Ground based observations for Gaia

1. Ground based observations for Gaia • 2001 : need to have reference stars to calibrate AP algorithms for Gaia i.e. stars with well-known APs that will observed by Gaia (ICAP documents) • March 2006 : CU8 1st meeting + splinter meeting on auxiliary data • Definition of work packages • Need of real spectra (training data + calibrations) • Action : coordinate with all CU8 WP and the other CUs the requirements and gathering of data • April 2006 : Inquiry within all CUs • May 2006 : report presented to the DACC and preliminary list on Livelink --> suggestion to organize a meeting • Caroline Soubiran • Observatoire de Bordeaux • GBOG meeting - Paris • 14-15 September 2006

2. Aims of the meeting according to DPACE : • produce detailed requirements (nb of stars, mag range, AP range, resolution, priorities..) • decide on which observatories and instruments • make a firm action plan (tasks, person in charge, deadlines, reports, products…) • We must avoid that similar proposals are independently submitted by different groups within the DPAC. This could damage our long-term prospects of getting data. • Observing proposals should be linked to a scientific proposal • Calibration data may already exist --> search through archives and publications • All data should be made publicly available. High level contact to observatory directors and observing programme committees may be necessary.

3. News (since preliminary list at 31 May 2006) : • observations of Gaia itself left out (CU3) • CU4 : Object processing ; solar system objects plan to build a network of CCD astrometric observationsfor follow-up and alerts during the mission, and/or before and after • CU5 have proposed to start very soon a pilot project • CU6 - CU8 - CU5 ? : a database to share spectra and other information and data was build by Arnaud Siebert • CU6-CU8 : contact with Pavel Koubsky who proposes observing runs on the new echelle spectrograph OES at Ondrejov observatory (Czech Republic) but we may prefer to limit the number of instruments

4. Requirements for GB observations • GWP-S-640 : Radial velocity zero point • GWP-S-640-03000 : Radial velocity reference sources : stars Establish the optimal grid of reference stars that will be observed by GAIA-RVS as calibrators of the RV zero point ( GWP-S-640-04000 : Radial velocity reference sources : asteroids • Define the RV zero point for the RVS in using asteroids ) GWP-S-811 : Training data • ( GWP-S-811-21000 AP reference stars : database • Provide a grid of reference stars with reliable determinations of APs, as calibrators of GSP-phot and GSP-spec) • GWP-S-811-22000 AP reference stars : GB observations • Provide new observations of reference stars and determine their APs

5. GWP-S-640-03000 : Radial velocity reference sources : stars Primary grid = 1000 to 2500 bright (6 < V < 10) FGK stars, stable at 300 m/s level, well sky distributed • Selection in Hipparcos  The Geneva-Copenhagen survey and Nidever et al’s catalogue • Pb of binarity and other kind of RV variability : follow-up observations must be done to verify the short and long term stability Secondary grid : fainter stars, large variety of spectral types, not as precisely measured than primary ones, to make some verifications (ex RAVE stars). Observations in north • 5 to 10 nights/year nearly guaranteed on SOPHIE and/or NARVAL echelle spectrographs • Ondrejov OES spectrograph ? Observations in south • 3 nights/year on CORALIE (agreement on swiss time) • FEROS ? Manpower : 3 active members, 3 collaborators, 0.5 FTE/yr

6. GWP-S-640-04000 : Radial velocity reference sources : asteroids • RV predictions at better than 1 m/s but bright asteroids not numerous enough and not well distributed on sky • GB observations only to understand systematic effects that affect stellar RV measurements

7. CU8 activities • Astrophysical Parameters (AP) to be determined = Teff, logg, [Fe/H], [X/Fe], vsini, Av.. • AP reference stars : stars with well determined APs (externally) that are observed by Gaia and serve as calibrators for the algorithms of parametrization : GSP-phot and GSP-spec • need to cover the full range of parameters i.e. HR diagram with variance in [Fe/H] • bright stars for GSP-spec (6 < V < 10 ?) - existing catalogues and data • faint stars for GSP-phot (10 < V < 18 ?) - OC and GC + test fields • higher priority on the most common FGK single stars (SSUs look at specific stars) 2 WPs related to AP reference stars : • GWP-S-811-21000 AP reference stars : database • Provide a grid of reference stars with reliable determinations of APs (compilation of existing catalogues and data, build a web server, define grid points, decide on new observations…) • GWP-S-811-22000 AP reference stars : GB observations Provide new observations of reference stars and determine their APs (coordinate observations with other WPs, write proposals, make and reduce observations)

8. Still to be clarified : • are the observations needed to improve the models part of the WPs on GAIA AP reference stars ? • what are the needs of other WPs (ex GWP-S-811-30000 : Assemble training data grids) in terms of real spectra ? • manpower Still to be defined : • which criteria make a star a reliable calibrator ? • optimal number and magnitude range of the calibrators ?

9. (UNDER CONSTRUCTION) • DATA (BOTH RVs AND STELLAR PARAMETERS) NEED TO BE • COLLECTED TO PREPARE THE GAIA MISSION AND VALIDATE • ITS OUPUT • NEED FOR A DATABASE TO STORE AND ACCESS THOSE DATA WHAT NEEDS TO BE STORED : DESCRIPTION OF THE OBSERVATION Target identifiers Telescope Instrument Resolution Observing conditions Date of the observation Path to data Peculiarities ... BASIC DATA Identifiers Photometry Position Proper motion Parallaxes Spectral type Variability ... RV MEASUREMENT Identifiers RV RV error Method used Template used Observation used Correlation (?) Chi Square (?) Date of the observation ... STELLAR PARAMETERS Identifiers Parameters (log g, Teff...) Errors Method used Observation used ...

10. LOCAL DISK STORAGE SPECTRA STORAGE TOMCAT AND APACHE SERVERS DATABASE UPDATE POSTGRES DATABASE BASIC DATA LIST QUERY EXTERNAL USERS WWW INTERFACE OBSERVATION DESCRIPTION OBJECT QUERY INDIVIDUAL OBS PARAMETER EST GET STATISTICS CONE SEARCH INDIVIDUAL OBS RV MEASURE