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<div id="root"></div>
+<div class="main">
+ <h2 id="explanation">Explanation</h2>
+ <div class="card">
+ <div class="card-body">
+ <h4 class="card-title">What is this?</h4>
+ <p class="lead">This is an implementation of the <a href="https://en.wikipedia.org/wiki/Gregorian_calendar">Gregorian
+ calendar</a>—which is the default civil calendar in most countries—with conversions to various other
+ calendars.</p>
+ <p>Currently, it displays the following conversions for each day, if possible:</p>
+ <ul>
+ <li>the <a href="https://en.wikipedia.org/wiki/Julian_calendar">Julian calendar</a> date;</li>
+ <li>the <a href="https://en.wikipedia.org/wiki/Julian_day">Julian day (JD) number</a>;</li>
+ <li>the <a href="https://en.wikipedia.org/wiki/Mesoamerican_Long_Count_calendar">Mesoamerican Long Count
+ calendar</a> date; and
+ </li>
+ <li>the <a href="https://en.wikipedia.org/wiki/French_Republican_calendar">French Republican
+ calendar</a> date.
+ </li>
+ </ul>
+ </div>
+ </div>
+ <div class="card">
+ <div class="card-body">
+ <h4 class="card-title">How are BCE years handled?</h4>
+ <p class="lead">The astronomical convention is used, i.e. year 0 is 1 BCE, year -1 is 2 BCE, etc.</p>
+ <p>Due to the way the common era (a.k.a. Anno Domini) year numbering system works, the year 1 BCE is
+ followed directly by 1 CE with no year zero. This makes math hard. As such, the astronomical convention
+ of making 1 BCE year 0 and extending this into the past was used.</p>
+ </div>
+ </div>
+ <div class="card">
+ <div class="card-body">
+ <h4 class="card-title">What is the JD (Julian day number) value?</h4>
+ <p>The integer <a href="https://en.wikipedia.org/wiki/Julian_day">Julian day (JD) number</a> is the
+ continuous count of days since the beginning of the Julian period, which is very useful in astronomy and
+ in software for calculating durations without worrying about weird calendar issues. In this respect,
+ it's very similar to Unix time.</p>
+ <p>JD 0 is assigned to the date Monday, January 1, 4713 BCE (Julian) or November 24, 4714 BCE (Gregorian).
+ More specifically, if fractional JDs are considered, then the integer value specifically refers to the
+ Universal Time noon on that date.</p>
+ </div>
+ </div>
+ <div class="card">
+ <div class="card-body">
+ <h4 class="card-title">What is the LC (Mesoamerican Long Count) date?</h4>
+ <p>The five (or more) numbers separated by dots is the corresponding
+ <a href="https://en.wikipedia.org/wiki/Mesoamerican_Long_Count_calendar">Mesoamerican Long Count
+ calendar</a> date. This is commonly known as the “Mayan calendar.” This calendar is not
+ available for dates before August 11, 3114 BCE (Gregorian) or September 6, 3114 BCE (Julian).</p>
+ </div>
+ </div>
+ <div class="card">
+ <div class="card-body">
+ <h4 class="card-title">What is the FR (French Republican calendar) date?</h4>
+ <p>The <a href="https://en.wikipedia.org/wiki/French_Republican_calendar">French Republican
+ calendar</a> was a calendar created and implemented during the French Revolution. It is also frequently
+ referred to as the <em>French Revolutionary Calendar</em>, but this is a misnomer:
+ year 1 of the calendar started on 22 September 1792, the day after the
+ <a href="https://en.wikipedia.org/wiki/Proclamation_of_the_abolition_of_the_monarchy">abolition of the
+ monarchy</a> and the founding of the <a href="https://en.wikipedia.org/wiki/French_First_Republic">French
+ First Republic</a>.</p>
+ <p>Specifically, the variant used here is <a href="https://frcal.qt.ax/">the one I computed from
+ astronomy</a>.</p>
+ </div>
+ </div>
+</div>
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