We have observed the H i distribution in an area 40 ^ { \prime } \times 40 ^ { \prime } around the neutron star candidate RX J0822–4300 , which is located in the supernova remnant Puppis A .
The observations of the \lambda 21 cm line were obtained with the Australia Telescope Compact Array ( ATCA ) and were combined with single dish data from the Southern Galactic Plane Survey .
The spatial resolution is 90 ^ { \prime \prime } , and the velocity resolution , 1 km s ^ { -1 } .
A sensitivity of \sim 0.7 K was achieved .
The results revealed a double lobed feature of reduced emission at +16 km s ^ { -1 } , centered on the central compact object ( CCO ) , and aligned with an H i hole blueshifted by 13 km s ^ { -1 } .
The H i depressions have probably been created by the sweeping up of \sim 2 M _ { \odot } .
The alignement between the lobes and the optical expansion centre of Puppis A suggests that the CCO could be ejecting two opposite jets .
The velocity at which the two lobes are best defined allowed us to confirm that the distance to Puppis A is 2.2 kpc , based on a systemic velocity of +16 km s ^ { -1 } .
The hydrogen column density computed using this systemic velocity is consistent with estimates from models for X-ray spectra , thus reinforcing our conclusion that the kinematic distance is 2.2 kpc .