MIRI Observing Modes

JWST's Mid-Infrared Instrument (MIRI) has 4 observing modes: imaging, coronagraphic imaging, low-resolution spectroscopy, and medium-resolution spectroscopy.

See also: MIRI APT Templates

The JWST Mid-Infrared Instrument (MIRI) provides imaging and spectroscopic observing modes from ~5 to 27.9 μm that correspond to templates in the Astronomer's Proposal Tool (APT):

  • Imaging—field of view is up to 74" × 113" with filters ranging from 5.6 to 25.5 μm. 
  • Low-resolution spectroscopy—slitted and slitless modes are available from 5 to 14 μm. Slitless modes are currently only available for time-series observations (TSOs).
  • Medium-resolution spectroscopy—integral field unit (IFU) spectroscopy is available from 4.9 to 27.9 μm.
  • Coronagraphic imaging—four individual coronagraphs are available, one of which is based on the classic design of Lyot and three of which are based on 4-quadrant phase masks (4QPM).


Table 1. Properties of MIRI observing modes

Observing mode

Wavelength
coverage 
(μm)

Field of view
or slit size
(arcsec)

Pixel scale
("/pixel)

Resolving
power
R = λ/Δλ

FWHM
 

Notes

Imaging

5.6 to 25.5 μm

74 × 113

0.113.5 – 16.12 pix @ 6.25 μm

Subarrays
available
FWHM = 2 pix × (λ/6.25 μm)
for λ > 6.25 μm

4QPM coronagraphic Imaging

10.65, 11.4, 15.5

24 × 24

0.1114.1 – 17.22 pix @ 6.25 μm


Lyot coronagraphic Imaging

2330 × 300.114.12 pix @ 6.25 μm

Low-resolution spectroscopy

5 to 14 μm

0.51 × 4.7 (slit size)

0.11

~100 @ 7.5 μm

2.6 pix @ 7.7 μm

Slit or slitless modes

Medium-resolution spectroscopy

4.9 to 27.9 μm

3.7 to 7.7

0.196–0.273~1550–32502 pix @ 6.2 μm

FWHM = 0.314" × (λ/10 μm)
for λ > 8 μm


Additional information about MIRI observing modes can be found in these articles:



Notable updates
  •  
    Updated MRS and LRS to in-flight numbers
Originally published