled at roughly 23.5 degrees. So far so good.
> 
> What confuses me is that the gnomon is aligned along the east/west axis, 
> which you can see by the Google Maps satellite view shown for the coordinates 
> 23°26'52.1"S 65°21'06.0"W
> 
> I've also read this description of the marker, automatically transited from 
> Spanish:
> 
>> Generally, this place is chosen so that the natives of here come and 
>> celebrate the Inti Raymi, thanking the Sun on June 21, as the Incas used to 
>> do many years ago. They await the arrival of the Sun which for them is a new 
>> year.
> 
> Would an east/west orientation be appropriate for a monument marking the June 
> solstice south of the equator?
> 
> Thanks for your help deciphering the design,
> John
> 
> 
> 
> 
> ---
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> 
> 
> 
>  <>No virus found in this message.
> Checked by AVG - www.avg.com <http://www.avg.com/>
> Version: 2016.0.7539 / Virus Database: 4556/12091 - Release Date: 04/24/16

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Tropic of Capricorn sundial

[John Goodman]

I was recently in northern Argentina at the Tropic of Capricorn. I saw a 
structure there that has been described as a sundial but I have trouble 
understanding how it could work. I'm attaching a small photo of the gnomon, 
which is angled at roughly 23.5 degrees. So far so good.

What confuses me is that the gnomon is aligned along the east/west axis, which 
you can see by the Google Maps satellite view shown for the coordinates 
23°26'52.1"S 65°21'06.0"W

I've also read this description of the marker, automatically transited from 
Spanish:

> Generally, this place is chosen so that the natives of here come and 
> celebrate the Inti Raymi, thanking the Sun on June 21, as the Incas used to 
> do many years ago. They await the arrival of the Sun which for them is a new 
> year.

Would an east/west orientation be appropriate for a monument marking the June 
solstice south of the equator?

Thanks for your help deciphering the design,
John

---
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Celestial engineering in the heart of Manhattan

[John Goodman]

Excerpts from a report in the New York Times:

Sunlight on Summer Solstice Will Light Up Fulton Center Hub

For nearly three hours on the summer solstice, a structure in the center known 
as the Sky Reflector-Net will send rays of light about 40 feet below sidewalk 
level to recesses on the lowest level.

Look closely at the circular skylight in the atrium and you will see a series 
of arcs formed by 88 glass blades. The angle of each blade has been calibrated 
to direct sunlight down to the concourses at certain hours of the day and times 
of the year.

As a poetic bonus, the patterns trace the sun's route through the sky, said Zak 
Kostura, a structural engineer at Arup. The shallower arcs express the 
trajectory of its wintertime journey; the longer arcs express its summertime 
path.

Furthermore, a straight line drawn through the apogees of the arcs exactly 
describes a true north-south axis - something that lower Broadway does not do.

We've always looked at this as a kind of calendar, a seasonal thing, said 
Richard Kress, the design director at James Carpenter Design Associates.

http://www.nytimes.com/2015/06/18/nyregion/sunlight-on-summer-solstice-will-light-up-fulton-center-hub.html

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Shadowless building

[John Goodman]

Not exactly a sundial, but demonstrating solar awareness.

“Architects at the firm NBBJ in London decided to see if they could come up 
with an entirely shadowless building. They used computer modeling to design a 
pair of buildings, one of which works like a gigantic, curved mirror. The glass 
surface of the northernmost building reflects light down into the shadow cast 
by its southern partner. And the carefully defined curve of that glass allows 
the reflected light to follow the shadow throughout the day.”

http://www.wired.com/2015/03/plan-build-skyscraper-doesnt-cast-shadow/
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RE: A question for the mathematically inclined (Jack Aubert)

[John Goodman]

I find this website very helpful for visualizing the changes in daylight over 
time and latitude.

Daylight Hours Explorer
http://astro.unl.edu/classaction/animations/coordsmotion/daylighthoursexplorer.html


 On Feb 3, 2015, at 3:36 PM, sundial-requ...@uni-koeln.de wrote:
 
 OK, I would also like to take a turn and ask a question to the mathematically 
 inclined:
 
 I have been trying to figure out how to plot the duration of daylight over 
 the course of the year as a function of latitude. (I would generate a curve 
 for each latitude I am interested in.)  
 
 I believe the result should be a sine curve which looks comparatively flat at 
 the equator, growing increasingly steeper until the polar circle, where it 
 would turn into a binary step curve and the six month day turns to six month 
 night -- leaving aside physical effects like refraction.  I am particularly 
 interested in the slope of the curve around the equinoxes at northern 
 latitudes, when the transition from long summer days to short winter days is 
 quite abrupt. 
 
 Jack Aubert  

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Re: A question for the mathematically inclined

[John Goodman]

Thanks to everyone who replied with suggestions, both on and off the list. 

When I asked my question, I assumed there was a trivial solution that could be 
simply explained. I realize now that the calculations are not straightforward. 

Roger Bailey has given me an approach that I believe will work for me. I’m now 
trying to understand how the math represents the spatial geometry of the 
problem. 

The variety of solutions I received are an indication of the broad experience 
and wisdom embodied in this group. I'm always grateful for that asset.


 On Jan 31, 2015, at 10:05 AM, John Goodman johngood...@mac.com wrote:
 
 Dear dialists,
 
 Does anyone know a formula for calculating the hour angle given the azimuth, 
 declination, and latitude? 
 
 I’d like to know the time of day, throughout the year, when the sun will be 
 positioned at a particular angle. This will allow me to determine when 
 sunshine will stream squarely through a window on any (sunny) day.
 
 I’ve seen several formulae for calculating azimuth. I suspect that one of 
 them could be rewritten to solve for the hour angle given the azimuth instead 
 of the finding the azimuth using the hour angle (plus the declination and 
 latitude). Unfortunately, I don’t have the math skills for this conversion.
 
 Thanks for any suggestions.

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A question for the mathematically inclined

[John Goodman]

Dear dialists,

Does anyone know a formula for calculating the hour angle given the azimuth, 
declination, and latitude? 

I’d like to know the time of day, throughout the year, when the sun will be 
positioned at a particular angle. This will allow me to determine when sunshine 
will stream squarely through a window on any (sunny) day.

I’ve seen several formulae for calculating azimuth. I suspect that one of them 
could be rewritten to solve for the hour angle given the azimuth instead of the 
finding the azimuth using the hour angle (plus the declination and latitude). 
Unfortunately, I don’t have the math skills for this conversion.

Thanks for any suggestions.
---
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Daylight Saving Time

[John Goodman]

For anyone who objects to daylight saving time, this is the video for you. It’s 
also funny for everyone else too.

https://www.youtube.com/watch?v=k4EUTMPuvHo
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Re: Planetarium app (Astrovisuals)

[John Goodman]

A list of star catalogs is available here - 
http://www.projectrho.com/public_html/starmaps/catalogues.php

There are many planetarium apps available from the iTunes store. This one is 
well-regarded - https://itunes.apple.com/us/app/the-night-sky/id475772902


On May 22, 2014, at 5:39 AM, sundial-requ...@uni-koeln.de wrote:

 Date: Thu, 22 May 2014 17:56:13 +1000
 From: Astrovisuals m...@astrovisuals.com.au
 To: sundial@uni-koeln.de
 Subject: Planetarium app
 Message-ID: B55D22B3B9B142D2A3175F623C66496E@ewiddowsonPC
 Content-Type: text/plain; charset=utf-8
 
 I wonder if anyone can help? I want to produce a basic planetarium app for 
 iPad that shows the appearance of the Night Sky anywhere on earth.
 I believe I need: 
 A program to convert RA and Dec to Alt-azimuth co-ordinates.
 A list of stars, plus details about how to add ?constellation lines? between 
 selected bright stars.
 A way of incorporating the Milky Way as a vector file.
 Would be grateful for any help; am happy to pay for programs, lists etc.
 
 And on a different subject, I would like to enter a sundial in the Italian 
 Astronomers? International contest for sundial makers, but cannot find the 
 form to fill in. Can someone supply a PDF or web address? 
 Thanks,
 David Widdowson, Astrovisuals Australia
 www.astrovisuals.com.au

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From garden planning to car design

[John Goodman]

A new solar-powered, self-moving concept car from Ford tracks the sun to 
maximize charging power:

 It parks itself under a simple structure, 4 meters by 5 meters (about 13 feet 
 by 16 feet), with a plexiglass lens for a roof. The car picks the north-south 
 coordinate according to the season of the year, and it adjusts the east-west 
 location over the course of the day. If the car is in the right spot, the 
 lens concentrates the sun’s rays by a factor of eight.


http://mobile.nytimes.com/2014/01/05/automobiles/from-ford-a-plug-in-that-tracks-the-sun.html

Video - 
http://video1.nytimes.com/video/2014/01/02/25280_1_ford-solar_wg_16x9_l_3g_mob.mp4
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Seasonal explanation

[John Goodman]

An explanation of celestial mechanics in the popular press:

The earliest sunset really comes in the first week in December, and the latest 
sunrise occurs in early January. Yet December 21 really is the shortest day of 
the year. What sort of astronomical hijinks are responsible for this absurd 
state of affairs?

http://www.theatlantic.com/technology/archive/2013/12/the-astronomical-hijinks-of-the-shortest-day-of-the-year/282109/
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Re: Thank you

[John Goodman]

Hi Donald,

The errors on your site are not very serious. As you may have discovered, going 
to http://validator.w3.org/ and typing in www.sundialsforlearning.com will give 
you a list of them. Most are simple formatting errors that most browsers ignore 
and process with no visible rendering problems.

For example, a line like:
brbr  b  p style=text-align: left; 
which appears repeatedly on you page, will generate three errors in the 
validator. The error report suggests how you can solve the problem. In this 
case, adding forwardslashes to the line where suggested:
br/br/  b  p style=text-align: left;/
eliminates the errors.

Your site deserves credit for having animations that don't require the 
proprietary and increasingly disparaged Flash plug-in. (Playing your video is 
unfortunately dependent on Flash.) I found that your site rendered properly on 
OS X using Safari and Firefox, on Windows XP using Internet Explorer, and on an 
iPhone. Not bad.

On Aug 22, 2012, at 6:00 AM, sundial-requ...@uni-koeln.de wrote:

 Message: 3
 Date: Wed, 22 Aug 2012 07:44:13 +1000
 From: Donald Christensen dchristensen...@gmail.com
 To: sundial@uni-koeln.de
 Subject: Thank you
 Message-ID:
   cac+ykpusykucu1ujspork7cmbbhalqed0haghqorv2brjoi...@mail.gmail.com
 Content-Type: text/plain; charset=iso-8859-1
 
 Thank you
 
 The response was amazing and much appreciated.
 
 The offers of help, advice, and feedback were very helpful. I'm in the
 process of making my site W3C
 
 
 
 
 Cheers
 Donald
 0423 102 090
 
 
 This e-mail is privileged and confidential. If you are not the intended
 recipient please delete the message and notify the sender.
 Un-authorizeduse of this email is subject to penalty of law.
 So there!
 -- next part --

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Re: Sundials in cinema

[John Goodman]

If you collect several references, consider adding sundials as a category to 
the newly-forming website smalldemons.com  As they describe it: 

 Song. Album. Movie. Fashion. Food. Cocktail. Car. 
 
 Much of how we come to know and love stories is by the things that help 
 define them. Why not let them lead to new experiences too? Like starting the 
 weekend sipping the cocktail a villain you secretly admire always orders. 
 ...
 The things in books are there because they mean something—to the character, 
 to the author. Right here is where you begin to discover what they can also 
 mean to you.


Why not encourage people to experience sundials as well as cocktails?

 
On Dec 18, 2011, at 5:36 PM, Darek Oczk wrote:

 Dear friends
 
 I've got two news for those interested in sundials in movies.
 
 1. In the very beginning of the latest movie by Lars von Trier (Melancholia) 
 there is a nice scene shoving a close view of a horizontal sundial. 
 Screenshot attached. Later it appears in the film several times more but only 
 from a distance.
 
 2. There is an Indian movie comapany Sundial Pictures. They have an 
 interesting sundial animation used as their motion logo. Follow the link 
 below to watch it:
 
 http://sundialpictures.in/index.html
 
 -- 
 Best regards
 Darek Oczki
 52N 21E
 Warsaw, Poland
 
 GNOMONIKA.pl
 Sundials in Poland
 http://gnomonika.pl

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Simple, inexpensive sundials

[John Goodman]

From time to time, list subscribers have posted links to low-cost, simple 
sundials. I'm helping a friend find a source for time-related gifts priced at 
less than $25. Can anyone please refer me to sundials that meet those price 
guidelines? 

Thanks very much,
John 

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Re: sun position

[John Goodman]

If you're looking for software libraries, I've been happy using these:

 AA+ is a C++ implementation for the algorithms as presented in the book 
 Astronomical Algorithms by Jean Meeus.

http://www.naughter.com/aa.html


On Aug 24, 2011, at 9:24 AM, David Patte wrote:
 
 If there is a need for someone on the list to generate a programme for 
 astronomical positions in higher accuracy, I have already coded in C++, 
 a complete windows library that computes Galactic (GLat/GLng), 
 Ecliptical (Elat/ELng), Equatorial (Rta/Dec) and Horizontal (Alt/Azi) 
 positions of the sun, moon, the major planets, comets and asteroids, 
 given Lat/Lng and Local Time.
 
 It understand the changing world timezone rules, and uses either 
 Keplerian or ELP2000/VSOP87 (higher accuracy) methods to get the Rta/Dec 
 of objects. It also handles precession, nutation, and the aberration and 
 refraction of light.
 
 The astronomical engine is used, for example, in our product Time Zone 
 Master to compute sunrise/set, moon phases, start of seasons, equation 
 of time, etc., and in Snap Sundial App to compute shadows for a given 
 lat/lng/Time.
 
 The code library is available under licence, or I can build code on top 
 of it, if it is required for a particular project.
 
 David
 
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Re: light poem

[John Goodman]

On Mon, 18 Jul 2011, at 8:54 AM, Mac Oglesby wrote:

 Also, I don't remember seeing any hint about the installation's location.

According to this YouTube post - http://www.youtube.com/watch?v=CvWh2xBbwrE - 
the pavilion is located at the Art Center College of Design in Pasadena, CA

See also, page 7 of this PDF - http://www.artcenter.edu/accd/files/MDP.pdf and 
this thesis webpage - http://people.artcenter.edu/~jsong5/portfolio/thesis.html
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Re: Longest day calculations

[John Goodman]

Thanks to all for the formulas. For me, the format that's most convenient is 
the one sent by Kevin Karney:

[acos(-tan{latitude} x tan{declination})] / 7.5

where declination = 23.5 at midsummer and -23.5 at midwinter. 

If you flip the signs on the declination angles, so that midsummer = -23.5 and 
midwinter = 23.5, you can get rid of the minus sign in the equation, making it:

[acos(tan{latitude} x tan{declination})] / 7.5

The divide by 7.5 works as long as you're calculating in degrees. Computers 
like to work in radians, so I divide by pi, which gives the answer as a 
fraction of a whole day. I can multiply by 24 if I want the result to be in 
hours.

Before consulting the list, I had found a website with a much more confusing 
explanation. In case anyone here is interested and hasn't seen it, the address 
is - http://herbert.gandraxa.com/length_of_day.aspx  I'm much happier with the 
advice given here.

Thanks again for sharing your knowledge,
John


On Jul 1, 2010, at 1:57 PM, Karney wrote:

 [acos(-tan{latitude} x tan{declination})] / 7.5
 
 Declination = 23.5 at  midsummer , 0 at equinox -23.5 at midwinter
 
 Kevin Karney
 Freedom Cottage, Llandogo, Monmouth, NP25 4TP
 Phone 01594 539 595. Mobile 07595 024 960
 
 On 1 Jul 2010, at 18:12, John Goodman johngood...@mac.com wrote:
 
 Hello all, 
 
 I usually shudder when I see equations in messages posted to the list, but 
 now I have a problem than needs a mathematical solution.
 
 I'm looking for a simple formula which calculates the number of hours that 
 the sun will be above the horizon on the summer solstice for any given 
 latitude. I don't need to worry about refraction, or take into account the 
 sun's diameter. I'm just interested in the simple geometric case, using the 
 center of the sun's disk for determining the start and end times. 
 
 For my purposes, these simple relationships will be true: If the answer for 
 summer solstice hours is SSH, then winter solstice hours will be 24 - SSH, 
 and equinox hours will be 12, regardless of the latitude. 
 
 Thanks very much,
 John
 
 ---
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Longest day calculations

[John Goodman]

Hello all, 

I usually shudder when I see equations in messages posted to the list, but now 
I have a problem than needs a mathematical solution.

I'm looking for a simple formula which calculates the number of hours that the 
sun will be above the horizon on the summer solstice for any given latitude. I 
don't need to worry about refraction, or take into account the sun's diameter. 
I'm just interested in the simple geometric case, using the center of the sun's 
disk for determining the start and end times. 

For my purposes, these simple relationships will be true: If the answer for 
summer solstice hours is SSH, then winter solstice hours will be 24 - SSH, and 
equinox hours will be 12, regardless of the latitude. 

Thanks very much,
John

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Re: Sundials/BHI

[John Goodman]

On Jun 13, 2010, at 12:16 PM, Jack Aubert wrote:

 I have been working on photo-engraved brass dials under the generous
 long-distance tutelage of Tony Moss, starting from a video that he presented
 at our most recent NASS conference.

Is this video online anywhere? I'm curious about how the process works.

Thanks,
John

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Re: DST Misconceptions

[John Goodman]

  In China there are 1.2bn people spread over
  60 degrees of longitude all living by the
  same clock time.
 
  Compared with their fellows in the easternmost
  15 degrees, the others are effectively living
  with single, double and quadruple summer time.

This is technically true, but in practice, not an ideal test. 

First of all, the vast majority of people in China live in a longitude band of 
less than 30 degrees, running from Kunming in the west to Harbin in the East. 
Time is standardized around Beijing, which is close to the center of that range.

I lived in Kunming for two years and I can't say that it was a problem living 
on Beijing time. However, when I traveled further west, to the frontier 
province of Xinjiang, Beijing time was noticeably out of sync with my 
expectations of when the sun should be shining.

In Xinjiang, Beijing time is used for national schedules, such as train 
timetables and government office hours. For everything else, people use local 
time, which is an hour earlier than Beijing time. People in Xinjiang are in 
the habit of ignoring many government dictates so keeping their own time is not 
a big challenge.

The other major western province in China is Tibet. I haven't been to Tibet but 
I have no trouble imagining that, like Xinjiang, people ignore a lot of what 
the government mandates. Neither province is ethnically or historically part of 
the Chinese empire and traditions have more authority than law.

Even in Kunming, a much more culturally Chinese area, people liked to quote the 
time-honored maxim that the mountains are tall and the emperor is far away. 
Standardized time doesn't count for much when habits are involved.

Much of China is still rural. It will be a long time before timepieces rule.

John 

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Re: Solar position calculator

[John Goodman]

Hi Greg,

The PyEphem Python scripts look great! Now that I've figured out how to use 
Python, these functions will be very useful. 

Thanks for passing on the link,
John

__
A sundial without the sun - www.annosphere.com

On Mar 3, 2010, at 1:56 PM, Greg G?mez wrote:

 Hello, everybody:
 
 I've been using PyEphem which seems to be accurate and fast.
 
 It'll calculate rise, set and transit for the sun, as well as the moon and 
 planets (or any other body given the orbital elements), and provide the 
 body's 
 position as Az/Alt and RA/Dec at rise/transit/set or any other time. It has a 
 bunch of other useful features, as well.
 
 I've found it to be a little quirky, but very usable.
 
 http://rhodesmill.org/pyephem/
 
 Cheers,
 Greg

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Solar position calculator

[John Goodman]

If anyone needs to make precise solar position calculations, the following 
software may be useful. There are a few caveats. The software is not a 
stand-alone application, it's a software library. The software library needs to 
be used from the command line and it runs using the Python programming language.

I'm a Mac user and this is one of those rare occasions when an arcane set of 
requirements actually favors the Mac. While Macintosh users tend to be allergic 
to the command line, it has existed in the OS for the past 10 years. Python is 
there too, lurking under the surface.

I don't know enough about the PC, but clearly the command line is there and 
Python is available too. ( http://www.python.org/download/windows/ )

With all that preface, here's what the code can do. Once the necessary files 
are installed, you can type the following commands and see the following 
results:

 import datetime, solar
 d = datetime.datetime(2010, 3, 3, 18, 0, 0)
 lat = 42.0
 long = -71
 solar.GetAltitude(lat, long, d)
39.203509044804704
 solar.GetAzimuth(lat, long, d)
-20.717667802423591
 

Someone with an ephemeris can check these results. The format for datetime is 
, mm, dd, hh, mm, ss, optionally followed by a number of microseconds. 
The time value entered is for UTC.

There are other functions for calculations that I haven't explored. You can 
read more about the software tools at http://pysolar.org/  Example uses are 
shown at http://wiki.github.com/pingswept/pysolar/examples  The software itself 
is at http://github.com/pingswept/pysolar/downloads

All of this software is the work of Brandon Stafford, who has generously 
offered his code free of charge to anyone who may find it useful. I have little 
experience with this software but, as much as I can, I'll be happy to help 
anyone trying to use it. 

If there are any questions, I can pass them on to Brandon. I hope this is 
helpful to some.

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Re: R: Solar position calculator

[John Goodman]

Thank you for checking the Python calculations against the results given by 
Orologi Solari. There a difference of less than 0.05 percent between the two 
calculations. (20.72373 vs. -20.71767, and 39.18438 vs. 39.20351) Is that to be 
expected and is it a meaningful level of precision? 

On Mar 3, 2010, at 1:10 PM, sun.di...@libero.it wrote:

 The simulation tool of Orologi Solari gives the following results (see 
 attachment) :
   azimuth = 20.72373
   height = 39.18438
 using DeltaT = 66.8 sec.
 
 Greetings.
 Gian Casalegno
 

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Re: antikythera mechanism

[John Goodman]

Another video on the topic of mechanical computers:

http://www.ted.com/talks/tom_wujec_demos_the_13th_century_astrolabe.html


 Date: Fri, 18 Dec 2009 15:51:46 -0500
 From: patrick_pow...@compuserve.com
 Content-Type: text/plain; charset=us-ascii
 
 Frank: An amazing device indeed.  Sadly I couldn't get to the one day 
 Cambridge Symposium on it last winter but I much enjoyed viewing the video 
 clip on the Nature web site:
 
 http://www.nature.com/nature/videoarchive/antikythera/
 
 I was left musing just how arrogant we are today to assume that the ancients 
 couldn't 'do' some things.  What's the betting now that Stonehenge was not 
 just a religious site but might indeed have been as Fred Hoyle believed?
 
 Patrick

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Indoor sundials

[John Goodman]

Dear dialists,

My knowledge of sundials is very limited compared to almost anyone on this 
list. I joined this list to help me understand what I would need to know to 
build an indoor sundial.

I did not start out with this plan. An interest in mechanisms led me to build a 
set of gears with a ratio of 365.2422 to 1. Having this, it seemed to make 
sense to use the ratio in a timepiece which simulates a sundial.

Since the shadow on a sundial varies over both the course of year as well as 
over the course of a day, any mechanical reproduction of a sundial needs to 
have both a daily cycle and a yearly cycle. The yearly cycle enables the 
representation of seasonal changes, such as equinoxes and solstices, and a 
daily progression of sunrise and sunset times.

My first indoor sundial is far from perfect. Most apparently, the length of day 
is a constant 24 hours, eliminating the EoT difference between solar time and 
civil time. (I will leave it to the dialists to decide whether this is a bug or 
a feature.)

I'm continuing to experiment with other models based on the day/year gear 
ratio. This list is an invaluable source of information about dialing. I'm very 
happy I have the opportunity to learn from it. 

You can see what I've built so far at http://annosphere.com/  Thank you all for 
sharing your knowledge and helping me to improve my design.

John

On Nov 21, 2009, at 6:01 PM, sundial-requ...@uni-koeln.de wrote:

 Date: Sat, 21 Nov 2009 10:20:13 -0700
 From: John Carmichael jlcarmich...@comcast.net
 Subject: RE: dalemain stolen dial
 
 Hi Jack:
 
 I don't have time to look for it right now, and my bad memory won't let me
 recall where I saw it, but earlier this year we discussed a german invention
 of an indoor sundial just like what you describe- with a mechanical driven
 moveable light mounted in the ceiling that cast a shadow fron a wall-mounted
 gnomon onto a wall sundial inside a building.  Try searching for indoor
 sundials  or mechanical sundials. If you can find that email thread,
 there are photos of it.
 
 John
 
 -Original Message-
 Sent: Saturday, November 21, 2009 9:34 AM
 To: 'Richard Mallett'; 'Frank King'
 Subject: RE: dalemain stolen dial
 
 Such a shame that we cannot have sundials inside.  
 
 What we need is for somebody to develop a motor-driven, geared apparatus
 that will move an electric through a path that picks up all the relevant
 celestial motions.   
 
 Jack

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Re: no analemman

[John Goodman]

Hello all,

I learned something recently about another time-related project that  
may be applicable here. A group of people are building something  
called the Clock of the Long Now that's expected to run unattended for  
10,000 years ( http://longnow.org/projects/clock/ )

The timekeeping part of the Long Now clock will be powered by day-to- 
night temperature differentials. The clock also includes somewhat  
elaborate displays and chimes, as well as dials indicating time (both  
solar and civil) and an orrery.

All of these ancillary displays are updated only when some person  
provides mechanical power. This is partly a decision based on  
practical necessity (due to the level of power needed) but it has an  
interesting side effect that may be relevant for sundial design. (You  
were wondering about that, right?)

If the sundial could be adjusted for civil time, in a manner easily  
understood and managed by a casual observer, it would record any  
attention received from viewers. For anyone interested in solar time,  
the dial would have a default, unadjusted position. For anyone  
interested in civil time, the dial could be repositioned by date to  
match.

The dial would stay in the last adjusted position until the next  
person came along to make a change. The date of the previous  
adjustment would be like a signature in a guest book, indicating the  
date of the last (involved) visitor.

I realize that an adjustable anything is asking for vandalism. I don't  
see this as a universal solution, only a perspective that may lead  
some viewers to a better understanding of solar dynamics.


On Oct 4, 2009, at 6:12 PM, Edley McKnight wrote:

 Hi Frank, Dial friends,

 If the dial is going to have adjuistments, it seems simpler and  
 better to simply have the dial mounted to a hinge parallel to the  
 earth's axis.  Then, when the dial varied from civil time by an  
 unacceptable amount, one could just rotate it slightly about the  
 hinge til it agreed.  This would be great for occasions where  
 daylight savings dates keep shifting around, or one moves a bit in  
 longitude for some reason.  Yes, I've heard of folks doing this, but  
 I have no pictures of it.  I'm not actually much in favor of civil  
 time dials either, but this would work simply with nearly any dial  
 that was not too firmly fixed or heavy for those that needed or  
 wanted a simple civil dial.

 Edley.

  Greetings fellow dialists,
  I'm not a great lover of displaying the equation of time on dials,
  except for maybe the finest. The main disadvantage, it seems to me,
  apart from the messiness of the addition of the analemma curve or a
  table of values, is the demand upon the viewer to make some
  understanding of what might appear rather complicated.
 
  Have there, I wonder, been dials made which simply show the required
  correction for the current month, e.g. [October] For clock time  
 apply
  [-14  minutes]? Variables are in brackets and the correction is for
  mid-month, near enough for dials which are divided to quarter  
 hours or
  worse. These are the vast majority. The correction would require  
 monthly
  attention, of course, but it would be possible to insert two
  interconnected windows, one for the month and one for the  
 correction, in
  the dial plate to accomplish this. And of course the month could  
 be set
  by the observer if desired. Longitude, too, could be included, to
  satisfy the clever fellows who examine the dial and then knowingly
  consult their watches.
 
  But am I going over already trodden ground? Do such dials already  
 exist?
  Frank 55N 1W
 
 
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Re: Another mechanical sundial

[John Goodman]

Dear dialists,

While we're stretching the definition of a sundial, I'll pass on a  
link to my version of a mechanical sundial that I call an annosphere.

The annosphere uses a set of gears to create a day-to-year ratio of 1  
to 365.2422. A ring, inclined at the angle of the ecliptic, turns once  
a year around a disk rotating once a day.

Riding on the inclined ring and shining on the disk, an LED rises and  
falls over the course of a year. The rising and falling LED/sun  
changes the duration of daylight on the disk. A gnomon centered on the  
disk casts a shadow indicating the time.

The disk can be angled to match any latitude in the northern  
hemisphere. This sundial shows clock time, with no simulation of the  
variations normally accounted for with the EoT.

I apologize for my confusing explanation. If you'd like a better  
understanding, please take a look at the photos on the website 
http://annosphere.com 
   An animated demonstration of the gearing is shown at 
http://annosphere.com/demo

Please note that the demo is interactive and, unfortunately, it can't  
work without installing a few plug-ins. Your browser will prompt you  
for permission, which you can refuse, but the demo will not run  
without them.

I knew next to nothing about sundials when I began this project (and I  
still know very little.) I joined this list to learn more and, even  
with my annosphere completed, I continue to enjoy the discussion and  
education that takes place here.

Thank you for regularly sharing your knowledge.
John


P.S.
Eduardo Catalano, the creator of the sun sculpture mentioned  
previously by John Carmichael, used to practice architecture just a  
few blocks from where I live.


 Date: Mon, 28 Sep 2009 11:58:40 -0700
 From: John Carmichael jlcarmich...@comcast.net
 Subject: Another mechanical sundial

 Hi Robert  others:


 Somewhat distantly related to this subject is this other type  
 mechanical
 sundial.


 It is called the Floralis Generica, a huge metal flower made by  
 Eduardo
 Catalano, an argentinian artist who was born in 1917. It was a gift  
 from the
 artist to Buenos Aires.   The structure of the flower is made of  
 steel and
 the shiny panels in the petals are made of aluminium. The sculpture  
 moves,
 closing its petals at night and opening them during the day. The  
 sculpture
 is the work of Argentinian architect Eduardo Catalano, who also was a
 Professor Emeritus at MIT.


 http://www.flickr.com/groups/floralisgenerica/pool/


 John

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RE: The Eternal Sundial

[John Goodman]

I copied the JPEGs from the website and posted them online at:

http://files.me.com/johngoodman/9wlbfj
http://files.me.com/johngoodman/mk48mj
http://files.me.com/johngoodman/asj8u2
http://files.me.com/johngoodman/0vbv3l
http://files.me.com/johngoodman/x0hk02

The links will be good for 30 days.


On May 13, 2009, at 12:35 PM, sundial-requ...@uni-koeln.de wrote:

 Hi Brian

 Not directly.  But I was able to print the undownloadable screen  
 image
 onto a PDF doc, then in Photoshop I cropped out the photo.


 John L. Carmichael


 From: Brian Albinson [mailto:brianalbin...@shaw.ca]
 Sent: Wednesday, May 13, 2009 9:01 AM
 To: John Carmichael
 Subject: Fw: The Eternal Sundial


 John

 Have you been able to download the photos in the address below?

 Brian Albinson


 There is a dial with real spiral face in Girona, Spain, though.

 See: http://photo.xuite.net/nycl.chiu/1477368/129.jpg

 ChiLian Chiu

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RE: Interesting Day Question from the mind of a child

[John Goodman]

On Jan 15, 2009, at 1:58 PM, Lufkin, Bradley (MS wrote:

 Here's a sundial which illustrates these points. It's an Oughtred dial
 set for the Arctic Circle without longitude, EOT, or refraction
 corrections. Note that the Sun is above the horizon for the entire day
 on the 21st of June (but just barely).
 Brad

It's nice to see a graphical answer to the question!

How was this sundial illustration created? Is there a software  
application that can create a chart like this for any place on earth,  
at any time of year?

Thanks for any additional info.
John

www.annosphere.com

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RE: Solar synchronizer (Andrew Pettit)

[John Goodman]

The equation of time is not ignored by the Long Now clock. In one of  
their FAQs they state:

 The clock is projected to be accurate to within one day every 20,000  
 years, but just in case it isn't, a solar synchronizer will correct  
 the time shown on the clockface. A lens on top of the clock will  
 advance or retard the display by phase-locking to the local noontime  
 sun. The digital mechanical design also allows the clock to adjust  
 for leap days, leap years, leap centuries–even for the precession of  
 the equinox


The mechanism for accommodating the EOT is described and pictured  
here: http://www.longnow.org/press/articles/ArtSoftwareDev.php#sidebar


 Date: Mon, 14 Jul 2008 16:30:22 +0100
 From: Andrew Pettit [EMAIL PROTECTED]
 Subject: RE: Solar synchronizer
 To: 'Frederick Jaggi' [EMAIL PROTECTED],  'Sundial Sundial List'

 Interesting!

 According to the video the clock synchronises to the sun at noon on  
 any
 sunny day.

 No mention is made of the Equation of Time correction.

 So it will be a curious Alice in Wonderland type clock that tells  
 the
 correct time by the sun precisely once on any sunny day and the  
 correct
 civil time occasionally throughout the year!

 Or an I missing something?

 Regards to all

 Andrew


 PS ~ for those that remember an earlier posting Help Oscar I am  
 planning a
 sundials day at his school tomorrow. Let me know off list if you are
 interested in feedback.



 -Original Message-
 From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] 
 ] On
 Behalf Of Frederick Jaggi
 Sent: 10 July 2008 23:53
 To: Sundial Sundial List
 Subject: Solar synchronizer

 There's an interesting tour in San Francisco to take place on July  
 12. One
 of the locations on the tour is the Long Now Foundation 1 year  
 clock
 which features a solar synchronizer (hence the sundial relevance!).
 See:
 http://www.longnow.org/mechanicrawl/ and link on the solar  
 synchronizer link
 on the right side of the page


 Fred Jaggi
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Re: Sundial Calculation Programme

[John Goodman]

On Apr 13, 2008, at 10:23 AM, Ricardo Cernic wrote:

 Dear Albert,

 I've never heard about a program for MAC OS, but considering that  
 Stundlin is mainly text oriented you could have the same output with  
 almost the same look using a spreadsheet. Have you considered using  
 this approach? What kind of spreadsheet is available for MAC OS (any  
 freeware)?

 Best regards,
 Ricardo Cernic
 S?o Paulo - Brazil

I haven't used this software myself, but there's a Mac spreadsheet  
based on open-source, cross-platform code that has the additional  
virtue of being free. Here's what one reviewer said:

 NeoOffice, a port of OpenOffice that runs natively in OS X, supports  
 Excel 2004's macros, at least to some degree. (Some of my macros  
 worked perfectly; others didn't.) It can also open Excel 2008's and  
 the Windows-only Excel 2007's new .xlsx file format, and it offers  
 excellent compatibility with Excel functions.

You can learn more at http://www.neooffice.org
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Re: Astronomical Clocks

[John Goodman]

I found a review of Geared to the Stars online, and it looks like a  
fantastic reference. While it's out of print, I'm lucky that there's a  
nearby library with a copy. I hope to go there soon to take a look.

Thanks for calling this to my attention. Many people have built  
amazing astronomical mechanisms over the years (including many members  
of this list (including the sender to whom I'm replying.)) It's nice  
to see their work recognized.


On Mar 29, 2008, at 9:46 PM, [EMAIL PROTECTED] wrote:

 The best reference on geared astronomical machines, including  
 monumental clocks such the Prague clock is:

 King, Henry C., Geared to the Stars, University of Toronto Press  
 (1978).

 (The late professor King also wrote The History of the Telescope.)

 This book has a fairly detailed description of the Prague gearing,  
 and the trains for many other astronomical machines.

 Best regards,

 Jim


 James E. Morrison
 [EMAIL PROTECTED]
 Astrolabe web site at astrolabes.org

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Re: astronomical clock - English version

[John Goodman]

The drawings are beautiful, and now, thanks to the English  
translation, I can actually understand the clock's functions!

Has anyone ever documented the mechanism that controls the  
interrelated movements? Having built a (mechanical) timepiece that  
incorporates the day-to-year ratio, I'm curious to see how others have  
done it (and more.)

On Mar 28, 2008, at 7:24 PM, [EMAIL PROTECTED] wrote:

 Thank you all who sent me their appreciation and comments concerning
 my web page with an explanation of the astronomical clock in Prague
 and the spreadsheet in the page that 'construct' the clock for each
 moment in the year and each place in the world.

 On general demand the web page is now translated in English.


 You find it at
 http://www.wijzerweb.be/prague.html

 I am waiting for your comments, even about my (Flemmish) English.

 Willy LEENDERS
 Hasselt in Flanders (Belgium)


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 --

 Message: 2
 Date: Sat, 29 Mar 2008 08:13:09 +
 From: Tony Moss [EMAIL PROTECTED]
 Subject: Email address please?
 To: Sundial Mailing List sundial@uni-koeln.de
 Message-ID: [EMAIL PROTECTED]
 Content-Type: text/plain; charset=ISO-8859-1; format=flowed

 Hi everyone,
 John Moir of BSS has been trying to contact me but
 his last telephone message was cut off  'bing' by my answer-phone
 halfway through his email address.  Can anyone put me in touch with  
 John
 please?

 Thanks in anticipation

 Tony Moss


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 ___
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 sundial@uni-koeln.de
 https://lists.uni-koeln.de/mailman/listinfo/sundial


 End of sundial Digest, Vol 27, Issue 25
 ***

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RE: Shadow Tapering

[John Goodman]

On Feb 10, 2008, at 6:00 AM, Patrick Powers wrote:

 Indeed, if you want a bit of fun, if you have Google Earth and care  
 to type
 in 52 45' 16.28N, 01 08' 12.33 W  then you go directly to the  
 second of
 these dials.

Even if you don't have Google Earth you can go to the http:// 
maps.google.com/ website and type in the coordinates. You'll get to  
the same place as Google Earth takes you, and if you click the  
Satellite button you can zoom in on the image just as you would in  
Google Earth.

I have a browser running whenever I'm at the computer (which is way  
too often) so using Google Maps is much more convenient than  
launching (and waiting for) Google Earth.
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Re: New York Times

[John Goodman]

For anyone who's imagination has been piqued (like mine) by this  
oblique discussion, you don't have to search out the unabridged OED.  
A quick visit to www.dictionary.com will give you the historical  
definition of quaint.'

For anyone who's seen the new film version of Atonement, you can  
even skip clicking on the link. Just answer the question posed by 13- 
year-old Briony Tallis - What's the worst word you can possibly  
imagine?

On Jan 16, 2008, at 6:00 AM, [EMAIL PROTECTED] wrote:

 Message: 1
 Date: Tue, 15 Jan 2008 12:11:22 +
 From: Frank King [EMAIL PROTECTED]
 Subject: Re: New York Times
 To: Willy Leenders [EMAIL PROTECTED]
 Cc: [EMAIL PROTECTED]
 Message-ID: [EMAIL PROTECTED]
 Content-Type: text/plain; charset=iso-8859-1

 Dear Willy,

 Following your suggestion?I was searching in a
 very big dictionary to find out more...

 Alas, your dictionary was not quite big enough!

 The full Oxford English Dictionary will give you
 details of the meaning of quaint as understood
 by Shakespeare and Chaucer.  Interestingly it is
 the FIRST meaning in the dictionary.

 The word dial also has several meanings, including
 (unsurprisingly) face.  Shakespeare often wrote a
 seemingly innocent sentence that could be interpreted
 in a quite different way!

 I will give you a private English lesson in an
 off-list reply.  Expect a second message soon.

 If you don't receive this second message it
 means that your spam filter is clever enough
 to filter out very rude English words!

 Frank

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Re: Hi Def Photo settings?

[John Goodman]

On Jul 15, 2007, at 10:43 AM, Brooke Clarke wrote:

 The photoshop print size is based on 72 DPI which at one time was  
 the common
 printer resolution.  If your DPI setting is not 72 then the actual  
 print size
 photoshop displays will be incorrect.


In the spirit of nit picking, I'll point out that 72 DPI was the  
screen resolution of the original Macintosh computer, which  
popularized bit-mapped graphics. The accompanying printer of that era  
was the ImageWriter, which had a resolution of 144 DPI.

At 72 DPI, a single pixel was a very close approximation of the  
printer's point. More on that point in Wikipedia - http:// 
en.wikipedia.org/wiki/Point_%28typography%29

The default unit of measurement in the PostScript graphical  
programming language is also 1/72 of an inch, for reasons closely  
related to the history mentioned above. 
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Re: NASS Compendium sample issue

[John Goodman]

Thanks for considering a change, Fred. If it's not too much trouble  
for you, it will make it easier for more subscribers.


Best wishes,
John

On Oct 5, 2006, at 11:55 AM, Fred Sawyer wrote:

Yes, perhaps I should have clarified when I said that the  
Compendium download was an executable file - it is a Windows  
executable.


That was a restriction that I believe once was imposed by the  
software at our ISP - but things appear to have changed and a zip  
download would be possible.  It would require a few other changes  
to procedures, but I'll consider it for future issues.


Fred Sawyer


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Re: NASS Compendium sample issue

[John Goodman]

The question isn't whether Mac users will be drawn to join by the  
change, the question is whether PC users will be driven to quit. If  
current subscribers are unaffected, and if it is convenient for Fred  
and the NASS, then what is there to lose?


John

On Oct 6, 2006, at 5:07 PM, Reinhold Kriegler wrote:


Dear Fred,

I have my doubts whether really some MAC users will join. So I  
expect a list of the names of the real new subscribers after this  
Compendium-mode-change in the SML.

My experience is: There is much lip service in the world ...

Saludos!
Reinhold

- Original Message -
From: John Goodman [EMAIL PROTECTED]
To: Fred Sawyer [EMAIL PROTECTED]
Cc: Sundial List sundial@uni-koeln.de
Sent: Friday, October 06, 2006 10:48 PM
Subject: Re: NASS Compendium sample issue

 Thanks for considering a change, Fred. If it's not too much trouble
 for you, it will make it easier for more subscribers.

 Best wishes,
 John

 On Oct 5, 2006, at 11:55 AM, Fred Sawyer wrote:

 Yes, perhaps I should have clarified when I said that the
 Compendium download was an executable file - it is a Windows
 executable.

 That was a restriction that I believe once was imposed by the
 software at our ISP - but things appear to have changed and a zip
 download would be possible.  It would require a few other changes
 to procedures, but I'll consider it for future issues.

 Fred Sawyer

 ---
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Re: NASS Compendium sample issue

[John Goodman]

I'm afraid I'll sound cranky by complaining about a gift, but the  
free sample issue of The Compendium, which I successfully downloaded,  
arrived as a Windows executable. Could I possibly be the only sundial  
enthusiast who uses a Macintosh?


I managed to unpack the files, going through the kinds software  
contortions that Mac users are often forced into, but really, should  
that be necessary? Why is an executable required for delivering the  
articles? A simple zip files would have served both Mac and PC users.  
(Macs can both read and create zip files without any third-party tools.)


I looked into NASS membership and see that there is an economical  
option that offers The Compendium as a download. Does this option  
unintentionally exclude Mac users? There's a wealth of valuable  
information in The Compendium download, but I'd enjoy it more if I  
didn't have to jump through hoops to read it.


Thanks for collecting and distributing your research. My complaints  
are only intended to encourage you to make the work more broadly  
accessible.


Best wishes,

John Goodman
www.annosphere.com


On Oct 4, 2006, at 6:00 AM, [EMAIL PROTECTED] wrote:


Date: Tue, 3 Oct 2006 16:53:26 -0400
From: Fred Sawyer [EMAIL PROTECTED]
Subject: NASS Compendium sample issue
To: Sundial List sundial@uni-koeln.de
Message-ID: [EMAIL PROTECTED]
Content-Type: text/plain; charset=iso-8859-1

NASS is making a recent issue of The Compendium available for  
download by members of this list.  If you are not familiar with The  
Compendium but would like to check it out, now's your chance.   
Follow the instructions below to get a copy of the June 2006 issue.


When you open the introductory file, please note that there is an  
option on the screen that will give you information on membership  
options and how to join.  Of course, you can also always go to our  
website at http://sundials.org .  Regardless of the method you  
select, we would be happy to welcome you as a member (whether you  
live in North America or not!)


Fred Sawyer
-- 
--
The June 2006 issue of The Compendium is available for download  
(5.1 MB) from the NASS website.  Point your browser to:


http://sundials.org/compendium/comp132  (If this link produces an  
error, please try typing the URL directly into your browser.)


You will be asked to provide a username and password to access the  
page.  Please use the following:


username: comp132
password: 15a476a7   (both username and password are case sensitive)

Once you have accessed this page, you can download the installation  
file (5.1 MB) by clicking on the button at the bottom of the page.   
When you have downloaded the file to your hard drive, execute it -  
and it will extract all the files needed for this issue of The  
Compendium.  During the extraction process you will have the  
opportunity to specify the folder you want the issue to go into.


Contents of this issue - Volume 13 Number 2, June 2006

Sundials for Starters: A Matter Of Longitude - Robert Kellogg
The Grand French Tradition In Gnomonics - André E. Bouchard
Quiz: Finding True North - Rolf Wieland
Ameyalli Xiuhcóatl: The Sun In The Snake - Reinhold R. Kriegler
Digital Bonus: Ozanam's Problems et al. - Ozanam, Bailey,  
Bercovitz, King  Moss

Peaucellier Sundials - Fred Sawyer
The Analemmic Equatorial Sundial - René J. Vinck
The Quadruplex Sundial Of Tinos - Theodossiou, Mantarakis  Manimanis
Quiz Answer: A Vertical Dial's Declination - Gianni Ferrari
The Tove's Nest



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Re: Delta Cad workshop

[John Goodman]

Willy Leenders wrote:


Delta Cad is only applicable for Windows. Is there a good alternative
for Macintosh?

Willy LEENDERS
Hasselt Flanders (Belgium)


I can't vouch for any of these products, but you can find  
descriptions of 34 different Mac 2D CAD packages at http://www.pure- 
mac.com/cad.html  Info on 3D products is here - http://www.pure- 
mac.com/3d.html


Also, for what it's worth, Google's free SketchUp software is  
available for the Mac too. ( http://sketchup.google.com/download.html )

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