MIRI APT Templates

A JWST MIRI observing program is designed using the one of the MIRI templates in the Astronomer's Proposal Tool (APT).

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MIRI offers 4 observing modesimaging, low resolution slit and slitless spectroscopy, medium resolution IFU spectroscopy, and coronagraphic imaging. Each mode has its own APT template.

All JWST observations at wavelengths between 5 and 28.5 μm require the use of MIRI.

Step-by-step in APT

The step-by-step instructions for using the MIRI observing templates in the APT are provided in the following JDox articles:

Additional information on all available options and restrictions for MIRI templates are available in MIRI Templates articles at the Proposal Parameters Documentation outside JDox.


The MIRI imaging mode offers broad-, medium- and narrowband imaging from 5.6 to 25.5 µm in a 74 × 113" FOV, or smaller FOVs if subarrays are used. The template provides a set of pre-defined dither patterns and mosaicing functionality for imaging of larger fields.

Low resolution spectroscopy

The MIRI low resolution spectroscopy (LRS) mode supports 5–14 µm single object slit and slitless spectroscopy at R ~ 100. 

Medium resolution integral field spectroscopy

Full spectroscopic 5–27.9 μm coverage is offered using the MIRI medium resolution spectroscopy (MRS) mode. This is accomplished by observing simultaneously using 4 different integral field units (IFUs; channels 1–4) with FOVs spanning 3.7" to 7.7". Three consecutive spectral settings are required for full spectral coverage. The spectral resolving power ranges from R ~ 1,550–3,250, depending on wavelength. The MRS template supports a selection of dither patterns as well as mosaicing. 

Coronagraphic imaging

MIRI has 4 different coronagraphs for high-contrast imaging of faint companions or extended emission around a bright point source: three different 4-quadrant phase masks (4QPMs) and one Lyot mask. The 4QPMs operate in 3 photometric bands at 10.65 μm, 11.40 μm, and 15.50 μm, while the Lyot operates at 23.00 μm. 

Creating an APT observation

Words in bold are GUI menus/
panels or data software packages; 
bold italics are buttons in GUI
tools or package parameters.

To create a new MIRI observation, choose an Observation Folder in the tree editor and click Add in the active GUI window. This will add a generic observation to the folder and open an observation form. The observation can be assigned a unique number and a text label (which does not need to be unique). Select MIRI from the Instrument drop-down parameter field. This populates the Template drop-down field with the MIRI templates; select one of them to continue working on the specifics of the observation.

Latest updates
    Updated with in-flight numbers

  • Updated list of dither parameters to better reflect current APT
Originally published