J/A+A/580/A75 Velocity precision in the Gaia-ESO Survey (Jackson+, 2015) ================================================================================ The Gaia-ESO Survey: Empirical determination of the precision of stellar radial velocities and projected rotation velocities. Jackson R.J., Jeffries R.D., Lewis J., Koposov S.E., Sacco G.G., Randich S., Gilmore G., Asplund M., Binney J., Bonifacio P., Drew J.E., Feltzing S., Ferguson A.M.N., Micela G., Neguerela I., Prusti T., Rix H-W., Vallenari A., Alfaro E.J., Allende Prieto C., Babusiaux C., Bensby T., Blomme R., Bragaglia A., Flaccomio E., Francois P., Hambly N., Irwin M., Korn A.J., Lanzafame A.C., Pancino E., Recio-Blanco A., Smiljanic R., Van Eck S., Walton N., Bayo A., Bergemann M., Carraro G., Costado M.T., Damiani F., Edvardsson B., Franciosini E., Frasca A., Heiter U., Hill V., Hourihane A., Jof P., Lardo C., de Laverny P., Lind K., Magrini L., Marconi G., Martayan C., Masseron T., Monaco L., Morbidelli L., Prisinzano L., Sbordone L., Sousa S.G., Worley C.C., Zaggia S. =2015A&A...580A..75J ================================================================================ ADC_Keywords: Clusters, open Keywords: stars: kinematics and dynamics - open clusters and associations: general Abstract: Description: The Gaia-ESO Survey (GES) is a large public spectroscopic survey at the European Southern Observatory Very LargeTelescope. A key aim is to provide precise radial velocities (RVs) and projected equatorial velocities (vsini) for representative samples of Galactic stars, which will complement information obtained by the Gaia astrometry satellite. We present an analysis to empirically quantify the size and distribution of uncertainties in RV and vsini using spectra from repeated exposures of the same stars. We show that the uncertainties vary as simple scaling functions of signal-to-noise ratio (S/N) and vsini, that the uncertainties become larger with increasing photospheric temperature, but that the dependence on stellar gravity, metallicity and age is weak. The underlying uncertainty distributions have extended tails that are better represented by Students t-distributions than by normal distributions. Parametrised results are provided, which enable estimates of the RV precision for almost all GES measurements, and estimates of the vsini precision for stars in young clusters, as a function of S/N, vsini and stellar temperature. The precision of individual high S/N GES RV measurements is 0.22-0.26km/s, dependent on instrumental configuration. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table2.dat 71 439 Log of VLT/Flames observations used in the analysis of RV and vsini measurement precision -------------------------------------------------------------------------------- See also: J/A+A/561/A94 : Velocities and photometry in Trumpler 20 (Donati+, 2014) J/A+A/563/A94 : Kinematics of the Gamma Vel cluster (Jeffries+, 2014) J/A+A/566/A50 : Classification of stellar spectra 644-681nm (Damiani+, 2014) J/A+A/567/A55 : Metallicity of the gamma Vel cluster (Spina+, 2014) J/A+A/569/A17 : Gaia-ESO Survey: NGC6705 (Cantat-Gaudin+, 2014) J/A+A/572/A33 : Abundances from Gaia-ESO Survey (Mikolaitis+, 2014) J/MNRAS/441/3127 : FeI oscillator strengths for Gaia-ESO (Ruffoni+, 2014) J/A+A/573/A115 : Radial velocities in seven globular clusters (Lardo+, 2015) J/A+A/574/L7 : Gaia-ESO Survey: Li-rich stars in NGC2547 (Sacco+, 2015) J/A+A/575/A4 : Activity and accretion in gamma Vel and ChaI (Frasca+, 2015) Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 5 A5 --- Filter Name of order sorting filter of spectrograph ("HR10", "HR15N" or "HR21") 7- 17 A11 "D/M/Y" Obs.date Date of observation (UTC) 19- 26 A8 "h:m:s" Obs.time Universal standard time of observation 27- 29 A3 --- --- [.0] 31- 32 I2 h RAh Right ascension field centre (J2000) 34- 35 I2 min RAm Right ascension field centre (J2000) 37- 40 F4.1 s RAs Right ascension field centre (J2000) 42 A1 --- DE- Declination sign of field centre (J2000) 43- 44 I2 deg DEd Declination field centre (J2000) 46- 47 I2 arcmin DEm Declination field centre (J2000) 49- 52 F4.1 arcsec DEs Declination field centre (J2000) 54- 57 I4 s Texp [600/2700] Exposure time of individual exposures 59 I1 --- Nexp [2/3] Number of exposures per observation block 61- 63 I3 --- Ntar [15/119] Number of stellar targets with allocated fibres 65- 71 A7 --- Cluster Short name for cluster for targets in cluster ("Cha_I", "gam2vel", "rho_oph", "ic4665", "ngc2264", "ngc2516", "ngc2547" or "ngc6633") -------------------------------------------------------------------------------- Acknowledgements: Richard Jackson, r.j.jackson(at)keele.ac.uk ================================================================================ (End) Richard Jackson [Keele University], Patricia Vannier [CDS] 20-Jul-2015