Description

Class:

jwst.spectral_leak.SpectralLeakStep

Alias:

spectral_leak

The MIRI MRS filters are designed to keep out-of-band light from interfering with the desired first order wavelengths dispersed in a given band. However, around 12.2 µm (channel 3A) a few-percent spectral leak admits second-order light from 6 µm (channel 1B) into the bandpass. This results in spectra produced by the pipeline containing additional flux around 12.2 µm that is only proportional to the object flux at 6 µm.

Applying the optimal spectral leak correction to MIRI MRS data in the calwebb_spec3 pipeline corrects for this feature in extracted channel 3A spectrum for a given target using the channel 1B spectrum of that target (if available). Note that since the channel 1B FOV is smaller than that for Ch3A no such correction is possible in general for extended sources that fill the entire FOV. An example of an uncorrected and corrected spectrum is given in the figure below for a G dwarf star.

Figure: MRS spectral leak as seen in G Dwarf star. The red extracted spectrum does not have the spectral_leak step applied, while the the black extracted spectrum has the spectral leak correction applied.