000002160 001__ 2160
000002160 005__ 20160706145823.0
000002160 0247_ $$2DOI$$a10.1051/0004-6361/201322721
000002160 037__ $$aASTROimport-317
000002160 100__ $$aDavid, M.
000002160 245__ $$aA multi-method approach to radial-velocity measurement for single-object spectra
000002160 260__ $$c2014
000002160 520__ $$aContext. The derivation of radial velocities from large numbers of spectra that typically result from survey work, requires automation. However, except for the classical cases of slowly rotating late-type spectra, existing methods of measuring Doppler shifts require fine-tuning to avoid a loss of accuracy due to the idiosyncrasies of individual spectra. The radial velocity spectrometer (RVS) on the Gaia mission, which will start operating very soon, prompted a new attempt at creating a measurement pipeline to handle a wide variety of spectral types.  Aims: The present paper describes the theoretical background on which this software is based. However, apart from the assumption that only synthetic templates are used, we do not rely on any of the characteristics of this instrument, so our results should be relevant for most telescope-detector combinations.  Methods: We propose an approach based on the simultaneous use of several alternative measurement methods, each having its own merits and drawbacks, and conveying the spectral information in a different way, leading to different values for the measurement. A comparison or a combination of the various results either leads to a "best estimate" or indicates to the user that the observed spectrum is problematic and should be analysed manually.  Results: We selected three methods and analysed the relationships and differences between them from a unified point of view; with each method an appropriate estimator for the individual random error is chosen. We also develop a procedure for tackling the problem of template mismatch in a systematic way. Furthermore, we propose several tests for studying and comparing the performance of the various methods as a function of the atmospheric parameters of the observed objects. Finally, we describe a procedure for obtaining a knowledge-based combination of the various Doppler-shift measurements.
000002160 700__ $$aBlomme, R.
000002160 700__ $$aFrémat, Y.
000002160 700__ $$aDamerdji, Y.
000002160 700__ $$aDelle Luche, C.
000002160 700__ $$aGosset, E.
000002160 700__ $$aKatz, D.
000002160 700__ $$aViala, Y.
000002160 773__ $$cA97$$pAstronomy and Astrophysics$$v562$$y2014
000002160 85642 $$ahttp://esoads.eso.org/abs/2014A%26A...562A..97D
000002160 905__ $$apublished in
000002160 980__ $$aREFERD