Exhibit
23.3
CONSENT
OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM
We have
issued our report dated March 12, 2009 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, 2008
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
August 7,
2009