Calculating the Equation of Time and other Solar Parameters
Dear Friends I have spend many happy hours during this wet, wet winter investigating and learning how to calculate all the solar parameters that a gnomonist might possibly need - Equation of Time, Declination, RA, Altitude, Azimuth, Time of Sunset/Rise, etc, etc. I have been surprised to find that - with traditional calculation methods and an absolute minimum of astronomical information - it is possible to calculate everything from first principles to a surprising degree of accuracy. Other than location and local time, only six pieces of astronomical information are required - obliquity, eccentricity, Sun’s GHA at 1/1/2000, longitude of perihelion, a single precessional constant and the length of the tropical year. Accuracies for the EOT are +/- 2 seconds of time For altitudes/azimuths, less than 1 minute of arc - much better than needed by most gnomonic problems. If any of you are interested in such calculations, I have loaded a document with all the astronomical theory and background plus the code onto my website www.precisedirections.co.uk/sundials The code is written in Python, a language available on every type of computer, which is very easily understood, quite easily learnt and very easily translated into any other coding language you might like. If you own an iPad or iPhone, and are prepared to buy a cheap little app called Pythonista, the code will extract locational time information from your phone - so you do not even have to input this to get your calculations done You might also like to see a graphic of a civil mean time horizontal dial, which I think is called a hectomoros dial, that is destined for my garden. This is also on the website. Enjoy Kevin--- https://lists.uni-koeln.de/mailman/listinfo/sundial
CORRECTION Calculating the Equation of Time and other Solar Parameters
My website is … http://www.precisedirections.co.uk/Sundials with a capital S for Sundial Sorry K--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Calculating the Equation of Time and other Solar Parameters
Kevin, I am excited about your article Basic Astronomy for the Gnomonist. It will take some time to digest, but it seems to have a very nice graphic analysis for the many formulas and solar positioning we deal with. I appreciate you making this reference available. I think what you call a Hectoromos dial is what I have heard described as a Singleton dial. Here is a link to a similar (vertical) dial at the University of Vermont. Fred Sawyer wrote about the Hectoromos dial in an early NASS compendium. I think Plato might have had something to do with it. -Bill On Sun, Feb 23, 2014 at 2:32 PM, Kevin Karney kar...@me.com wrote: Dear Friends I have spend many happy hours during this wet, wet winter investigating and learning how to calculate all the solar parameters that a gnomonist might possibly need - Equation of Time, Declination, RA, Altitude, Azimuth, Time of Sunset/Rise, etc, etc. I have been surprised to find that - with traditional calculation methods and an absolute minimum of astronomical information - it is possible to calculate everything from first principles to a surprising degree of accuracy. Other than location and local time, only six pieces of astronomical information are required - obliquity, eccentricity, Sun's GHA at 1/1/2000, longitude of perihelion, a single precessional constant and the length of the tropical year. Accuracies for the EOT are +/- 2 seconds of time For altitudes/azimuths, less than 1 minute of arc - much better than needed by most gnomonic problems. If any of you are interested in such calculations, I have loaded a document with all the astronomical theory and background plus the code onto my website *www.precisedirections.co.uk/sundials http://www.precisedirections.co.uk/sundials* The code is written in Python, a language available on every type of computer, which is very easily understood, quite easily learnt and very easily translated into any other coding language you might like. If you own an iPad or iPhone, and are prepared to buy a cheap little app called Pythonista, the code will extract locational time information from your phone - so you do not even have to input this to get your calculations done You might also like to see a graphic of a civil mean time horizontal dial, which *I think* is called a hectomoros dial, that is destined for my garden. This is also on the website. Enjoy Kevin --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
online manuscript by Mayall and Mayall
Dear All, As those who attended last summer's meeting of the North American Sundial Society know, I have done some research on the Margaret Mayall and R. Newton Mayall, authors of the well-known, Sundials: How To Know, Use, and Make Them, and their connections to sundials presently in Harvard's Collection of Historical Scientific Instruments. My research paper has not yet been published. One of the manuscripts I have used was a typescript catalog of the Ernst Collection by the Mr. and Mrs. Mayall. The document is held at the Harvard College Observatory. It was recently digitized and is now available online. You can find it here: The Harold C. Ernst Collection of Portable Sundials Mayall, R. Newton Mayall, Margaret W. http://zenodo.org/record/8326 Best wishes, Sara Sara J. Schechner, Ph.D. David P. Wheatland Curator of the Collection of Historical Scientific Instruments Department of the History of Science, Harvard University Science Center 251c, 1 Oxford Street, Cambridge, MA 02138 Tel: 617-496-9542 | Fax: 617-496-5932 | sche...@fas.harvard.edumailto:sche...@fas.harvard.edu http://scholar.harvard.edu/saraschechner/ http://chsi.harvard.edu/ --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Calculating the Equation of Time and other Solar Parameters
Thanks Kevin, A quick review demonstrated how useful your work can be for folk like us. Here is a specific example. I have been working with solar and lunar ephemerides date from the JPL Horizons website. http://ssd.jpl.nasa.gov/horizons.cgi#top This site provides a wealth of data that the user can customize for their own purposes. The problem is the user does not know how the data was calculated nor how it is to be used The Explanatory Supplement helps but it is difficult to understand. One simple example is understanding a solar data compilation that provided among other things Right Ascension and Declination. But I really wanted the EQT. Your formula 9 in Part 1 gave me the simple relationship, obvious in hindsight that I was looking for, the conversion of RA to EQT. I look forward making good use of your work. Thank you for making it available. Thanks again, Roger Bailey Walking Shadow Designs From: Kevin Karney Sent: Sunday, February 23, 2014 11:32 AM To: sundial@uni-koeln.de List Subject: Calculating the Equation of Time and other Solar Parameters Dear Friends I have spend many happy hours during this wet, wet winter investigating and learning how to calculate all the solar parameters that a gnomonist might possibly need - Equation of Time, Declination, RA, Altitude, Azimuth, Time of Sunset/Rise, etc, etc. I have been surprised to find that - with traditional calculation methods and an absolute minimum of astronomical information - it is possible to calculate everything from first principles to a surprising degree of accuracy. Other than location and local time, only six pieces of astronomical information are required - obliquity, eccentricity, Sun’s GHA at 1/1/2000, longitude of perihelion, a single precessional constant and the length of the tropical year. Accuracies for the EOT are +/- 2 seconds of time For altitudes/azimuths, less than 1 minute of arc - much better than needed by most gnomonic problems. If any of you are interested in such calculations, I have loaded a document with all the astronomical theory and background plus the code onto my website www.precisedirections.co.uk/sundials The code is written in Python, a language available on every type of computer, which is very easily understood, quite easily learnt and very easily translated into any other coding language you might like. If you own an iPad or iPhone, and are prepared to buy a cheap little app called Pythonista, the code will extract locational time information from your phone - so you do not even have to input this to get your calculations done You might also like to see a graphic of a civil mean time horizontal dial, which I think is called a hectomoros dial, that is destined for my garden. This is also on the website. Enjoy Kevin --- https://lists.uni-koeln.de/mailman/listinfo/sundial No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4335 / Virus Database: 3705/7118 - Release Date: 02/23/14 - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4335 / Virus Database: 3705/7118 - Release Date: 02/23/14 --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Calculating the Equation of Time ..
Kevin, Welcome the the wonderful world of celestial mechanics ... you need to have only six orbital parameters plus time epoch plus earth inclination and sidereal spin, so total of 8 parameters are required Bob On 2/23/2014 6:49 PM, sundial-requ...@uni-koeln.de wrote: Send sundial mailing list submissions to sundial@uni-koeln.de To subscribe or unsubscribe via the World Wide Web, visit https://lists.uni-koeln.de/mailman/listinfo/sundial or, via email, send a message with subject or body 'help' to sundial-requ...@uni-koeln.de You can reach the person managing the list at sundial-ow...@uni-koeln.de When replying, please edit your Subject line so it is more specific than Re: Contents of sundial digest... Today's Topics: 1. Calculating the Equation of Time and other Solar Parameters (Kevin Karney) 2. CORRECTION Calculating the Equation of Time and other Solar Parameters (Kevin Karney) 3. Re: Calculating the Equation of Time and other Solar Parameters (Bill Gottesman) 4. online manuscript by Mayall and Mayall (Schechner, Sara) 5. Re: Calculating the Equation of Time and other Solar Parameters (Roger Bailey) -- Message: 1 Date: Sun, 23 Feb 2014 19:32:37 + From: Kevin Karney kar...@me.com To: sundial@uni-koeln.de List sundial@uni-koeln.de Subject: Calculating the Equation of Time and other Solar Parameters Message-ID: d9c80f35-d4a1-4414-bac3-d1074c51c...@me.com Content-Type: text/plain; charset=windows-1252 Dear Friends I have spend many happy hours during this wet, wet winter investigating and learning how to calculate all the solar parameters that a gnomonist might possibly need - Equation of Time, Declination, RA, Altitude, Azimuth, Time of Sunset/Rise, etc, etc. I have been surprised to find that - with traditional calculation methods and an absolute minimum of astronomical information - it is possible to calculate everything from first principles to a surprising degree of accuracy. Other than location and local time, only six pieces of astronomical information are required - obliquity, eccentricity, Sun?s GHA at 1/1/2000, longitude of perihelion, a single precessional constant and the length of the tropical year. Accuracies for the EOT are +/- 2 seconds of time For altitudes/azimuths, less than 1 minute of arc - much better than needed by most gnomonic problems. If any of you are interested in such calculations, I have loaded a document with all the astronomical theory and background plus the code onto my website www.precisedirections.co.uk/sundials The code is written in Python, a language available on every type of computer, which is very easily understood, quite easily learnt and very easily translated into any other coding language you might like. If you own an iPad or iPhone, and are prepared to buy a cheap little app called Pythonista, the code will extract locational time information from your phone - so you do not even have to input this to get your calculations done You might also like to see a graphic of a civil mean time horizontal dial, which I think is called a hectomoros dial, that is destined for my garden. This is also on the website. Enjoy Kevin -- next part -- An HTML attachment was scrubbed... URL: https://lists.uni-koeln.de/mailman/private/sundial/attachments/20140223/b50a01bb/attachment-0001.html -- Message: 2 Date: Sun, 23 Feb 2014 20:06:51 + From: Kevin Karney kar...@me.com To: sundial@uni-koeln.de List sundial@uni-koeln.de Subject: CORRECTION Calculating the Equation of Time and other Solar Parameters Message-ID: dc4a7b4d-7d8f-4a83-97b9-c2ed7732c...@me.com Content-Type: text/plain; charset=windows-1252 My website is ? http://www.precisedirections.co.uk/Sundials with a capital S for Sundial Sorry K -- next part -- An HTML attachment was scrubbed... URL: https://lists.uni-koeln.de/mailman/private/sundial/attachments/20140223/75ac7917/attachment-0001.html -- Message: 3 Date: Sun, 23 Feb 2014 15:52:57 -0500 From: Bill Gottesman billgottes...@comcast.net To: Kevin Karney kar...@me.com Cc: sundial@uni-koeln.de List sundial@uni-koeln.de Subject: Re: Calculating the Equation of Time and other Solar Parameters Message-ID: CAMDsn==32iapzw47q7zo4-wwyxbcttzcjcjax+y8vvtv_fd...@mail.gmail.com Content-Type: text/plain; charset=iso-8859-1 Kevin, I am excited about your article Basic Astronomy for the Gnomonist. It will take some time to digest, but it seems to have a very nice graphic analysis for the many formulas and solar positioning we deal with. I appreciate you making this reference available. I think what you call a Hectoromos dial is what I have heard described as a Singleton dial. Here is a link to a similar (vertical) dial at the University
