Transition to the synchronous reference system and estimation of the metric tensor components at the boundary of R- and T-regions

Requirements imposed on transformations leading to a synchronous reference system are obtained. The spherical symmetry case is considered in detail. It is shown that the known synchronous metrics can be obtained as a particular case of those indicated in the paper. The method developed is used for obtaining estimates of the components of the metric tensor in a rigid reference system on approaching the boundary of the R and T regions from the side of the R region in the case of the presence of a matter