  We present a new Spitzer IRAC images of the HH 34 outflow. These are the
first images that detect both the knots along the southern jet and the northern
counterjet (the counterjet knots were only detected previously in a long slit
spectrum). This result removes the problem of the apparent coexistence of a
large scale symmetry (at distances of up to approx.1 pc) and a complete lack of
symmetry close to the source (at distances of approx. 1.e+17 cm) for this
outflow. We present a quantitative evaluation of the newly found symmetry
between the HH 34 jet and counterjet, and show that the observed degree of
symmetry implies that the jet production region has a characteristic size <2.8
AU. This is the strongest constraint yet derived for the size of the region in
which HH jets are produced.
