  We describe the pre-OmegaTranS project, a deep survey for transiting
extra-solar planets in the Carina region of the Galactic Disk. In 2006-2008 we
observed a single dense stellar field with a very high cadence of ~2min using
the ESO Wide Field Imager at the La Silla Observatory. Using the Astronomical
Wide-field System for Europe and the Munich Difference Imaging Analysis
pipeline, a module that has been developed for this project, we created the
light curves of 16000 stars with more than 4000 data points which we searched
for periodic transit signals using a box-fitting least-squares detection
algorithm. All light curves are publicly available. In the course of the
pre-OmegaTranS project we identified two planet candidates - POTS-1b and
POTS-C2b - which we present in this work. With extensive follow-up observations
we were able to confirm one of them, POTS-1b, a hot Jupiter transiting a mid-K
dwarf. The planet has a mass of 2.31+-0.77M_Jup and a radius of 0.94+-0.04R_Jup
and a period of P=3.16d. The host star POTS-1 has a radius of 0.59+-0.02R_Sun
and a mass of 0.70+-0.05M_Sun. Due to its low apparent brightness of I=16.1mag
the follow-up and confirmation of POTS-1b was particularly challenging and
costly.
