There is a fascinating seven-page article about the history of the GMT and its
restoration effort in the current (October) issue of Sky & Telescope, now on
newsstands. It was written by well-known science writer Trudy E. Bell.
Roger S.
-Original Message-
From: sundial
I agree with Helmut!
When I see a blank subject line, I become suspicious and often just delete
the message without opening it.
Roger
-Original Message-
From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of Helmut
Haase
Sent: Tuesday, May 22, 2018 10:11 AM
To:
Roger (and others),
A slight correction concerning the motion of Earth's perihelion with respect to
the seasons. Owing to precession, the equinoxes and solstices drift slowly
westward along the ecliptic in a cycle of about 26,000 years. But at the same
time perturbations by the other
Dan,
I’m just guessing, but maybe the two holes and two spots are placed so that, no
matter what the Sun’s declination is, at least one of the spots will fall on a
smooth, uncluttered part of the floor.
Roger
From: sundial [mailto:sundial-boun...@uni-koeln.de] On Behalf Of
c function
with time, i.e. the frequency of leap seconds increases quadratically with
time. This will be a big problem for our grandgrandgrand...children.
Best regards,
Wolfgang
Gesendet: Montag, 30. November 2015 um 12:18 Uhr
Von: "Roger W. Sinnott" <roger.sinn...@verizon.net>
Rudolf,
If the day length starts at 86400 seconds and grows by 0.17 second each
year, it would indeed reach 86401 seconds in about 6 years. But if this
rate is uniform, the tiny fractional increases would accumulate to 1 second in
just 343 years, so I think that's when the first
Brent,
The "small circle" route is the one that takes you on a curved path, always
toward due east.
You could also start out going due east on a "great circle" route, and in
that case, as you note, the path would gradually veer southward.
Both of these routes start out perpendicularly
Hi Brad,
It seems that your listing uses the Julian calendar before year +1600, as it
should. But the Julian calendar is not a perfect fit to the tropical year,
and the same problem that necessitated the Gregorian calendar reform would
also apply, in reverse, when going backward in time. In
Brad,
Are you sure you are using the full VSOP87 theory? I don't think it has
been published in print form, anywhere. The appendix in Jean Meeus's
Astronomical Algorithms gives an abridged form of VSOP87, and this could
explain your discrepancies with Table 27.E.
Roger
On Thu,
Dynamical Time on 2012 March 20. So in this
case it does agree to the second with Meeuss Astronomical Tables of the
Sun, Moon, and Planets (2nd ed., 1995).
Roger
From: Brad Lufkin [mailto:bradley.luf...@gmail.com]
Sent: Friday, September 30, 2011 8:25 AM
To: Roger W. Sinnott
Cc: sun.di
Andrew:
I think your numbers make sense.
You didn’t mention the date, but I suspect your calculation was for July 30,
2011. For this date at 11:18 a.m. EDT, and the lat/long of Boston, I find the
following values ---
Sun’s declination: +18.5 degrees
Sun’s azimuth:
Mac,
I encountered exactly the same problem in December. I bought a PC that came
with Windows 7 Home Premium and tried to run Turbo Basic (very similar to
QBasic). I have literally hundreds of programs I've written over the years
in Turbo Basic and absolutely had to be able to run them.
The
All,
I am trying to find a YouTube video that was linked to from this list
several years ago.
It shows a large analemmatic sundial located in a public park in Moscow (I
think). Various passersby tried to figure out how it worked, where to
stand, etc., and it was pretty funny. This could not
to.)
Roger
Direct link: http://www.youtube.com/user/AleksandrBoldyrev?gl=RU
http://www.youtube.com/user/AleksandrBoldyrev?gl=RUhl=ru hl=ru
From: Reinhold Kriegler [mailto:reinhold.krieg...@gmx.de]
Sent: Wednesday, March 09, 2011 5:47 PM
To: 'Roger W. Sinnott'; 'Sundial List'
Subject: AW
Frank,
The Wikipedia article does not say proper motion, and I'm sure that was
not the reason for correcting the stars' positions on the flag of Brazil.
Rather, the stars may have been carelessly plotted on the original flag
(even if shown more accurately than on the flags of many other
It's also possible to think of degrees, arcminutes, etc., as a cryptic
notation, given the long history of timekeeping. I have a set of 7-place
trig tables, published in 1958 by H.M. Nautical Almanac Office, with the
argument in time.
For example, this book lists the tangent of 1h 38m 13s as
Tracy,
I am facing similar problems. Two weeks ago I got a new desktop computer
with Windows 7 Home Premium on it. I quickly discovered that when I try to
run any of the old DOS programs I get the same error message you are
reporting. I tried opening a command-line window, which works, but
Brent,
Yes, I think you *could* determine your longitude by observing a
geosynchronous satellite whose location was known. There would be some
uncertainty if it wanders a little. Much more important, however, is
figuring out which geosynchronous satellite you are looking at. You'd
Brent,
I think you could determine your latitude this way, but not your longitude.
For the longitude, you would need some way to relate your local sunrises and
sunsets to the local time at some known longitude, such as that of
Greenwich.
In other words, the geolocation tagging gadget must
Tony,
These are fascinating, well-made videos! I am curious: How deep are the
recesses etched by this technique?
-- Roger
- Original Message -
From: Tony Moss t...@lindisun.demon.co.uk
To: Sundial Mailing List sundial@uni-koeln.de
Cc: Jack Aubert j...@chezaubert.net; Mike
All,
A friend of mine (Joe Rao of New York City) just sent me this neat link.
Check it out!
-- Roger
-
A different way to display time on the green time line.
This is a real cool clock! I believe it comes from a
Brad,
No, Meeus's Elements of Solar Eclipses book does not tell how to calculate
the Besselian elements. Rather, it LISTS these elements for all solar
eclipses from 1951-2200. Its real strength is that it provides detailed
numerical examples of how to USE these elements to calculate the path
All,
A bronze sundial of this type was designed James Hartness of Springfield,
Vermont, and patented in 1917. It is on display in the underground museum
at the Hartness House, which sits on a hill in the center of town.
Two pictures of it are here:
I have to agree with Robert, who appears to have constructed an amazing
instrument!
Surely, there is room in this world for *two* types of sundials:
(1) Those that stay true to the concept of time before mechanical clocks,
when local apparent solar time was the real time, no matter what
- Original Message -
From: The Thurstons thurs...@hornbeams.com
To: 'Peter Mayer' peter.ma...@adelaide.edu.au; 'Sundials'
sund...@rrz.uni-koeln.de
Sent: Friday, July 03, 2009 12:45 PM
Subject: RE: Sundial compass on eBay
Folks,
Alerted by Peter's message below, I have just bought
to prevent turning by mistake.
-- Roger
- Original Message -
From: Roger W. Sinnott rsinn...@post.harvard.edu
To: thurs...@hornbeams.com; 'Peter Mayer' peter.ma...@adelaide.edu.au;
'Sundials' sund...@rrz.uni-koeln.de
Sent: Saturday, July 04, 2009 12:34 PM
Subject: Re: Sundial
Doug,
I'm in complete agreement with all the excellent points you make! A
GPS-derived bearing can't be accurate to 0.1 arcsecond -- that's absurd. I
just meant that the latitudes and longitudes of an accurate GPS fix agree with
Google Earth's coordinates (on the WGS84 datum) to roughly that
At 11:01 AM 1/26/2007 -0500, J. Tallman wrote:
I guess I am not entirely willing to automatically accept their output
as 100% perfect...and I wonder if anybody on the list has any
interesting thoughts or practical experience re: Google Earth and the
accuracy of their geographic grid.
Jim,
At 11:52 AM 9/1/2006 -0700, John Carmichael wrote:
Hello Roger (Sinnott): Humm... I read your concerns that a threesided pyramid and a 3 sided post are problematic gnomons. And I tried tounderstand your reasoning, but for the life of me, I can't understand theproblem you
John (and Larry),
I think there may be a problem with two of the seven designs. Numbering them 1 through 7 from left to right in your illustration, the problematic ones are No. 3 (the three-sided pyramid) and No. 4 (the three-sided pointed post).
All the others have the shadow axis of the pole,
List:
I'm sure Mike meant that the Greenwich Meridian Line is about 5 west, not 5' west, of where it is shown on Google Earth. (I just looked to confirm this!)
This discrepancy is simply due to Google Earth's adopted geodetic datum, WGS84. GPS receivers can often be set to show coordinates
All,
I realize this is not the question John Carmichael originally asked, but I
decided to find out how much the Equation of Time varies over several years on
the SAME month and day. I used Jean Meeus's Astronomical Algorithms, chapter 27
(actually, the method is attributed to W. M. Smart)
John and others,
Maybe I'm being dense, but isn't the variation of the equation of time
with longitude masked (or at least complicated) by the similar variation,
from one year to the next, due to our use of a 365-day calendar and
occasional leap year?
It's hard for me to imagine that the
At 08:25 AM 12/21/01 +1100, David Pratten wrote:
Dear Walter,
Greetings.
There is another factor which limits sundial accuracy to about +/-22
seconds. This is the variation in the value of Equation of Time from
year to year within a leap cycle. See
At 10:48 AM 8/12/01 EDT, Bill Gottesman wrote:
Hello All,
I know Fred must be right about the declination being non-zero at the
equinoxes, but I can't figure out why. As I understand, solar celestial
right ascension must equal solar ecliptic longitude (Lambda) on the equinoxes
(0 degrees
At 11:23 PM 12/11/99 -0500, Larry Bohlayer wrote:
In lay-mans terms it will be a super bright full moon, much more than the
usual AND it hasn't happened this way for 133 years! Our ancestors 133
years ago saw this. Our descendents 100 or so years from now will see this
again.
Dr. Robert
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