  We present a major update to the 3D coronal rope ejection (3DCORE) technique
for modeling coronal mass ejection flux ropes in conjunction with an
Approximate Bayesian Computation (ABC) algorithm that is used for fitting the
model to in situ magnetic field measurements. The model assumes an empirically
motivated torus-like flux rope structure that expands self-similarly within the
heliosphere, is influenced by a simplified interaction with the solar wind
environment, and carries along an embedded analytical magnetic field. The
improved 3DCORE implementation allows us to generate extremely large ensemble
simulations which we then use to find global best-fit model parameters using an
ABC sequential Monte Carlo (SMC) algorithm. The usage of this algorithm, under
some basic assumptions on the uncertainty of the magnetic field measurements,
allows us to furthermore generate estimates on the uncertainty of model
parameters using only a single in situ observation. We apply our model to
synthetically generated measurements to prove the validity of our
implementation for the fitting procedure. We also present a brief analysis,
within the scope of our model, of an event captured by Parker Solar Probe (PSP)
shortly after its first fly-by of the Sun on 2018 November 12 at 0.25 AU. The
presented toolset is also easily extendable to the analysis of events captured
by multiple spacecraft and will therefore facilitate future multi-point
studies.
