The Cattery is a set of MeqTrees-based frameworks for simulation and calibration of radio interferometers. Pretty much everything is done via a Cattery package these days.
Cattery bugs should be reported via the main MeqTrees repository here:
MeqTrees is a software package for implementing Measurement Equations. This makes it uniquely suited for simulation and calibration of radioastronomical data, especially that involving new radiotelescopes and observational regimes.
$ python setup.py install
Read everything about MeqTrees on the wiki: