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Approximation 2: First order developments and velocity conventions

As formula 4 is mostly correct when $\ensuremath{v_{\ensuremath{\mathrm{}}}^{\ensuremath{\mathrm{obs}}}}\ll \ensuremath {c}$, we can as well continue to develop in $\ensuremath{v_{\ensuremath{\mathrm{\parallel}}}^{\ensuremath{\mathrm{obs}}}}/\ensuremath{c}$ and limit ourselves to the first order term. However, there are two ways to do this development, starting either from the frequency Doppler formula (radio velocity convention) or from the wavelenght one (optical velocity convention).



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Gildas manager 2015-03-19