Re: DIALIST

[Brad Lufkin]

Something weird is going on. If I click on the link
http://www.shadow.net/~bobt/dcomp/dcomp.htm
on the page
http://www.sundials.co.uk/nasscomp.htm
I get a page having to do with vaporizers!
http://vapeforest.com/reviews/
Anyone know (or can figure out) what's going on?
Brad


On Thu, Dec 26, 2013 at 3:28 PM,  wrote:

>  Dialist’s Companion from NASS:
>
>
> *http://www.sundials.co.uk/nasscomp.htmhttp://www.sundials.co.uk/nasscomp.htm*<http://www.sundials.co.uk/nasscomp.htmhttp://www.sundials.co.uk/nasscomp.htm>
>
> Roderick.
>
>
> *From:* Brad Lufkin 
> *Sent:* Friday, 27 December, 2013 6:29 AM
> *To:* Rod Wall 
>
> Roderick:
> where can I get the Dialist's Companion?
> Regards, Brad
>
>
> On Thu, Dec 26, 2013 at 12:37 PM,  wrote:
>
>>  Dialist’s Companion with DOSbox also works on Windows 8.1.
>>
>> Where would we be without Dialist’s Companion, it is a great program.
>>
>> Roderick Wall.
>>
>> *From:* Brian Albinson 
>> *Sent:* Friday, 27 December, 2013 4:28 AM
>> *To:* Sundial Group 
>>
>> Hi all;
>>
>> If anyone is nostalgic for DOS, and has a copy of the "Dialist's
>> Companion" ;  and would like to run it on Windows 7;  I have found
>> DOSbox (free) to work well.   DOSBox is also advertised to be compatible
>> with  Linux, Mac OS X and OS/2.
>>
>>
>> Brian Albinson
>>
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>>
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>>
>>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

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

[Brad Lufkin]

Dear John:
attached is the table you've asked for. It includes the astronomical year,
the month, day, and time of the event, and azimuth (in degrees) of sunrise
and sunset. Azimuth is measured from North towards East (so North = 0
degrees, East = 90, South = 180, West = 270).
The table is based on VSOP87D for the position of the Sun. I used a
combination of Lasker and Borger for the obliquity of the ecliptic. And the
assumed latitude of the site is 34 degrees South. Many thanks to all who
contributed to the discussion, in particular to Roger Bailey for pointing
to the Borger reference. Roger solved the azimuth problem with his
spreadsheet and charts. The attached table includes the dates as well as
the azimuths.
Brad

On Thu, Jun 21, 2012 at 12:55 AM, John Pickard wrote:

> **
> Good evening on a chilly Winter Solstice in Sydney,
>
> As part of my research on fences, I need to calculate the azimuth of
> sunrise and sunset back to 25,000 y ago. The question arises from the
> disputed origins of some dry stone walls found in southern New South
> Wales. A local historian has suggested that they are an astronomical
> alignment built by Aborigines, but they were recorded as fences on survey
> plans in the late 19th C. The locations suggest to me that the walls were
> built as fences on terrain too steep for the log fences of the time.
>
> What I would like to is calculate the azimuths of sunrise and sunset at
> Winter Solstice back 25,000 y (about the length of time Aborigines occupied
> the area) in annual increments (or decrements to be pedantic!). I know that
> I can do this for any specific date in a number of excellent programs, but
> I don't relish the notion of that many calculations. Even if I increase the
> interval to 100 y, I would still have 250 calculations.
>
> My question is: does anyone know of a way of automating this to generate a
> table of the dates and the azimuth of sunrise and sunset?
>
>
> Many thanks, John
>
> John Pickard
> john.pick...@bigpond.com
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
-23,000 Dec 24 08:13:49 TDT 63.2 296.8
-22,900 Dec 22 19:38:35 TDT 63.2 296.8
-22,800 Dec 22 08:16:54 TDT 63.2 296.8
-22,700 Dec 20 20:44:04 TDT 63.2 296.8
-22,600 Dec 20 07:45:18 TDT 63.1 296.9
-22,500 Dec 18 23:14:32 TDT 63.1 296.9
-22,400 Dec 18 07:02:19 TDT 63.1 296.9
-22,300 Dec 17 01:55:38 TDT 63.1 296.9
-22,200 Dec 16 06:17:55 TDT 63.1 296.9
-22,100 Dec 15 04:42:58 TDT 63.1 296.9
-22,000 Dec 14 05:16:40 TDT 63.1 296.9
-21,900 Dec 13 08:16:33 TDT 63.1 296.9
-21,800 Dec 12 05:04:20 TDT 63.0 297.0
-21,700 Dec 11 10:41:57 TDT 63.0 297.0
-21,600 Dec 10 05:28:29 TDT 63.0 297.0
-21,500 Dec 09 13:44:43 TDT 63.0 297.0
-21,400 Dec 08 06:13:27 TDT 63.0 297.0
-21,300 Dec 07 16:25:52 TDT 63.0 297.0
-21,200 Dec 06 07:56:48 TDT 62.9 297.1
-21,100 Dec 05 17:54:53 TDT 62.9 297.1
-21,000 Dec 04 10:14:28 TDT 62.9 297.1
-20,900 Dec 03 20:04:13 TDT 62.9 297.1
-20,800 Dec 02 13:31:26 TDT 62.9 297.1
-20,700 Dec 01 21:54:15 TDT 62.8 297.2
-20,600 Nov 30 16:46:47 TDT 62.8 297.2
-20,500 Nov 29 23:17:06 TDT 62.8 297.2
-20,400 Nov 28 20:05:20 TDT 62.8 297.2
-20,300 Nov 28 00:34:05 TDT 62.8 297.2
-20,200 Nov 27 00:42:46 TDT 62.7 297.3
-20,100 Nov 26 01:58:12 TDT 62.7 297.3
-20,000 Nov 25 05:03:05 TDT 62.7 297.3
-19,900 Nov 24 04:25:06 TDT 62.7 297.3
-19,800 Nov 23 09:22:28 TDT 62.7 297.3
-19,700 Nov 22 06:51:06 TDT 62.7 297.3
-19,600 Nov 21 13:44:23 TDT 62.6 297.4
-19,500 Nov 20 09:51:25 TDT 62.6 297.4
-19,400 Nov 19 17:35:04 TDT 62.6 297.4
-19,300 Nov 18 13:48:52 TDT 62.6 297.4
-19,200 Nov 17 21:55:01 TDT 62.6 297.4
-19,100 Nov 16 18:09:39 TDT 62.5 297.5
-19,000 Nov 16 01:49:28 TDT 62.5 297.5
-18,900 Nov 14 23:11:25 TDT 62.5 297.5
-18,800 Nov 14 05:43:04 TDT 62.5 297.5
-18,700 Nov 13 04:18:28 TDT 62.5 297.5
-18,600 Nov 12 10:13:32 TDT 62.4 297.6
-18,500 Nov 11 09:47:47 TDT 62.4 297.6
-18,400 Nov 10 14:13:34 TDT 62.4 297.6
-18,300 Nov 09 15:51:00 TDT 62.4 297.6
-18,200 Nov 08 18:32:57 TDT 62.4 297.6
-18,100 Nov 07 22:02:56 TDT 62.3 297.7
-18,000 Nov 06 23:38:02 TDT 62.3 297.7
-17,900 Nov 06 04:40:15 TDT 62.3 297.7
-17,800 Nov 05 05:15:21 TDT 62.3 297.7
-17,700 Nov 04 11:06:51 TDT 62.3 297.7
-17,600 Nov 03 11:00:06 TDT 62.2 297.8
-17,500 Nov 02 17:32:53 TDT 62.2 297.8
-17,400 Nov 01 17:04:15 TDT 62.2 297.8
-17,300 Nov 01 00:23:25 TDT 62.2 297.8
-17,200 Oct 31 00:17:52 TDT 62.1 297.9
-17,100 Oct 30 07:07:40 TDT 62.1 297.9
-17,000 Oct 29 07:47:16 TDT 62.1 297.9
-16,900 Oct 28 14:08:01 TDT 62.1 297.9
-16,800 Oct 27 15:22:29 TDT 62.1 297.9
-16,700 Oct 26 21:18:55 TDT 62.0 298.0
-16,600 Oct 25 23:26:26 TDT 62.0 298.0
-16,500 Oct 25 04:35:20 TDT 62.0 298.0
-16,400 Oct 24 07:48:35 TDT 62.0 298.0
-16,300 Oct 23 12:15:43 TDT 62.0 298.0
-16,200 Oct 22 16:56:26 TDT 61.9 298.1
-16,100 Oct 21 20:15:05 TDT 61.9 298.1
-16,000 Oct 21 01:49:32 TDT 61.9 298.1
-15,900 Oct 20 04:51:47 TDT 61.9 298.1
-15,800 Oct 19 10:43:18 TDT 61.9 298.1
-15,700 Oct 18 13:54:22 TDT 61.9

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

[Brad Lufkin]

Roger:
I think your spreadsheet, and specially the graphs, are spot-on! The key
point in answering John's original question is that, regardless of the
obliquity model one assumes, the values of the azimuth at sunrise at the
northern solstice only vary by about 5-6 degrees over the range of +2000 to
-23,000 years. I really doubt that a fence's alignment (if as old as
-23,000 years) can be measured to anywhere near that level of accuracy. So,
if the fence seems to be aligned at ~64 degrees, it might be an
astronomical instrument, but I'd sure like a lot more evidence.
Regards, Brad

On Sat, Jun 23, 2012 at 11:53 PM, Roger Bailey  wrote:

> **
> Hello John, Brad and all,
>
> John, you were correct in assuming some of us have been there and done
> these calculations. Brad, you were correct that Meeus's Algorithms have
> their limits. I have hacked a spreadsheet I have used to calculate Moslem
> Prayer times on really old sundials to give the table you were seeking, the
> azimuth of solstice events, based on several assumptions on the calculation
> of the solstice, declination, the obliquity of the earth's orbit. Meeus
> algorithm for obliquity is a cubic function of time that takes off with
> extreme periods of time. Obliquity is known to be periodic with a period of
> about 41,00 years. The revised spreadsheet calculates obliquity and hence
> declination at the solstice and the azimuth using both the Meeus algorithm
> and a data set used for the Milankovitch Cycles, Orbit 91 by Berger. They
> agree to 12,00 years ago and then show pronounced variations. One was
> devised for short term predictions, millennia while the other covers 5
> million years with data points only every thousand years. Which is correct?
> Neither! Does anyone have a better estimate for obliquity over tens of
> thousands of years? The "Explanatory Supplement to the Astronomical
> Almanac" has an algorithm very similar to Meeus. Is there anything better
> for John's purpose?
>
> In the attached spreadsheet, the user input parameters, latitude and the
> altitude of the horizon are highlighted with blue. The output is a couple
> of charts superimposed on the calculated data tables. This is a typical
> kludge spreadsheet, fit for purpose but somewhat abstruse. Hack as you wish
> to improve the output. The numbers are all there. I have done little error
> checking and I am error prone so reality checks would be appreciated. I am
> taking advantage of the symmetry of trig ambiguities. The azimuth
> calculated is from the north south axis for the solstices There is symmetry
> for the direction and angle. Set the signs to give the correct bearings for
> the season.
>
> This note is to all on the SML and has the spreadsheet attached. At 146
> kb, it may not get through the size filter. If so, I will resend the
> message and forward the spreadsheet to anyone interested.
>
> Regards,
> Roger Bailey
>
>  *From:* Brad Lufkin 
> *Sent:* Saturday, June 23, 2012 5:58 AM
> *To:* John Pickard 
> *Cc:* Sundial Mailing List 
> *Subject:* Re: Calculating azimuth of sunrise and sunset from present
> back 25,000 years
>
> Dear John:
> I may be able to help. I can write a custom program that would generate
> the data you are asking for. There is a glitch, however, and that is the
> accuracy of the models to be used over such a long period of time. In
> particular, I would use the following models:
> (a) VSOP87D for the position of the Sun.
> (b) Equations from Chapter 22 of Meeus's Astronomical Algorithms, 2nd
> Edition, for the obliquity of the ecliptic.
> I'm not too concerned about (a). The use of (b), however, implies the
> attached graph for the obliquity. I have no way of judging whether this is
> reasonable. It matches the Figure on page 148 of Meeus where the two are
> comparable (no surprise there), but Meeus's graph only goes back to -8000,
> whereas you are looking to go back to -23,000.
> In any case, I plan on proceeding, since this looks like an interesting
> exercise! In the meantime, could you tell me what the latitude of the place
> of interest is?
> Best regards, Brad
>
> On Thu, Jun 21, 2012 at 12:55 AM, John Pickard 
> wrote:
>
>> **
>> Good evening on a chilly Winter Solstice in Sydney,
>>
>> As part of my research on fences, I need to calculate the azimuth of
>> sunrise and sunset back to 25,000 y ago. The question arises from the
>> disputed origins of some dry stone walls found in southern New South
>> Wales. A local historian has suggested that they are an astronomical
>> alignment built by Aborigines, but they were recorded as fences on survey
>> plans in the late 19th C. The locations suggest to me that the walls were
>&g

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

[Brad Lufkin]

Dear John:
I may be able to help. I can write a custom program that would generate the
data you are asking for. There is a glitch, however, and that is the
accuracy of the models to be used over such a long period of time. In
particular, I would use the following models:
(a) VSOP87D for the position of the Sun.
(b) Equations from Chapter 22 of Meeus's Astronomical Algorithms, 2nd
Edition, for the obliquity of the ecliptic.
I'm not too concerned about (a). The use of (b), however, implies the
attached graph for the obliquity. I have no way of judging whether this is
reasonable. It matches the Figure on page 148 of Meeus where the two are
comparable (no surprise there), but Meeus's graph only goes back to -8000,
whereas you are looking to go back to -23,000.
In any case, I plan on proceeding, since this looks like an interesting
exercise! In the meantime, could you tell me what the latitude of the place
of interest is?
Best regards, Brad

On Thu, Jun 21, 2012 at 12:55 AM, John Pickard wrote:

> **
> Good evening on a chilly Winter Solstice in Sydney,
>
> As part of my research on fences, I need to calculate the azimuth of
> sunrise and sunset back to 25,000 y ago. The question arises from the
> disputed origins of some dry stone walls found in southern New South
> Wales. A local historian has suggested that they are an astronomical
> alignment built by Aborigines, but they were recorded as fences on survey
> plans in the late 19th C. The locations suggest to me that the walls were
> built as fences on terrain too steep for the log fences of the time.
>
> What I would like to is calculate the azimuths of sunrise and sunset at
> Winter Solstice back 25,000 y (about the length of time Aborigines occupied
> the area) in annual increments (or decrements to be pedantic!). I know that
> I can do this for any specific date in a number of excellent programs, but
> I don't relish the notion of that many calculations. Even if I increase the
> interval to 100 y, I would still have 250 calculations.
>
> My question is: does anyone know of a way of automating this to generate a
> table of the dates and the azimuth of sunrise and sunset?
>
>
> Many thanks, John
>
> John Pickard
> john.pick...@bigpond.com
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
<>---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Sundials in cinema

[Brad Lufkin]

The two light sources are the whole point of the movie! So I shan't say
more. BTW, it's a visually stunning piece of work, though a bit bizarre in
other respects.
Brad

On Sun, Dec 18, 2011 at 7:52 PM, Bill Gottesman
wrote:

> The dial and the trees show two shadows from different light sources.
>  Would it give too much away to explain why that is?  -Bill
>
> On Sun, Dec 18, 2011 at 5:36 PM, Darek Oczki  wrote:
>
>> Dear friends
>>
>> I've got two news for those interested in sundials in movies.
>>
>> 1. In the very beginning of the latest movie by Lars von Trier
>> (Melancholia) there is a nice scene shoving a close view of a horizontal
>> sundial. Screenshot attached. Later it appears in the film several times
>> more but only from a distance.
>>
>> 2. There is an Indian movie comapany Sundial Pictures. They have an
>> interesting sundial animation used as their motion logo. Follow the link
>> below to watch it:
>>
>> http://sundialpictures.in/index.html
>>
>> --
>> Best regards
>> Darek Oczki
>> 52N 21E
>> Warsaw, Poland
>>
>> GNOMONIKA.pl
>> Sundials in Poland
>> http://gnomonika.pl
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>>
>>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
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Re: Lunar Eclipse of 2011 Dec 10

[Brad Lufkin]

John:
We can predict the eclipses. The weather, on the other hand, is not yet
under under our control.
Cheers, Brad

On Fri, Dec 9, 2011 at 10:32 PM, John Pickard wrote:

> **
> Hi Brad,
>
> The eclipse tonight (Sydney time) has made it to out national news, both
> on radio and TV.
>
>
> http://www.abc.net.au/news/2011-12-09/rain-may-spoil-blood-red-eclipse/3723564
>
> Unfortunately, it's currently totally overcast, with no break expected.
>
>
> Cheers, John
>
> John Pickard
> john.pick...@bigpond.com
> In cloudy northern Sydney (and with nothing worth watching on TV as a
> substitute for an eclipse)
>
> - Original Message -
> *From:* Brad Lufkin 
> *To:* Sundial Mailing List 
> *Sent:* Thursday, December 08, 2011 6:05 PM
> *Subject:* Lunar Eclipse of 2011 Dec 10
>
> I thought some of you might be interested in the upcoming lunar eclipse on
> the 10th of this month. I've attached a diagram showing the regions of
> visibility of the eclipse.
> Brad
>
> --
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---
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Lunar Eclipse of 2011 Dec 10

[Brad Lufkin]

I thought some of you might be interested in the upcoming lunar eclipse on
the 10th of this month. I've attached a diagram showing the regions of
visibility of the eclipse.
Brad
<>---
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Re: Re: Re: RE: R: Where it wil be equinox, at noon

[Brad Lufkin]

Roger:
Blast!
My program predicts the time as 2012 Mar 20 05:15:3*3* DT, not 05:15:3*2*.
All kidding aside: as I said in a previous post, I think the difference is
that I'm using a too-simple nutation model.
I hope I haven't strained the patience of those sundialists whose interests
don't extend to these arcana.
Brad

On Fri, Sep 30, 2011 at 9:09 AM, Roger W. Sinnott  wrote:

> **Ø  **The full version is available from. . .
>
> ** **
>
> Brad,
>
> ** **
>
> So it is! – Thanks very much for letting me know about this.
>
> ** **
>
> But VSOP87 is about of the same vintage as the older JPL ephemeris DE200,
> about 25 years ago.  JPL is now up to DE421, and calculations consistent
> with DE421 are available from the free computer program SOLEX, written by
> Aldo Vitagliano:
>
> http://chemistry.unina.it/~alvitagl/solex/
>
> ** **
>
> I just tried Solex 11.0, using DE421 with aberration and nutation turned
> on, and found that the apparent geocentric ecliptic longitude of the Sun
> will be 0deg 00’ 00.00” at 5h 15m 32s Dynamical Time on 2012 March 20.  So
> in this case it does agree to the second with Meeus’s 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...@libero.it; Sundial Mailing List
> *Subject:* Re: Re: Re: RE: R: Where it wil be equinox, at noon
>
> ** **
>
> Roger:
> I'm pretty sure I am using the full theory. I'm definitely not using the
> abridged form from Meuus's Appendix.
>
> The full version is available from an FTP server. But I found (I confess I
> don't remember where) an ASCII text file that, based on a more than cursory
> examination, seems to be an exact match to the version available from the
> FTP server.
> You can find a link to the FTP server at the end of the wiki article on
> VSOP.
>
> The wiki article is at:
> http://en.wikipedia.org/wiki/Secular_variations_of_the_planetary_orbits
>
> The FTP server is at:
> ftp://ftp.imcce.fr/pub/ephem/planets/vsop87/
>
> Regards, Brad
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
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Re: Re: Re: RE: R: Where it wil be equinox, at noon

[Brad Lufkin]

Sincere apologies to Mr Meeus, whose last name I've been misspelling. His
book (Astronomical Algorithms) has been a revelation about how to write
about applied mathematical astronomy.
With deepest respect, Brad

On Fri, Sep 30, 2011 at 8:24 AM, Brad Lufkin wrote:

> Roger:
> I'm pretty sure I am using the full theory. I'm definitely not using the
> abridged form from Meuus's Appendix.
>
> The full version is available from an FTP server. But I found (I confess I
> don't remember where) an ASCII text file that, based on a more than cursory
> examination, seems to be an exact match to the version available from the
> FTP server.
> You can find a link to the FTP server at the end of the wiki article on
> VSOP.
>
> The wiki article is at:
> http://en.wikipedia.org/wiki/Secular_variations_of_the_planetary_orbits
>
> The FTP server is at:
> ftp://ftp.imcce.fr/pub/ephem/planets/vsop87/
>
> Regards, Brad
>
> On Fri, Sep 30, 2011 at 7:40 AM, Roger W. Sinnott <
> rsinn...@post.harvard.edu> wrote:
>
>> 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, Sep 29, 2011 at 2:24 PM, Brad Lufkin 
>> wrote:
>>
>> Gian:
>> Continuing my investigation, I tried to reproduce Table 27.E of Meuus's
>> Astro Algorithms, 2nd Edition. The table shows the time, to the nearest
>> second, of the solstices and equinoxes for the years 1996-2005. The table is
>> based on the full VSOP87 theory.
>> I too am using the full theory, along with the corrections for aberration
>> and nutation (though I'm using the simpler version of the nutation model
>> described in chapter 22 of Meuus--this may be significant).
>> In any case, the following histogram shows the difference in seconds
>> between my results and Meuus's table:
>>
>> -4 x
>> -3 
>> -2 
>> -1 x
>>  0 x
>> +1 xx
>> +2 
>> +3 xx
>> +4 x
>>
>> So what the histogram shows is that we have exact agreement in 5 out of 40
>> cases, +1 second difference in 10 out of 40 cases, -1 second difference in 5
>> out of 40 cases, and so on. In no case is the difference greater than 4
>> seconds (which corresponds to a difference of one-sixth of an arcsecond).
>> The histogram seems fairly normal, with no clear evidence of systematic
>> bias.
>> I plan on implementing the more accurate nutation model. I'll let you know
>> what happens.
>> Regards, Brad
>>
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>>
>>
>
---
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Re: Re: Re: RE: R: Where it wil be equinox, at noon

[Brad Lufkin]

Roger:
I'm pretty sure I am using the full theory. I'm definitely not using the
abridged form from Meuus's Appendix.

The full version is available from an FTP server. But I found (I confess I
don't remember where) an ASCII text file that, based on a more than cursory
examination, seems to be an exact match to the version available from the
FTP server.
You can find a link to the FTP server at the end of the wiki article on
VSOP.

The wiki article is at:
http://en.wikipedia.org/wiki/Secular_variations_of_the_planetary_orbits

The FTP server is at:
ftp://ftp.imcce.fr/pub/ephem/planets/vsop87/

Regards, Brad

On Fri, Sep 30, 2011 at 7:40 AM, Roger W. Sinnott  wrote:

> 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, Sep 29, 2011 at 2:24 PM, Brad Lufkin 
> wrote:
>
> Gian:
> Continuing my investigation, I tried to reproduce Table 27.E of Meuus's
> Astro Algorithms, 2nd Edition. The table shows the time, to the nearest
> second, of the solstices and equinoxes for the years 1996-2005. The table is
> based on the full VSOP87 theory.
> I too am using the full theory, along with the corrections for aberration
> and nutation (though I'm using the simpler version of the nutation model
> described in chapter 22 of Meuus--this may be significant).
> In any case, the following histogram shows the difference in seconds
> between my results and Meuus's table:
>
> -4 x
> -3 
> -2 
> -1 x
>  0 x
> +1 xx
> +2 
> +3 xx
> +4 x
>
> So what the histogram shows is that we have exact agreement in 5 out of 40
> cases, +1 second difference in 10 out of 40 cases, -1 second difference in 5
> out of 40 cases, and so on. In no case is the difference greater than 4
> seconds (which corresponds to a difference of one-sixth of an arcsecond).
> The histogram seems fairly normal, with no clear evidence of systematic
> bias.
> I plan on implementing the more accurate nutation model. I'll let you know
> what happens.
> Regards, Brad
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

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

[Brad Lufkin]

Gian:
I'm becoming convinced that the use of the simpler nutation model is the
culprit. I did a detailed analysis of a case where the difference between
Meuus and my result is 1 second, and it turns out that the simpler nutation
model differs from the more complex one by an amount that accounts for 0.8
seconds.
According to Meuus, the simpler nutation model can be off by 0.5 arcseconds,
which translates into as much as an error of 12 seconds.
More to follow.
Regards, Brad

On Thu, Sep 29, 2011 at 2:24 PM, Brad Lufkin wrote:

> Gian:
> Continuing my investigation, I tried to reproduce Table 27.E of Meuus's
> Astro Algorithms, 2nd Edition. The table shows the time, to the nearest
> second, of the solstices and equinoxes for the years 1996-2005. The table is
> based on the full VSOP87 theory.
> I too am using the full theory, along with the corrections for aberration
> and nutation (though I'm using the simpler version of the nutation model
> described in chapter 22 of Meuus--this may be significant).
> In any case, the following histogram shows the difference in seconds
> between my results and Meuus's table:
>
> -4 x
> -3 
> -2 
> -1 x
>  0 x
> +1 xx
> +2 
> +3 xx
> +4 x
>
> So what the histogram shows is that we have exact agreement in 5 out of 40
> cases, +1 second difference in 10 out of 40 cases, -1 second difference in 5
> out of 40 cases, and so on. In no case is the difference greater than 4
> seconds (which corresponds to a difference of one-sixth of an arcsecond).
> The histogram seems fairly normal, with no clear evidence of systematic
> bias.
> I plan on implementing the more accurate nutation model. I'll let you know
> what happens.
> Regards, Brad
>
>
> On Wed, Sep 28, 2011 at 3:36 AM, sun.di...@libero.it 
> wrote:
>
>> Many thanks Brad, that really makes me feel better !
>>
>> I will let you know the results of my analysis.
>>
>> Ciao.
>>
>> Gian
>>
>> Messaggio originale
>> Da: bradley.luf...@gmail.com
>> Data: 28/09/2011 3.58
>>
>> A: "sun.di...@libero.it"
>> Cc: "Sundial Mailing List"
>> Ogg: Re: Re: RE: R: Where it wil be equinox, at noon
>>
>> Gian:
>> I calculated the longitude using VSOP87D and all the corrections mentioned
>> in Meuus's Astro Algorithms and, if it makes you feel any better, my result
>> agrees with yours (i.e., the Sun's longitude is closest to 180 degrees at
>> 9:05:41 DT).
>> Brad
>>
>>
>> On Tue, Sep 27, 2011 at 2:22 PM, sun.di...@libero.it > > wrote:
>>
>>> Brad,
>>>
>>> sun parameters are computed by OS using the VSOP87 theory as for Meeus
>>> results.
>>>
>>> Aberration and nutation are taken into account (or they should be, this
>>> is one of the points I have to check).
>>>
>>> I did not interpolate but just manually changed the simulation time in
>>> order to get 180.0 degrees for the sun longitude.
>>>
>>> Therefore I guess I really have to check my code.
>>>
>>> Of course the error is trivial, but it can / it must be removed.
>>>
>>> Ciao.
>>>
>>> Gian
>>>
>>> Messaggio originale
>>> Da: bradley.luf...@gmail.com
>>> Data: 27/09/2011 12.01
>>> A: "sun.di...@libero.it"
>>> Cc: "Sundial Mailing List"
>>> Ogg: Re: RE: R: Where it wil be equinox, at noon
>>>
>>> Gian et al:
>>> I need to take back my last statement: it turns out that VSOP is accurate
>>> to about 10**(-6) degrees.
>>> Brad
>>>
>>>   On Tue, Sep 27, 2011 at 5:36 AM, Brad Lufkin >> > wrote:
>>>
>>>>  Gian:
>>>> it's likely that the difference between your result and the result in
>>>> Meuus is due to (a) the complexity of the model used and (b) effects
>>>> included or ignored (such as aberration, nutation, and so on). Let's
>>>> remember that the average speed of the Sun in longitude is on the order of
>>>> 10**(-5) degrees/second, so a difference of 3 seconds is trivial. Also,
>>>> determining when the longitude is exactly 180 degrees requires some sort of
>>>> approximation or interpolation, since the longitude is on the left-hand 
>>>> side
>>>> of the relevant equations whereas time is on the right-hand side (i.e., 
>>>> time
>>>> is an input, longitude an output). It's also worth noting that none of the
>>>> models commonly used (includ

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

[Brad Lufkin]

Gian:
Continuing my investigation, I tried to reproduce Table 27.E of Meuus's
Astro Algorithms, 2nd Edition. The table shows the time, to the nearest
second, of the solstices and equinoxes for the years 1996-2005. The table is
based on the full VSOP87 theory.
I too am using the full theory, along with the corrections for aberration
and nutation (though I'm using the simpler version of the nutation model
described in chapter 22 of Meuus--this may be significant).
In any case, the following histogram shows the difference in seconds between
my results and Meuus's table:

-4 x
-3 
-2 
-1 x
 0 x
+1 xx
+2 
+3 xx
+4 x

So what the histogram shows is that we have exact agreement in 5 out of 40
cases, +1 second difference in 10 out of 40 cases, -1 second difference in 5
out of 40 cases, and so on. In no case is the difference greater than 4
seconds (which corresponds to a difference of one-sixth of an arcsecond).
The histogram seems fairly normal, with no clear evidence of systematic
bias.
I plan on implementing the more accurate nutation model. I'll let you know
what happens.
Regards, Brad

On Wed, Sep 28, 2011 at 3:36 AM, sun.di...@libero.it wrote:

> Many thanks Brad, that really makes me feel better !
>
> I will let you know the results of my analysis.
>
> Ciao.
>
> Gian
>
> Messaggio originale
> Da: bradley.luf...@gmail.com
> Data: 28/09/2011 3.58
>
> A: "sun.di...@libero.it"
> Cc: "Sundial Mailing List"
> Ogg: Re: Re: RE: R: Where it wil be equinox, at noon
>
> Gian:
> I calculated the longitude using VSOP87D and all the corrections mentioned
> in Meuus's Astro Algorithms and, if it makes you feel any better, my result
> agrees with yours (i.e., the Sun's longitude is closest to 180 degrees at
> 9:05:41 DT).
> Brad
>
>
> On Tue, Sep 27, 2011 at 2:22 PM, sun.di...@libero.it 
> wrote:
>
>> Brad,
>>
>> sun parameters are computed by OS using the VSOP87 theory as for Meeus
>> results.
>>
>> Aberration and nutation are taken into account (or they should be, this is
>> one of the points I have to check).
>>
>> I did not interpolate but just manually changed the simulation time in
>> order to get 180.0 degrees for the sun longitude.
>>
>> Therefore I guess I really have to check my code.
>>
>> Of course the error is trivial, but it can / it must be removed.
>>
>> Ciao.
>>
>> Gian
>>
>> Messaggio originale
>> Da: bradley.luf...@gmail.com
>> Data: 27/09/2011 12.01
>> A: "sun.di...@libero.it"
>> Cc: "Sundial Mailing List"
>> Ogg: Re: RE: R: Where it wil be equinox, at noon
>>
>> Gian et al:
>> I need to take back my last statement: it turns out that VSOP is accurate
>> to about 10**(-6) degrees.
>> Brad
>>
>>   On Tue, Sep 27, 2011 at 5:36 AM, Brad Lufkin 
>> wrote:
>>
>>>  Gian:
>>> it's likely that the difference between your result and the result in
>>> Meuus is due to (a) the complexity of the model used and (b) effects
>>> included or ignored (such as aberration, nutation, and so on). Let's
>>> remember that the average speed of the Sun in longitude is on the order of
>>> 10**(-5) degrees/second, so a difference of 3 seconds is trivial. Also,
>>> determining when the longitude is exactly 180 degrees requires some sort of
>>> approximation or interpolation, since the longitude is on the left-hand side
>>> of the relevant equations whereas time is on the right-hand side (i.e., time
>>> is an input, longitude an output). It's also worth noting that none of the
>>> models commonly used (including VSOP) is accurate to that level.
>>> Brad
>>>
>>>On Tue, Sep 27, 2011 at 2:47 AM, sun.di...@libero.it <
>>> sun.di...@libero.it> wrote:
>>>
>>>>Axel,
>>>>
>>>> from "Astronomical tables of the Sun, Moon and Planets", Jean Meeus,
>>>> second edition, page 151: Semptember equinox in 2011 is on day 23rd at
>>>> 9:05:44 (Dinamical Time). To convert to Universal Time one must subtract 
>>>> the
>>>> value of DeltaT.
>>>>
>>>>
>>>> Orologi Solari considers a value of DeltaT = 67.5 so that the equinox
>>>> time should be 9:04:36 (UT) while the value computed by OS is 3 seconds
>>>> earlier. I need to investigate on this (although small) difference.
>>>>
>>>>
>>>> Ciao.
>>>>
>>>> Gian
>>>>
>>>>
>>>>
>>>>  -

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

[Brad Lufkin]

Gian:
I calculated the longitude using VSOP87D and all the corrections mentioned
in Meuus's Astro Algorithms and, if it makes you feel any better, my result
agrees with yours (i.e., the Sun's longitude is closest to 180 degrees at
9:05:41 DT).
Brad

On Tue, Sep 27, 2011 at 2:22 PM, sun.di...@libero.it wrote:

> Brad,
>
> sun parameters are computed by OS using the VSOP87 theory as for Meeus
> results.
>
> Aberration and nutation are taken into account (or they should be, this is
> one of the points I have to check).
>
> I did not interpolate but just manually changed the simulation time in
> order to get 180.0 degrees for the sun longitude.
>
> Therefore I guess I really have to check my code.
>
> Of course the error is trivial, but it can / it must be removed.
>
> Ciao.
>
> Gian
>
> Messaggio originale
> Da: bradley.luf...@gmail.com
> Data: 27/09/2011 12.01
> A: "sun.di...@libero.it"
> Cc: "Sundial Mailing List"
> Ogg: Re: RE: R: Where it wil be equinox, at noon
>
> Gian et al:
> I need to take back my last statement: it turns out that VSOP is accurate
> to about 10**(-6) degrees.
> Brad
>
> On Tue, Sep 27, 2011 at 5:36 AM, Brad Lufkin wrote:
>
>> Gian:
>> it's likely that the difference between your result and the result in
>> Meuus is due to (a) the complexity of the model used and (b) effects
>> included or ignored (such as aberration, nutation, and so on). Let's
>> remember that the average speed of the Sun in longitude is on the order of
>> 10**(-5) degrees/second, so a difference of 3 seconds is trivial. Also,
>> determining when the longitude is exactly 180 degrees requires some sort of
>> approximation or interpolation, since the longitude is on the left-hand side
>> of the relevant equations whereas time is on the right-hand side (i.e., time
>> is an input, longitude an output). It's also worth noting that none of the
>> models commonly used (including VSOP) is accurate to that level.
>> Brad
>>
>>   On Tue, Sep 27, 2011 at 2:47 AM, sun.di...@libero.it <
>> sun.di...@libero.it> wrote:
>>
>>>   Axel,
>>>
>>> from "Astronomical tables of the Sun, Moon and Planets", Jean Meeus,
>>> second edition, page 151: Semptember equinox in 2011 is on day 23rd at
>>> 9:05:44 (Dinamical Time). To convert to Universal Time one must subtract the
>>> value of DeltaT.
>>>
>>>
>>> Orologi Solari considers a value of DeltaT = 67.5 so that the equinox
>>> time should be 9:04:36 (UT) while the value computed by OS is 3 seconds
>>> earlier. I need to investigate on this (although small) difference.
>>>
>>>
>>> Ciao.
>>>
>>> Gian
>>>
>>>
>>>
>>> Messaggio originale
>>> Da: atg...@hotmail.com
>>> Data: 24/09/2011 22.33
>>> A: , "Sundials"
>>> Ogg: RE: R: Where it wil be equinox, at noon
>>>
>>> Thanks for your answers, and for you Fabio that personally wrote to my
>>> mail,
>>>
>>>  We all arrived at different results, but the differences are minute
>>>  in longitude and with a circumference of the earth at latitude 0 °,
>>> (Equator)
>>>  of which is 40.075,036 kilometers, every minute of that difference is
>>> 1.855,32 meters
>>>  for purposes of building a sundials they are not important. But in
>>> mathematics
>>>  uuuf.
>>>
>>>  I think each one has its source, and are different and the problem
>>>  is that we come to different results.
>>>
>>>  James Morrison, with "Electric Astrolabe",
>>>
>>> 42 ° 20'59 "EAST, UT 9:10:36
>>>  The calculated (12:00:00 -09:10:36) * 15 °
>>>
>>> David Patte, with "Time Zone Master",
>>> 
>>>  41
>>> ° 52'45 "EAST, UT 9:12:28
>>> The calculated (12:00:00 -09:12:28-1) * 15 ° ... it, -1
>>>
>>> Gian, "Orologi-Solari"
>>> 
>>>  41
>>> ° 59'30 "EAST, UT 9:04:33
>>>  The calculated is  (12:00:00 -09:04:33-449) * 15  449 Eot
>>>
>>>  Me Axel, R. Cernica Sun v.5.6  42 ° 12'48 "EAST UT 9:03:42
>>>  The calculation (12:00:00 -09:03:42-446.68) * 15 ° ... 446.68
>>>
>>> where is the right thing
>>>
>>> My best regards for al

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

[Brad Lufkin]

Gian et al:
I need to take back my last statement: it turns out that VSOP is accurate to
about 10**(-6) degrees.
Brad

On Tue, Sep 27, 2011 at 5:36 AM, Brad Lufkin wrote:

> Gian:
> it's likely that the difference between your result and the result in Meuus
> is due to (a) the complexity of the model used and (b) effects included or
> ignored (such as aberration, nutation, and so on). Let's remember that the
> average speed of the Sun in longitude is on the order of 10**(-5)
> degrees/second, so a difference of 3 seconds is trivial. Also, determining
> when the longitude is exactly 180 degrees requires some sort of
> approximation or interpolation, since the longitude is on the left-hand side
> of the relevant equations whereas time is on the right-hand side (i.e., time
> is an input, longitude an output). It's also worth noting that none of the
> models commonly used (including VSOP) is accurate to that level.
> Brad
>
> On Tue, Sep 27, 2011 at 2:47 AM, sun.di...@libero.it 
> wrote:
>
>> Axel,
>>
>> from "Astronomical tables of the Sun, Moon and Planets", Jean Meeus,
>> second edition, page 151: Semptember equinox in 2011 is on day 23rd at
>> 9:05:44 (Dinamical Time). To convert to Universal Time one must subtract the
>> value of DeltaT.
>>
>>
>> Orologi Solari considers a value of DeltaT = 67.5 so that the equinox time
>> should be 9:04:36 (UT) while the value computed by OS is 3 seconds earlier.
>> I need to investigate on this (although small) difference.
>>
>>
>> Ciao.
>>
>> Gian
>>
>>
>>
>> Messaggio originale
>> Da: atg...@hotmail.com
>> Data: 24/09/2011 22.33
>> A: , "Sundials"
>> Ogg: RE: R: Where it wil be equinox, at noon
>>
>> Thanks for your answers, and for you Fabio that personally wrote to my
>> mail,
>>
>>  We all arrived at different results, but the differences are minute
>>  in longitude and with a circumference of the earth at latitude 0 °,
>> (Equator)
>>  of which is 40.075,036 kilometers, every minute of that difference is
>> 1.855,32 meters
>>  for purposes of building a sundials they are not important. But in
>> mathematics
>>  uuuf.
>>
>>  I think each one has its source, and are different and the problem
>>  is that we come to different results.
>>
>>  James Morrison, with "Electric Astrolabe",
>>
>> 42 ° 20'59 "EAST, UT 9:10:36
>>  The calculated (12:00:00 -09:10:36) * 15 °
>>
>> David Patte, with "Time Zone Master",
>>  
>> 41
>> ° 52'45 "EAST, UT 9:12:28
>> The calculated (12:00:00 -09:12:28-1) * 15 ° ... it, -1
>>
>> Gian, "Orologi-Solari"
>>  
>> 41
>> ° 59'30 "EAST, UT 9:04:33
>>  The calculated is  (12:00:00 -09:04:33-449) * 15  449 Eot
>>
>>  Me Axel, R. Cernica Sun v.5.6  42 ° 12'48 "EAST UT 9:03:42
>>  The calculation (12:00:00 -09:03:42-446.68) * 15 ° ... 446.68
>>
>> where is the right thing
>>
>> My best regards for all the list
>> and sorry my english
>> Axel
>> 32°39'59" S
>> 70°42'41" W
>>
>>
>>
>>  --
>> Date: Sat, 24 Sep 2011 15:33:58 +0200
>> From: sun.di...@libero.it
>> To: sundial@uni-koeln.de
>> Subject: R: Where it wil be equinox, at noon
>>
>> Here is my answer to Axel's question.
>>
>> With "Orologi Solari" in simulation mode, looking for the time of sun
>> longitude = 180 degrees, I find:
>> my time (TMEC + DST) = 11:04:33 that corresponds to GMT 9:04:33.
>>
>> At that time sun is on the local meridian of a place with longitude =
>> (12:00:00 - 9:04:33 - EoT)*15 = 41:59:30 east.
>>
>> A verification can be done by setting in OS 41:59:30 E 0:0:0 N (a place in
>> Somalia) and then verifying in simulation mode that at 11:04:33 (my time)
>> the local time is really 12:00:00.
>>
>> Ciao.
>> Gian
>> http://digilander.libero.it/orologi.solari
>>
>> Messaggio originale
>> Da: atg...@hotmail.com
>> Data: 23/09/2011 2.57
>> A: 
>> Ogg: Where it wil be equinox, at noon
>>
>>  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

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

[Brad Lufkin]

Gian:
it's likely that the difference between your result and the result in Meuus
is due to (a) the complexity of the model used and (b) effects included or
ignored (such as aberration, nutation, and so on). Let's remember that the
average speed of the Sun in longitude is on the order of 10**(-5)
degrees/second, so a difference of 3 seconds is trivial. Also, determining
when the longitude is exactly 180 degrees requires some sort of
approximation or interpolation, since the longitude is on the left-hand side
of the relevant equations whereas time is on the right-hand side (i.e., time
is an input, longitude an output). It's also worth noting that none of the
models commonly used (including VSOP) is accurate to that level.
Brad

On Tue, Sep 27, 2011 at 2:47 AM, sun.di...@libero.it wrote:

> Axel,
>
> from "Astronomical tables of the Sun, Moon and Planets", Jean Meeus, second
> edition, page 151: Semptember equinox in 2011 is on day 23rd at 9:05:44
> (Dinamical Time). To convert to Universal Time one must subtract the value
> of DeltaT.
>
>
> Orologi Solari considers a value of DeltaT = 67.5 so that the equinox time
> should be 9:04:36 (UT) while the value computed by OS is 3 seconds earlier.
> I need to investigate on this (although small) difference.
>
>
> Ciao.
>
> Gian
>
>
>
> Messaggio originale
> Da: atg...@hotmail.com
> Data: 24/09/2011 22.33
> A: , "Sundials"
> Ogg: RE: R: Where it wil be equinox, at noon
>
> Thanks for your answers, and for you Fabio that personally wrote to my
> mail,
>
>  We all arrived at different results, but the differences are minute
>  in longitude and with a circumference of the earth at latitude 0 °,
> (Equator)
>  of which is 40.075,036 kilometers, every minute of that difference is
> 1.855,32 meters
>  for purposes of building a sundials they are not important. But in
> mathematics
>  uuuf.
>
>  I think each one has its source, and are different and the problem
>  is that we come to different results.
>
>  James Morrison, with "Electric Astrolabe",
>
> 42 ° 20'59 "EAST, UT 9:10:36
>  The calculated (12:00:00 -09:10:36) * 15 °
>
> David Patte, with "Time Zone Master",
>  
> 41
> ° 52'45 "EAST, UT 9:12:28
> The calculated (12:00:00 -09:12:28-1) * 15 ° ... it, -1
>
> Gian, "Orologi-Solari"
>  
> 41
> ° 59'30 "EAST, UT 9:04:33
>  The calculated is  (12:00:00 -09:04:33-449) * 15  449 Eot
>
>  Me Axel, R. Cernica Sun v.5.6  42 ° 12'48 "EAST UT 9:03:42
>  The calculation (12:00:00 -09:03:42-446.68) * 15 ° ... 446.68
>
> where is the right thing
>
> My best regards for all the list
> and sorry my english
> Axel
> 32°39'59" S
> 70°42'41" W
>
>
>
>  --
> Date: Sat, 24 Sep 2011 15:33:58 +0200
> From: sun.di...@libero.it
> To: sundial@uni-koeln.de
> Subject: R: Where it wil be equinox, at noon
>
> Here is my answer to Axel's question.
>
> With "Orologi Solari" in simulation mode, looking for the time of sun
> longitude = 180 degrees, I find:
> my time (TMEC + DST) = 11:04:33 that corresponds to GMT 9:04:33.
>
> At that time sun is on the local meridian of a place with longitude =
> (12:00:00 - 9:04:33 - EoT)*15 = 41:59:30 east.
>
> A verification can be done by setting in OS 41:59:30 E 0:0:0 N (a place in
> Somalia) and then verifying in simulation mode that at 11:04:33 (my time)
> the local time is really 12:00:00.
>
> Ciao.
> Gian
> http://digilander.libero.it/orologi.solari
>
> Messaggio originale
> Da: atg...@hotmail.com
> Data: 23/09/2011 2.57
> A: 
> Ogg: Where it wil be equinox, at noon
>
>  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°39'59"S
> 70°42'41"W
>
>
>
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Walking Shadow Riddle

[Brad Lufkin]

My guess is he ends up where he started, i.e., the wise man is telling him,
in the usual pseudo-wise ways of pseudo-wise movies, that he already has the
treasure but just doesn't realize it.

On Tue, Sep 6, 2011 at 2:08 PM, John Carmichael wrote:

>  A Riddle:
>
> ** **
>
> I was watching a dumb movie last weekend and there was a bit of dialogue
> that caught my attention.  I’m sure this relates to sundials and mapping,
> but the answer eludes me.
>
> ** **
>
> One of the characters was told by the wise man to: “walk towards your
> shadow all day, starting at sunrise and stopping at sunset” at which point
> the walker would discover the location of a treasure.
>
> ** **
>
> So I asked myself, *what would the path of the trek look like on a map?*But I 
> can’t figure it out.  This is as far as I get in my thinking: I
> started considering an example with these conditions.- The walk begins at
> dawn on the equinox, and the man is on the equator. And the walk ends at
> sunset.  So we know that the walk will last twelve hours. If the average
> speed of a walking man is 5 km/hr. , it is 12 hours from sunrise to sunset;
> then we know that he will walk  60 km.  He’ll start walking towards the west
> at dawn and his path will turn towards the north in the morning as the sun
> heads south.  After Solar Noon, his path will turn towards the east he’ll
> end up facing due east at sunset. And we know that the path will be a curve
> since his shadow will always be changing direction.  But what would the
> curve look like on a map?  Would it be a hyperbola? How would the curve
> change if he walks on the summer solstice instead?   What if he’s at the
> North Pole?
>
> ** **
>
> John C.
>
> ** **
>
> ** **
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
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Re: Google's Art Project and dialling

[Brad Lufkin]

It must be acknowledged, though, that Mr Hockney's views are not shared by
the majority of art historians. As always, caveat emptor.
Brad

On Fri, Feb 4, 2011 at 1:40 PM, Jackie Jones  wrote:

> Dear All,
>
> To read more about the structure of *The Ambassadors*, I can recommend *Secret
> Knowledge* by David Hockney (Thames and Hudson, 2001).  He discusses,
> amongst other topics, the different vanishing points of the 2 books on the
> lower table, suggesting that they seen from different viewpoints at
> different times.  To get the accuracy in the picture, he believes they used
> a room camera obscura and a camera lucida.The scull could have been
> distorted so accurately by tilting the surface onto which the image is
> projected; Hockney has squeezed it back into shape on a computer.
>
> Best wishes,
>
> Jackie Jones
>
>
>
> *From:* sundial-boun...@uni-koeln.de [mailto:sundial-boun...@uni-koeln.de]
> *On Behalf Of *Kevin Karney
> *Sent:* 04 February 2011 16:49
> *To:* patrick_pow...@compuserve.com
> *Cc:* sund...@rrz.uni-koeln.de
> *Subject:* Re: Google's Art Project and dialling
>
>
>
> Now take a look at Holbein's *Nicholas Kratzer, *painted in 1528 which is
> in the Louvre (copy in National Portrait Gallery). Kratzer was a German
> mathematician, astronomer and instrument maker who worked as King Henry
> VIII's astrologer. He was a drinking friend of Holbein. Find his picture in
> the Wikepedia entry for Nicholas Kratzer.
>
>
>
> Holbein was probably using Kratzer's instruments in the Ambassador's
> picture, which was painted a few years later in 1533. Same shepherd's dial,
> same strange instrument, same polyhedral dial (but unfinished), same little
> dial-like thing with the spike and square hole on his table.
>
>
>
> Best regards
>
> Kevin Karney
> Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK
> 51° 44' N 2° 41' W Zone 0
> + 44 1594 530 595
>
> On 4 Feb 2011, at 07:59, patrick_pow...@compuserve.com wrote:
>
>
>
>
> After only recently learning of the Google Art Project, I looked at
> Holbein's *Ambassadors *today and like many others I was amazed at the
> resolution. This huge painting, it's not far off 7ft square, is here in
> London at the National Gallery and it is now available to view under
> Google's Art Project at:
>
>
>
> http://www.googleartproject.com/museums/nationalgallery/the-ambassadors
>
>
>
> Painted in 1533 it has the most interesting collection of contemporary
> dialling equipment all of which are painted in immense detail.  There are
> two globes (one terrestrial and one celestial), a quadrant, a torquetum, a
> polyhedral dial and a shepherd's dial and some others I don't know, all of
> which are set in such a way as to tell some 'story' to the understanding
> viewer.
>
>
>
> Until now it has been almost impossible for a sundial-interested visitor to
> the gallery to attempt to understand much of the detail - there just isn't
> time - but now with this view you can. You can even see for yourself the
> four place names marked on the terrestrial globe (one of which helped to
> identify one of the depicted persons as Jean de Dinteville, the Seigneur
> of Polisy) and you can even read the music and words in the open book and
> guess at the date and time shown on the shepherd's dial..
>
>
>
> It doesn't (I think) help with viewing the anamorphic skull as a skull - or
> at least you still have to turn your monitor round to do so! - and I STILL
> don't understand the object behind the shepherd's dial...  Anybody know what
> that might be?
>
>
>
> Patrick
>
>
>
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
> --
>
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 10.0.1204 / Virus Database: 1435/3422 - Release Date: 02/04/11
>
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>
>
>
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Re: Solar Position Calculator

[Brad Lufkin]

Meeus's Astronomical Algorithms is not out of print. Check out
http://www.willbell.com/math/mc1.htm. Also, it's cheaper on the publisher's
website ($30 + S&H).
Brad

On Thu, Feb 3, 2011 at 5:41 AM, Kevin Karney  wrote:

> Hi Kaarigar
> Firstly WELL done. Your web interface is very nice. I think it's great when
> people get back to basics and understand the background physics/astronomy
> behind their gnomonics. I remember the satisfaction that came when I first
> worked things out and found I could generate results of surprising accuracy.
>
> To calibrate your routines you should use NASA's JPL's Horizons program or
> US Naval Observatory MICA - which others have mentioned. The Horizons web
> application is superb inasmuch as it is easy-to-use, free, fast and can
> deliver results in spreadsheet format back to your computer. It is
> continuously updated for the earth's erratic slowing and its internal DE405
> routines for the positions of solar system bodies are used by MICA as well -
> so represents the best available technology. The Horizons printable user
> guide (which you do not need) contains the wonderful exhortation "if your
> career or spacecraft depends on a non-lunar satellite or small body
> ephemeris, contact JPL before using it...".
>
> The most sophisticated do-it-yourself astronomical routines available are
> to be found in Meeus' book "Astronomical Algorithms" which is (I think) out
> of print, expensive but usually available on abebooks.com. (Does anyone
> know of a book that betters Meeus ???)
>
> What is of interest to gnomonists are *simple* routines that give *
> sufficient* accuracy for sundials. I made a tiny check on your results for
> today at 8 & 20 hrs UTC = midnight & midday California time using MICA.
> RA was correct to 11 secs of arc
> Declination was correct to 3 secs of arc
> Altitude was correct to 21 & 87 secs of arc
> Azimuth was correct to 82 & 39 secs of arc
> The variable error in altitude & azimuth *may* *be* because you just
> calculated a geocentric RA & Decl, whereas to be entirely thorough one
> should calculate the topographic RA & Decl. But, on that tiny sample, your
> routines are MORE than good enough for any gnomonic studies !
>
> A few small points to clarify on your web interface...
> 1) Right Ascension has no units, you have put it in degrees - but it is
> frequently quoted in hours ? Also, by convention, it is always rectified to
> within 0 - 24 hours or 0 - 360 degrees. (In contrast, Hour angles by
> convention are always rectified to -180 to +180 degrees).
> 2) Are your times in local mean time, local standard time or UTC? Your
> results seem to be in local standard time - which is logical !
> 3) The sign used for your longitude conforms to IAU convention, but many
> gnomonists seem to prefer +ve West
>
> I was interested to know where you came from - so assumed your web
> interface default location was your home. You appear to live at sea, in the
> San Francisco Bay!!
>
> What is the background of your calculations ?
>
> Best regards
> Kevin Karney
> Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK
> 51° 44' N 2° 41' W Zone 0
> + 44 1594 530 595
>
>
> On 2 Feb 2011, at 20:22, triplederby100-pro...@yahoo.com wrote:
>
>
>
>
>
>
>
>
> I had asked a question earlier about how to design a contraption such that
> a sunlight beam falls on a place (or point) exactly each year at a specific
> time. Having gone through the responses and realizing that I will have to
> learn to do some basic solar position calculations myself, I have
> implemented it and made it available through a web site - please check it
> out and let me know if it is right/wrong/ or simply works. Thanks!
>
> http://www.heliometry.com/solpos
>
> Kaarigar
> 
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
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Re: Re: Fwd: [Flags] (pt) Canedo Commune (Ribeira de Pena Municipality, Portugal)

[Brad Lufkin]

I may have jumped the gun with my last statement. While the orthographic
projection clearly does not apply, several other azimuthal ones show
promise, in particular the Airy, equidistant, and equal-area.
Brad

On Wed, Jan 26, 2011 at 4:59 PM, Brad Lufkin wrote:

> I tried to send the following message with a 40K diagram attached but it
> bounced, so I'm re-sending it without the diagram. I thought the limit was
> 50K?
> Brad
>
> On Wed, Jan 26, 2011 at 4:54 PM, Brad Lufkin wrote:
>
>> Here's a diagram of an orthographic projection centered at Rio at the time
>> in question. It's clear that this diagram does not match the flag of Brazil.
>> While the north-south arm of Crux is indeed at the longitude of Rio, the arm
>> itself can never be truly north-south, as the two stars have slightly
>> different hour angles. Also, and far more importantly, Crux is too far north
>> on the flag, being nearly at the same latitude as Rio (the center of the
>> map). In fact, the declination of Crux is around -60 degrees, whereas Rio,
>> as we know, is nearly on the Tropic of Capricorn.
>> To find Crux in the diagram, look about two-thirds of the way down. It's
>> the constellation containing Mimosa.
>> I can't think of any projection, other than an artistic one, that would
>> put the stars in these relative positions.
>>  Brad
>>
>>
>> On Wed, Jan 26, 2011 at 2:11 PM, James E. Morrison <
>> janus.astrol...@verizon.net> wrote:
>>
>>>  Frank,
>>>
>>> It would take some effort to make a conclusive argument as to the
>>> projection used on Brazil's flag, but the description on Widipedia says it
>>> is an orthographic projection (the projection origin is at infinity).  The
>>> date and time when Crux (the Southern Cross) was on the meridian are correct
>>> in the Widipedia article. I'll look at in more detail as time permits.
>>>
>>> Best regards,
>>>
>>> Jim
>>>
>>> James E. Morrison
>>> janus.astrol...@verizon.net
>>> Astrolabe web site at http://astrolabes.org
>>>
>>> Jan 26, 2011 05:21:44 AM, frank.k...@cl.cam.ac.uk wrote:
>>>
>>> Dear Roger (with a question for James Morrison),
>>>
>>> You prompt an interesting side-track in your
>>> observation that...
>>>
>>> > The national flag for Brazil also incorporates
>>> > an armillary sphere...
>>>
>>> It seems that you are living just a bit in the past
>>> here. Aren't we all? The flag of Brazil incorporated
>>> an armillary sphere until 1816 when it was largely
>>> covered up and in 1826 it disappeared from the flag
>>> altogether. See:
>>>
>>> http://en.wikipedia.org/wiki/Flag_of_Brazil
>>>
>>> This article describes the current flag in great
>>> detail. It is dominated by a representation of
>>> the night sky over Rio de Janeiro at 08:37 on
>>> the morning of 15 November 1889.
>>>
>>> In an intriguing note, the article explains that
>>> the positions of the stars were altered slightly
>>> in 1992 to account for proper motion since 1889.
>>>
>>> The Brazilians are to be commended for their
>>> insistence on precision but this alteration means
>>> that the flag no longer represents the night sky
>>> in November 1889. As such the current flag is
>>> a bit of an iconoclast.
>>>
>>> I do hope that "Instruction on the Design of the
>>> National Flag" is in the school curriculum in
>>> Brazil. No wonder the country is doing well!
>>>
>>> The only detail that I would like explained is
>>> just what projection is used.
>>>
>>> Can James Morrison comment please?
>>>
>>> Frank King
>>> Cambridge, UK.
>>>
>>> ---
>>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>>
>>>
>>> ---
>>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>>
>>>
>>>
>>
>
---
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Re: Re: Fwd: [Flags] (pt) Canedo Commune (Ribeira de Pena Municipality, Portugal)

[Brad Lufkin]

I tried to send the following message with a 40K diagram attached but it
bounced, so I'm re-sending it without the diagram. I thought the limit was
50K?
Brad

On Wed, Jan 26, 2011 at 4:54 PM, Brad Lufkin wrote:

> Here's a diagram of an orthographic projection centered at Rio at the time
> in question. It's clear that this diagram does not match the flag of Brazil.
> While the north-south arm of Crux is indeed at the longitude of Rio, the arm
> itself can never be truly north-south, as the two stars have slightly
> different hour angles. Also, and far more importantly, Crux is too far north
> on the flag, being nearly at the same latitude as Rio (the center of the
> map). In fact, the declination of Crux is around -60 degrees, whereas Rio,
> as we know, is nearly on the Tropic of Capricorn.
> To find Crux in the diagram, look about two-thirds of the way down. It's
> the constellation containing Mimosa.
> I can't think of any projection, other than an artistic one, that would put
> the stars in these relative positions.
> Brad
>
>
> On Wed, Jan 26, 2011 at 2:11 PM, James E. Morrison <
> janus.astrol...@verizon.net> wrote:
>
>>  Frank,
>>
>> It would take some effort to make a conclusive argument as to the
>> projection used on Brazil's flag, but the description on Widipedia says it
>> is an orthographic projection (the projection origin is at infinity).  The
>> date and time when Crux (the Southern Cross) was on the meridian are correct
>> in the Widipedia article. I'll look at in more detail as time permits.
>>
>> Best regards,
>>
>> Jim
>>
>> James E. Morrison
>> janus.astrol...@verizon.net
>> Astrolabe web site at http://astrolabes.org
>>
>> Jan 26, 2011 05:21:44 AM, frank.k...@cl.cam.ac.uk wrote:
>>
>> Dear Roger (with a question for James Morrison),
>>
>> You prompt an interesting side-track in your
>> observation that...
>>
>> > The national flag for Brazil also incorporates
>> > an armillary sphere...
>>
>> It seems that you are living just a bit in the past
>> here. Aren't we all? The flag of Brazil incorporated
>> an armillary sphere until 1816 when it was largely
>> covered up and in 1826 it disappeared from the flag
>> altogether. See:
>>
>> http://en.wikipedia.org/wiki/Flag_of_Brazil
>>
>> This article describes the current flag in great
>> detail. It is dominated by a representation of
>> the night sky over Rio de Janeiro at 08:37 on
>> the morning of 15 November 1889.
>>
>> In an intriguing note, the article explains that
>> the positions of the stars were altered slightly
>> in 1992 to account for proper motion since 1889.
>>
>> The Brazilians are to be commended for their
>> insistence on precision but this alteration means
>> that the flag no longer represents the night sky
>> in November 1889. As such the current flag is
>> a bit of an iconoclast.
>>
>> I do hope that "Instruction on the Design of the
>> National Flag" is in the school curriculum in
>> Brazil. No wonder the country is doing well!
>>
>> The only detail that I would like explained is
>> just what projection is used.
>>
>> Can James Morrison comment please?
>>
>> Frank King
>> Cambridge, UK.
>>
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>>
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>>
>>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: 360 degree/Fabian

[Brad Lufkin]

On Thu, Jan 20, 2011 at 12:29 PM, Brad Lufkin wrote:

> I think having the JDN change at noon UTC avoids a lot of confusion.
> Consider this: when is Thursday midnight? Is it the instant between
> Wednesday and Thursday or the instant between Thursday and Friday? With the
> current definition, it's crystal clear when the JDN changes: Thursday noon
> is unambiguous.
> Brad
>
>
> On Thu, Jan 20, 2011 at 12:23 PM, Brent  wrote:
>
>> Napoleons' last orders to his troops at Waterloo:
>>
>> Napoleon: Alright men, listen up, we will attack precisely at 8 o'clock
>> today.
>>
>> Private #1: You mean we will attack tonight in the dark?
>>
>> Napoleon: No, 8 o'clock tonight is actually tomorrow.
>>
>> Private #2: But it is already past 8 o'clock today.
>>
>> Napoleon: That's the old time, we are using Revolutionary time now.
>>
>> Private #3: Well my sundial says 8 o'clock today is 2 hours before
>> midnight.
>>
>> Napoleon: Well that can't be right because then tomorrow would be today
>> and today would be yesterday and we can't fight a battle yesterday. Maybe
>> you are looking at your sundial upside down.
>>
>> Napoleon: Is everyone clear on the attack time now?
>>
>> The troops look at one another with raised eyebrows.
>>
>> Napoleon: Alright men, synchronize your sundials, may god be with you.
>>
>> brent
>>
>> Frank King wrote:
>>
>>> Dear Andrew (and Fer),
>>>
>>> Many thanks for this reference...
>>>
>>>  http://www.aandc.org/research/nautical_time_and_date.html
>>>
>>> That is a splendid article and shows just what pitfalls
>>> one can fall into when attempting to force historical
>>> data to fit the present way of thinking!
>>>
>>> I share your thought...
>>>
>>>  I can't really imagine that even sailors (or
>>>  astronomers) would have had the day changing
>>>  name at midday...
>>>
>>> That said, I have a feeling that when Italian Hours
>>> were in common use in Italy both the date and the
>>> day name changed at sunset.
>>>
>>> This is a cue for Italian readers of the list to
>>> say that this has been widely discussed before
>>> (which is true) and that no widespread agreement
>>> has been established :-)
>>>
>>> One hang-over which still persists in astronomy is
>>> the Julian Day Number which changes at noon UTC.
>>>
>>> As I write, it is Thursday and the JDN is 2455581.
>>> In just over four hours time it will still be
>>> Thursday but the JDN will be 2455582.
>>>
>>> The scope for confusion is almost endless.  This
>>> splendid list has now provided us with pictures
>>> of one French Revolution Hours sundial with noon
>>> shown as 10 and another with noon shown as 5.
>>> Maybe Napoleon didn't write a rigorous spec?
>>>
>>> Frank
>>>
>>>
>>>
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>>
>
---
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Re: life before clocks

[Brad Lufkin]

Probably the best book on the invention and impact of mechanical clocks is
"Revolution in Time" by David S. Landes. Not sure if it's still in print.
Brad

On Fri, Nov 19, 2010 at 5:09 PM, R Wall wrote:

> Hi Brent,
>
> That reminds be of a book that I read that indicated that some society or
> club meetings were held on certain days close to the full moon. For example,
> every month on the Thursday after the full moon at 9pm. I assume that was to
> allow you to use the moon light to travel at night in the days when there
> was no street lighting. I suppose they could have used a moon dial to
> determine 9pm because there would be moon light.
>
> Roderick Wall.
>
> -Original Message- From: Brent
> Sent: Saturday, November 20, 2010 8:41 AM
> To: Sundial List
> Subject: life before clocks
>
>
> I wonder what life was like before mechanical clocks.
>
> I suppose your day was less structured than ours are today.
> Maybe to work at sunrise, go home at sunset.
> Eat when you are hungry, sleep when you are tired.
>
> I wonder how many people used sundials? Was it a common thing to have?
> Was it a necessity?
>
> How did everyone show up on time for a 9pm Opera?
>
> What was the accurate time of day good for back then?
>
> Before mechanical clocks you probably wasted a lot of time waiting for
> people or events.
>
> Who cared about accurate time, and why?
>
> Churches?
> Armies?
> Courts?
> Scientists?
> Governments?
> Sailers?
>
> Sundials became very sophisticated, but why?
>
> thanks;
> brent
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
> -
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 10.0.1153 / Virus Database: 424/3265 - Release Date: 11/18/10
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>
>
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Re: FW: Sundial Information

[Brad Lufkin]

I suspect there's no relationship. The publishers of the humor magazine were
probably making an oblique reference to the owl of Athena, which is a symbol
of wisdom. A bit sly, but also a bit self-congratulatory (but this is a
college humor magazine, not Dean Swift).
Brad

On Fri, Nov 19, 2010 at 10:43 AM, John Carmichael
wrote:

>  Hi Dialists:
>
>
>
> I received this intriguing letter from Ohio State University.  The writer
> talks about an old publication called “The Sundial”.  And then asked me if I
> am aware of any relationship between sundials and owls!  I am not aware of
> any association between the two.  I asked him to send me any photos of
> this.  Meanwhile, I’m asking you guys if you have seen any relationship
> between owls and sundials.
>
>
>
> Thanks!
>
>
>
> I’ll forward your answers to him, or you can write him directly.
>
>
>
> John
>
>
>
>
>
>
>
> *From:* Nathan Varrone [mailto:nathanvarr...@gmail.com]
> *Sent:* Friday, November 19, 2010 1:20 AM
> *To:* jlcarmich...@comcast.net
> *Subject:* Sundial Information
>
>
>
> Dear John Carmichael,
>
>
>
> I am currently reviving a humor magazine titled *The Sundial *at The Ohio
> State University. In old issues of *The Sundial*, I often see an owl on
> top of the drawn images of sundials. Is there any association with owls and
> sundials that you would know of?
>
>
>
> Thanks so much for your time, we may do business with you in the future!
>
>
>
> Best,
>
> --
> Nathan L. Varrone
> The Ohio State University
> Associate Director, 8th Floor Improv
> President, The Sundial
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
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Re: What can be calculated with a sun dial?

[Brad Lufkin]

The longitude and latitude of the Sun (i.e., the location on the Earth that
the Sun is directly above).

On Wed, Nov 17, 2010 at 8:39 AM, Kevin Karney  wrote:

> This list - together with all the additions - is great !
>
> But, it would be nice to see which of the many items can be done well by a
> sundial and how many items would be a 'stretch'. To find the moment of
> equinox - for example - is theoretically possible - but in actuality is not
> realistic since the Sun's declination is changing so slowly at those times:
> (a problem the astronomers of antiquity struggled with).  Equally, I think
> one would be hard pressed to find aphelion & perihelion from a dial - except
> in a very indirect fashion.
>
> But let's get the list complete !
>
> Best regards
> Kevin Karney
>
> On 16 Nov 2010, at 21:38, Jos Kint wrote:
>
> Dear sun dialists,
>
> What can be calculated with a good sun dial? Here is a list of 19 topics.
> Can you add some more items?
> 1. The hour of the day
> 2. The day of the year.
> 3. The solar altitude.
> 4. The solar azimuth.
> 5. The longitude of the sun dial.
> 6. The latitude of the sun dial.
> 7. The moment of the equinoxes
> 8. The moment of the solstices.
> 9. The length of the tropical year
> 10. The equation of time
> 11. The excentricity of the earth orbital around the sun.
> 12. The obliquity of the eclips
> 13. A compass function
> 14. The declination of the sun.
> 15. The moment of the perihelion
> 16. The moment of the aphelion
> 17. The moment of the next sun set
> 18. The Babylonic time
> 19. The Italian time
>
>
> Jos Kint
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
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Sundials and Google Maps

[Brad Lufkin]

I've incorporated Google Maps into an Oughtred dial. As you know, the
Oughtred dial can be drawn on any azimuthal map projection (Oughtred himself
chose the Stereographic). Since the dial is drawn on a map, it's possible to
drawn Earth features such as countries as part of the dial. What I've done
(and I'm pretty sure this is new) is incorporate the ability to download and
use Google Maps in the dial. The technique works with geographic dials as
well.
I tried to send an example to the SML but the image is 90KB+ so will not
pass the size filter. I'd be happy to send the diagram to whomever is
interested.
Brad
---
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Re: Re Sundial Atlas

[Brad Lufkin]

In Corsica ("Corse" in French), cats eat bouillabaisse. In the old days,
before Corsica was sold to the French, they used to eat pasta.

On Mon, Aug 9, 2010 at 2:23 PM, Fabio  wrote:

> Dear John, no problem, there was not offensive words in your email. I'm
> only surprise this matter is associated to SA.
>
> Roger, I don't know what the cats eat where you live but I think you have
> the same internet I surf at home.
> I don't know if someone wrote to websites like Flickr about this matter.
> I'd like to know the reply. If any. (and for compensation even more).
>
> When in april I wrote to the gnomonic associations to announce the start up
> of SA someone of you described me his worry about the problem of the sundial
> thefts. I took care of it, in SA a sundial may be registered and described
> without posting the exact position (5 km, 50 km, more than 50 km), giving to
> all of us the pleasure of the knowledge without dangers.
>
> I prefer the website like Wikipedia where the info are managed and
> verified. Not a censoring but a quality control, and this is the model for
> SA.
> Nobody is requested to post data but everyone may do it. So I planned a
> level of volunteers, enthusiast of this project and with care of any
> features of it, to verify the data of a known territory and with the
> possibility to cancel data wich are not rilevant, or wrong, or offensive, or
> inopportune, or not authorized.
> I started sending these notes to the gnomonic associations more than three
> months ago, this is the reason of my surprise.
>
> Everyone of you may become a manager of SA (I'd like to disappear in a
> webmaster rule) and I thought first to contact the register managers who
> also can find a info source in SA.
> In september the manager level will become fully operative and I hope to
> find you active to collect, to take info and to take care of our loved art.
>
> Ciao Fabio Savian
>
> PS now I'm in France, in Corse exactly, and last nigth I slept in a small
> house in the middle of a wood. The night was warm and there was nobody all
> around. I left the door opened and a cat entered into my room. It jumped on
> the bed and it settled near my wife. It was not afraid. Now I'm curious to
> know what the cats eat here.
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
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Sunday's Solar Eclipse

[Brad Lufkin]

Attached is a diagram showing the locations and times of Sunday's solar
eclipse. The solid stripe in the middle of the diagram shows the area of the
globe where the eclipse is total.
Brad
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Tomorrow's Eclipse

[Brad Lufkin]

Attached is a diagram showing the regions and times of visibility of
tomorrow's eclipse. Looks like the best place to be is in the South Pacific.
Brad
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Test Message--Ignore

[Brad Lufkin]

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Fwd: Fwd: how italian hours

[Brad Lufkin]

Just realized I'd neglected to add the SML to the distro.
Brad

-- Forwarded message --
From: Brad Lufkin 
Date: Sun, Apr 4, 2010 at 9:29 AM
Subject: Re: Fwd: how italian hours
To: Warren Thom 
Cc: LISTA INGLESE , Gianni Ferrari <
gfme...@gmail.com>


Warren:
here's a dial that shows the current position of the Sun. It's an Oughtred
Dial on a gnomonic projection (instead of the stereographic that Oughtred
used). I've also added the current sunset/sunrise terminator and the area of
the globe that is currently illuminated (ignoring refraction, the terminator
is a straight line, as are all great circles on such a projection).
The terminator is perpendicular to the shadow line. The distance between the
terminator and the center of the dial is proportional to the height of the
dial node and to the tangent of the Sun's altitude. Also, the point of
closest approach of the terminator to the center goes through the altitude
line that is 90 - the altitude of the Sun (note that on the dial, the Sun is
at 30 degrees altitude and the terminator just touches the 60-degree line).
I suppose one could devise a nomogram to make the calculation.
Oh, I've also added Babylonian hours (this is supposed to be a sundial,
after all).
Brad



On Sat, Apr 3, 2010 at 6:30 AM, Warren Thom  wrote:

> All,
>
> I have enjoyed the discussion about Italian hours.  My first dial was an
> hours to sunset dial on my garage door done in the 1970s.  Mac Oglesby's
> models and dials are inspiring to me.  I had a globe parallel to the earth
> in the 1980s that I liked to view on a sunny day.  I could observe where
> on earth the sun was overhead and where the sun was setting at that very
> moment.  About six years ago I worked on a design that would cast a shadow
>  from a nodus onto a map that would show where on earth the sun was
> directly overhead.  It was an ugly confusing map.  My question is:
>
> Hour and prayer lines are fine.  Is there other information, that uses
> Italian hour calculations (or solar declinations) , that would be of
> interest to a broad audience?  Fred Sawyer created a universal dial of
> modern hours based on a world map.  Is it possible to create a "map" dial
> that would show where the sun is setting at that moment?  What could it
> look like?  Would it require a line shadow casting instead of a point?
> Any thoughts?
>
> Thank you -- Warren Thom
>
>
> On Sat, 03 Apr 2010 06:33:11 -0400, Gianni Ferrari 
> wrote:
>
> > In Ottoman Sundials we find often the Italic hours because these hours
> > give
> > the time  to the sunset, when the Muslims  must say the Prayer Maghrib.
> >
> > These hours are given not from 0 (sunset) to 24 (sunset of the next day),
> > but, as Roger has written, in two cycles of 12 hours and  are called
> > Ezanic
> > hours.
> >
> > So at sunset we have the end of the 12th hour of a cycle and the
> > beginning
> > of the 1st of the next.
> >
> > In such a way only at the equinoxes at noon the  Ezanic, Modern (French),
> > Babylonian and Temporary hours have all the value 6.
> >
> > In different days this is not true as you can see in the table attached.
> >
> >
> >
> > In Ottoman Sundials  generally we don’t find Babylonian hours, while we
> > have
> > often the lines of the Solar Time that give to the Muslims the time to
> > noon,
> > that is the time to the Zuhr prayer.
> >
> > These hours are not numbered as in our clocks or sundials, but,
> > generally,
> > with the number of hour to noon (in the morning) or after it (in the
> > afternoon). So  : 5, 4, 3, 2, 1, noon, 1, 2, 3, 4, 5.
> >
> >
> >
> > They use “Arabic numbers” or, in oldest sundials, numbers written with
> > “letters” ( Abjad method)
> >
> >
> >
> > Gianni Ferrari
> >
> >
> >
>
>
> --
> Using Opera's revolutionary e-mail client: http://www.opera.com/mail/
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
<>---
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Re: Fwd: how italian hours

[Brad Lufkin]

Warren:
here's a dial that shows the current position of the Sun. It's an Oughtred
Dial on a gnomonic projection (instead of the stereographic that Oughtred
used). I've also added the current sunset/sunrise terminator and the area of
the globe that is currently illuminated (ignoring refraction, the terminator
is a straight line, as are all great circles on such a projection).
The terminator is perpendicular to the shadow line. The distance between the
terminator and the center of the dial is proportional to the height of the
dial node and to the tangent of the Sun's altitude. Also, the point of
closest approach of the terminator to the center goes through the altitude
line that is 90 - the altitude of the Sun (note that on the dial, the Sun is
at 30 degrees altitude and the terminator just touches the 60-degree line).
I suppose one could devise a nomogram to make the calculation.
Oh, I've also added Babylonian hours (this is supposed to be a sundial,
after all).
Brad


On Sat, Apr 3, 2010 at 6:30 AM, Warren Thom  wrote:

> All,
>
> I have enjoyed the discussion about Italian hours.  My first dial was an
> hours to sunset dial on my garage door done in the 1970s.  Mac Oglesby's
> models and dials are inspiring to me.  I had a globe parallel to the earth
> in the 1980s that I liked to view on a sunny day.  I could observe where
> on earth the sun was overhead and where the sun was setting at that very
> moment.  About six years ago I worked on a design that would cast a shadow
>  from a nodus onto a map that would show where on earth the sun was
> directly overhead.  It was an ugly confusing map.  My question is:
>
> Hour and prayer lines are fine.  Is there other information, that uses
> Italian hour calculations (or solar declinations) , that would be of
> interest to a broad audience?  Fred Sawyer created a universal dial of
> modern hours based on a world map.  Is it possible to create a "map" dial
> that would show where the sun is setting at that moment?  What could it
> look like?  Would it require a line shadow casting instead of a point?
> Any thoughts?
>
> Thank you -- Warren Thom
>
>
> On Sat, 03 Apr 2010 06:33:11 -0400, Gianni Ferrari 
> wrote:
>
> > In Ottoman Sundials we find often the Italic hours because these hours
> > give
> > the time  to the sunset, when the Muslims  must say the Prayer Maghrib.
> >
> > These hours are given not from 0 (sunset) to 24 (sunset of the next day),
> > but, as Roger has written, in two cycles of 12 hours and  are called
> > Ezanic
> > hours.
> >
> > So at sunset we have the end of the 12th hour of a cycle and the
> > beginning
> > of the 1st of the next.
> >
> > In such a way only at the equinoxes at noon the  Ezanic, Modern (French),
> > Babylonian and Temporary hours have all the value 6.
> >
> > In different days this is not true as you can see in the table attached.
> >
> >
> >
> > In Ottoman Sundials  generally we don’t find Babylonian hours, while we
> > have
> > often the lines of the Solar Time that give to the Muslims the time to
> > noon,
> > that is the time to the Zuhr prayer.
> >
> > These hours are not numbered as in our clocks or sundials, but,
> > generally,
> > with the number of hour to noon (in the morning) or after it (in the
> > afternoon). So  : 5, 4, 3, 2, 1, noon, 1, 2, 3, 4, 5.
> >
> >
> >
> > They use “Arabic numbers” or, in oldest sundials, numbers written with
> > “letters” ( Abjad method)
> >
> >
> >
> > Gianni Ferrari
> >
> >
> >
>
>
> --
> Using Opera's revolutionary e-mail client: http://www.opera.com/mail/
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
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Re: Equinoctial Announcement

[Brad Lufkin]

Here's what the World looks now.
Brad


On Sat, Mar 20, 2010 at 5:56 AM, Gianni Ferrari  wrote:

> Frank,
>
> Congratulation !!!
>
>
>
> You wrote:
>
> *The great thing about using sunrise and sunset as reference times is that
> governments can't change these times by legislation.*
>
> and
>
> *It is a shame it is cloudy now.  *
>
>
>
> In Italy there is the saying “Piove, governo ladro!”   that means "It
> rains, government thief!"
>
> Perhaps your government  does not agree with your attempt to disobey the
> laws
> J
>
>
>
> Happy Equinox
>
> Gianni Ferrari
>
>
>
>
>
>
> 2010/3/20 Frank King 
>
> Dear All,
>> Happy Equinox
>>
>> As well as grumbling about Daylight Saving Time
>> I do frivolous things like designing sundials...
>>
>> I decided it was time that rather more of the
>> world knew about Babylonian Hours and Italian
>> Hours so, yesterday, I (and many others) put
>> up my latest creation on a south-facing wall of
>> Selwyn College, here in Cambridge (a place that
>> does its best to educate people!).
>>
>> You can see some of the action at:
>>
>>   
>> http://www.cl.cam.ac.uk/~fhk1/SelwynPic.jpg
>>
>> This photograph was taken at...
>>
>> Hey, you can all work that out for yourselves :-)
>>
>> It is fun how the scaffolding echoes the noon
>> crossing point on the equinoctial line :-)
>>
>> It was the day before the equinox and you can
>> see that the shadow isn't quite centred on the
>> equinoctial line.
>>
>> I still find it magical that you can fiddle
>> with all these sines and cosines and the end
>> result actually works!
>>
>> The great thing about using sunrise and sunset
>> as reference times is that governments can't
>> change these times by legislation.
>>
>> Hmmm.  Maybe they can?
>>
>> For more pictures and a non-technical account
>> written for the College in the early hours of
>> this morning you can look at:
>>
>>  
>> http://www.cl.cam.ac.uk/~fhk1/Selwyn.pdf
>>
>> It is a shame it is cloudy now.  The U.K. is
>> not a good place for sun :-(
>>
>> Frank King
>> Cambridge, U.K.
>>
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>>
>
>
> --
> Mail to :  gfme...@gmail.com
> Lat.44;38,18.5N
> Long. 10;56,05.3E
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
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Re: refraction formula

[Brad Lufkin]

the term "a" in your formula is the Sun's apparent altitude in degrees (see
Chapter 16 of Meuus's Astronomical Algorithms).

On Tue, Mar 16, 2010 at 12:27 PM, Thomas Steiner wrote:

> Hi all,
> I am looking for a formula for refraction.
> At http://www.sundialsoc.org.uk/glossary/equations/equations.htm ist says:
>
> 10. Sun’s refraction
> Ro=1/ (tan(a+7.31/(a+4.4)))
> Ro is the refraction in arcmins for a temperature of 10ºC and an
> atmospheric pressure of 1010 mb. For other conditions, a multiplying
> factor of 0.28P/T is required, where P is the pressure in mb and T is
> the temperature in kelvins ( = temp in ºC + 273).
>
> but obviously refraction does also change with the sun's altitude.
> Only for low altitudes there will be refraction. Do you have a simple
> formula or source for this by hand?
> Danke,
> Thomas
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
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Re: DST Misconceptions

[Brad Lufkin]

It certainly seems to be causing some heart-burn on this list.

On Mon, Mar 15, 2010 at 11:11 AM, John Carmichael
wrote:

>
> I also heard of a study last year that concluded that DST caused heart
> attacks!
>
>
>
>
>
> -Original Message-
> From: sundial-boun...@uni-koeln.de [mailto:sundial-boun...@uni-koeln.de]
> On
> Behalf Of Simon [illustratingshadows
> Sent: Monday, March 15, 2010 6:29 AM
> To: 'Sundial Mailing List'; Frank King
> Subject: Re: DST Misconceptions
>
> My understanding, not having followed this thread, is that at best there is
> a believed savings of energy to the order of 1%. I have no idea if that is
> statistically valid. I am also told that the shift from standard to
> daylight
> time causes some 263 traffic deaths during the transitional period,
> compared
> to the norm. No consideration is given to the southern states.
>
> This is political folly at its best, and we like sheep.
>
> Congratulations Arizona on standing firm, with a NO to DST.
>
> Simon
>
>
> Simon Wheaton-Smith
> www.illustratingshadows.com
> Silver City, New Mexico W108.2 N32.75 and
> Phoenix, Arizona, W112.1 N33.5
>
>
> --- On Mon, 3/15/10, Frank King  wrote:
>
> > From: Frank King 
> > Subject: Re: DST Misconceptions
> > To: "'Sundial Mailing List'" 
> > Date: Monday, March 15, 2010, 4:10 AM
> > Dear John and Jack,
> >
> > Reading about the benefits of Daylight Saving
> > Time always reminds me of Betrand Russell's
> > remark:
> >
> >   If you make a single false assumption you
> >   can prove anything.
> >
> > Daylight Saving Time is just a legislative
> > trick to get people out of bed an hour early
> > by telling lies about the time.
> >
> > By telling these lies you can make all kinds
> > of dubious claims but suppose, for a moment,
> > that we accept all these claims...
> >
> >   Let us accept that there are huge economic,
> >   social and conservation benefits from getting
> >   up an hour earlier.
> >
> > In which case why aren't people doing this of
> > their own accord?
> >
> > There is no need to tell lies about the time!
> >
> > Frank King
> > Cambridge, U.K.
> >
> > P.S.
> >
> > Russell was once challenged at a talk...
> >
> >   OK, suppose you accept the false assumption
> >   that 1+1 = 3, can you prove that you are
> >   the Pope?
> >
> >   Certainly said Russell.  You subtract one
> >   from both sides to give 1 = 2.  Now the
> >   Pope and I are two people so this means
> >   that the Pope and I are one person and,
> >   therefore, I am the Pope.
> >
> > ---
> > https://lists.uni-koeln.de/mailman/listinfo/sundial
> >
> >
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
> ---
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>
>
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Re: Nasa website

[Brad Lufkin]

Roger:
now that I've got the solar-eclipse problem solved, is there an equivalent
book for lunar eclipses?
BTW, while I'm using the full VSOP87D theory to predict the position of the
Sun, it turns out that I can get quite respectable results using the
simplified model of the Sun's longitude that appears in Meeus's
"Astronomical Algorithms". (For the position of the Moon, I'm using Meeus's
model in "Algorithms"). Also, the besselian elements as recorded in Meeus's
"Elements of Solar Eclipses" are (in the case of the variables x, y, and d)
computational overkill. The quadratic and cubic terms for x and y are 5
orders of magnitude smaller than the linear term, and for d, the quadratic
term is always very close to zero. This shows that it's really safe to
ignore those terms, which I've chosen to do with no ill effects. I've
compared the maps I get to those on the NASA website and they're (visually
at least) indistinguishable.
Brad

On Tue, Dec 22, 2009 at 6:00 PM, Roger W. Sinnott  wrote:

> 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 of
> totality (northern and southern edge), as well as the appearance,
> magnitude,
> contact times, and limit curves of the partial phases.  It also explains
> how
> to determine the circumstances of the eclipse at any specific latitude and
> longitude.
>
> To calculate the Besselian elements themselves, if you want to, first you
> need a source of highly accurate ephemerides for the Sun and Moon (such as
> from the Astronomical Almanac, NASA's Horizons, or Aldo Vatagliano's Solex
> shareware program).  Then you need the algorithms for deriving the
> elements.
> These are given is such places as the Explanatory Supplement to the
> Astronomical Almanac (either the 1992 or 1961 edition), or William
> Chauvenet's Manual of Spherical Astronomy (various editions, 1863 to 1891;
> also reprinted by Dover in 1960).  Calculating the elements is actually
> more
> straightforward than using them to get accurate local preditions and curves
> for an eclipse.
>
>   -- Roger
>
>
> - Original Message -
> From: "Brad Lufkin" 
> To: "Sundial Mailing List" 
> Sent: Tuesday, December 22, 2009 3:07 PM
> Subject: Re: Nasa website
>
>
> > Speaking of Meeus, does anyone know if his "Elements of Solar Eclipses"
> > includes algorithms for calculating the Besselian elements of eclipses or
> > just presents tables of results? Also, does the book present algorithms
> > for
> > calculating the paths of eclipses? It's not clear from the description on
> > the bookseller's website.
> > Regards, Brad
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
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Re: Fwd: Re: Re: Solar position calculator

[Brad Lufkin]

Frankly, I think using a 6th order polynomial to approximate data with so
much uncertainty is questionable. I would use linear, piece-wise
interpolation on the tables and the trends outside the range of the tables
(suitably adjusted to match the values at the beginning and end of the
tables).
Brad

On Thu, Mar 4, 2010 at 1:16 PM, sun.di...@libero.it wrote:

> Jim, I agree with you about all but one detail : the current value of
> DeltaT.
>
> The last measured values I know are the following (
> http://maia.usno.navy.mil/ser7/deltat.data) :
>
> 
> 2008  1   65.4574
> 2008  2   65.4868
> 2008  3   65.5152
> 2008  4   65.5450
> 2008  5   65.5781
> 2008  6   65.6127
> 2008  7   65.6288
> 2008  8   65.6370
> 2008  9   65.6493
> 2008 10   65.6760
> 2008 11   65.7097
> 2008 12   65.7461
> 2009  1   65.7768
> 2009  2   65.8025
> 2009  3   65.8237
> 2009  4   65.8595
> 2009  5   65.8973
> 2009  6   65.9323
> 2009  7   65.9509
>
> Therefore 72 s looks too much to me.
>
> As the value of DeltaT cannot be known in advance but just assumed from
> previous measurements, Orologi Solari uses the following polynomial
> expansion as suggested by Espenak and Meeus (
> http://eclipse.gsfc.nasa.gov/SEhelp/deltatpoly2004.html)
>
>  ΔT = 62.92 + 0.32217 * t + 0.005589 * t^2
>  where: t = y - 2000
>
> that gives 66.7 s for 2010.
>
> Regards.
>
> Gian
>
> Messaggio originale
> Da: janus.astrol...@verizon.net
> Data: 04/03/2010 3.48
> A: 
> Ogg: Fwd: Re: Re: Solar position calculator
>
>
> Dipping my oar in the water, Delta-T is absolutely required for accurate
> calculations.  Almost all of the published polynomials for calculating
> orbital values are in the form of a polynomical based on the fraction of a
> Julian century for the epoch.  This variable, T, is calculated from the
> Julian day number.  The fraction of the Julian day number is the the
> fraction of the day since noon in dynamical time (which is now called
> Terrestrial Time, TT).  To calculate values for a given UT, you have to
> adjust Terrestrial (i.e. dynamical) time by the factor Delta-T = TT-UT.
>
> So, if you want to do a calculation at noon UT, it is not for Julian day
> number xxx.5, but at xxx.5 - delta T (currently about 72 sec.).  Clearly,
> the adjustment is not a big deal for a contemporary sundial, but is very,
> very important for reproductions or studies for times far in the past.  Note
> that almost all values in the Astronomical Almanac are for 12 hr TT.  The
> only subject that uses UT is eclipses (I think).
>
> I trust my program, "The Electric Astrolabe" which can be downloaded from
> my web site.  I trust it because of the hundreds of hours I have spent
> confirming it gives good answers and I know how it works.  It's hard to
> trust any program that doesn't tell you how the answers are calculated.
>
> Best regards,
>
> Jim
>
> James E. Morrison
> janus.astrol...@verizon.net
> Astrolabe web site at http://astrolabes.org
>
>
>  Forwarded message 
> From: *Aimo Niemi* 
> Date: Mar 3, 2010
> Subject: Re: Re: Solar position calculator
> To: sun.di...@libero.it 
>
>
> Hi
>
> 2010/3/3 sun.di...@libero.it 
>
> I think that no comparison can be made between different programs results
> without knowing the value of DeltatT that has been used.
>
> I again think that DeltaT is not needed if we calculate apparent places and
> use UT.
> Most accurate link capable for that (what I know)  is at
> http://ssd.jpl.nasa.gov/horizons.cgi#results
> If refraction is not calculated, the link gives
> azimuth=200.7239 and altitude = 39.1824 (39.2031 if refraction is included)
> Regards
> Aimo
>
> Ephemeris tables usually declare the value of DeltaT that was used.
> It is also worthy to note that for gnomonic applications all these results
> are more than correct :-)
> Regards.
> Gian
>
> Messaggio originale
> Da: ai...@wippies.fi
> Data: 03/03/2010 20.51
> A: "John Goodman"
> Cc: "Sundial List"
> Ogg: Re: Solar position calculator
>
>
> Hi
> I got following results from the link
> http://www.roman-britain.org/astronomy/astro.htm#
> which I believe is trustworthy
>
> azimuth=200.7233  (20.7233 if south is the zeropoint)
> altitude= 39.1827
> I also tested the results with my own semi-accurate PcAllakka
> with following results
> azimuth=200.715 and altitude=39.188
> Anyone interested can load the program from
> http://pc-calculator.110mb.com/allakka/
> or perhaps some of you is curious enough to visit my solar tracking sundial
> pages at
> http://pc-calculator.110mb.com/tracker/solartracker.html
> Greetings
> Aimo Niemi
>
>
>  2010/3/3 John Goodman 
>
> If anyone needs to make precise solar position calculations, the following
> software may be useful. There are a few caveats. The software is not a
> stand-alone application, it's a software library. The software library needs
> to be used from the command line and it runs using the Python programming
> language.
>
>
> I'm a Mac user and this is 

Re: Re: Solar position calculator

[Brad Lufkin]

Just for laffs, here's what I come up with:
Using VSOP87D, with deltaT = 79 seconds, taking into account all known
effects except refraction:
azimuth = 200.72354871227333
altitude = 39.1844374748319
with refraction 39.20512111866974

Using the simpler Sun model in Meuus which only gives the ecliptic
longitude, but includes the nutation and the aberration:
azimuth = 200.71774169672503
altitude = 39.18821032219071
with refraction 39.2088912042855
I agree with Gian.
Brad

On Wed, Mar 3, 2010 at 6:33 PM, Aimo Niemi  wrote:

> Hi
>
> 2010/3/3 sun.di...@libero.it 
>
>> I think that no comparison can be made between different programs results
>> without knowing the value of DeltatT that has been used.
>>
>
>
> I again think that DeltaT is not needed if we calculate apparent places and
> use UT.
> Most accurate link capable for that (what I know)  is at
> http://ssd.jpl.nasa.gov/horizons.cgi#results
> If refraction is not calculated, the link gives
> azimuth=200.7239 and altitude = 39.1824 (39.2031 if refraction is included)
> Regards
> Aimo
>
>
>
>
>
>> Ephemeris tables usually declare the value of DeltaT that was used.
>> It is also worthy to note that for gnomonic applications all these results
>> are more than correct :-)
>> Regards.
>> Gian
>>
>>
>>
>> Messaggio originale
>> Da: ai...@wippies.fi
>> Data: 03/03/2010 20.51
>> A: "John Goodman"
>> Cc: "Sundial List"
>> Ogg: Re: Solar position calculator
>>
>>
>> Hi
>> I got following results from the link
>> http://www.roman-britain.org/astronomy/astro.htm#
>> which I believe is trustworthy
>>
>> azimuth=200.7233  (20.7233 if south is the zeropoint)
>> altitude= 39.1827
>>
>> I also tested the results with my own semi-accurate PcAllakka
>> with following results
>> azimuth=200.715 and altitude=39.188
>> Anyone interested can load the program from
>> http://pc-calculator.110mb.com/allakka/
>>
>> or perhaps some of you is curious enough to visit my solar tracking
>> sundial pages at
>> http://pc-calculator.110mb.com/tracker/solartracker.html
>>
>> Greetings
>> Aimo Niemi
>>
>>
>>  2010/3/3 John Goodman 
>>
>>> If anyone needs to make precise solar position calculations, the
>>> following software may be useful. There are a few caveats. The software is
>>> not a stand-alone application, it's a software library. The software library
>>> needs to be used from the command line and it runs using the Python
>>> programming language.
>>>
>>>
>>> I'm a Mac user and this is one of those rare occasions when an arcane set
>>> of requirements actually favors the Mac. While Macintosh users tend to be
>>> allergic to the command line, it has existed in the OS for the past 10
>>> years. Python is there too, lurking under the surface.
>>>
>>> I don't know enough about the PC, but clearly the command line is there
>>> and Python is available too. ( http://www.python.org/download/windows/ )
>>>
>>> With all that preface, here's what the code can do. Once the necessary
>>> files are installed, you can type the following commands and see the
>>> following results:
>>>
>>> >>> import datetime, solar
>>> >>> d = datetime.datetime(2010, 3, 3, 18, 0, 0)
>>> >>> lat = 42.0
>>> >>> long = -71
>>> >>> solar.GetAltitude(lat, long, d)
>>> 39.203509044804704
>>> >>> solar.GetAzimuth(lat, long, d)
>>> -20.717667802423591
>>> >>>
>>>
>>> Someone with an ephemeris can check these results. The format for
>>> datetime is ", mm, dd, hh, mm, ss", optionally followed by a number of
>>> microseconds. The time value entered is for UTC.
>>>
>>> There are other functions for calculations that I haven't explored. You
>>> can read more about the software tools at http://pysolar.org/  Example
>>> uses are shown at http://wiki.github.com/pingswept/pysolar/examples  The
>>> software itself is at http://github.com/pingswept/pysolar/downloads
>>>
>>> All of this software is the work of Brandon Stafford, who has generously
>>> offered his code free of charge to anyone who may find it useful. I have
>>> little experience with this software but, as much as I can, I'll be happy to
>>> help anyone trying to use it.
>>>
>>> If there are any questions, I can pass them on to Brandon. I hope this is
>>> helpful to some.
>>>
>>> ---
>>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>>
>>>
>>
>>
>>
>> ---
>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>
>>
>>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
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Re: Nasa website

[Brad Lufkin]

Roger:
I've been able to use Meuus's Elements (for the algorithms, as you so kindly
pointed out) and other sources (for how to calculate the Besselian elements)
to build a solar-eclipse predictor that shows paths of totality and
magnitude of the partial phases.
I was going to include an image with the results for the upcoming 11 July
2010 eclipse (which occurs over the southern Pacific), but it's beyond the
25Kb limit of the SML. I'd be happy to send the image off-list to anyone who
wants it. The program is also available (it's an extension to the program
I've already sent to several members of the list; I've also added an orrery
to the program).
Regards, Brad

On Tue, Dec 22, 2009 at 6:00 PM, Roger W. Sinnott  wrote:

> 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 of
> totality (northern and southern edge), as well as the appearance,
> magnitude,
> contact times, and limit curves of the partial phases.  It also explains
> how
> to determine the circumstances of the eclipse at any specific latitude and
> longitude.
>
> To calculate the Besselian elements themselves, if you want to, first you
> need a source of highly accurate ephemerides for the Sun and Moon (such as
> from the Astronomical Almanac, NASA's Horizons, or Aldo Vatagliano's Solex
> shareware program).  Then you need the algorithms for deriving the
> elements.
> These are given is such places as the Explanatory Supplement to the
> Astronomical Almanac (either the 1992 or 1961 edition), or William
> Chauvenet's Manual of Spherical Astronomy (various editions, 1863 to 1891;
> also reprinted by Dover in 1960).  Calculating the elements is actually
> more
> straightforward than using them to get accurate local preditions and curves
> for an eclipse.
>
>   -- Roger
>
>
> - Original Message -
> From: "Brad Lufkin" 
> To: "Sundial Mailing List" 
> Sent: Tuesday, December 22, 2009 3:07 PM
> Subject: Re: Nasa website
>
>
> > Speaking of Meeus, does anyone know if his "Elements of Solar Eclipses"
> > includes algorithms for calculating the Besselian elements of eclipses or
> > just presents tables of results? Also, does the book present algorithms
> > for
> > calculating the paths of eclipses? It's not clear from the description on
> > the bookseller's website.
> > Regards, Brad
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Ephemeris Longitude

[Brad Lufkin]

Thanks to all the people who answered my query. I (think) I now understand
what's going on. The clearest explanation is in the Supplement to the
Astronomical Almanac.
Regards, Brad

On Tue, Mar 2, 2010 at 1:43 AM,  wrote:

> Not sure if this explanation helps but I found it.
> "Ephemeris Longitude is the terrestrial dynamical longitude assuming a
> uniformly rotating Earth.
> True Longitude is calculated by correcting the Ephemeris Longitude for
> the non-uniform rotation of Earth.
> (T.L. = E.L. + 1.002738*ΔT/240, where ΔT(in seconds) = TDT - UT)
> (ΔT = 66.2 s =000°16'35.5")
>
>  Because ΔT is not known in advance, the value used in the predictions is
> an
> extrapolation based on pre-2009 measurements. The actual value is expected
> to fall within ±0.3 seconds of the estimated ΔT used here".
>
>  Patrick
>
>
>
> -Original Message-
> From: Brad Lufkin 
> To: Sundial Mailing List 
> Sent: Mon, Mar 1, 2010 7:27 pm
> Subject: Ephemeris Longitude
>
>  Can anyone explain (or point me to a resource that explains) what the
> "ephemeris longitude" is and why it's related to the geodetic longitude by
> the expression:
>
> ephemeris longitude = 1.002738 (geodetic longitude)
>
> Regards, Brad
>
> ---https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Ephemeris Longitude

[Brad Lufkin]

Can anyone explain (or point me to a resource that explains) what the
"ephemeris longitude" is and why it's related to the geodetic longitude by
the expression:

ephemeris longitude = 1.002738 (geodetic longitude)

Regards, Brad
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Nasa website

[Brad Lufkin]

Roger:
that's what I was afraid of. And that's why I held of buying the book until
I was sure, though supporting Mr Meeus in his retirement(?) with meager book
royalties is something I'm not loath to do--his Astronomical Algorithms is a
masterpiece. The more I use it, the more I realize how well it's organized
and how well the material is presented in each chapter. (BTW, thanks to you
for your contribution to the solution of Kepler's equation; yours is the
implementation I've used.)
As to data sources, I'm using Meeus's abbreviated version of VSOP as well as
his lunar model. With those, I can reproduce the images of eclipses on the
NASA website for a given date/time/position. The next step seems to be to
reproduce the maps as well, hence my interest in the Besselian elements and
so on.
Many thanks for the references.
Best regards, Brad

On Tue, Dec 22, 2009 at 6:00 PM, Roger W. Sinnott  wrote:

> 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 of
> totality (northern and southern edge), as well as the appearance,
> magnitude,
> contact times, and limit curves of the partial phases.  It also explains
> how
> to determine the circumstances of the eclipse at any specific latitude and
> longitude.
>
> To calculate the Besselian elements themselves, if you want to, first you
> need a source of highly accurate ephemerides for the Sun and Moon (such as
> from the Astronomical Almanac, NASA's Horizons, or Aldo Vatagliano's Solex
> shareware program).  Then you need the algorithms for deriving the
> elements.
> These are given is such places as the Explanatory Supplement to the
> Astronomical Almanac (either the 1992 or 1961 edition), or William
> Chauvenet's Manual of Spherical Astronomy (various editions, 1863 to 1891;
> also reprinted by Dover in 1960).  Calculating the elements is actually
> more
> straightforward than using them to get accurate local preditions and curves
> for an eclipse.
>
>   -- Roger
>
>
> - Original Message -
> From: "Brad Lufkin" 
> To: "Sundial Mailing List" 
> Sent: Tuesday, December 22, 2009 3:07 PM
> Subject: Re: Nasa website
>
>
> > Speaking of Meeus, does anyone know if his "Elements of Solar Eclipses"
> > includes algorithms for calculating the Besselian elements of eclipses or
> > just presents tables of results? Also, does the book present algorithms
> > for
> > calculating the paths of eclipses? It's not clear from the description on
> > the bookseller's website.
> > Regards, Brad
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re: Nasa website

[Brad Lufkin]

Speaking of Meeus, does anyone know if his "Elements of Solar Eclipses"
includes algorithms for calculating the Besselian elements of eclipses or
just presents tables of results? Also, does the book present algorithms for
calculating the paths of eclipses? It's not clear from the description on
the bookseller's website.
Regards, Brad

On Sun, Dec 20, 2009 at 5:32 PM, Bill Gottesman
wrote:

>  According to calculations in Meeus' book, 2009 Solstice is on 12/21 at
> 12:47:50 PM Eastern Standard Time.  This is supposed to be within 1 minute
> of VSOP87 theory.
> -Bill Gottesman
>
> PATRICK O'HEARN wrote:
>
> Hello All,
> May I recommend to everyone today's (12/20/09) astronomy picture of the day
> at http://apod.nasa.gov/apod/.  Turkish photographers have taken a
> beautiful analemma which includes a total eclipse of the sun.  I know many
> list members already visit the site regularly but, for those that don't,
> please do.
> One note however, the description says the winter solstice is on Tuesday,
> which differs from almost every source I find listing the solstice as
> tomorrow (Monday).  Oh well, they are only government astronomers 
> Happy Solstice to all
> Pat O'Hearn
> Anacortes, Wa, USA
>
> --
>
> ---https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
> ---
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
>
---
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Analemma

[Brad Lufkin]

I created diagram of an Oughtred Dial for 1246 AD. The noon line illustrates
the point that Frank King made about the bilateral symmetry of the analemma
in that year. Note also that the longest day of the year (in the northern
hemisphere) was around June 10th and the shortest was around Dec 10th. This
is, of course, due to the fact the Julian calendar was still in use that
year.
I tried posting the diagram o the list but it got rejected because it was
over the 50K limit, even though the diagram is only 29K--not sure why this
happened. In any case, I'll be happy to send the diagram to anyone who wants
it.
 Brad
---
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Test Message-Ignore

[Brad Lufkin]

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