<!DOCTYPE html>
<!-- Generated by pkgdown: do not edit by hand --><html lang="en"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><meta charset="utf-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no"><title>Convert Julian-Day-Number to Julian Century — julianCenturyAnomaly • oce</title><script src="../deps/jquery-3.6.0/jquery-3.6.0.min.js"></script><meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no"><link href="../deps/bootstrap-5.3.1/bootstrap.min.css" rel="stylesheet"><script src="../deps/bootstrap-5.3.1/bootstrap.bundle.min.js"></script><link href="../deps/font-awesome-6.4.2/css/all.min.css" rel="stylesheet"><link href="../deps/font-awesome-6.4.2/css/v4-shims.min.css" rel="stylesheet"><script src="../deps/headroom-0.11.0/headroom.min.js"></script><script src="../deps/headroom-0.11.0/jQuery.headroom.min.js"></script><script src="../deps/bootstrap-toc-1.0.1/bootstrap-toc.min.js"></script><script src="../deps/clipboard.js-2.0.11/clipboard.min.js"></script><script src="../deps/search-1.0.0/autocomplete.jquery.min.js"></script><script src="../deps/search-1.0.0/fuse.min.js"></script><script src="../deps/search-1.0.0/mark.min.js"></script><!-- pkgdown --><script src="../pkgdown.js"></script><meta property="og:title" content="Convert Julian-Day-Number to Julian Century — julianCenturyAnomaly"><meta name="description" content="Convert a Julian-Day number to a time in julian centuries since noon on
January 1, 1900. The method follows Equation 15.1 in Reference 1.  The
example reproduces the Example 15.a of the same source, with fractional
error 3e-8."><meta property="og:description" content="Convert a Julian-Day number to a time in julian centuries since noon on
January 1, 1900. The method follows Equation 15.1 in Reference 1.  The
example reproduces the Example 15.a of the same source, with fractional
error 3e-8."></head><body>
    <a href="#main" class="visually-hidden-focusable">Skip to contents</a>


    <nav class="navbar navbar-expand-lg fixed-top bg-light" data-bs-theme="light" aria-label="Site navigation"><div class="container">

    <a class="navbar-brand me-2" href="../index.html">oce</a>

    <small class="nav-text text-muted me-auto" data-bs-toggle="tooltip" data-bs-placement="bottom" title="">1.8-4</small>


    <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbar" aria-controls="navbar" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
    </button>

    <div id="navbar" class="collapse navbar-collapse ms-3">
      <ul class="navbar-nav me-auto"><li class="active nav-item"><a class="nav-link" href="../reference/index.html">Reference</a></li>
<li class="nav-item dropdown">
  <button class="nav-link dropdown-toggle" type="button" id="dropdown-articles" data-bs-toggle="dropdown" aria-expanded="false" aria-haspopup="true">Articles</button>
  <ul class="dropdown-menu" aria-labelledby="dropdown-articles"><li><a class="dropdown-item" href="../articles/A_oce.html">1. Introduction to Oce</a></li>
    <li><a class="dropdown-item" href="../articles/B_ctd.html">2. Analysis of CTD data</a></li>
    <li><a class="dropdown-item" href="../articles/C_adp.html">3. Analysis of acoustic-Doppler data</a></li>
    <li><a class="dropdown-item" href="../articles/D_map_projections.html">4. Using map projections</a></li>
    <li><a class="dropdown-item" href="../articles/E_flags.html">5. Dealing with data-quality flags</a></li>
    <li><a class="dropdown-item" href="../articles/F_subclassing.html">6. Subclassing oce objects</a></li>
    <li><a class="dropdown-item" href="../articles/G_altering_defaults.html">7. Altering oce Defaults</a></li>
    <li><a class="dropdown-item" href="../articles/H_tides.html">8. Tidal Analysis</a></li>
  </ul></li>
<li class="nav-item"><a class="nav-link" href="../news/index.html">Changelog</a></li>
      </ul><ul class="navbar-nav"><li class="nav-item"><form class="form-inline" role="search">
 <input class="form-control" type="search" name="search-input" id="search-input" autocomplete="off" aria-label="Search site" placeholder="Search for" data-search-index="../search.json"></form></li>
<li class="nav-item"><a class="external-link nav-link" href="https://github.com/dankelley/oce/" aria-label="GitHub"><span class="fa fab fa-github fa-lg"></span></a></li>
      </ul></div>


  </div>
</nav><div class="container template-reference-topic">
<div class="row">
  <main id="main" class="col-md-9"><div class="page-header">

      <h1>Convert Julian-Day-Number to Julian Century</h1>
      <small class="dont-index">Source: <a href="https://github.com/dankelley/oce/blob/HEAD/R/astronomy.R" class="external-link"><code>R/astronomy.R</code></a></small>
      <div class="d-none name"><code>julianCenturyAnomaly.Rd</code></div>
    </div>

    <div class="ref-description section level2">
    <p>Convert a Julian-Day number to a time in julian centuries since noon on
January 1, 1900. The method follows Equation 15.1 in Reference 1.  The
example reproduces the Example 15.a of the same source, with fractional
error 3e-8.</p>
    </div>

    <div class="section level2">
    <h2 id="ref-usage">Usage<a class="anchor" aria-label="anchor" href="#ref-usage"></a></h2>
    <div class="sourceCode"><pre class="sourceCode r"><code><span><span class="fu">julianCenturyAnomaly</span><span class="op">(</span><span class="va">jd</span><span class="op">)</span></span></code></pre></div>
    </div>

    <div class="section level2">
    <h2 id="arguments">Arguments<a class="anchor" aria-label="anchor" href="#arguments"></a></h2>


<dl><dt id="arg-jd">jd<a class="anchor" aria-label="anchor" href="#arg-jd"></a></dt>
<dd><p>a julian day number, e.g. as given by <code><a href="julianDay.html">julianDay()</a></code>.</p></dd>

</dl></div>
    <div class="section level2">
    <h2 id="value">Value<a class="anchor" aria-label="anchor" href="#value"></a></h2>
    <p>Julian century since noon on January 1, 1900.</p>
    </div>
    <div class="section level2">
    <h2 id="references">References<a class="anchor" aria-label="anchor" href="#references"></a></h2>

<ol><li><p>Meeus, Jean. Astronomical Formulas for Calculators. Second Edition.
Richmond, Virginia, USA: Willmann-Bell, 1982.</p></li>
</ol></div>
    <div class="section level2">
    <h2 id="see-also">See also<a class="anchor" aria-label="anchor" href="#see-also"></a></h2>
    <div class="dont-index"><p>Other things related to astronomy:
<code><a href="angle2hms.html">angle2hms</a>()</code>,
<code><a href="eclipticalToEquatorial.html">eclipticalToEquatorial</a>()</code>,
<code><a href="equatorialToLocalHorizontal.html">equatorialToLocalHorizontal</a>()</code>,
<code><a href="julianDay.html">julianDay</a>()</code>,
<code><a href="moonAngle.html">moonAngle</a>()</code>,
<code><a href="siderealTime.html">siderealTime</a>()</code>,
<code><a href="sunAngle.html">sunAngle</a>()</code>,
<code><a href="sunDeclinationRightAscension.html">sunDeclinationRightAscension</a>()</code></p>
<p>Other things related to time:
<code><a href="ctimeToSeconds.html">ctimeToSeconds</a>()</code>,
<code><a href="julianDay.html">julianDay</a>()</code>,
<code><a href="numberAsHMS.html">numberAsHMS</a>()</code>,
<code><a href="numberAsPOSIXct.html">numberAsPOSIXct</a>()</code>,
<code><a href="secondsToCtime.html">secondsToCtime</a>()</code>,
<code><a href="unabbreviateYear.html">unabbreviateYear</a>()</code></p></div>
    </div>
    <div class="section level2">
    <h2 id="author">Author<a class="anchor" aria-label="anchor" href="#author"></a></h2>
    <p>Dan Kelley</p>
    </div>

    <div class="section level2">
    <h2 id="ref-examples">Examples<a class="anchor" aria-label="anchor" href="#ref-examples"></a></h2>
    <div class="sourceCode"><pre class="sourceCode r"><code><span class="r-in"><span></span></span>
<span class="r-in"><span><span class="va">t</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/base/ISOdatetime.html" class="external-link">ISOdatetime</a></span><span class="op">(</span><span class="fl">1978</span>, <span class="fl">11</span>, <span class="fl">13</span>, <span class="fl">4</span>, <span class="fl">35</span>, <span class="fl">0</span>, tz <span class="op">=</span> <span class="st">"UTC"</span><span class="op">)</span></span></span>
<span class="r-in"><span><span class="va">jca</span> <span class="op">&lt;-</span> <span class="fu">julianCenturyAnomaly</span><span class="op">(</span><span class="fu"><a href="julianDay.html">julianDay</a></span><span class="op">(</span><span class="va">t</span><span class="op">)</span><span class="op">)</span></span></span>
<span class="r-in"><span><span class="fu"><a href="https://rdrr.io/r/base/cat.html" class="external-link">cat</a></span><span class="op">(</span><span class="fu"><a href="https://rdrr.io/r/base/format.html" class="external-link">format</a></span><span class="op">(</span><span class="va">t</span><span class="op">)</span>, <span class="st">"is Julian Century anomaly"</span>, <span class="fu"><a href="https://rdrr.io/r/base/format.html" class="external-link">format</a></span><span class="op">(</span><span class="va">jca</span>, digits <span class="op">=</span> <span class="fl">8</span><span class="op">)</span>, <span class="st">"\n"</span><span class="op">)</span></span></span>
<span class="r-out co"><span class="r-pr">#&gt;</span> 1978-11-13 04:35:00 is Julian Century anomaly 0.78865684 </span>
<span class="r-in"><span></span></span>
</code></pre></div>
    </div>
  </main><aside class="col-md-3"><nav id="toc" aria-label="Table of contents"><h2>On this page</h2>
    </nav></aside></div>


    <footer><div class="pkgdown-footer-left">
  <p>Developed by Dan Kelley, Clark Richards.</p>
</div>

<div class="pkgdown-footer-right">
  <p>Site built with <a href="https://pkgdown.r-lib.org/" class="external-link">pkgdown</a> 2.1.0.9000.</p>
</div>

    </footer></div>





  </body></html>

