  We describe a method for obtaining analytic solutions corresponding to exact
marginal deformations in open bosonic string field theory. For the photon
marginal deformation we have an explicit analytic solution to all orders. Our
construction is based on a pure gauge solution where the gauge field is not in
the Hilbert space. We show that the solution itself is nevertheless perfectly
regular. We study its gauge transformations and calculate some coefficients
explicitly. Finally, we discuss how our method can be implemented for other
marginal deformations.
