Original meaning
Originalists of all stripes cite "The Federalist Papers". It is fairly tenuous to suggest that this represents a good source for the original "intent": after all, Alexander Hamilton, who wrote the majority of those essays, was absent for the greater part of the Philadelphia Convention, and John Jay did not attend it at all. However, James Madison, the principal framer of the Constitution also wrote a substantial amount of "The Federalist Papers". Also, to suggest Hamilton and Jay's absence from the convention implies their ignorance as to the Constitution's original meaning is demeaning to those two men and inaccurate. The collected anti-Federalist papers, of course, will be no use at all to a person searching for the original "intent" of the framers. However, as evidence of how a reasonable person at the time would have understood the words of the Constitution, "The Federalist Papers" and the anti-Federalist essays are evidence of direct relevance.
United States Constitution
Two parties soon developed, one in opposition, the Anti-Federalists, and one in support, the Federalists, of the Constitution; and the Constitution was debated, criticized, and expounded upon clause by clause. Hamilton, Madison, and Jay, under the name of Publius, wrote a series of commentaries, now known as "The Federalist Papers", in support of ratification in the state of New York, at that time a hotbed of anti-Federalism. These commentaries on the Constitution, written during the struggle for ratification, have been frequently cited by the Supreme Court as an authoritative contemporary interpretation of the meaning of its provisions. The dispute over additional powers for the central government was close, and in some states ratification was effected only after a bitter struggle in the state convention itself.