Hi Dan, The advice you have received from Gian and others is excellent. I use his "Sol et Umbra" android app in a smartphone and tablet. It is a great app.
But you asked for a spreadsheet. Attached is one implementation of Meeus's simplified solar coordinate calculation. Helmut Sonderegger developed this and added it to my spreadsheet for calculating analemmatic sundials. I have copied it into several other spreadsheets whenever I needed declination and the equation of time. This is a reduced version small enough to get through the SML size filter. Input the start date and time into cell A7. Change the increment from 1 day to whatever in cell A8. Copy row 8 and paste it in below for as many rows as you wish. Copy the spreadsheet into other spreadsheets using solar coordinates but be aware of the absolute address to the degree to radian conversion in row 1 I answered this question about a year ago for Jack Aubert. he was interested in the rate of change of declination near the equinox and solstice. I sent him a full implementation of that included calculating and plotting the time of sunrise near the winter solstice. The copy to the SML was filtered out but I will forward his note and my reply with the original spreadsheet. To answer this question I needed to review Meeus's Astronomical Algorithms, specifically Chapter 25 Solar Coordinates pg 163-170. This great reference book is now available as a free download. Just Google Meeus Astronomical Algorithms free. Is this an example of fair use, a single copy of a library copy or a copyright violation? I don't know but I was glad to find it. meeus discusses the accuracy of the simple calculation compared to the more rigorous version. For sundials the simple version is fine. Regards, Roger Bailey From: Dan-George Uza Sent: Tuesday, October 25, 2016 9:38 AM To: [email protected] Subject: Solar Declination Hello, Can you provide a free accurate spreadsheet for the calculation of daily solar declination across a leap year as well as non-leap year? Thanks, Dan Uza -------------------------------------------------------------------------------- --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial -------------------------------------------------------------------------------- No virus found in this message. Checked by AVG - www.avg.com Version: 2016.0.7859 / Virus Database: 4664/13266 - Release Date: 10/24/16
SolarEphem.xls
Description: MS-Excel spreadsheet
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