Seth
a6b3f039d8
Pages: /, /simple, /decimal, /seth, /calendar, /astro, /convert, /timegov Features: Seth Calendar (10×36 + holidays), decimal time, moon phases, astronomy (sun/moon), bidirectional time converter, Seth date display, leap day split cell in calendar grid.
268 lines
12 KiB
HTML
268 lines
12 KiB
HTML
<!doctype html>
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<html lang="en">
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<head>
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<meta charset="utf-8">
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<meta name="viewport" content="width=device-width, initial-scale=1">
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<title>SethPC Seth Date</title>
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<link rel="icon" type="image/png" href="https://storage.googleapis.com/sethfreiberg.com/sethflix/favicon.png">
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<link rel="stylesheet" href="/style.css">
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<style>
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.seth-note {
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margin: 0 0 1rem;
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font-size: 0.85rem;
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color: var(--muted);
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line-height: 1.5;
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}
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.ref-table {
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width: 100%;
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border-collapse: collapse;
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font-size: 0.82rem;
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margin: 0.4rem 0 0.9rem;
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}
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.ref-table th {
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text-align: left;
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color: var(--accent);
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border-bottom: 1px solid var(--border);
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padding: 0.2rem 0.5rem 0.2rem 0;
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font-weight: 600;
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}
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.ref-table td {
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padding: 0.15rem 0.5rem 0.15rem 0;
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color: var(--muted);
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border-bottom: 1px solid #2a2a2a;
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}
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.ref-table td:first-child {
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color: var(--text);
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width: 2rem;
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}
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.time-compare {
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display: flex;
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flex-direction: column;
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gap: 0.2rem;
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}
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.time-compare p {
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margin: 0;
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font-family: "JetBrains Mono", monospace;
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font-size: 1rem;
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letter-spacing: 0.02em;
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color: var(--muted);
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}
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.seth-details {
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margin: 0.75rem 0 0;
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}
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.seth-details summary {
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cursor: pointer;
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color: var(--accent);
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font-size: 0.85rem;
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user-select: none;
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padding: 0.3rem 0;
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}
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.seth-details summary:hover {
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color: var(--accent-hover);
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}
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.seth-details .seth-note {
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margin-top: 0.6rem;
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}
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</style>
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</head>
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<body>
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<main class="wrap">
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<div class="brand-row">
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<img class="logo-img" src="https://storage.googleapis.com/sethfreiberg.com/sethflix/favicon.png" alt="SethPC logo">
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<span class="brand-text">SethPC Seth Date</span>
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</div>
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<p class="kicker">Seth Calendar & Decimal Time ·
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<a href="/calendar/" style="color:var(--accent);text-decoration:none;font-size:0.85rem;">Calendar</a> ·
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<a href="/convert" style="color:var(--accent);text-decoration:none;font-size:0.85rem;">Converter</a> ·
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<a href="/decimal" style="color:var(--accent);text-decoration:none;font-size:0.85rem;">Decimal Time</a> ·
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<a href="/astro" style="color:var(--accent);text-decoration:none;font-size:0.85rem;">Astronomy</a>
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</p>
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<h1 id="dateLine">Loading date...</h1>
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<p id="digital" class="digital">-:--.--</p>
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<div class="controls">
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<label class="zone-picker" for="zoneSelect">Display Time Zone</label>
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<select id="zoneSelect"></select>
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</div>
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<div class="meta-grid">
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<div class="time-compare" style="grid-column: span 2;">
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<p class="mono">DECI: <span id="decimalTime">-</span></p>
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<p class="mono">GREG: <span id="gregorianTime">-</span></p>
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</div>
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<p><strong>Time Zone:</strong> <span id="zoneLabel">-</span></p>
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<p><strong>Day of Year:</strong> <span id="dayOfYear">-</span></p>
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<p><strong>Status:</strong> <span id="offsetLabel">calibrating...</span></p>
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<p><strong>Week of Year:</strong> <span id="weekOfYear">-</span></p>
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<p><strong>Gregorian UTC:</strong> <span id="utcLabel">-</span></p>
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<p><strong>Source:</strong> Hosted by SethPC</p>
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</div>
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<details class="seth-details">
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<summary>History</summary>
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<div class="seth-note">
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<p>
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The Seth Calendar was invented by <strong>Seth Freiberg</strong> in 2026 as a personal design project,
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born out of frustration with the irregularity of the Gregorian calendar — unequal month lengths,
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weeks that don't divide months evenly, and no clean mapping between days and dates.
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</p>
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<p>
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The goal was a calendar with a simple, regular structure: 10 months of exactly 36 days,
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each month divided into 6 weeks of 6 days, with a small block of holiday days at the year end
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to absorb the remainder. Year numbers and the January 1 new year are kept from the Gregorian
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calendar to stay compatible with the existing world.
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</p>
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<p>
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Decimal time was paired with it for the same reason: the standard 24-hour clock is an arbitrary
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Babylonian inheritance. Dividing the day into 10 hours of 100 minutes of 100 seconds gives a
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fully base-10 time system that is easier to reason about and calculate with.
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All units in the Seth system — months, weeks, days, hours, minutes, seconds — are zero-indexed.
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</p>
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<p>
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Credit is due to the <strong>French Republican Calendar</strong> (1793), which pioneered both ideas:
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a reformed calendar with equal 30-day months and 5–6 complementary days at year end,
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and a decimal clock dividing the day into 10 hours of 100 minutes of 100 seconds.
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The French system was officially used from 1793 to 1805 before Napoleon abolished it.
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The Seth Calendar was designed independently in the same spirit, with a different month structure
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and the addition of zero-indexing throughout.
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</p>
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</div>
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</details>
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<details class="seth-details">
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<summary>About Seth Date</summary>
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<div class="seth-note">
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<p>
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<strong>Seth Date</strong> uses the same year numbers and January 1 new year as the Gregorian
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calendar. The year is divided into <strong>10 months of 36 days</strong> (6 weeks of 6 days each),
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followed by <strong>5 holiday days</strong> at year end (6 on leap years).
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All units are <strong>zero-indexed</strong>: months 0–9, days 0–35, weeks 0–5, weekdays 0–5.
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Time uses the same decimal system: 10 hours, 100 minutes, 100 seconds per day.
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The Seth second is derived from the Unix second (which equals the SI second, leap seconds aside)
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at a fixed ratio: <strong>1 Seth second = 0.864 SI seconds</strong> (86,400 SI seconds per day ÷ 100,000 Seth seconds per day).
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</p>
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<p>
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<strong>Leap Day</strong> (Gregorian Feb 29) is a special intercalary day that exists
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<em>outside</em> the normal month and week structure. It is inserted between Month 1, Week 3, Day 4
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and Month 1, Week 3, Day 5 — occupying DOY 60 in its own slot. After Leap Day the calendar
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resumes at D5 unchanged, which is why every Seth date from March 1 onward falls on the same
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Gregorian date every year (e.g. Christmas is always Month 9, Day 34). On the calendar it appears
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as a split cell sharing the D4 column: the top half is the normal D4 day, the bottom half is Leap Day.
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</p>
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<p><strong>Reading the date:</strong> dates are written as
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<em>Year M W D</em> —
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e.g. <em>Month 3, Week 2, Day 4</em> means the 3rd month (0-indexed), week 2, day 4 of that week,
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which is day 16 of the month (2×6 + 4).
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Holiday days are written as <em>Holiday N</em> (N = 0–4, or 0–5 on leap years) and fall outside any month or week.
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</p>
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<p><strong>Months</strong> (months 0–9, days 0–35, approx. Gregorian ranges):</p>
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<table class="ref-table">
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<thead><tr><th>#</th><th>Days</th><th>Approx. Gregorian</th><th>Notes</th></tr></thead>
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<tbody>
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<tr><td>0</td><td>0–35</td><td>Jan 1 – Feb 5</td><td></td></tr>
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<tr><td>1</td><td>0–35</td><td>Feb 6 – Mar 13</td><td></td></tr>
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<tr><td>2</td><td>0–35</td><td>Mar 14 – Apr 18</td><td></td></tr>
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<tr><td>3</td><td>0–35</td><td>Apr 19 – May 24</td><td></td></tr>
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<tr><td>4</td><td>0–35</td><td>May 25 – Jun 29</td><td></td></tr>
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<tr><td>5</td><td>0–35</td><td>Jun 30 – Aug 4</td><td></td></tr>
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<tr><td>6</td><td>0–35</td><td>Aug 5 – Sep 9</td><td></td></tr>
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<tr><td>7</td><td>0–35</td><td>Sep 10 – Oct 15</td><td></td></tr>
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<tr><td>8</td><td>0–35</td><td>Oct 16 – Nov 20</td><td></td></tr>
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<tr><td>9</td><td>0–35</td><td>Nov 21 – Dec 26</td><td>Ends Dec 25 on leap years</td></tr>
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</tbody>
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</table>
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<p><strong>Weeks</strong> (weeks 0–5 within each month, days 0–5 within each week):</p>
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<table class="ref-table">
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<thead><tr><th>Week</th><th>Days</th></tr></thead>
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<tbody>
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<tr><td>0</td><td>0–5</td></tr>
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<tr><td>1</td><td>6–11</td></tr>
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<tr><td>2</td><td>12–17</td></tr>
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<tr><td>3</td><td>18–23</td></tr>
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<tr><td>4</td><td>24–29</td></tr>
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<tr><td>5</td><td>30–35</td></tr>
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</tbody>
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</table>
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<p><strong>Holiday days</strong> (after Month 9, Day 35):</p>
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<table class="ref-table">
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<thead><tr><th>Holiday</th><th>Normal year</th><th>Leap year</th></tr></thead>
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<tbody>
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<tr><td>H0</td><td>Dec 27</td><td>Dec 26 — Boxing Day</td></tr>
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<tr><td>H1</td><td>Dec 28</td><td>Dec 27</td></tr>
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<tr><td>H2</td><td>Dec 29</td><td>Dec 28</td></tr>
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<tr><td>H3</td><td>Dec 30</td><td>Dec 29</td></tr>
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<tr><td>H4</td><td>Dec 31 — New Year's Eve</td><td>Dec 30</td></tr>
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<tr><td>H5*</td><td>—</td><td>Dec 31 — New Year's Eve</td></tr>
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</tbody>
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</table>
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<p style="font-size:0.8rem;">
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* Leap years only.<br>
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Christmas (Dec 25) falls on Month 9, Day 34 in normal years, and Month 9, Day 35 in leap years.<br>
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Dec 26 (Boxing Day) is Month 9, Day 35 in normal years, and Holiday 0 in leap years.
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</p>
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</div>
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</details>
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<details class="seth-details">
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<summary>Time Conversions</summary>
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<div class="seth-note">
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<p>Each decimal hour = 2 hours 24 minutes Gregorian. Each Gregorian hour = ~0:41:67 decimal.</p>
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<div style="display:grid; grid-template-columns: 1fr 1fr; gap: 0 2rem;">
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<div>
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<p><strong>Decimal → Gregorian</strong></p>
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<table class="ref-table">
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<thead><tr><th>Decimal hour</th><th>Gregorian (24h)</th></tr></thead>
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<tbody>
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<tr><td>0:00</td><td>00:00</td></tr>
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<tr><td>1:00</td><td>02:24</td></tr>
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<tr><td>2:00</td><td>04:48</td></tr>
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<tr><td>3:00</td><td>07:12</td></tr>
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<tr><td>4:00</td><td>09:36</td></tr>
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<tr><td>5:00</td><td>12:00</td></tr>
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<tr><td>6:00</td><td>14:24</td></tr>
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<tr><td>7:00</td><td>16:48</td></tr>
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<tr><td>8:00</td><td>19:12</td></tr>
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<tr><td>9:00</td><td>21:36</td></tr>
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</tbody>
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</table>
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</div>
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<div>
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<p><strong>Gregorian → Decimal</strong></p>
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<table class="ref-table">
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<thead><tr><th>Gregorian (24h)</th><th>Decimal hour</th></tr></thead>
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<tbody>
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<tr><td>00:00</td><td>0:00</td></tr>
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<tr><td>01:00</td><td>0:41:67</td></tr>
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<tr><td>02:00</td><td>0:83:33</td></tr>
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<tr><td>03:00</td><td>1:25:00</td></tr>
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<tr><td>04:00</td><td>1:66:67</td></tr>
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<tr><td>05:00</td><td>2:08:33</td></tr>
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<tr><td>06:00</td><td>2:50:00</td></tr>
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<tr><td>07:00</td><td>2:91:67</td></tr>
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<tr><td>08:00</td><td>3:33:33</td></tr>
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<tr><td>09:00</td><td>3:75:00</td></tr>
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<tr><td>10:00</td><td>4:16:67</td></tr>
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<tr><td>11:00</td><td>4:58:33</td></tr>
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<tr><td>12:00</td><td>5:00:00</td></tr>
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<tr><td>13:00</td><td>5:41:67</td></tr>
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<tr><td>14:00</td><td>5:83:33</td></tr>
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<tr><td>15:00</td><td>6:25:00</td></tr>
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<tr><td>16:00</td><td>6:66:67</td></tr>
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<tr><td>17:00</td><td>7:08:33</td></tr>
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<tr><td>18:00</td><td>7:50:00</td></tr>
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<tr><td>19:00</td><td>7:91:67</td></tr>
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<tr><td>20:00</td><td>8:33:33</td></tr>
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<tr><td>21:00</td><td>8:75:00</td></tr>
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<tr><td>22:00</td><td>9:16:67</td></tr>
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<tr><td>23:00</td><td>9:58:33</td></tr>
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</tbody>
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</table>
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</div>
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</div>
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</div>
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</details>
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</main>
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<script src="/seth.js"></script>
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</body>
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</html>
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