  The manuscript is concerned with uniqueness and stability for inverse source
problem of determining spatially varying factor $f(x)$ of a source term given
by $R(t)f(x)$ with suitable given $R(t)$ in the right hand side of the
Schr\"odinger equation with time independent coefficients. In order to
establish these results we provide a simple proof of a logarithmic conditional
stability of the Cauchy problem for the Schr\"odinger equation with
time-independent coefficients and the zero Dirichlet boundary conditions on the
whole boundary and a proof of uniqueness of solution to the Cauchy problem for
the Schr\"odinger equation with data on an arbitrary small part of a lateral
boundary. We do not assume any geometrical constraints on subboundary and a
time interval is arbitrary. The key is an integral transform, with a kernel
solving a null controllability problem for the 1-D Schr\"odinger, which changes
a solution of the Schr\"odinger equation to a solution of an elliptic equation.
