You will be presented with the full text of a science research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
the elodie library is based on spectra retrieved from the observatoire de haute - provence archive ( moultaka et al . 2004 ) .
the spectra were obtained with the elodie spectrograph attached to the 1.93 m telescope , they have a spectral resolution of about r=42000 and consists of 67 echelle orders covering in total the wavelength range 389.2 to 680 nm without any gap .
some of the spectra were acquired for the purpose of building a stellar library , and others were selected from the archive to complete the coverage in effective temperature ( t@xmath0 ) , surface gravity ( @xmath1 ) and metallicity ( [ fe / h ] ) and to achieve the flux calibration ( by providing enough external comparisons and repeated observations of the same stars ) .    an early library , not calibrated in flux , was published in soubiran et al .
the first flux - calibrated release of the library was published by prugniel & soubiran ( 2001 ) , it contained 906 spectra .
the last previous release , elodie.3 was announced in prugniel & soubiran ( 2004 ) and represented a major progress in the coverage of the space of atmospheric parameters ( t@xmath0 , @xmath1 and [ fe / h ] ) .    the present version , elodie.3.1 is based on the same collection of spectra than elodie.3 . fig .
1 , 2 and 3 show the distribution of the 1388 stars of the library in the hr diagram , t@xmath0 - [ fe / h ] and t@xmath0 - @xmath1 planes .
the main interest of this new version is the extended wavelength coverage , now including the h & k lines , and limited by the blue limit of the spectrograph .
some important improvements are also summarized in the next section .
the library has been used for population synthesis using the pegase.hr program ( le borgne et al .
2004 ) , and these models were used to study the stellar populations of galaxies and star clusters . the advantage of these models is the high spectral resolution provided by the library which allows to constrain simultaneously the internal kinematics and the parameters of the stellar population ( for instance age and metallicity ) . thanks to this library , the analysis is not anymore limited to the low resolution of the spectrophotometric indices .
specific methods for the simultaneous analysis of the kinematics and of the stellar population were developed in ocvirk et al .
( 2006 ) and chilingarian ( 2007 ) .
it was found that these approaches of full spectrum fitting are increasing the precision on age and metallicity by a factor 3 ( a factor 10 on observing time to get the same precision ) ( koleva et al .
2006 ) .
the comparison between models based on the current release of the library and other models are presented in koleva et al ( 2007a ) and validation using galactic clusters in koleva et al .
( 2007b ) .
we are now preparing a further version , elodie.4 , which will contain about 5000 spectra .
this will allow a better investigation of the effect of the @xmath3-element abundances in stellar populations , possibly by coupling the library with a basis of theoretical spectra as presented in prugniel et al .
since the first version of the library , the reduction procedure described in prugniel & soubiran ( 2001 ) has been improved in several aspects but the general philosophy remains the same .
the first steps of the data processing up to the extraction of the orders are made with the standard elodie pipeline ( baranne et al . , 1996 ) .
the reconnection of the orders , and the flux calibration are explained in prugniel & soubiran ( 2001 ) .
extension of the wavelength range .
: :    in the previous releases the first 4 orders in the blue were not    processed because of the difficulty of their reconnection and    calibration due to the low signal - to - noise ratio ( s / n ) .
the    sensitivity of the detector is indeed dramatically dropping near the    blue limit .
we improved our procedure and we could include the blue    region , extending to the h & k lines .
subtraction of the diffuse light . : :    when working on the blue region of the spectra , we discovered that the    diffuse light on the standard pipeline was often under - subtracted .
the    consequence was that some sharp lines in the blue were not deep    enough .
the correction that we applied was validated by comparing with    spectra from other archives or libraries .
improvement of the atmospheric parameters .
: :    to use the library for population synthesis , a key factor is to obtain    the atmospheric parameters of the stars with the highest accuracy . in    the present case ,
the atmospheric parameters are first compiled from    the literature , and an inter - comparison in the library allow to detect    inconsistencies and to determine internal values : each wavelength    point of the spectra is modeled as polynomials in    t@xmath0 , @xmath1 and [ fe / h ] fitted to the    compiled parameters and the inversion of this function returns    internal determinations of the parameters ( see prugniel & soubiran    2001 , le borgne et al .
2004 ) . +    on one side we have updated the compiled input parameters , using    recent publications and fixing errors , and on the other side we    improved the polynomial functions used to model the spectra .
the    present version is better , but , as seen in fig .
2 and 3 , some    artifacts persist in the temperature range 6500 - 7500k at low    metallicity ( some input metallicities are underestimated ) .
+    by comparing the observed spectra with the polynomial model , we get an    idea of the quality of the model and of the consistency of the    atmospheric parameters .
the rms residuals from the absolute model    ( ie . using the input atmospheric parameters ) is 2.0% .
the rms    residuals from the internal model ( iterated using the atmospheric    parameters returned after an inversion with the absolute model ) is    1.4% .
the decrease of the rms residuals after the iteration is due to    an improvement of the consistency of the atmospheric parameters .
the    final residuals include the effect of the noise and of all the    neglected parameters , like rotation , detailed abundances ... the    internal determination of the atmospheric parameters may be biased    with respect to the input values : we checked these biases by averaging    them in some regions of the parameters space , and did not find    evidence for clear bias .
tables 1 & 2 , and fig .
4 & 5 compare the lick indices measured on the elodie spectra with those of the lick ( worthey et al .
1994 ) and jones ( worthey & ottaviani , 1997 ) libraries .
the comparison with the lick data shows an important spread due to the lower quality of the lick data , but the comparison with jones library reveals an excellent consistency .
the zero - points are extremely small , and the slope between the two series is close to 1 .
this test of the slope is critical since it may unveil some data - reduction errors in the cosmic ray clipping , the rebinning or the scattered light subtraction : these three aspects potentially affecting more the strong lines , hence high metallicity stars .    .
comparison with lick indices from the lick library .
col . 1 : designation of the lick index ; col
. 2 , 3 : index(elodie ) = offset + slope @xmath4
index(worthey ) ; col .
4 : rms dispersion from the linear fit . [ cols="<,^,^,^ " , ]     * acknowledgments .
* we thank observatoire de haute - provence , and in particular sergio ilovaisky , for maintening a public archive of their observations .
many improvements of this library were possible thanks to the feed - back of the users .
we present elodie.3.1 , an updated release of the library published in prugniel & soubiran ( 2001 , 2004 ) . 
 the library includes 1962 spectra of 1388 stars obtained with the elodie spectrograph at the observatoire de haute - provence 193 cm telescope in the wavelength range 390 to 680 nm . 
 it provides a wide coverage of atmospheric parameters : t@xmath0 from 3100 k to 50000 k , @xmath1 from -0.25 to 4.9 and [ fe / h ] from -3 to + 1 . 
 the library is given at two resolutions : r@xmath242000 , with the flux normalized to the pseudo - continuum , fwhm=0.55(r@xmath210000 ) calibrated in physical flux ( reduced above earth atmosphere ) with a broad - band photometric precision of 2.5% and narrow - band precision of 0.5% .    
 in this new release the data - reduction ( flux calibration , reconnection of the echelle orders ) has been improved , and in particular the blue region , between 390 and 400 nm has been added .    the fits files for each spectra , and the measured atmospheric parameters are publicly available . 
 see the elodie.3.1 page for more details : + http://www.obs.u-bordeaux1.fr/m2a/soubiran/elodie_library.html    email : prugniel@obs.univ-lyon1.fr