Branching Fractions and CP-Violating Asymmetries in Radiative B Decays to eta K gamma

We present measurements of the CP-violation parameters S and C for the radiative decay B{sup 0}{yields}{eta}K{sub S}{sup 0}{gamma}; for B{yields}{eta}K{gamma} we also measure the branching fractions and for B{sup +}{yields}{eta}K{sup +}{gamma} the time-integrated charge asymmetry A{sub ch}. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 465x10{sup 6} BB pairs produced in e{sup +}e{sup -} annihilation. The results are S=-0.18{sub -0.46}{sup +0.49}{+-}0.12, C=-0.32{sub -0.39}{sup +0.40}{+-}0.07, B(B{sup 0}{yields}{eta}K{sup 0}{gamma})=(7.1{sub -2.0}{sup +2.1}{+-}0.4)x10{sup -6}, B(B{sup +}{yields}{eta}K{sup +}{gamma})=(7.7{+-}1.0{+-}0.4)x10{sup -6}, and A{sub ch}=(-9.0{sub -9.8}{sup +10.4}{+-}1.4)x10{sup -2}. The first error quoted is statistical and the second systematic.