Who is the narrator of Franz Kafka's The Trial?

In Kafka's novels, most of the narration takes place in the third person, and by extension, the author appears far removed from the narrator and the characters with whom the narrator is concerned. The Trial features a third-person (limited omniscient) narrator. By "limited omniscient," we see that the narrator focuses solely on Josef K. (the protagonist) rather than a host of characters. As a result, the reader learns about Josef K. through the limited scope of the narrator. However, in some rare instances, the narrator includes information with respect to other characters. For example, the narrator reveals Frau Grubach's shame after she divulges something inappropriate to Josef K. (this takes place in Chapter One). These instances are few and far between throughout the text. And, even when the reader receives insight into the psychological state of someone other than Josef K., such information is still filtered through the narrator's limited voice.