The eShel spectrograph: A radial-velocity tool at the wise observatory

Abstract

The eShel, an off-the-shelf, fiber-fed echelle spectrograph (R ≈ 10,000), was installed on the 1 m telescope at the Wise observatory in Israel. We report the installation of the multi-order spectrograph, and describe our pipeline to extract stellar radial velocity from the obtained spectra. We also introduce a new algorithm-UNICOR, to remove radial-velocity systematics that can appear in some of the observed orders. We show that the system performance is close to the photon-noise limit for exposures with more than 107 counts, with a precision that can get better than 200 m s-1 for F-K stars, for which the eShel spectral response is optimal. This makes the eShel at Wise a useful tool for studying spectroscopic binaries brighter than mV=11. We demonstrate this capability with orbital solutions of two binaries from projects being performed at Wise.