Self Propelled Heavy Artillery
From Imperial Wiki
Grand Army of the Republic during the Clone Wars. The SPHA can be outfitted with several modular weapons, including a concussion missile launcher, ion cannon, or a heavy turbolaser. The turbolaser could be used to bring down spacecraft in the size range of Trade Federation core ships.
It should be noted that -- despite the name -- the SPHA is not actually an artillery piece, as it generally cannot drop ordnance on targets that are not in its line of sight (the concussion missile launcher module may be the exception).
- SPHA-T on StarWars.Com