Hi Ken I you want to observe how the Equation of Time varies over the years, go to my website http://www.precisedirections.co.uk/Sundials/index.html
The second item may be of interest to you. It gives a table of EoTs (including the longitude correction for your time zone). And you can choose either a single year or a four year cycle. For the four-year cycle, the average local noon EoT is calculated for each calendar date, except 29 Feb, which stands on its own. If you want the EoT without the longitude correction, set your longitude to your time zone longitude. The calculations used are far more rigorous than needed for gnomonic purposes. They use the complete VSOP theory as described by Meeus and the EoT is topographical rather than geocentric (which only makes a marginal difference). If you use browser (like Chrome) which allows you to see the web-page source, you can see the calculations involved. (In Chrome, select View>Developer>View Source) EoTs calculated have an accuracy of +/- .06 secs of time - using US Naval Observatory's MICA program as standard. I think it is interesting to see how the 4-year table changes as one jumps 4 years into the future... See the first item on the original page for comments on the calculations and consider using a "Victorian EOT" table which gives all the information needed but in a tenth of the space The Latitude/Longitude finder - using Google Earth is a bit ratty, but seems to work for Elizabethtown..... Let me know if you have any problems. Best wishes Kevin > On 26 Jan 2017, at 00:21, Kenneth R clark <krcl...@embarqmail.com> wrote: > > I had an error message from AOL Sorry for no subject line and my files were > not sent. > Let me retry with this account. > > Hi everyone, > > I am working on my Equation of Time plaque for my aluminum cross > sundial. All the instructions and graphics and EQT will be on an 8 ½” > diameter ½” aluminum plate. I do not want to use the standard graph found on > many sundials but instead a chart for the whole year, mins and secs, to add > or subtract total correction to get watch time. I do not have much room for > detailed instructions. > > I looked at difference sources for the chart and would like to verify > the most accurate times to use the four year leap year cycle for a church at > 40.1526N, 76.6038W. I have looked at the Solar Noon calculator, Sonne and > Shadows-(cannot input decimal degrees?) Are there other sources or > spreadsheet programs? > > I like to convey that sundials are accurate. I envision that a person > will wait till the shadow is on a line and the person will know what time it > is suppose to be even though this type of sundial may not be design for > precision. > > I made a quick drawing. There will be some type of sun image at the top > and a logo at the bottom for the location. The chart in the center is from > another project that I did just to see how it would look and if the printing > is large enough to read. I would have to change the inputs to standard time > for the whole year. I have also attached a picture of the sundial. > > I just want to know if I am using the right times and would appreciate > any comments or suggestions. > > Thanks very much > > Ken Clark > > > Elizabethtown, PA > <churchplaque1.pdf><churchcrossnewbasepic_page_001.jpg>--------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > <https://lists.uni-koeln.de/mailman/listinfo/sundial>
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