public static function Nut06a($date1, $date2, &$dpsi, &$deps) {
    $t;
    $fj2;
    $dp;
    $de;

    /* Interval between fundamental date J2000.0 and given date (JC). */
    $t = (($date1 - DJ00) + $date2) / DJC;

    /* Factor correcting for secular variation of J2. */
    $fj2 = -2.7774e-6 * $t;

    /* Obtain IAU 2000A nutation. */
    IAU::Nut00a($date1, $date2, $dp, $de);

    /* Apply P03 adjustments (Wallace & Capitaine, 2006, Eqs.5). */
    $dpsi = $dp + $dp * (0.4697e-6 + $fj2);
    $deps = $de + $de * $fj2;
    
    return;
  }