If this is part of your job duties, then you have no copyright. The work would be considered a "work for hire". The copyright would remain with the organization that hired you.
From Wikipedia: http://en.wikipedia.org/wiki/Work_for_hire
The circumstances in which a work is considered a "work made for hire" is determined by the United States Copyright Act of 1976 as either
(1) a work prepared by an employee within the scope of his or her employment; or (2) a work specially ordered or commissioned for use as a contribution to a collective work, as a part of a motion picture or other audiovisual work, as a translation, as a supplementary work, as a compilation, as an instructional text, as a test, as answer material for a test, or as an atlas, if the parties expressly agree in a written instrument signed by them that the work shall be considered a work made for hire. (17 U.S.C. § 101)
I think part no. 1 would apply to your situation. 2 only applies to contractors.