Comparison of the Pulkovo Compilation of Radial Velocities with the RAVE DR1 Catalogue

TL;DR

This study compares RAVE DR1 and Pulkovo Compilation of Radial Velocities, confirming high radial-velocity accuracy and identifying a zero-point offset that can be corrected with targeted observations.

Contribution

It provides a detailed comparison of two major radial velocity catalogs, quantifies the zero-point offset, and demonstrates a method for correction to improve measurement accuracy.

Findings

No systematic dependence in velocity differences except zero-point offset.

High radial-velocity accuracy better than 1 km/s for bright stars.

Zero-point offset can be corrected with targeted PCRV star observations.

Abstract

The Data Release 1 of the Radial-Velocity Experiment (RAVE DR1, 24 748 stars) is compared with the May 15, 2006 version of the Pulkovo Compilation of Radial Velocities (PCRV, 35 495 stars). RAVE DR1 includes mostly $9^m-13^m$ stars, while the PCRV contains brighter stars. Analysis of the "RAVE minus PCRV" radial-velocity differences for 14 common stars has revealed no systematic dependences on any factors, except the effect due to the RAVE radial-velocity zero-point offset known from the RAVE observations. This effect shows up for ten of these stars observed on a single night as a sine wave with an amplitude of 1.5 km s$^{-1}$ in the dependence of the radial-velocity difference on the ordinal number of the optical fiber used and, accordingly, on the star position angle in the field of view of the RAVE instrument. The detection of this dependence confirms a high radial-velocity accuracy in both catalogs: on average, better than 1 km s$^{-1}$ for stars brighter than $10^m$ (for the RAVE, after applying a correction for the zeropoint offset). The RAVE zero-point offset can be corrected for with an accuracy better than 1 km s$^{-1}$ by observing several PCRV stars in each RAVE frame and by analyzing the "RAVE minus PCRV" radialvelocity differences.