code: public final double estimatedLatitude(long et)
      {
          et = correctedTime(et);
          lock.lock();
          try
          {
              calc();
              if (rateOfTurn == 0)
              {
                  double dist = calcDist(et);
                  return latitude+deltaLatitude(dist, bearing);
              }
              else
              {
                  double deg = calcDeg(et);
                  return centerLatitude+deltaLatitude(radius, deg);
              }
          }
          finally
          {
              lock.unlock();
          }
      }
docs: Returns estimated latitude at et
  @param et
  @return