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Paper: A Detailed Analysis of the Short- and Long-term Precision of Stellar Radial Velocities Obtained Using HERCULES
Volume: 289, The Proceedings of the IAU 8th Asian-Pacific Regional Meeting, Volume I
Page: 17
Authors: Skuljan, J.
Abstract: An analysis has been made to examine the overall stability and final precision of relative stellar radial velocities obtained using the Hercules spectrograph. The velocities are measured by cross-correlation between one-dimensional spectra in logarithmic wavelength space. Some delicate reduction steps are performed in order to achieve the highest precision possible. A typical precision of a few metres per second is easily obtained during one observing night. Stellar velocities are somewhat affected by insufficient scrambling by the optical fibre. The long-term velocities also exhibit some systematic run-to-run differences. A preliminary analysis shows that these problems can be eliminated by making some minor modifications to the equipment and also by careful comparison of thorium images. This is expected to bring the overall precision to a level of several metres per second, which would make Hercules fully capable of detecting extra-solar planets.
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