We present the wavelength and spectral resolution characterisation of the Integral Field Unit ( IFU ) Medium Resolution Spectrometer for the Mid-InfraRed Instrument ( MIRI ) , to fly onboard the James Webb Space Telescope in 2014 .
We use data collected using the Verification Model of the instrument and develop an empirical method to calibrate properties such as wavelength range and resolving power in a portion of the spectrometer ’ s full spectral range ( 5-28 \ > \mu m ) .
We test our results against optical models to verify the system requirements and combine them with a study of the fringing pattern in the instrument ’ s detector to provide a more accurate calibration .
We show that MIRI ’ s IFU spectrometer will be able to produce spectra with a resolving power above R = 2800 in the wavelength range 6.46 - 7.70 \ > \mu m , and that the unresolved spectral lines are well fitted by a Gaussian profile .