Left: the MIRISim model prediction for the commissioning observation of the LMC astrometric field (using the F560W filter). Right: the commissioning observation (PID 1024). The agreement between the images was an early encouraging indication that MIRI’s performance was close to pre-flight predictions. We note that the transmission of the coronagraphic phase masks at the left hand side of the field was set to unity in the MIRISim model.