I noticed that "the God of heaven" is a common title used for God in the book of Daniel. Is this name used anywhere else in the Scriptures? Why is it used so much in the book of Daniel? (Perhaps for contrast with the pagan gods?) What all does the phrase denote?
According to F.F. Bruce's Israel and the Nations (p 108):
"the God of Heaven" is a title by which Yahweh is commonly designated under the Persian regime
The phrase is not just used in Daniel, but also used in Ezra 7:12 where Ezra is designated "scribe of the law of the God of heaven" in Artaxerxe's letter to Ezra.
It is used throughout the book of Daniel, because of the title's use in official court documents, and Daniel's living in the royal palace.