  We present a method for deriving a probabilistic estimate of the true source
of a detected TESS transiting event. Our method relies on comparing the
observed photometric centroid offset for the target star with models of the
offset that would occur if the event was either on the target or any of the
Gaia identified nearby sources. The comparison is done probabilistically,
allowing us to incorporate the uncertainties of the observed and modelled
offsets in our result. The method was developed for TESS Full Frame Image
lightcurves produced from the SPOC pipeline, but could be easily adapted to
lightcurves from other sources. We applied the method on 3226 TESS Objects of
Interest (TOIs), with a released lightcurve from SPOC. The method correctly
identified 96.5% of 655 known exoplanet hosts as the most likely source of the
eclipse. For 142 confirmed Nearby Eclipsing Binaries (NEBs) and Nearby Planet
Candidates (NPCs), a nearby source was found to be the most likely in 96.5% of
the cases. For 40 NEBs and NPCs where the true source is known, it was
correctly designated as the most likely in 38 of those. Finally, for 2365
active planet candidates, the method suggests that 2072 are most likely
on-target and 293 on a nearby source. The method forms a part of an
in-development vetting and validation pipeline, called RAVEN, and is released
as a standalone tool.
