Wavelength calibration of the JWST-MIRI medium resolution spectrometer

TL;DR

This paper details the wavelength and spectral resolution calibration of the JWST-MIRI medium resolution spectrometer, ensuring accurate spectral measurements for its upcoming scientific observations.

Contribution

It introduces an empirical calibration method for the MIRI spectrometer's wavelength range and resolution, validated against optical models and detector fringing analysis.

Findings

Spectral resolution above R=2800 in 6.46-7.70 microns range

Unresolved spectral lines fit well with Gaussian profiles

Calibration method improves spectral accuracy

Abstract

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 microns). 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 microns, and that the unresolved spectral lines are well fitted by a Gaussian profile.