Comparison of the spectrum of GY 11 with the synthetic spectra of objects with log g = 3.5 and different T_eff. A spectrum with T_eff = 2700 K produces the best fit. Given that no spectrophotometric calibration of the GY 11 spectrum was possible with the available data (Sect. 3), the combined effects of reddening and wavelength-dependent instrumental response on the spectrum of GY 11 have been accounted for by computing the ratio of a low-order polynomial fit to it and to the original synthetic spectra. The synthetic spectra have then been multiplied by this ratio, and the results are the spectra displayed in the figure. In this way the overall slopes of the spectra of GY 11 and the comparison spectra are the same, which facilitates their comparison.