  The determination of fundamental parameters in low-mass X-ray binaries
typically relies on measuring the radial velocity curve of the companion star
through optical or near-infrared spectroscopy. It was recently suggested that
high resolution X-ray spectroscopy might enable a measurement of the radial
velocity curve of the compact object by monitoring the Doppler shifts induced
by the orbital motion of the disc wind or the disc atmosphere. We analysed a
Chandra-HETG+NuSTAR soft state observation of MXB 1659-298, an eclipsing
neutron star low-mass X-ray binary (LMXB). We measured a radial velocity curve
whose phase offset and semi-amplitude are consistent with the primary star. We
derived the value for the semi-amplitude of the radial velocity for the compact
object $K_1=89\pm19$ km s$^{-1}$, constrained the mass of the secondary
($0.3\leq M_2\leq0.8$ M$_\odot$) and the orbital inclination of the binary
system ($73\leq i\leq77^\circ$). These values are consistent with previous
estimates from independent methods. Via the same technique, the next generation
of X-ray observatories equipped with high spectral resolution instruments
(e.g., Athena) will have the potential to measure the radial velocity curve of
the primary in high inclination X-ray binaries to an accuracy of a few per
cent.
