solar magic

2009-09-23 Thread sasch stephens 

Yoda is so en(light)ened. May the force be with you!   sasch stephens
  
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RE: Equinox and Equatorial Rings

2009-09-23 Thread John Carmichael 


I agree.  I have a polar dial with an equinox line and I see this every
equinox. It's not that subtle.  You can see it easily over just a few hours.


-Original Message-
From: sundial-boun...@uni-koeln.de [mailto:sundial-boun...@uni-koeln.de] On
Behalf Of Frank King
Sent: Wednesday, September 23, 2009 1:39 PM
To: Roger Bailey
Cc: sundial@uni-koeln.de
Subject: Re: Equinox and Equatorial Rings

Dear Roger,

It is good of you to remind us of the bronze
ring set in the Square Hall of Alexandria.

You add...

> You can repeat this experiment on any
> correctly aligned equatorial sundial
> or armillary sphere.

You can in fact undertake the essentials
of the experiment using ANY sundial equipped
with a nodus and an equinoctial line.

When I was setting up the Pembroke Sundial
in 1997, I spent a lot of time tracing the
path of the shadow of the nodus across the
dial and comparing the observed results
with my calculations.

For each day's observations I assumed the
declination at noon held good all day.
Observed results and calculated results
matched pretty well during June and July
and I became complacent.

At the autumnal solstice, observed results
and calculated results didn't agree so well.
I was puzzled by this at first.  Then I
appreciated the obvious.  The declination
is changing so rapidly at the equinoxes
(about 1 minute an hour) that you can
no longer assume the declination at noon
holds good all day.

Contrary to what simple sundial guides tell
you, the shadow of a point cast onto a plane
DOESN'T follow a straight line on the day of
an equinox.  It actually follows an S shape,
albeit a very narrow S.

Have a good winter.

Frank

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Re: exact time of 2009 Autumn equinox

2009-09-23 Thread Roger Bailey 
I am wrong. I quoted the time listed in the RASC Observers Guide wrong. They 
list 21:19 UT. Close enough for sundials.

Regards, Roger


From: Jos Kint 
Sent: Wednesday, September 23, 2009 11:29 AM
To: sundial@uni-koeln.de 
Subject: exact time of 2009 Autumn equinox


Hello Roger Bailey,

According to the United States Naval Observatory ( 
http://aa.usno.navy.mil/data/docs/EarthSeasons.php) the 2009 equinox falls on 
sept 22 at 21:18:00 UT. This is 61 minutes different from your value. Who is 
right?


Jos Kint
Eeuwfeestlaan 38
9840 De Pinte
Tel: 09.282.57.61
GSM: 0477.966.760
Email: jos.k...@skynet.be




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Re: Equinox and Equatorial Rings

2009-09-23 Thread Frank King 
Dear Roger,

It is good of you to remind us of the bronze
ring set in the Square Hall of Alexandria.

You add...

> You can repeat this experiment on any
> correctly aligned equatorial sundial
> or armillary sphere.

You can in fact undertake the essentials
of the experiment using ANY sundial equipped
with a nodus and an equinoctial line.

When I was setting up the Pembroke Sundial
in 1997, I spent a lot of time tracing the
path of the shadow of the nodus across the
dial and comparing the observed results
with my calculations.

For each day's observations I assumed the
declination at noon held good all day.
Observed results and calculated results
matched pretty well during June and July
and I became complacent.

At the autumnal solstice, observed results
and calculated results didn't agree so well.
I was puzzled by this at first.  Then I
appreciated the obvious.  The declination
is changing so rapidly at the equinoxes
(about 1 minute an hour) that you can
no longer assume the declination at noon
holds good all day.

Contrary to what simple sundial guides tell
you, the shadow of a point cast onto a plane
DOESN'T follow a straight line on the day of
an equinox.  It actually follows an S shape,
albeit a very narrow S.

Have a good winter.

Frank

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Re: exact time of 2009 Autumn equinox

2009-09-23 Thread Frank King 
Dear Jos,

You raise an interesting point...

> According to the United States Naval Observatory
> ... the 2009 equinox falls on sept 22 at 21:18:00 UT.
> This is 61 minutes different from your value.
> Who is right?

I would use the USNO time myself but your question
isn't as easy as it seems...

There is more than one definition of "equinox".  For
example there is "the mean equinox of the date" and
so on.

Here is a simple definition which turns out to need
further interpretation:

   The instant of an equinox is the moment the
   sun reaches one of the two points where the
   ecliptic and the celestial equator intersect.

One snag is that both the ecliptic and the celestial
equator are slightly wobbly...

The earth's orbit is disturbed by the moon and by
Jupiter and is therefore not quite a plane.  Hence
the perceived orbit of the sun round the earth, the
ecliptic, is not quite a plane either.

Another effect is nutation which means that the
orientation of the earth's axis wobbles about, so
the celestial poles wobble in sync, and hence the
celestial equator wobbles too.

You therefore have a wobbly ecliptic intersecting
a wobbly celestial equator.  You have a choice:

  1.  Do you average out the wobbles and take
  only long-term effects into account?

  2.  Do you take everything into account and
  give yourself a stiff calculation?

Most published results are the result of option 2
and this means that the intervals between successive
vernal equinoxes (say) can vary by several minutes
year on year.

By several minutes I mean about 5 to 7 minutes,
definitely not 61 minutes!

You will have many long winter evenings ahead of
you to ponder all this.

Best wishes

Frank King
Cambridge, U.K.


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Re: Lichtuhr

2009-09-23 Thread fer de vries 
John,

I have no idea about the light's speed but the pattern of the hours on the wall 
isn't like a real sundial.
See an example on the site, attached here.
The VI-VI hourlines aren't in the right direction.

Best wishes, Fer. 

Fer J. de Vries

De Zonnewijzerkring
http://www.de-zonnewijzerkring.nl

Molens
http://www.collsemolen.dse.nl

Eindhoven, Netherlands
lat.  51:30 N  long.  5:30 E

  - Original Message - 
  From: John Carmichael 
  To: 'Peter Kunath' 
  Cc: 'Sundial' 
  Sent: Wednesday, September 23, 2009 7:34 PM
  Subject: RE: Lichtuhr


  Very interesting Peter!  The time lapse movie shows the concept well.  Does 
the motor that moves the ceiling-mounted light move it at a constant speed I 
wonder?  Since the light is mounted on the ceiling and does not revolve around 
the gnomon, then wouldn't the shadow move at different speeds during the day 
making the shadow speed variable and therefore making the clock inaccurate?
Or are the hour lines spaced to compensate for the motor's constant speed?

   

  By the way, you have spelling error in the website URL

   

  You wrote: www.lichtuhr,de

   

  It should be: www.lichtuhr.de

   

  Hope you are well!

   

  John

   

   

  From: sundial-boun...@uni-koeln.de [mailto:sundial-boun...@uni-koeln.de] On 
Behalf Of Peter Kunath
  Sent: Wednesday, September 23, 2009 9:37 AM
  To: sund...@rrz.uni-koeln.de
  Cc: m...@lichtuhr.de
  Subject: Lichtuhr

   


  Dear friends, 
  days are getting shorter. 
  May I recommend you the "Lichtuhr", vulgo "light-watch" or an unusal 
indoor-sundial? 
  www.lichtuhr,de 
  Point to english version and the second screen "design" and "3D-animation". 
  I own a CD with further details and I try to get the permission of the 
  designer Andreas Engelmann to make a copy for you. 
  The "Lichtuhr" can be visited in different towns in Germany (Cologne too). 
  Best regards 
  Peter 



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Re: Solor Coordinate Calculation

2009-09-23 Thread Edley McKnight 
Hi James, Dialists,

Not exactly the polynomials, but ICE (Interactive Computer Ephemeris) from the 
Naval 
Observatory originally, is still available and covers up to 2047. It is 
freeware and now public 
domain. It is available from a number of places.  It is a DOS program and the 
latest version is 
0.51.  Various Ephemerises are available for it. One place is 
http://www.celnav.de/ice.zip
The Naval Observatory does provide MICA (Multi Year Computer Almanac) on CD for 
a price.

I hope this helps!

Edley

> Each year, the Astronomical Almanac publishes polynomials for
> calculating the mean solar orbital 
> elements (mean longitude, mean anomaly, etc.) as a polynomial with
> the day-of-year as the 
> index. The formulas are valid only for a given year.
> 
> Does anyone know of a place on-line to get the polynomials for
> 2010?
> 
> Best regards,
> 
> Jim
> 
> James E. Morrison
> janus.astrol...@verizon.net
> Astrolabe web site at http://astrolabes.org 


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exact time of 2009 Autumn equinox

2009-09-23 Thread Jos Kint 
Hello Roger Bailey,

According to the United States Naval Observatory ( 
http://aa.usno.navy.mil/data/docs/EarthSeasons.php) the 2009 equinox falls on 
sept 22 at 21:18:00 UT. This is 61 minutes different from your value. Who is 
right?


Jos Kint
Eeuwfeestlaan 38
9840 De Pinte
Tel: 09.282.57.61
GSM: 0477.966.760
Email: jos.k...@skynet.be---
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RE: Lichtuhr

2009-09-23 Thread John Carmichael 
Very interesting Peter!  The time lapse movie shows the concept well.  Does
the motor that moves the ceiling-mounted light move it at a constant speed I
wonder?  Since the light is mounted on the ceiling and does not revolve
around the gnomon, then wouldn't the shadow move at different speeds during
the day making the shadow speed variable and therefore making the clock
inaccurate?Or are the hour lines spaced to compensate for the motor's
constant speed?

 

By the way, you have spelling error in the website URL

 

You wrote: www.lichtuhr  ,de

 

It should be: www.lichtuhr.de

 

Hope you are well!

 

John

 

 

From: sundial-boun...@uni-koeln.de [mailto:sundial-boun...@uni-koeln.de] On
Behalf Of Peter Kunath
Sent: Wednesday, September 23, 2009 9:37 AM
To: sund...@rrz.uni-koeln.de
Cc: m...@lichtuhr.de
Subject: Lichtuhr

 


Dear friends, 
days are getting shorter. 
May I recommend you the "Lichtuhr", vulgo "light-watch" or an unusal
indoor-sundial? 
www.lichtuhr,de 
Point to english version and the second screen "design" and "3D-animation". 
I own a CD with further details and I try to get the permission of the 
designer Andreas Engelmann to make a copy for you. 
The "Lichtuhr" can be visited in different towns in Germany (Cologne too). 
Best regards 
Peter 

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AW: Lichtuhr

2009-09-23 Thread Reinhold Kriegler 
An indoor-sundial???
Good Lord!
There is only a Black Forest cuckoo missing or a Big Ben striking
mechanism …
 

 
Just in case you want to try a real indoor- reflex-sundial, try the
little YouTube film below!
 
* ** ***  * ** ***
Reinhold R. Kriegler
Lat. 53° 6' 52,6" Nord; Long. 8° 53' 52,3 Ost; 48 m ü. N.N.  
www.ta-dip.de
 
http://de.youtube.com/watch?v=XyCoJHwzzjU&fmt=18
-Ursprüngliche Nachricht-
Von: sundial-boun...@uni-koeln.de [mailto:sundial-boun...@uni-koeln.de]
Im Auftrag von Peter Kunath
Gesendet: Mittwoch, 23. September 2009 18:37
An: sund...@rrz.uni-koeln.de
Cc: m...@lichtuhr.de
Betreff: Lichtuhr
 

Dear friends, 
days are getting shorter. 
May I recommend you the “Lichtuhr”, vulgo “light-watch” or an unusal
indoor-sundial? 
www.lichtuhr,de 
Point to english version and the second screen “design” and
“3D-animation”. 
I own a CD with further details and I try to get the permission of the 
designer Andreas Engelmann to make a copy for you. 
The “Lichtuhr” can be visited in different towns in Germany (Cologne
too). 
Best regards 
Peter 
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RE: sunset/sunrise times

2009-09-23 Thread Tom Kreyche 
The Explanatory Supplement to the Astronomical Almanac has several separate
and extensive discussions on this topic, in particular section 9.33 in the
1992 edition, page 487. A small portion of the section is:

 

"At sunrise and sunset the apparent altitude of the upper limb on the
horizon is zero and hence the adopted true altitude in degrees is h = -50/60
- .0353 * square roof of H where H is the height, in meters, of the observer
above the horizon."

 

Atmospheric refraction has so many uncertainties that making such a small
adjustment is meaningless for practical purposes but it's an interesting
mathematical exercise.

 

 

From: sundial-boun...@uni-koeln.de [mailto:sundial-boun...@uni-koeln.de] On
Behalf Of Th. Taudin Chabot
Sent: Wednesday, September 23, 2009 2:41 AM
To: sund...@rrz.uni-koeln.de
Subject: sunset/sunrise times

 

All programs that calculate the sunrise/sunset times use an eye height of
0m. Many take the refraction in their calculations.
But what is the effect of a normal eye height of 1.5 m when the observer is
standing at sealevel like the beach. And when the eye height is even
considerabel higher because the observationpoint is something like 300m
above sealevel.
Thibaud



  _  

Th. Taudin Chabot, . tcha...@dds.nl




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Lichtuhr

2009-09-23 Thread Peter Kunath 
Dear friends,
days are getting shorter.
May I recommend you the ?Lichtuhr?, vulgo ?light-watch? or an unusal 
indoor-sundial?
www.lichtuhr,de
Point to english version and the second screen ?design? and 
?3D-animation?.
I own a CD with further details and I try to get the permission of the 
designer Andreas Engelmann to make a copy for you.
The ?Lichtuhr? can be visited in different towns in Germany (Cologne too).
Best regards
Peter
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sunset/sunrise times

2009-09-23 Thread Th. Taudin Chabot 
All programs that calculate the sunrise/sunset times use an eye 
height of 0m. Many take the refraction in their calculations.
But what is the effect of a normal eye height of 1.5 m when the 
observer is standing at sealevel like the beach. And when the eye 
height is even considerabel higher because the observationpoint is 
something like 300m above sealevel.

Thibaud


--
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Fwd: Solar Coordinate Calculation (well one of them!)

2009-09-23 Thread patrick_powers 

Hi Jim,







I cannot really help you other than to say that the following are the 
coefficients for a 9th order polynomial which calculates in decimals of a 
minute the Equation of Time at Noon for each day in 2010 (not a leap year) 
where x is the serial number of the day ie Jan1 is 1 and Dec 31st is 365.?



?Apart from the end effects of the final two days of the year it produces 
results within (and often well within) 15 secs of that obtained from Smart's 
formula (from which it is derived courtesy of Excel's LINEST function). ?The 
last two days of the year are within 26 secs of the Smart figures. ?









Regards



Patrick



_













x9 ?-5.49274E-19









x8 ?8.53571E-16









x7 ?-5.21923E-13









x6 ?1.55941E-10









x5 ?-2.24411E-08









x4 ?1.17534E-06









x3 ?1.95441E-06









x2 ?0.00441065









x ?-0.490197443









c ?-3.076415827























































































































2009/9/21 James E. Morrison 





Each year, the Astronomical Almanac publishes polynomials for calculating the 
mean solar orbital elements (mean longitude, mean anomaly, etc.) as a 
polynomial with the day-of-year as the index.? The formulas are valid only for 
a given year.




Does anyone know of a place on-line to get the polynomials for 2010?



Best regards,



Jim



James E. Morrison

janus.astrol...@verizon.net


Astrolabe web site at http://astrolabes.org 

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