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Our main goal is to establish a firm empirical calibration of the surface brightness vs. (V-K) color relation for early type stars based on high quality spectroscopic and infrared observations of early-type detached eclipsing systems in the Large Magellanic Cloud (LMC). Our calibration of this relation will allow distance determinations accurate to about 2.5% to a single object located well beyond the Magellanic Clouds. This will let us calibrate other distance indicators, including period-luminosity relations for Cepheids. The first step of the project is to determine precise parameters for a sample of B-type systems in the LMC. We have already made a preliminary analysis of light and radial velocity curves for selected objects and measured their masses and radii. Here we present the results for one such system.

We performed deep near-infrared J and K photometry of a field in the Sculptor Group spiral galaxy NGC 7793 using ESO VLT and HAWK-I instrument. We produced a sample of 14 Cepheids whose locations and periods of pulsation were known from our previous paper on distance determination to this galaxy based on V and I bands. We determined mean J and K magnitudes based on measurements from two nights and produced period-luminosity relations for both filters. Using those near-infrared dependencies together with relations for bands V and I obtained before, we were able to obtain true distance modulus for NGC 7793. We also calculated the mean reddening affecting our Cepheids.