Rainbow Corporation has a contract with the National Science Foundation to conduct research in Antarctica. Harriet, a U. S. employee of Rainbow, spent all of last year and part of this year working at McMurdo Station on Ross Island, Antarctica. When filing her return for last year, Harriet excluded her income from the contract, based on the fact that she worked outside of the United States. Her income was not in excess of the excludible ceiling. Is Harriet correct in her treatment of last year’s income?