The Relative Calibration of Radial Velocity for LAMOST Medium Resolution
  Stellar Spectra
  The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST)
started median-resolution spectroscopic (MRS, R$\sim$7500) survey since October
2018. The main scientific goals of MRS, including binary stars, pulsators, and
other variable stars are launched with a time-domain spectroscopic survey.
However, the systematic errors, including the bias induced from wavelength
calibration and the systematic difference between different spectrographs have
to be carefully considered during radial velocity measurement. In this work, we
provide a technique to correct the systematics in the wavelength calibration
based on the relative radial velocity measurements from LAMOST MRS spectra. We
show that, for the stars with multi-epoch spectra, the systematic bias which is
induced from the exposures of different nights can be well corrected for LAMOST
MRS in each spectrograph. And the precision of radial velocity zero-point of
multi-epoch time-domain observations reaches below 0.5 km/s . As a by-product,
we also give the constant star candidates, which can be the secondary
radial-velocity standard star candidates of LAMOST MRS time-domain surveys.
