Codes on fiber products of hyperelliptic curves

The purpose of this paper is to construct a new family of smooth projective curves over a finite field $F_q$ with a lot of $F_q$-rational points. The genus in this family is considerably less than the number of rational points, so that the corresponding geometric Goppa codes have rather good parameters.
The work was supported by Bilkent University, 06533 Bilkent, Ankara, Turkey.