& 19 & 1.300 & 3.60 & 0.735 & 0.017\

As demonstrated above, we constructed the optimal hydrodynamic model for the long distance (model D11 in Table \[tab:hydmods\]). The model reproduces the observed bolometric light curve of SN 1999em very well (Fig. \[fig:hmd117\]a). In Fig. \[fig:hmd117\]b the calculated expansion velocity at the photosphere level, the photospheric velocity, is compared with the radial velocities at maximum absorption of the different spectral lines measured by Hamuy et al. ([@hpm01]) and Leonard et al. ([@lfg02]). The photospheric velocity of model D11 is consistent with the observed points, at least for the first 60 days. To verify the hydrodynamic model by matching the constraints from the spectral observations of SN 1999em, we examined the H$\alpha$ profile on days 26.24 and 52.14 computed in the time-dependent approach.

In the time-dependent atmosphere model for SN 1987A, we considered two extreme cases to allow for the uncertainty of our approximation in a description of the ultraviolet radiation field: (i) the photospheric brightness is black-body with the effective temperature (model A); (ii) the photospheric brightness corresponds to the observed spectrum (model B) (Utrobin & Chugai [@uc05]). For SN 1999em the photospheric brightness in model B is black-body with 