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                                                                     Exhibit 4.4

            THIS THIRD SUPPLEMENTAL INDENTURE (this "Supplemental Indenture"),
dated as of October 20, 2000, among Anteon Corporation, a Virginia corporation
(the "Company"), Sherikon, Inc., a Louisiana corporation ("Sherikon"), and The
Bank of New York, as trustee (the "Trustee").

            WHEREAS, the Company, Techmatics, Inc., a Virginia corporation,
Analysis and Technology, Inc., a Connecticut corporation, Vector Data Systems,
Inc., a Virginia corporation, and Interactive Media Corp., a Delaware
corporation, entered into an Indenture, dated as of May 11, 1999, as
supplemented, to provide for the issuance of the Company's 12% Senior
Subordinated Notes due 2009 (the "Indenture");

            WHEREAS, on the date hereof, the Company has acquired all of the
issued and outstanding common stock of Sherikon, and accordingly, Sherikon
became a wholly-owned subsidiary of the Company;

            WHEREAS, pursuant to Section 4.10 of the Indenture, Sherikon, as a
new Restricted Subsidiary, is required to enter into this Supplemental Indenture
as a Subsidiary Guarantor;

            WHEREAS, the Company, Sherikon and the Trustee are authorized to
enter into this Supplemental Indenture;

            NOW, THEREFORE, for and in consideration of the premises and the
mutual covenants contained in this Supplemental Indenture and for other good and
valuable consideration, the receipt and sufficiency of which are herein
acknowledged, the Company, Sherikon and the Trustee hereby agree for the equal
and the ratable benefit of all Holders of the Securities as follows:

                                   ARTICLE ONE

                                   DEFINITIONS

            1.1 DEFINITIONS. For purposes of this Supplemental Indenture, the
terms defined in the recitals shall have the meanings therein specified; any
terms defined in the Indenture and not defined herein shall have the same
meanings herein as therein defined; and references to Articles or Sections
shall, unless the context indicates otherwise, be references to Articles or
Sections of the Indenture.

                                   ARTICLE TWO

                   GUARANTY OF SECURITIES AND OTHER PROVISIONS

            2.1 SHERIKON GUARANTEE.
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                  (a) Sherikon hereby unconditionally and irrevocably
guarantees, jointly and severally, to each Holder and to the Trustee and its
successors and assigns (i) the full and punctual payment of principal of and
interest on the Securities when due, whether at maturity, by acceleration, by
redemption or otherwise, and all other monetary obligations of the Company under
this Indenture and the Securities and (ii) the full and punctual performance
within applicable grace periods of all other obligations of the Company under
the Indenture and the Securities (all the foregoing being hereinafter
collectively called the "Obligations"). Sherikon further agrees that the
Obligations may be extended or renewed, in whole or in part, without notice or
further assent from Sherikon and that Sherikon will remain bound under this
Section notwithstanding any extension or renewal of any Obligation.

                  (b) Sherikon, the Trustee and each Holder by its acceptance of
a Security hereby agrees that the Subsidiary Guaranty of Sherikon provided
hereunder shall be subject to all terms, provisions and conditions in the
Indenture that relate to a Subsidiary Guaranty (including, without limitation,
Articles 11 and 12 of the Indenture). Sherikon further agrees to be bound by,
and to comply with, all provisions of the Indenture and Subsidiary Guarantee
that are applicable to a Subsidiary Guarantor.

            2.2 EXECUTION AND DELIVERY OF SUBSIDIARY GUARANTIES.

            The delivery of any Security by the Trustee, after the
authentication thereof under the Indenture, shall constitute due delivery of the
Subsidiary Guaranty on behalf of Sherikon.

            2.3 NO PERSONAL LIABILITY.

            No stockholder, officer, director, employee or incorporator, past,
present or future, of Sherikon, as such, shall have any personal liability under
the Subsidiary Guaranty of Sherikon by reason of his, her or its status as such
stockholder, officer, director, employee or incorporator.

                                  ARTICLE THREE

                                  MISCELLANEOUS

            3.1 EFFECT OF THE SUPPLEMENTAL INDENTURE. This Supplemental
Indenture supplements the Indenture and shall be a part and subject to all the
terms thereof. Except as supplemented hereby, the Indenture and the Securities
issued thereunder shall continue in full force and effect.

            3.2 COUNTERPARTS. This Supplemental Indenture may be executed in
counterparts, each of which shall be deemed an original, but all of which shall
together constitute one and the same instrument. The parties hereto confirm that
any facsimile
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copy of another party's executed counterparts of this Supplemental Indenture (or
its signature page hereof) will be deemed to be an executed original thereof.

            3.3 GOVERNING LAW. THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY,
AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.
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            IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed on the date first above written.


                                 ANTEON CORPORATION


                                 By:
                                    ------------------------------------
                                    Name: Carlton B. Crenshaw
                                    Title: Senior Vice President, Finance and
                                           Administration


                                 SHERIKON, INC.


                                 By:
                                    ------------------------------------
                                    Name: Curtis L. Schehr
                                    Title: Vice President


                                 THE BANK OF NEW YORK, as Trustee


                                 By:
                                    ------------------------------------
                                    Name: Geovanni Barris
                                    Title: Vice President