code: public final double estimatedLongitude(long et)
      {
          et = correctedTime(et);
          lock.lock();
          try
          {
              calc();
              if (rateOfTurn == 0)
              {
                  double dist = calcDist(et);
                  return addLongitude(longitude, deltaLongitude(latitude, dist, bearing));
              }
              else
              {
                  double deg = calcDeg(et);
                  return addLongitude(centerLongitude, deltaLongitude(latitude, radius, deg));
              }
          }
          finally
          {
              lock.unlock();
          }
      }
docs: Return estimated longitude at et
  @param et
  @return