Frequency spectra of the β Cephei variable SBL303. The bottom panels show five steps in our data evaluation. The top panels show light curves for all bands. Since too many models passed through our error box, the mode identification panel is not displayed here. However, f₃ shows increasing amplitude with wavelength which is only seen in l = 4 modes. All notations are the same as in Fig. A.3. The frequencies take the values f₁ = 10.1225d^-1, f₂ = 10.991d^-1, f₃ = 10.5106d^-1, f₄ = 11.6904d^-1, f₅ = 12.045d^-1, and f₆ = 11.902d^-1. Their errors range from σ_f1 = 0.0002d^-1 to σ_f6 = 0.001d^-1.