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The detection of molecular hydrogen in Herbig-Haro objects and jets has long been used to understand the physical conditions of their environment and interaction with it. This interaction is through shocks in most cases, although other processes like photoionization, photodissociation and entrainment can also play an important role in their dynamics and energetics. \vspace*{0.1cm}
In this work we present a series of molecular hydrogen ``narrow'' band images of the Herbig-Haro 1 - 2 system at the 1 - 0 S(1) transition at 2.121 $\mu$m, with a slightly better resolution than previous observations. The distribution of H2 is then compared with that of the excitation, measured by the [S~II] 6717+6731 to H$\alpha$ line ratio. \vspace*{0.1cm}
We find a strong correlation between the low excitation and the H2 gas emission (as notice before by some other authors). There are, however, regions of high excitation where the H2 is quite strong suggesting that photodissociation by the 150-200 km s$^{-1}$ shocks is taking place. Among other interesting morphological features of the H2 emission is its presence in regions without optical counterparts. H2 is detected along VLA 1 jet and south of the C-S star there is a bright `knot' of emission suggesting the presence of a bow shock.
