2 Observational material, TGMET, basic data

The reader is encouraged to read Paper I to gain a detailed description of ELODIE spectra and TGMET. The TGMET software has been installed at the Observatoire de Haute-Provence to provide astronomers observing with ELODIE an on-line estimation of the atmospheric parameters of their stars if they fall in the correct temperature interval. At a mean S/N of 100, an internal accuracy of 85 K, 0.28, 0.16 is obtained on $T_\mathrm{eff}$, $\log g$ and [Fe/H] respectively. TGMET runs in two phases: preparation of the target spectrum and comparison to the library of reference spectra. All the reference spectra underwent the first phase, the main lines of which are recalled here. The second phase of TGMET was performed on the standards in a way which is described in Sect. 3. The ELODIE spectrograph and the estimation of radial velocities by cross-correlation are presented in Baranne et al. (1996) and in the Inter-Tacos user's guide (Queloz 1996). For the kind of stars we are dealing with, the radial velocities have an accuracy better than 100 m s^-1. They are given in Table 1 (only available at the CDS). ELODIE spectra cover the interval [390 nm, 680 nm] over 67 orders. Because of the under-illumination of the bluest orders, we only kept 47 orders covering the range [440 nm, 680 nm]. Each extracted spectrum was treated to remove all the features which are not intrinsic to the star. This treatment includes the correction of the blaze efficiency, thanks to a polynomial fitted on the spectra of several very metal-poor stars, and the removal of cosmic ray hits and telluric lines.

The 211 standards were observed between April 1994 and January 1998 with a S/N at 550 nm ranging between 36 and 381. The average value of S/N is 120, but lower S/N correspond to faint metal-poor stars kept in the library to have a good coverage of the full metallicity range. Some spectra have also been kindly made available by several observers.

We compiled basic data which can be helpful for people who want to use the library. All the stars of the library, except the Sun, belong to the Hipparcos catalogue from which coordinates, proper motions and parallaxes were taken. Spectral types and visual magnitudes are from the Hipparcos Input Catalogue. For 192 stars which have a relative error on parallax lower than 30%, absolute magnitudes, distances and one sigma error bars were computed. The bolometric correction was applied according to the relation depending on $T_{\rm eff}$ and [Fe/H] established by Alonso et al. (1995). For 5 stars too cool for this correction, the M_v absolute magnitude is given instead of $M\rm _{bol}$. The 3 components (U, V, W) of spatial velocities with respect to the Sun were also computed. Basic data are listed in Table 1, only available at the CDS, together with the atmospheric parameters described in the next section.

To enable astronomers to make use of this library, the 211 spectra are available in FITS format at the CDS via anonymous ftp or WWW. Each spectrum is made of a file of $1024 \times 47$ wavelengths with their corresponding flux (not normalised) plus a header containing observational information. The pixels eliminated through the straightening and cleaning processes are flagged by a value of the corresponding flux of -100. No attempt was made to recombine the 47 orders in a single spectrum.