On the mass of the neutron star in Cyg X-2
  We present new high resolution spectroscopy of the low mass X-ray binary Cyg
X-2 which enables us to refine the orbital solution and rotational broadening
of the donor star. In contrast with Elebert et al (2009) we find a good
agreement with results reported in Casares et al. (1998). We measure
$P=9.84450\pm0.00019$ day, $K_2=86.5\pm1.2$ km s$^{-1}$ and $V \sin
i=33.7\pm0.9$ km s$^{-1}$. These values imply $q=M_{2}/M_{1}=0.34 \pm 0.02$ and
$M_{1}=1.71\pm 0.21$ M$_{\odot}$ (for $i=62.5 \pm 4^{\circ}$). Therefore, the
neutron star in Cyg X-2 can be more massive than canonical. We also find no
evidence for irradiation effects in our radial velocity curve which could
explain the discrepancy between Elebert et al's and our $K_2$ values.
