  We compare two versions of the GW150914 gravitational wave signal analysis by
the LIGO/Virgo collaboration. The first version was published in 2016 by this
collaboration along with their announcement of the first experimental detection
of gravitational waves. It was based on the gravitational wave waveforms with
the fully non-linear general-relativistic treatment of the coalescing two-body
problem. The second analysis of this signal by the same authors, published in
2017, was based on the quadrupole post-Newtonian (PN) flat spacetime
approximation of General Relativity. The authors had shown that the PN-based
mass estimation of the system coincide with that obtained by using rigorous
relativistic treatment in their first publication. In our view, this
coincidence implies that the rigorous non-linear theory for gravitational
waveforms of coalescing blackhole binaries does not fully account for the
difference between the source and detector reference frames - because the
PN-approximation, which is used for the comparison, does not make any
distinction between these two reference frames: by design and by the principles
and conditions for building the PN-approximation. We discuss possible
implications of this conflict and find that the accuracy of most of the
previously estimated characteristic (chirp) masses of coalescing binary
blackhole systems is likely to be affected by a substantial systematic error.
The corresponding luminosity distances of these sources also turn out to be
overestimated.
