  We present a spectrum of the symbiotic star V1016 Cyg observed with the 3.6 m
Canada-France-Hawaii Telescope, in order to illustrate a method to measure the
covering factor of the neutral scattering region around the giant component
with respect to the hot emission region around the white dwarf component. In
the spectrum, we find broad wings around H$\alpha$ and a broad emission feature
around 6545${\rm \AA}$ that is blended with the [N II]$ \lambda$ 6548 line.
These two features are proposed to be formed by Raman scattering by atomic
hydrogen, where the incident radiation is proposed to be UV continuum radiation
around Ly$\beta$ in the former case and He II $\lambda$ 1025 emission line
arising from $n=6\to n=2$ transitions for the latter feature. We remove the
H$\alpha$ wings by a template Raman scattering wing profile and subtract the [N
II] $\lambda$ 6548 line using the 3 times stronger [N II] $\lambda$ 6583
feature in order to isolate the He II Raman scattered 6545 \AA line. We obtain
the flux ratio $F_{6545}/F_{6560}=0.24$ of the He II $\lambda$ 6560 emission
line and the 6545 \AA feature for V1016 Cyg. Under the assumption that the He
II emission from this object is isotropic, this ratio is converted to the ratio
$\Phi_{6545}/\Phi_{1025}=0.17$ of the number of the incident photons and that
of the scattered photons. This implies that the scattering region with H I
column density $N_{HI}\ge 10^{20}{\rm cm^{-2}}$ covers 17 per cent of the
emission region. By combining the presumed binary period $\sim 100$ yrs of this
system we infer that a significant fraction of the slow stellar wind from the
Mira component is ionized and that the scattering region around the Mira
extends a few tens of AU, which is closely associated with the mass loss
process of the Mira component.
