highest score in the collection of the best combinations of templates, where the score takes into account the goodness of the fit expressed by the minimum of the residuals. We have thus derived a spectral types for the primary and secondary component of V2653Oph as F2 and F7 main-sequence stars, with an uncertainty of about 0.5 spectral subclass. The effective temperature and surface gravity of the two components of the system are obtained as the weighted average of the values of the best spectra at phases near to the quadratures combinations of templates adopting a weight $w_i=1/\sigma_i^2$, where $\sigma_i$ is the average of residuals for the $i$-th combination. The standard error of the weighted mean was adopted for the atmospheric parameters. The atmospheric parameters obtained by the code and their standard errors are reported in Table3. The observed spectra of V2653Oph at phase near to the quadrature is shown in Fig.2 together with the combination of two reference spectra which gives the best match and their residuals.

Spectroscopic light ratio
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For the detached eclipsing binaries, where the temperature of the two stars are closely similar, the light ratio can be calculated from the cross–correlation functions (CCF) of the various 