The provisions of section 502(a) require that any surety company with which a bond is placed pursuant to that section must be a corporate surety which holds a grant of authority from the Secretary of the Treasury under the Act of July 30, 1947 (6 U.S.C. 6-13), as an acceptable surety on Federal bonds. That Act provides, among other things, that in order for a surety company to be eligible for such grant of authority, it must be incorporated under the laws of the United States or of any State and the Secretary of the Treasury shall be satisfied of certain facts relating to its authority and capitalization. Such grants of authority are evidenced by Certificates of Authority which are issued by the Secretary of the Treasury and which expire on the June 30 following the date of their issuance. A list of the companies holding such Certificates of Authority is published annually in the Federal Register, usually in July. Changes in the list, occurring between July 1 and June 30, either by addition to or removal from the list of companies, are also published in the Federal Register following each such change.