code: def sun_ecliptic_longitude(utc_time):
      
      jdate = jdays2000(utc_time) / 36525.0
      # mean anomaly, rad
      m_a = np.deg2rad(357.52910 +
                       35999.05030 * jdate -
                       0.0001559 * jdate * jdate -
                       0.00000048 * jdate * jdate * jdate)
      # mean longitude, deg
      l_0 = 280.46645 + 36000.76983 * jdate + 0.0003032 * jdate * jdate
      d_l = ((1.914600 - 0.004817 * jdate - 0.000014 * jdate * jdate) * np.sin(m_a) +
             (0.019993 - 0.000101 * jdate) * np.sin(2 * m_a) + 0.000290 * np.sin(3 * m_a))
      # true longitude, deg
      l__ = l_0 + d_l
      return np.deg2rad(l__)
docs: Ecliptic longitude of the sun at *utc_time*.