We explore approximations to the effective S factor for the Be-7(p, ga
mma)B-8 reaction using:different approximations for the integral over
the Gamow peak. In the temperature range of interest for solar neutrin
o production, S-eff may be determined to within 0.5% from S(20) with n
o direct information on the derivatives of S(E). [S0556-2813(98)01911-
6].