Two years ago, the OGLE-III survey (Optical Gravitational Lensing Experiment)
announced the detection of 54 short period multi-transiting objects in the
Galactic bulge (Udalski et al., 2002a, 2002b). Some of these objects were
considered to be potential hot Jupiters. In order to determine the true nature
of these objects and to characterize their actual mass, we conducted a radial
velocity follow-up of 18 of the smallest transiting candidates. We describe
here our procedure and report the characterization of 8 low mass star
transiting companions, 2 grazing eclipsing binaries, 2 triple systems, 1
confirmed exoplanet (OGLE-TR-56b), 1 possible exoplanet (OGLE-TR-10b), 1 clear
false positive and 3 unsolved cases. The variety of cases encountered in our
follow-up covers a large part of the possible scenarii occuring in the search
for planetary transits. As a by-product, our program yields precise masses and
radii of low mass stars.Comment: accepted in A&