Robert, John, Willy, and All,
Using a satellite dish as a sundial is a great
idea. And a fully functioning dish with hour
markings could work as a satellite re-aiming tool
- Since a working dish that is locked into place
and then marked with hour lines could be used to
re-aim the dish after it was moved out of
alignment - by storm or wind. A common problem,
and very serious in areas of violent storms -
Florida for instance. Using sunshine instead of a satellite service call.
Thank you so much for recalling my site -
although it is inactive.... it is possible to aim
a dish using a sundial... but the biggest problem
for me is defining what I call the "Axis of
Focus" which is the alignment line from the dish
to the satellite during which the signal is
perfectly tuned. My invention is software used
to calibrate an adjustable gnomon - using the
shadow to a single point at the base of the axis
of focus. ( apologies that my site is not current )
However, finding the axis of focus is something a
dish manufacturer would best solve. Or in the
case that you are marking a functioning and
focused dish -- then you are also setting the
axis of focus and using a fixed gnomon. Then the
sundial becomes useful for reaiming the dish
I think this is a very worthy task to work
on. Call it functional gnomonics
Richard Pauli
SundialSetup
At 04:58 PM 6/21/2007, Robert Terwilliger wrote:
This reference strays a bit from the topic, but
this chap has a method (and a program for sale)
which will aim a dish at a satellite using a quasi-sundial approach.
<http://www.sundialsetup.com/>http://www.sundialsetup.com/
Also John Davis made what I believe was a
decliner recliner from a satellite dish. Perhaps
he will chime in or someone has a photo.
Bob
Also... Here are a couple of pages from
Astronomy Picture of the Day that some might find interesting:
Stars and the Solstice Sun
<http://antwrp.gsfc.nasa.gov/apod/astropix.html>http://antwrp.gsfc.nasa.gov/apod/astropix.html
Astronomy Picture of the Day Search Results for "analemma"
<http://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search?analemma>http://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search?analemma
----------
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of John Carmichael
Sent: Thursday, June 21, 2007 6:57 PM
To: 'Willy Leenders'
Cc: 'Sundial List'
Subject: RE: Direct South Dial
Dear Willy
Im not sure I agree with you. I think the
empirical method automaticly corrects for the
longitude shift. If you mark the shadows
location using a watch on a day when the EOT is
zero, then the longitude correction is
there. The sundial will be marking watch time
when the EOT is zero. The longitude correction will be built in.
I look at it this way. My sundials that I make
are all corrected for longitude when I make
them. If I were to erase all the hourlines on
one of them, I could recreate the erased lines
by using the empirical method without making further corrections for longitude.
I think I am correct in this. But Ive been
wrong on many things in the past so Im willing
to listen to someone tell me why I am wrong.
Respectfully,
John
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From: Willy Leenders [mailto:[EMAIL PROTECTED]
Sent: Thursday, June 21, 2007 1:17 PM
To: John Carmichael
Cc: 'Andrew Corl'; 'Sundial List'
Subject: Re: Direct South Dial
Hi John,
Using your empirical method, not only the
equation of time must be zero, you have to take
in account the correction for longitude.
Willy Leenders
Hasselt in Flanders (Belgium)
Op 21-jun-07, om 21:24 heeft John Carmichael het volgende geschreven:
Hello Andrew:
There is an easy way to mark the hourlines on a
satellite dish or any surface for that matter,
without using any formulas or math. Use what
some call the empirical method. This method
is useful for oddly shaped surfaces.
1. Position the dish in the direction that you
want it to face. (Due south or even slightly
away from south. It doesnt matter.)
2. Attach your gnomon so that the shadow casting
edge points directly at the north celestial pole
(Youll probably attach it at the center of the
dish, and you will probably be using a rod
gnomon, but it could be attached anywhere. It doesnt matter).
3. On a sunny day, when the Equation of Time is
zero (the next date this occurs is September
1st), using an accurate time source, mark where
the gnomons shadow falls on the dish at the
times you want to indicate (hours, ½ hours, ¼ hours, whatever).
4. Done!
Your sundial will now indicate solar time adjusted for longitude.
You can mark your sundial in the same fashion on
any day of the year if you take into
consideration the Equation of Time value for the date that you do it.
Real easy!
John L. Carmichael
Sundial Sculptures
925 E. Foothills Dr.
Tucson AZ 85718-4716
USA
Tel: 520-6961709
Email: <mailto:[EMAIL PROTECTED]>[EMAIL PROTECTED]
My Websites:
(business) Sundial Sculptures:
<http://www.sundialsculptures.com/>http://www.sundialsculptures.com
(educational): Earth & Sky Equatorial Sundial:
<http://advanceassociates.com/Sundials/Earth-Sky_Dial/>http://advanceassociates.com/Sundials/Earth-Sky_Dial/
(educational) My Painted Wall Sundial:
<http://www.advanceassociates.com/WallDial>http://www.advanceassociates.com/WallDial
(educational) Painted Wall Sundials:
<http://advanceassociates.com/WallDial/PWS_Home.html>http://advanceassociates.com/WallDial/PWS_Home.html
(educational) Stained Glass Sundials:
<http://www.stainedglasssundials.com/>http://www.stainedglasssundials.com
(educational) Sundial Cupolas, Towers &
Chimneys:
<http://stainedglasssundials.com/CupolaSundial/index.html>http://StainedGlassSundials.com/CupolaSundial/index.html
----------
From: [EMAIL PROTECTED]
[<mailto:[EMAIL PROTECTED]>mailto:[EMAIL PROTECTED]
On Behalf Of Andrew Corl
Sent: Thursday, June 21, 2007 10:27 AM
To: Sundial List
Subject: Direct South Dial
Greetings all,
Several months ago I bought a house and the
previous owners left me with one of those 12"
diameter satellite dishes. I have no need or
want of Direct TV or satellite TV.
I was sitting there thinking one day that it
would make a really nice direct south facing
sundial. My house already faces a little east
of south anyway, and the location where the dish
is gets direct sunlight almost all year round.
My questions is this: Do I need to make any
adjustment in the calculations of the hour lines
for the shape of the dish? If so what is the formula?
I am going to install a simple style using a
metal road about a half inch in diameter. I
want this sundial to tell solar time not
necessarily actual time. Though one day I may
install an equation of time underneat the dial .
Boardwalk for $500? In 2007? Ha!
<http://us.rd.yahoo.com/evt=48223/*http:/get.games.yahoo.com/proddesc?gamekey=monopolyherenow>Play
Monopoly Here and Now (it's updated for today's economy) at Yahoo! Games.
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