Exhibit 23.3
 
CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM
 
We have issued our report dated March 17, 2008 with respect to the consolidated financial statements of ATS Corporation and subsidiary included in the Annual Report of ATS Corporation on Form 10-K for the year ended December 31, 2007 which are incorporated by reference in this Registration Statement.  We consent to the incorporation by reference in the Registration Statement of the aforementioned report.
 
/s/ GRANT THORNTON LLP
 
McLean, Virginia
February 27, 2009