There is a Java applet showing the effects of refraction
and flattening at:
http://www.jgiesen.de/refract/index.html
If it came from this list originally, I apologize in advance.
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Theater lighting gels are plastic sheets that
come in a large variety of colors and are inexpensive.
I don't know if they will stick to windows or would
work in a computer printer. Rosco is one of the major
brands.
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There are a lot of navigation calculations at:
http://williams.best.vwh.net/avform.htm
It includes the distance and course between points.
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An original Porter Garden Telescope recently sold at the
Skinner auction in Boston.
http://www.dickkoolish.com/rmk_page/pictures_032207.html
There a couple of Porter sundials in the telescope making museum
at the Hartness House in Springfield VT.
Here is a sundial at Mt. Auburn Cemetery in
Cambridge MA, USA.
It's probably not a cremation container, but certainly
could be.
http://www.dickkoolish.com/rmk_page/sundials/payson_mtauburn.html
Hi all,
Was having a look at Google Patents using the key word sundial and =
found a number
Two moon phase calculators that do exist are at:
http://www.lunawheel.com/
http://www.moonstick.com/
Dear sundial friends,
To celebrate the solar eclipse tomorrow, I prepared a DeltaCad macro for
finding the MEAN MOON PHASES.
All callendar constructions use somehow corrections for
I put some pictures of the Kennedal Sky Pointer on a web page at
http://www.dickkoolish.com/rmk_page/pictures_032306.html.
Sky Publishing used to sell them. You can set the RA and Dec
of an object and the date and time and it will point to the
position in the sky. Or you can set the Dec and
day, the declination of the moon changes a lot every day,
since it goes through the cycle from maximum to minimum
declination every month, while the sun takes a whole year
to go through that cycle.
Yes, I knew that. And I heard as well that the moon's
extreme declinations vary from
On March 20, the declination of the sun is 0, so it rises
due east and sets due west. The moons declination on that
day is almost -26 degrees so it rises south of east.
The full moon rise this past Tuesday was almost due east.
Unlike the sun, whose declination changes just a bit every
day, the
See: http://www.mreclipse.com/Totality/TotalityCh11.html
This is from Fred Espenak at NASA.
http://www.mreclipse.com/Totality/TotalityCh11.html
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There's a pinhole camera photo of the Portland Oregon Union Station sundial
at: http://web.pdx.edu/%7Eharveyt/C1.html
Don Yeier, ex Vernonscope owner is having a scientific instruments auction
on Saturday, May 19, 2001, in Candor, New York (near Binghamton). In addition
to antique telescopes, binoculars, clocks, etc. the flyer says there is an
Augsberg equitorial dial and other sundials. Catalog is $20.00
Actually it is dark, but the lights are on. See the amazing photo at
http://antwrp.gsfc.nasa.gov/apod/image/0011/earthlights_dmsp_big.jpg
Daniel Wenger
We amateur astronomers call that 'Light Pollution'.
http://www.darksky.org/ida/index.html
From the web page:
http://sunearth.gsfc.nasa.gov/eclipse/SEhelp/SEgeometry.html
Eclipse geometry is complicated by the fact that Earth's orbit around the Sun
is elliptical. As a result, the Sun's apparent semi-diameter varies from 944
arc-seconds at aphelion to 976 arc-seconds at perihelion.
Take a look at this sundial:
http://www.angelsandearthlythings.com/hp4500.html
I think it has problems. Am I correct?
The cover of the June 2000 issue of Embedded Systems programming has
a sundial with the gnomon pointing in the wrong direction. I've already
emailed them about it.
It's on my web page at:
http://linux.bbn.com/~koolish
with the full scan in:
Isn't Beltane the other side of Candlemas?
I am looking forward to an authoritative answer based on solar declination.
Roger Bailey
Beltane explanation (and other cross-quarter days):
http://www.isleofavalon.co.uk/edu/g-bank/articles/beltane.html
There is an article in the most recent edition of Sky and Telescope magazine
about photographing the analemma.
It describes how photos have been taken which show the movement of the sun.
They rely on time lapse (either 365 or 12 exposures over the course of a
year), with each exposure
The synodic month (full moon to full moon) averages 29.53 days, while
the anomalistic month (perigee to perigee) is 27.55 days, so the phases
drift with respect to perigee.
see: http://www.treasure-troves.com/astro/AnomalisticMonth.html
There's a great web site for eclipse info, both solar and lunar at:
http://sunearth.gsfc.nasa.gov/eclipse/eclipse.html
A page of solar filter sources is:
http://umbra.gsfc.nasa.gov/eclipse/970309/text/filter-sources.html
There's a page of books on atmospheric phonomena at:
http://www.treasure-troves.com/astro/AtmosphericPhenomena.html
One book that I like is:
Greenler, R., Rainbows, Halos, and Glories,
Cambridge University Press, 1980.
A paper recently put on the web about pinhole photography has a section
about something called a 'Pinspeck Camera' that might have the same
properties as the bead in the hole shadow sharpener.
See: http://www.pinhole.com/resources/articles/Young/index.html
and look down near the end of the
Patrick Powers wrote:
It is simply the pin hole camera effect again. Light passing through any
small aperture is focused . As the hole's size is changed the focusing
parameters are changed too. So with a fixed distance from hole to plate
there will be one size that works. A different size
I've put a picture of what I think is a sun tracking device on my web page at
linux.bbn.com/~koolish. If anybody has seen one or knows how it was used, let
me know. There are no markings on it.
A web search turned up glass spheres at:
http://www.angelsandearthlythings.com/s-sphere.html
I scanned the Sundicator and put an image on my web page:
http://linux.bbn.com/~koolish
Click on the small image to get the big image (296K).
We are coming up to the day when sunset lines up with the Infinite Corridor
at MIT (Massachusetts Institute of Technology) in Cambridge, MA, USA.
I may try and observe it this year.
http://w3.mit.edu/afs/athena.mit.edu/org/p/planning/www/mithenge
After being out of print for many years, the Explanatory Supplement
was re-written and re-published in 1992. It is now the
Explanatory Supplement to the Astronomical Almanac, edited by
Kenneth Seidelmann and is published by University Science Books,
20 Edgehill Rd, Mill Valley, CA 94941.
I know this is slightly off-topic, but I thought it might be interesting.
This is an animation of the lunar phases that clearly shows the libration.
http://www.geocities.com/CapeCanaveral/5409/lunation.gif
Daniel Roth's movies can be played on UNIX systems with the XAnim program.
It's available from:
http://xanim.va.pubnix.com/home.html
The following web page has a table for every day of 1998, giving the
declination of the sun, the equation of time, and the declination of
Polaris.
http://www.cadastral.com/eph1998b.htm
There is a graph of the refraction error at:
http://www.cadastral.com/papersl1.htm
There are free raytracing packages available that allow you to
describe a 3-dimensional object and render an image of it with
light sources placed at will. Has anybody used these to simulate
sundials? Seems like it should work.
http://www.fordham.edu/halsall/source/chaucer-astro.html
There is a sundial cartoon in the March 9th issue of the New Yorker
magazine. I scanned it in and put it on my web page.
http://linux.bbn.com/~koolish
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