An updated MILES stellar library and stellar population models
  (Aims) We present a number of improvements to the MILES library and stellar
population models. We correct some small errors in the radial velocities of the
stars, measure the spectral resolution of the library and models more
accurately, and give a better absolute flux calibration of the models.
(Methods) We use cross-correlation techniques to correct the radial velocities
of the offset stars and the penalised pixel-fitting method, together with
different sets of stellar templates, to re-assess the spectral resolution of
the MILES stellar library and models. We have also re-calibrated the zero-point
flux level of the models using a new calibration scheme. (Results) The end
result is an even more homogeneously calibrated stellar library than the
originally released one, with a measured spectral resolution of ~2.5\AA, almost
constant with wavelength, for both the MILES stellar library and models.
Furthermore, the new absolute flux calibration for the spectra excellently
agrees with predictions based on independent photometric libraries.
(Conclusions) This improved version of the MILES library and models (version
9.1) is available at the project's website (http://miles.iac.es).
