2 Observations

SV Cam was observed in the spectral range 6500-6700 Å with resolution 0.19 Å/pixel on 3 consecutive nights from November 30 to Dec. 2, 1999. We used a CCD camera mounted on the Coude spectrograph (grating $B\&L632/14.7{\hbox{$^\circ$ }}$) of the 2m telescope operated by the National Astronomical Observatory in Rozhen (Bulgaria). The seeing during the observations did not exceed 2 arcsec (FWHM). The exposure time was 20 min. The bias frames and flat-field integrations were obtained at the beginning and end of each night. All stellar integrations were alternated with Fe comparison source exposures. The data were processed in a standard way using the PCIPS (Smirnov et al. 1992) and Rewia (Borkowski 1988) software packages. The S/N ratio was around 120-160. The spectra were reduced by bias substraction, flat-field division and wavelength calibration. The normalization of the continuum was made to the whole line-free spectral range.

Apart from the H$_{\alpha }$ line, in the range 6500-6700 Å there are several weaker Fe lines, whose radial velocities change with the orbital period of SV Cam. However, only the H$_{\alpha }$ and FeI 6678 Å lines show apparent double profiles out of the eclipses. For instance, the FeI 6593 line is stronger than FeI 6678 but it is blended with surrounding lines whose contribution is difficult to separate. An appropriate Fourier noise filter was applied to the weaker FeI 6678 line in order to remove the high-frequency noise. This procedure causes some smoothing of the profiles without loss of their important details (Gray 1992).

The data were phased using the ephemeris of Kreiner (2001):

$$JHD({\rm MinI})=2426949.3881 + 0.59307167 * E.$$ (1)