ACCRETION DISK IMAGE RECONSTRUCTIONS IN V4140-SGR (NSV-12615)

We have developed a program to map the accretion disk brightness distribution in cataclysmic variables from their eclipse light curves. This program is an alternative implementation of the Eclipse Mapping Method (Horne, 1985), employing penalty function optimization techniques with a conjugate-gradient algorithm. To improve the method's performance when faced with relatively low signal-to-noise (S/N) input data we used the combination of chi-2 and another statistic (T'), which measures the correlation between the residuals and the inverse of the measured fluxes, as the statistical consistency check. This avoids the occurence of biased residuals in the light curve, present when the chi-2 statistic alone is used. We applied this method to map the accretion disk brightness in V4140 Sgr (NSV 12615). The analysis of the reconstructed images suggests the existence of an optically thick disk, which presents a temperature distribution with radial dependency very close to the one expected from the standard accretion disk model (T is-proportional-to R-3/4). The results are compatible with the scenario proposed for V4140 Sgr by Baptista, Jablonski & Steiner (1989), emphasizing the differences between this system and the ultra-short period eclipsing dwarf novae.