The first version of the Yearly-Calendar was published 20 years ago today.
Read time: 3 min, 30 s
The beginning
Excerpt from the beginnings (Swiss German)
- V.0.1 - 12.02.2004 - Basic Version
- V.0.2 - 13.02.0204 - with public holidays, New Year, Bertold's Day, Three Kings, St Joseph's Day, Ascension Day, All Saints' Day, Conception Day, Christmas Day, St Stephen's Day and New Year's Eve
- V.0.3 - 15.02.2004 - with variable feast days; Easter, Easter Monday, Palm Sunday, Whitsun, Whit Monday, Good Friday, White Sunday, Ascension Day, Ash Wednesday and Corpus Christi
- V.0.4 - 16.02.2004 - with public holiday, Mother's Day, Labour Day, St. Clause's Day and Valentine's Day
- V.0.5 - 17.02.2004 - with public holiday, Advent, Eidg. Buss und Bettag.
- V.0.6 - 18.02.2004 - printout in PDF with http://www.fpdf.org
- V.1.0 - 19.02.2004 - First Released
- V.1.1 - 26/02/2004 - Period error message
- V.1.2 - 02.03.2004 - Display PHP sourecode
- V.1.3 - 28.06.2004 - Display of the current day
- V.1.4 - 17/06/2007 - New Father's Day
The first code consisted of about 100 lines of PHP code.
Here is version 1.4 for viewing jahreskalender_1.4.php
At the time, it was a first project with PHP programming
The annual calendar had around 200 visitors per month in 2005. The number of visitors increased steadily so that in 2010 there were about 2,000 per month.
The expansion to several countries
It was not until 2010 that the annual calendar was further developed and countries such as Germany and the USA were added. In 2016, there were between 60 countries.
In 2014, there were 60 countries. In March 2014 around 14,000 visitors, today there are 74 countries.
Getting started with the mobile version
Around 55,000 visitors in April 2017
The integration of the lunar calendar
In 2008 a moon phase calendar was added. Based on the Perl module Astro::MoonPhase, version 0.60, which in turn was taken from the code of John Walker, the formula was in turn taken from the book Astronomical Formulae for Calculators by Jean Meeus, today also under Astronomical Algorithms Second Edition (ISBN 978-0-943396-61-3). The calculation is described from chapter 47 "Position of the Moon" and has a deviation of +/- 2 minutes.
This year I have implemented the extended calculation from the book Astronomical Algorithms Second Edition (ISBN 978-0-943396-61-3) by J. Meeus. This is described in chapter 49 "Phases of the Moon" from pages 349ff, with a deviation of only about +/- 4 seconds, maximum 17 seconds. The calculation is somewhat more complex and also requires a little more computing time.
Example: Full moon on February 9, 2024, the calculation according to chapter 47 results in UTC time 23:00:44 according to chapter 49 UTC time 22:59:01.
According to Central European Time, the full moon is then on February 9 instead of February 10, even if there is only a one-minute difference. On the internet you will find some calendars with the first calculation with (imprecise) minute indications, for pure day indications this calculation is sufficient.
The calculations according to the book Astronomical Formulae for Calculators by J.Meeus is very well known, most of the calculations are based on the books by J. Meeus.
The correction data for the second calculation are also provided by NASA itself Polynomial Expressions for Delta T (ΔT) and referred to Meeus. This data of the second calculation of the lunar calendar can also be verified with NASA -> MoonPhases.
This allows a more accurate calculation for a lunar calendar by minutes, to seconds makes no sense (the calculations are rounded to the nearest minute). The new calculation is used for the years 2000 to 2050 in the annual calendar. The other years are still calculated using the first method because of the calculation run.
The changeover to a framework
The website with the structure and web technology was getting on in years. So I decided to migrate it in 2020 to the PHP framework Laravel and to the new modern CSS Tailwindcss, the whole migration took about 6 months until it could be published in summer 2020.
I am delighted that the calendar is being used so actively and that I can make a contribution to a valuable resource.