We discuss multiple Very Long Baseline Interferometry ( VLBI ) continuum and spectral line imaging observations and Westerbork Synthesis Radio Telescope spectroscopy of the compact variable nuclear radio jet source in the elliptical galaxy NGC 1052 .
Absorption and emission signatures reveal ionised , atomic , and molecular components of the surrounding medium .

Ten epochs of Very Long Baseline Array ( VLBA ) data at 15 GHz , spanning almost six years , show bi-symmetric jets , in which multiple sub-parsec scale features display outward motions of typically v _ { app } \sim 0.26 c ( { H } _ { 0 } = 65 km s ^ { -1 } Mpc ^ { -1 } ) on each side .
The jets are most likely oriented near the plane of the sky .

Multi-frequency VLBA observations at seven frequencies between 43 and 1.4 GHz show free-free absorption in the inner parsec around the nucleus , probably together with synchrotron self-absorption .
The free-free absorption is apparently due to a structure which is geometrically thick and oriented roughly orthogonal to the jets , but which is patchy .
The western jet is covered more deeply and extensively , and hence is receding .

H i spectral line VLBI observations reveal atomic gas in front of the approaching as well as the receding jet .
There appear to be three velocity systems .
Broad , shallow absorption asymmetrically straddles the systemic velocity spanning -35 to 85 km s ^ { -1 } .
This gas could be local to the AGN environment , or distributed on galactic scales .
Superimposed in the range 25 to 95 km s ^ { -1 } are several sharper ( 3–15 km s ^ { -1 } ) features , each detectable over a few tenths of a pc at various places along the inner 2 pc of the approaching jet .
The third , deepest system is at “ high velocities ” , which is receding by 125 to 200 km s ^ { -1 } with respect to the systemic velocity of NGC 1052 .
It may have a continuous velocity gradient across the nucleus of some 10 km s ^ { -1 } pc ^ { -1 } .
This atomic gas seems restricted to a shell 1–2 pc away from the core , within which it might be largely ionised .

Westerbork Synthesis Radio Telescope spectroscopy has revealed the 18 cm OH main lines ( 1667 and 1665 MHz ) in absorption along the full velocity span of -35 to 200 km s ^ { -1 } , with their line ratio varying roughly from 1:1 to 2:1 .
They are deepest in the high velocity system , where the OH profiles are similar to H i , suggesting co-location of that atomic and molecular gas , and leaving unclear the connection to the H _ { 2 } O masing gas seen elsewhere .
In the high velocity system we have also detected the 18 cm OH satellite lines : 1612 MHz in absorption , and 1720 MHz in emission .
The conjugate behaviour of the satellite line profiles , and the variable main line ratio resemble the situation in Cen~A and NGC 253 .