Imperial artillery on Hoth?

[VT-16]

I´ve been looking at scripts of ESB on the net (mostly from the movie section on massassi.yavin4.com) and I noticed some thing that may indicate the presence of Imperial artillery used during the battle of Hoth.

From what I understand, the command center was hit some moments before the rebel soldiers began retreating from the front lines, and the generator was targeted. Now, if I´m not mistaken, isn´t the command center deep inside the mountain behind the shield generator and therefore effectively out of the AT-AT´s range? Does this mean there were artillery units firing from another angle or perhaps shooting over their intended target, the generator? Or am I on a wild goose chase...
-___- ;;;

[wautd]

I doubt it. It may very well be the Empire has artillery but i doubt they used it at Hoth. I dont think they needed them as the AT-AT's with snowtroopers where overkill for the poor rebels