and effective temperature. After fixing the range of $\log T_\mathrm{eff}$ in the right panel of Fig.\[fig6\], the separation between phases before and after core helium ignition can be noticeable.

Fig.\[fig7\] presents how the photometric observables depend on the mode frequency considering again the BR Johnson passbands and the same models as in the right panel of Fig.\[fig6\]. From this plot we can conclude that much better separation between modes of different values of $\ell$, from both the amplitude ratios and phase differences, occurs for higher frequency modes which are unstable only in Model1.

Pulsations in HD 163899 {#hd163899}
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![Comparison of evolution times in the pulsational unstable region of HR diagram during hydrogen shell burning phase and on the blue loop. The solid and dashed lines depict models with masses $16.0 M_\odot$ and $14.7M_\odot$, respectively. The models have been calculated with $Z=0.01$ and OPAL opacity tables. The grey area depicts the error of $\log T_\mathrm{eff}$ for HD 163899 (Saio et al. 2006).[]{data-label="fig8"}](fig8.eps){width="88mm"}

The greatest uncertainty concerning SPBsg stars is their evolutionary status. Although the basic parameters ($\log T_\mathrm{eff}$, $\log g$, $Z$, $V \sin i$, etc.) of HD 163899 are very poorly determined or unknown, our calculations still can give some 