Re: DMARC Wrapping.

[David Patte]

Is it really necessary to throw in your political right wing spin when 
answering a simple question?



On 2018-09-10 23:31, Roger wrote:
Perhaps it is the nanny state insisting on things that restrict 
freedom  “for your protection”. 


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Re: Watches that display EoT

[David Patte ₯]

The unfortunate thing is that many that can actually afford to buy it 
likely won't have a clue what it represents.



On 2017-03-19 19:01, Dan-George Uza wrote:

Hello,

Here's an interesting wristwatch from this year that shows the 
Equation of Time in a clever way. "Sex on a wrist!" - to quote a comment.


https://www.hodinkee.com/articles/vacheron-constantin-les-cabinotiers-celestia-astronomical-grand-complication-introducing

Of course there are many more in this category, all rather untouchable 
because of the price. But could there be one for us mortals? Made in 
China, perhaps? I suppose smartwatch faces already exist for this. But 
would it be difficult to design a mechanical EoT timepiece?


Dan Uza


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Re: An interesting piece of timekeeping

[David Patte ₯]

True, but if I can get 125 sponsors of $400 each I can write you a 
smartphone app that has all the same features, looks similiar, and is 10 
times more accurate - and it will adjust to your local timezone and 
labelling in 10 languages to boot :)




 2017-01-16 21:42, J. Tallman wrote:

It is not a sundial, but interesting nonetheless:

http://www.ablogtowatch.com/vacheron-constantin-les-cabinotiers-celestia-astronomical-grand-complication-3600-watch/

It is quite a feast for the eyes, and the mind...and if you have a 
spare million lying around, it could be yours!



Best,

Jim Tallman
Artisan Industrials

www.artisanindustrials.com 

www.spectrasundial.com 


jtall...@artisanindustrials.com
513-253-5497


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Re: Happy Nowruz!

[David Patte ₯]

They returned to one of the other British North American colonies, Nova 
Scotia.
Yes - there where more than 13 British colonies in North America in the 
1770s.  :)



On 2016-03-17 22:38, kool...@dickkoolish.com wrote:

In Boston MA USA, today was Evacuation Day, which
celebrates the evacuation of British troops from
Boston during the Revolutionary War. :-)

https://en.wikipedia.org/wiki/Evacuation_Day_%28Massachusetts%29


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Sundial Art

[David Patte ₯]

http://hyperallergic.com/260217/olafur-eliassons-sundial-of-melting-icebergs-clocks-in-at-half-past-wasteful/
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Re: due east

[David Patte ₯]

They are east-west lines, but they are not straight. They are circles.



On 2015-09-15 12:30, Brent wrote:
If I was in halifax at sunrise on the equinox and the earth stopped 
rotating and I walked due east (towards the sun) across the ocean
I would end up in Southern Spain and not on my same latitude which is 
in Southern France.


So I conclude that latitude lines are not east-west lines.

Correct?

thanks;
brent



On 9/15/2015 9:01 AM, Frank Evans wrote:

Hi Brent and all,
Compass directions that are pursued make spiral curves towards the 
poles, if north of east-west then towards the north pole, if south of 
east-west then towards the south pole. If east or west then they do 
neither but continue east-west. Try Googling "loxodromic curve". It's 
what you draw on a chart. Sailors call it a "rhumb line".

Frank 55N 1W

On 15/09/2015 15:10, Brent wrote:

I'm confused maybe.

I live in the northern hemishpere and anticipating the equinox on 
the 23rd.


Supposedly the sun will rise due east.

So if due east is a right angle from north south and I traveled due 
east I would not follow my line of latitude.
I would get further and further south of my latitude the further I 
traveled.


So either the lines of latitude are not east west lines or due east 
is not a straight line but curved.

I suspect lines of latitude are not east west lines?
They would work fine if the earth was not tilted, but it is.

Wouldn't it make sense to coordinate the globe so lines of latitude 
(or call them something else) are straight and a right angle

from north south?

brent




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Re: App for iPad

[David Patte ₯]

We are in the midst of developing a sundial app for iOS and Andriod. We 
don't have a timeframe for release yet, though.


The app, as designed, will also work on Windows, and OSX (Mac).

We are interested in receiving feature requests, so if there are things 
you would like to see in a sundiial app - please feel free to contact us 
directly, off this list.


David





On 2015-01-13 12:13, Richard Mallett wrote:

On 13/01/2015 16:36, Larry McDavid wrote:
Tony's report of this phone app for the iPad has made me wonder if 
any of us uses an Android app for a smart cell phone that provides 
a similar orrery function.


I just got a new Galaxy S5 smart cell phone with a large oled 
display. Can anyone recommend an Adroid app helpful with sundialing?


Larry
NASS


There are plenty of GPS apps that will tell you where you are. Not 
sure what else you need in a small device.






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Re: Friday 13 and Friday 13

[David Patte ₯]

Merry 358 and Happy 1, or is it Merry 357 and Happy 0 :)


On 2015-01-06 18:07, John Pickard wrote:
If nothing else, the replies show that dates are rather tricky things 
with some interesting mathematics behind them. Wouldn't it be simpler 
to move to decimal time and a decimal calendar? (NOT a serious question!) 



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Re: Friday 13 and Friday 13

[David Patte ₯]

Two sequential Friday 13ths can only happen on Feb  March, and only in 
non-leap years. So, i would guess it happens 3/28 years, or about 11% of 
the time.



On 2015-01-05 16:35, John Pickard wrote:

Good morning all, and a happy 2015 to everyone.

Looking at my diary this morning, I noticed that 2015 is a bit unusual 
in having Friday 13 in consecutive months: February and March.


Does anyone know how often this occurs, when was the last time, and 
when is the next time it will happen?


(And no, I don't place any particular significance in the day!)


Cheers, John

John Pickard
john.pick...@bigpond.com

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Re: Polaris

[David Patte ₯]

To get your mean coordinates of a particular equinox into apparent 
coordinates for a particular date, you will have to make a few 
calculations


1) apply proper motion of polaris until the new date
2) precess the result to the new date
3) convert to ecliptic cordinates using the mean obliquity of the new date
4) apply nutation to the ecliptic longitude
5) apply annual aberration to the true ecliptic coordinate
5a) apply diurnal aberration and parallax (these two are generally ignored)
6) if rqd, convert back to equatorial by using the true obliquity of the 
new date


Also, don't forget to use the apparent lst if converting to Declination 
and HrAngle


Finally, apply refraction to the altitude if you want it in alt-azi form

Many star chart programmes miss a few of these steps, but I would check 
out some of them and see if they provide the numbers you are looking for.




On 2014-11-28 23:52, James E. Morrison wrote:
I am working on two modest projects, both of which require accurate 
coordinates (RA and declination) of Polaris several hundred years ago. 
 I have been using a spreadsheet of my own doing to calculate 
precessed stellar coordinates using the formulae in Meeus, but I'm not 
very confident in the results as I have only one sample giving 
confirmed values.  I am hoping someone in the sundial brain trust can 
direct me to an available trusted source of Polaris coordinates for 
years in the past.  A few accurate values that I can try to replicate 
would also be useful.


Best regards,

Jim
James E. Morrison
janus.astrol...@verizon.net mailto:janus.astrol...@verizon.net
Astrolabe web site at http://astrolabes.org


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Re: CORRECTIONS Extensions to A few new Tables for the Gnomonist...

[David Patte ₯]

I also write astronomical algorithms and astronomical software. And I 
also use Meeus for my inspiration.


Meeus, though an astronomer, also recommends measuring from South, but I 
have decided over several astronomical products to continue measuring 
from North, which more laymen are familiar with.



products to ,On 2014-06-12 13:12, Kevin Karney wrote:

Dear Friends

Thanks for the positive comments!
And thanks to Gianni Ferrari, Patrick Powers, Edward French and Jack 
Aubert for pointing out the MAJOR error in the Annual Equation of Time 
Table.
It was giving EoT values /across/ the table instead of /down/, which 
is an error I had corrected before - but had crept back in!

That has been corrected Many apologies

Also, by popular request,  I have changed the sign of EoT from the 
strict astronomical convention to the more usual gnomonical convention 
(the correction to get from sundial to local mean time).


Gianni also wants Azimuth measured from the South... I am a 0 deg at 
North person. Any thoughts ? I will probably change things to give a 
radio button, so you can choose.


I have had requests for a solar noon table and solar east/west table 
and a half-minute Victorian table - which I shall implement in due course


Best wishes
Kevin


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Re: Planetarium app

[David Patte ₯]

As mentioned on the list, there are several planetarium apps available 
already, for various OSs.


But If you would like to write something custom, I am available as a 
programmer consultant. I wrote the first planetarium programme for 
Windows called 'MyStars!' which peaked in popularity around 2001.


Writing an accurate planetarium programme requires numerous formulas, 
including those to do precession, nutation, and refraction calculations. 
If you want planets and moons as well, you also have to add formulas to 
calculate orbital positions then project these onto the celestial sphere.


Most planetarium programs use the 'Bright Star Catalog'. Scientific data 
is generally free, as well as the formulas, if you know what you are 
looking for.


David Patte

P.S. I have also writen Sundial Simulators, by the way.

On 2014-05-22 3:56, Astrovisuals wrote:
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 http://www.astrovisuals.com.au


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Re: Windows upgrade and older sundial programs

[David Patte ₯]

32 bit apps in general should run fine on 64bit, but they may still have 
16 bit installers. In this case you may have to install them on 64 bit 
machines using 'compatibility mode'.


On 2013-12-14 11:14, J. Tallman wrote:

Hello All,

A previous thread discussed the issues with some of the older sundial
programs on 64 bit Windows computers, but does anyone know for sure whether
Dialist Companion will run on Windows 7 32 bit version?

I need to upgrade some of the older computers on my network since Windows XP
will soon no longer be supported by Microsoft. I can get Windows 7 in 32 bit
form but would rather know if it can run DC before buying it. The other
alternative would be to just remove one of the XP computers from the network
altogether and keep it as a stand-alone legacy computer for running some of
the older sundial programs.

If anyone knows for sure, please advise. After years of using DC to
calculate remote declinations, I just like the program and want to maintain
access to it one way or the other.


Best,

Jim Tallman
www.spectrasundial.com
www.artisanindustrials.com
jtall...@artisanindustrials.com
513-253-5497


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Re: temporal hour including refraction

[David Patte ₯]

Refraction affects apparent altitude at a particular time. The apparent 
azimuth at a particular time does not change.


But the time of sunrise/sunset is changed due to refraction, so 
therefore there is a different solar azimuth at this adjusted time.


On 2013-11-13 11:28, Frank King wrote:

Dear David,

You say, in the context of calculating solar
azimuth that...


Refraction has no effect on azimuth...

Hmmm.  This is absolutely true but, alas, the
truth may well throw a beginner.

Imagine calculating the azimuth of sunrise
and going out with a friend one morning
before dawn and pointing confidently
where the sun will rise.

Unless your calculation takes account of
refraction you will have the time of
sunrise wrong and hence the azimuth.

Refraction means that the sun appears
to rise before naive calculation says
it will and, hence, its azimuth will
be displaced.

One of the great things about sundials
is that even the simplest problem gets
tougher once you look at it carefully!

Frank King
Cambridge, U.K.





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Re: 08:09:10 11/12/13

[David Patte ₯]

In Canada, I am waiting for 13-12-11 10:09 = 2013, December 11th at 
10:09 in the morning.




On 2013-11-12 13:43, Willy Leenders wrote:

You can also come to Europe, Bill.
In my country, 11/12/13 is the eleventh day of December 2013

Willy Leenders
Hasselt in Flanders (Belgium)

Visit my website about the sundials in the province of Limburg 
(Flanders) with a section 'worth knowing about sundials' (mostly in 
Dutch): http://www.wijzerweb.be








Op 12-nov-2013, om 19:18 heeft Bill Gottesman het volgende geschreven:

Did anyone catch this auspicious moment, 08:09:10 11/12/13?  I missed 
it, but will go for another try this PM.


-Bill
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Odd emails

[David Patte ₯]

Just a note of caution to say that someone is sending emails on and off 
this list claiming to be me, or claiming to work for my software/website 
development company.


The emails seem to be related to a posting from last April referring to 
'human sundials' originally posted by a 'Reena Gagneja'


If you recently received an odd email that seems to be from me, it may 
not have been from me, but from someone masquerading as me.


Sorry for any confusion



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Re: sunrise/set/twilight calculators ? TZM

[David Patte ₯]

A good chance for me to plug my Free Windows App (Time Zone Master) from 
relativedata.com, which gives


Sunrise6:54 CLT
Transit12:42:06 CLT
Sunset 18:29 CLT

Moonrise5:05 CLT
Transit11:59:33 CLT
Moonset 17:57 CLT

Also has local mean and apparent time, phase times and season times for 
multiple desktop clocks at once, with timezone corrections back to the 
beginning of standard time

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Re: Today's Google Banner - More

[David Patte ₯]

I just checked using Time Zone Master
The sign of the equation of time indeed did change on April 15, 1707 - 
at very close to 21:00 UT


On 2013-04-15 5:03, Frank King wrote:

Dear John,

Tee hee...


The EoT might change sign on Euler's
306th birthday but I very much doubt
(without checking!) that the changeover
was the same on the date of his birth!

I did wonder about that and hoped no one
would query it!!!

According to the NOAA Solar Calculator,
the changeover on 15 April 1707 was
about 19h GMT.

He was born in Basel and I think they
went over to the Gregorian Calendar
in 1700/01.  We were still Julian of
course.

Of course Basel is about half an hour
ahead of Greenwich but this wouldn't
shift the changeover date.

I very much look forward to being
corrected on several fronts by all
the experts on this list!

Frank

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Re: Is East/West always at exact 'right-angles', to North/South?

[David Patte ₯]

Yes, at the point of intersection they are, but don't forget though that 
lat and long are great circles, not straight lines.


Of course, there is no east or west at the poles.

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Re: Is East/West always at exact 'right-angles', to North/South?

[David Patte ₯]

True - correction accepted, except at the equator :)

I wonder if the poles have infinitely small latitude 'circles' ;)



On 2013-04-10 22:02, kool...@dickkoolish.com wrote:

While longitude lines are great circles, latitude
lines are small circles.



David Patte wrote:
Yes, at the point of intersection they are, but don't forget though that
lat and long are great circles, not straight lines.

Of course, there is no east or west at the poles.

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Re: Is East/West always at exact 'right-angles', to North/South?

[David Patte ₯]

Yes the distance around the equator is larger than twice the distance 
from pole to pole. The flattening of the earth (oblateness) is minor 
though. I can find the exact number if you are interested. I write 
astronomy software that has to take this into effect.


actually - latitude (contrary to popular misconception) is not measured 
as an angle from the centre of the earth, but from the angle from the 
celestial equator. This makes a difference because the earth is 
flattened as mentioned above.


An interesing side effect is that the latitudes are not equally spaced 
on the globe, as one might expect from geometry. The distance of 5 
degrees latitude depends on the latitude. I forget offhand if latitude 
circles are closer together at the poles or the equator.


I have heard that the high tide is in fact because the earth is being 
pulled away from the water on the other side of the earth - a slight 
difference which explains why high tides are on opposite sides of the 
earth at the same time.


On 2013-04-10 23:23, R Wall ml wrote:
And at the Equator, would the Longitude circle be the biggest circle 
of them all, because there is a bulge at the Equator. A bulge because 
the mass is forced out due the the Earth spinning? Anyone know the 
answer, I don't?


I believe the moon also warps the Longitude circles because that is 
why there is a high tide in two places on the Earth at the same time. 
The moon's gravity pulls the Earth mass and that also makes a high 
tide on the opposite side of the Earth away from the moon. The high 
tide on the moon side of the Earth is caused by the moon's gravity 
pull on the water.


Looks to me that the Latitude/Longitude circles are all warping and 
changing?


Do I have this correct?

Roderick Wall.



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Re: Calculating azimuth of sunrise and sunset from present back 25, 000 years

[David Patte ₯]

If I'm not mistaken:

25,000 x 6 mm = 150,000 mm = 150m, not 1500m

Did you mean cm?


On 2012-06-25 0:11, Roger Bailey wrote:
At this time I am moving 6 mm per year towards the east, as determined 
by precise GPS and laser surveys. Over 25,000 years this movement is a 
mile, 1.5 km and a lot of earthquakes. 



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Re: Couldn't view the transit of Venus with Rainbow Symphony Inc's Eclipse Shades.

[David Patte ₯]

I clearly saw venus with my eclipse shades, but I wore them over my eye 
glasses.


On 2012-06-11 16:09, RW Mail List wrote:

Hi all,

I have two Eclipse Shades that I tried to use to view the transit of 
Venus on the 6th June 2012 (Australia). I could see the sun but I 
couldn’t see Venus. For some reason they didn’t work, was it because 
the filter are designed for Eclipses and are not designed to view the 
transit of Venus? I was able to view Venus in front of the Sun with my 
telescope projecting an image onto a white cardboard. So Venus was 
there but I couldn’t see Venus with the Eclipse Shades.


Did anyone else have this problem?

I sent an email to Rainbow Symphony Inc, the following was their reply 
(including spelling mistake). They didn’t say I should have been able 
to have viewed the transit of Venus with their Eclipse Shades. If you 
can’t see Venus then what hope have you got of seeing sun spots. They 
say “Quality Paper Eyewear and Specialty Optics”.


Roderick Wall.

Hi Roderick, Venus is very, very small transiting the sun. I was hard 
to see naked eye. Better with a telescope or binoculars with the 
proper filters.


Mark


Rainbow Symphony, Inc.

6860 Canby Ave. #120

Reseda, CA 91335
http://www.rainbowsymphony.com BLOCKED::http://www.rainbowsymphony.com/
Ph# 818-708-8400
Fax# 818-708-8470
Quality Paper Eyewear and Specialty Optics

No virus found in this message.
Checked by AVG - www.avg.com http://www.avg.com
Version: 2012.0.1913 / Virus Database: 2433/5062 - Release Date: 06/11/12



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Re: sundial on the moon

[David Patte]

From a point on the moon, the suns motion is probably not smooth enough to 
build a usable sundial to measure a lunar day (which is close to a terrestrial 
month). 
And using 'earth light' on a lunar based dial would probably not be very 
effective either, since the earth's position in the lunar sky, except for minor 
variations, is mostly constant from any position on the moon. 
Sent from my BlackBerry. 

-Original Message-
From: Mac Oglesby ogle...@sover.net
Sender: sundial-boun...@uni-koeln.de
Date: Mon, 21 May 2012 10:36:20 
To: clar...@aol.com
Cc: Sundial Mailing Listsundial@uni-koeln.de
Subject: Re: sundial on the moon


Hello Ken,

Since I don't have the skills myself, I'm hoping 
someone on this list will accept your challenge 
to design a sundial for Armstrong's landing site, 
and share the design with us.

Best wishes,

Mac Oglesby




Hi everyone,

  I finally got to meet Homer Hickam the 
author of Rocket Boys at the Science and 
Engineering Festival in Washington DC.  I 
designed a sundial based on the book (file 
attached) in 2004 while doing educational 
sundial displays telling people about the two 
sundials that NASA put on the Mars rovers.
  I am now reading his new book Crater which 
is about people living on the moon in the 
future.  He talks about the long shadow, periods 
of darkness, when the sun is not up.  What would 
a horizontal sundial look like on the moon at 
the Neil Armstrong landing site?  What kind of 
time system would be used on the moon?
  I am just looking for some ideas to suggest 
to him to include a sundial in his next book. 
Thanks in advanced.
Ken Clark 
Elizabethtown, PA

Attachment converted: Macintosh HD:onebkpic (2).jpg (/«IC») (003222A2)
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Re: Eratosthenes (Robert Kellogg)

[David Patte]

Refraction?

On 2012-03-19 23:47, Tom Laidlaw wrote:

Hello the list,
So them vernal/autumnal equinox is just about an hour away. I was 
looking at several epemerides expedting that at solar noon tomorrow 
the altitude of the sun would equal my latitude (45.6N), but it seems 
to be about a degree low. What am I missing?

Tom Laidlaw


*From:* sundial-boun...@uni-koeln.de 
[mailto:sundial-boun...@uni-koeln.de] *On Behalf Of *Robert Kellogg

*Sent:* Monday, March 19, 2012 7:48 PM
*To:* sundial@uni-koeln.de
*Subject:* RE: Eratosthenes (Robert Kellogg)



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Re: Eratosthenes [SEC=UNCLASSIFIED]

[David Patte]

I believe the original definition of a kilometer was based on 1/1 of 
the distance from a pole to the equator.


metre was On 2012-03-18 21:52, Hank de Wit wrote:

Hello Axel,
I think you have made a mistake with the number 40231.264 (miles?).
If you take the formula for size of a latitude degree, as you stated:
dx/d theta = 111.133+0.559*cos(2*theta)   km per degree latitude
if we integrate this formula with respect to theta from 0 to 360
X = 111.133 * ( 360 - 0) + 2*0.559 * (sin(2 * 360) - sin (2 * 0))
the two terms with sin equate to 0, so
X = 360 * 111.133
  = 40007.88 km
Cheers
Hank


*From:* sundial-boun...@uni-koeln.de
[mailto:sundial-boun...@uni-koeln.de] *On Behalf Of *axel törnvall
gonzalez
*Sent:* Monday, 19 March 2012 11:42
*To:* Sundials
*Subject:* Eratosthenes

I am studying a subject related to the Greek Eratosthenes, as
measured by the circumference of the earth, but I have a problem
with measuring the distance between 2 points (coordinates)
formulas I used were taken from writings of Carl Sabanski, who
says that books are ancient astronomy. No further information;
1 ° latitude = 111,133 to 0,559 cos (2 x latitude) [km]
1 ° longitude = 111,413 cosine (latitude) - 0.094 cos (3 x
latitude) [km]
By calculation using the formula 1 ° latitude, for each grade,
from 0 ° to 90 ° for the southern hemisphere and 1 ° to 90 ° for
the northern hemisphere the result is 40,231.264 miles, and as I
read the value is 40,009.15 km

I have not found more formulas or ways of doing the calculation to
get a better result.

I will thank answers

Best Regards

Axel



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Re: solar time calculator

[David Patte]

Not sure what you did wrong, but you can download Time Zone Master for 
free from www.relativedata.com which shows sundial time for any 
location, and corrects for EoT, light refraction, aberration, nutation 
and precession, as well as any of about 100 different timezone rules.



On 2011-10-13 23:10, Donald Christensen wrote:


Not sure what I'm doing wrong

I wrote a program so that I can set my watch to solar time.

Something is wrong. Either my program is wrong or my sundial is 
inaccurate.


To use the program

Set your computer accurately to clock time

Run the macro 'recalc'. This will make the clock on your computer 
display on the spreadsheet in real time. This will also input today's 
date. This date will lookup the EOT and either add or subtract the time


Set your watch to solar time

The purple cell is for troubleshooting. 1 = add the eot values 
(positive or negative). -1 will subtract these values. Once I figure 
out which one to use, it will be true for all days. At the moment, 
neither work


My objective is to make a solar compass that will work for my area only

I'll simply rotate the sundial that I designed with longitude 
correction until it agrees with my watch that I set to solar time.


I understand that the EOT has accuracy problems. However, I thought it 
was accurate enough for what I want it for. I'd like your feedback on 
that. I'd also like your feedback on whether or not my goal is 
realistic in spite of the accumulation of small errors such as eot, 
sundial accuracy, gnomon placement and gnomon perpendicular to the dial




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Cheers
Donald
0423 102 090


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intended recipient please delete the message and notify the sender. 
Un-authorized use of this email is subject to penalty of law.

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Re: R: Where it wil be equinox, at noon

[David Patte]

Just for clarity:

http://aa.usno.navy.mil/data/docs/EarthSeasons.php shows the following 
UT values:


20112011
Perihelion  Jan   3 19Equinoxes  Mar   20 23 21Sept  23 09 05
AphelionJuly  4 15Solstices  June  21 17 16Dec   22 05 30

ie: 9:05 UT

from there you need either the RTA of the sun at that time, or you can 
extrapolate it using the sidereal time.


--
We don't serve your type in our bar!, exclaimed the Bartender.
A faster-than-light Neutrino enters a bar.

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Re: Fwd: Where it wil be equinox, at noon

[David Patte]

Also using Time Zone Master
1) Clicking any clock and going to the equinox page, you then click on 
the equinox (5:05 EDT for my case - Ottawa)

2) Then go to the sidereal page it shows 9:12:28 GST (sidereal time)
3) The time difference to noon is 2h 57m 31s
Multiply x 15 - you get 44d 22m 45s E
It shows a delta-T of 67 seconds


On 2011-09-22 23:59, James E. Morrison wrote:
My logic for answering the question of where on Earth will it be 
apparent noon at the instant of the autumnal equinox is:
1.  The Greenwich sidereal time at the time of the equinox (Julian day 
2455827.87793) is 09:10:36.1
2. We want the longitude where the local sidereal time = 12:00:00 at 
this instant.

3. The sidereal time difference is 02:49:24.
4. Times 15 for degrees = 42d 20m 59s E.
This corresponds to a meridian passing through Georgia, east Turkey 
and bit west of Baghdad.
I used The Electric Astrolabe with a Delta-T of 66 sec to get the GST 
value.  Other programs may improve on the result.

Best regards,
Jim
James E. Morrison
janus.astrol...@verizon.net mailto:janus.astrol...@verizon.net
Astrolabe web site at http://astrolabes.org
From: axel törnvall gonzalez
Date: Sep 22, 2011 8:58:05 PM
Subject: Where it wil be equinox, at noon
To: sundial@uni-koeln.de
This is my Subject;
Finding the position, Longitud, where, the sprig equinox, will ocurr 
at noon, I found some diference between the results of The Dialist´s 
Companion, and Sun v.5.6 Of R.Cernic, both programs I work for some 
time.


 In Longitud  42°12,80 E at 13:03:42  PM it will be Noon, for my studies
Then I placed both programs in Latitud and longitud 0°, and in Sun 
v5.6 of R.Cernic I got UT 09:03:59 AM and in The Dialist´s Companion, 
I found the nearest cero declination at 08:44:47AM the altitude 
measure have a difference of almost 5°, I Know The Dialist Companion I 
Use vers 1.1.b is old.

Sorry my english, it´s not my first language
Best regards for all of you
Axel
32°39'59S
70°42'41W




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Re: Fwd: Where it wil be equinox, at noon

[David Patte]

Don't you hate it when you publish numbers with errors
I manually subtracted from noon incorrectly

3) The time difference to noon is actually 2h 47m 31s
Multiply by 15 gives 41d 52m 45s E

Open a new clock and enter the longitude, and equator
The result is near a town called Chisimayu in Somalia, near the Kenya 
border, where the sun will be overhead at solar noon, at the equinox



On 2011-09-23 2:12, David Patte wrote:

Also using Time Zone Master
1) Clicking any clock and going to the equinox page, you then click on 
the equinox (5:05 EDT for my case - Ottawa)

2) Then go to the sidereal page it shows 9:12:28 GST (sidereal time)
3) The time difference to noon is 2h 57m 31s
Multiply x 15 - you get 44d 22m 45s E
It shows a delta-T of 67 seconds


On 2011-09-22 23:59, James E. Morrison wrote:
My logic for answering the question of where on Earth will it be 
apparent noon at the instant of the autumnal equinox is:
1.  The Greenwich sidereal time at the time of the equinox (Julian 
day 2455827.87793) is 09:10:36.1
2. We want the longitude where the local sidereal time = 12:00:00 at 
this instant.

3. The sidereal time difference is 02:49:24.
4. Times 15 for degrees = 42d 20m 59s E.
This corresponds to a meridian passing through Georgia, east Turkey 
and bit west of Baghdad.
I used The Electric Astrolabe with a Delta-T of 66 sec to get the GST 
value.  Other programs may improve on the result.

Best regards,
Jim



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Re: Where it wil be equinox, at noon

[David Patte]

Looking at our free windows programme - time zone master - it indicates 
the autumn starts at 5:05 EDT
adding other clocks - Nairobi (and that whole timezone) turns out to 
have the equinox at 12:05 EAT - (pretty close to noon)


its available from www.relativedata.com
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Re: The Sun's Azimuth

[David Patte]

I recently heard someone say The weather has been very odd recently, 
and i certainly can't believe all this scientific bunk about global 
climate change, but i have heard that the sun's azimuth is wrong, and if 
thats the case it sounds pretty serious.


It amazing how a few people would rather believe that somehow the whole 
world has tipped over, or stopped rotating (presumably on its own ), 
than to believe that a half billion internal cumbustion engines running 
every day might change the temperature of the atmosphere a few degrees 
per century.


To Spencer, for the record, many on this list watch their sundials 
daily, and many on this list are astronomers, or experts in celestial 
dynamics. I have not heard anyone with a solid understanding of the 
earths azimuth, in this or any other scientificly-based list, suggest 
the azimuth of the sun has been unexpectedly offset.


But a lot of very good and qualified scientists have been reporting that 
there is a very serious issue that is potential catastophic to mankind 
and life as we know it on earth. If you are interested in why the sun 
seems hotter, etc., you may want to listen to these atmospheric experts 
instead.




On 2011-09-17 12:49, Spencer Duane wrote:
Has anyone noticed any differences in the sun's azimuth lately? I have 
found some pretty compelling information regarding the azimuth not 
being where it is historically expected to be...

What have you guys found?

'If you're going through hell, keep going.'
 - Winston Churchill

Spencer D. Miles
CB: 7; SURVEYOR


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Re: sun position

[David Patte]

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: sun position

[David Patte]

The suns position is specified as altitude and azimuth from the 
observers position.


This can be computed from the Declination and Right Ascension of the sun 
if you know the current local sidereal time and the latitude.


Then you have to adjust the altitude to compensate for the refraction of 
light through the atmosphere.





On 2011-08-23 22:29, Donald Christensen wrote:

I need to write a spreadsheet to find the sun position. I know there are
already many programs that do this. However, I need to write one myself
because:

1. I'll learn as I write
2. It will give the sun position in the format that I need
3. I can tweak the spreadsheet to give the same answer but in another
format.

My question is, where do I start?

I want to input

Latitude
Longitude
Time

The sun position will then be in X Y Z coordinates.

I'll back up. I'm drawing a sundial in Autodesk Inventor. I can place
lights that represent the sun. I can move the lights while I film my
animation and watch the shadows move.

That's why I need the sun position in XYZ format. I want the shadows
accurate. I don't need the sun to be 150,000,000 km away from my
sundial. It only needs to be 100 meters away

I want to first write it to output azmith and altitude. (or the same as
other programs whatever the output is) I'll then tweak my spreadsheet to
convert this to XYZ



--
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-authorized
use of this email is subject to penalty of law.
So there!


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Re: special events

[David Patte]

not sure if it has a name, but they sure don't get much of a shadow at 
noon on that day :)



On 2011-07-26 23:26, Brent wrote:

Hello again;

The equinoxes and solstices are special solar events for all of us.

The people who live in the tropics have another special event, when 
the sun is directly over their latitude.


Does this special day have a name?

Does anyone take notice of it or mark it on dials or have a celebration?

thanks again;
brent

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Re: off topic questions

[David Patte]

The moon is the right size and distance for a perfect eclipse. This is 
true, and also a coincidence. Current theory says that the moon and 
earth split from each other eons ago, so we just happen to be living at 
the right time.


Now, something else very odd about the moon, which most of us take for 
granted, without thinking much about it, is that it always shows the 
same face to us. This means that it rotates on its own axis in the same 
amount of time as it takes to rotate around the earth - 1 month. On the 
moon , a day IS a month. Stranger still, if you where on the moon, 
looking back at the earth, the earth would always be (pretty much) in 
the same position in the sky all the time, never rising and never 
setting - just always sitting there.  If you plan to buy land on the 
moon take that into consideration first :)


But the rotation of the moon being tied to its rotation around the earth 
is NOT a coincidence. It is caused by 'tidal forces'. The same process 
that causes the tides has caused the moon to slow down its rotation to 
synchronize with its rotation around the earth - all caused by gravity.


And why are the tides better some places then elsewhere. Its mostly to 
do with the physical geography and shape of the land below the water. If 
there are any geologists on the list, Im sure they can explain things 
better than I can. But from what i remember every container as a 
'resonant frequency'. A small bottle has a high frequency, if you blow 
across the top like wwe all did as a kid. A larger bottle has a lower 
frequency, etc. The largest tides in the world are in the Bay of Fundy, 
Canada. It turns out that the resonant frequency of that bay is just 
about 2 cycles per day - very low, but the same frequency as the tides. 
The bay of fundy tends to suck its tides in and toss its tides out just 
because of its shape!



David Patte
RelativeData.com


On 2011-07-03 20:55, Brent wrote:

Hello again;

I ask because there are a lot of very smart people on this list.

It seems odd to me that the moon just happens to be the right size and 
the right distance between the earth and the sun to do the perfect 
eclipse. Is this just coincidence or is there some good reason for that?


Also, they say the moon is responsible for our tides and our waves. 
Why are the waves so much bigger in California and New Zealand than in 
Thailand or the Philippines?

Their surf is pathetic.

thanks;
brent

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