src/Marando/AstroDate/Traits/SolsticeEquinoxTrait.php
protected static function equinoxSeptember($year, $vsop = true) {
    $month = 9;

    if ($vsop)
      return static::accurate($year, static::meanTerms($month, $year), $month);
    else
      return static::approx($year, static::meanTerms($month, $year));
  }
protected static function equinoxSeptember($year, $vsop = true) {
    $month = 9;

    if ($vsop)
      return static::accurate($year, static::meanTerms($month, $year), $month);
    else
      return static::approx($year, static::meanTerms($month, $year));
  }
Finds the date of the time of the September Equinox for a given year

@param float $year The year
@param bool  $vsop If true calculates the result using the VSOP model; If
false approximates the result.

@return float The JD and time of the September Equinox in TD