of 106 minutes, split over two observation blocks (each observation block consisted of $2 \times 20$ minute exposures).

Basic data reductions, i.e. gain and cross-talk correction as well as bias subtraction were performed as part of the automated reduction pipeline of SALT [@Crawford2010]. We performed cosmic ray rejection on the science images by using the `LACosmic` package [@2001]. Wavelength calibrations were then performed with standard `IRAF` [@Tody1986; @Tody1993] tasks. We determined the spectroscopic redshift of each galaxy in the SALT sample by fitting the observed SALT spectrum against the ‘Early-type’ SDSS galaxy spectral template (hereafter reference spectrum). The rest wavelengths of the Calcium II $H$ and $K$ absorption lines in the reference spectrum were shifted to match those in the galaxy’s observed SALT spectrum.

In Table \[table:SALT\_sample\] we present a summary of the galaxies in the SALT sample along with their SDSS spectroscopic redshifts (if available). For each close pair we indicate the velocity difference as derived from the SALT spectroscopy. The BCG and companion in each pair were observed in the same slit and share the same wavelength calibration. Thus the velocity differences, which are our ultimate goal, are more robust than if we had used a combination of 