Stellar Calibrators for the Medium Resolution Spectrometer of the Mid Infra-Red Instrument on Board the JWST

For the spectro-photometric calibration of space based instruments, like the Medium Resolution Spectrometer (MRS) of the Mid InfraRed Instrument (MIRI) on board the James Webb Space Telescope (JWST), the accuracy is limited to our knowledge of the spectra of the sources used as calibrators. As the sensitivity of this instrument is much higher than previous ones, there is a need for stars with a more accurately modeled spectrum which can be used as a calibrator. In the selection of such sources we include objects with different spectral types and make sure we cover the whole flux range of the instrument.