LEMONY – a library of empirical medium-resolution spectra by observations with the NAOC Xinglong 2.16-m and YNAO Gaomeigu 2.4-m telescopes.

In this study, we expand the coverage and improve the homogeneity of the distribution of MILES template stars in the parameter space, as well as extend the wavelength coverage of the template spectra to the far red beyond the Ca  ii triplet. To achieve this, we have carried out a major observational campaign using two long-slit spectrographs: the OMR mounted on the National Astronomy Observatory of China (NAOC) 2.16-m telescope and the Yunnan Faint Object Spectrograph and Camera (YFOSC) mounted on the Yunnan Astronomical Observatory (YNAO) 2.4-m telescope. The original sample is based on the MILES library, supplemented by 918 stars selected from the PASTEL data base. In total, 822 OMR and 1324 YFOSC spectra have been collected and reduced, covering the wavelength ranges λλ3800–5180 and λλ5150–9000, respectively. The spectra have a mean resolution full width at half-maximum of ∼3.3 Å and are wavelength- and flux-calibrated to an accuracy of ∼20 km s−1 and ∼5 per cent, respectively. The spectra are further corrected for systematic errors in the wavelength calibration to an accuracy of ∼4 km s−1 by cross-correlating with the theoretical spectra. Almost all the spectra have an average signal-to-noise ratio better than 100 per pixel. Combined with the MILES spectra, there are now 1731, 1542, 1324 and 1273 stars with spectra covering λλ3800–5180, λλ3800–7500, λλ5150–9000 and λλ3800–9000, respectively. In this paper, we describe our template star selection, the observation and data reduction, and we present the reduced spectra collected hitherto. [ABSTRACT FROM AUTHOR]