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

MIRI offers 4 observing modes: imaging, 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 27.9 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:

• MIRI Imaging APT Template
• MIRI LRS APT Template
• MIRI MRS APT Template
• MIRI Coronagraphic Imaging APT Template

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

---

Imaging

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

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.

---

---