MIRI Coronagraphic Imaging Template Parameters

JWST's MIRI Coronagraphic Imaging template, available in the Astronomer’s Proposal Tool (APT), has parameters for specifying and scheduling observations.


 Format definitions...

Purple text indicates the parameter is Limited Access.

Boldface italics type indicates the name of an APT parameter or a value for a parameter.

(warning)Red text indicates restrictions on a parameter.

(red star) Black text indicates an important note.

Brown text indicates notes for the developers.

Green text indicates the name of the parameter used by Commanding.

Items in brackets - <value> - are required values.

Items in square brackets - [<value>] - are optional.

The MIRI Coronagraphic Imaging template is to be used for all observations using the coronagraphic imaging mode of MIRI, and this article describes allowed values for all parameters. Advice on how to choose values which optimize your science can be found in the MIRI Coronagraphic Imaging APT Template article and in MIRI Coronagraphic Imaging.

The MIRI Coronagraphic Imaging template consists of the following parameters:

FieldDetailsValues Notes
General Information   
Observation Numberassign observation number


Observation Label provide observation labeltextoptional
Observation Commentsprovide observation commentstextoptional
Target Nameselect Target Namechoose from listfrom Target List

ETC Wkbk. Calc. ID

specify ETC Workbook Calculation IDnumberfor science exposures (optional) and target acquisition exposures
Special Requirementsspecify special requirementschoose from listif needed
Template Specific Information   
Target Acquisition Exposure
Target Acquisition Quadrantselect target acquisition quadrantnumber

Target Acquisition Filter

select filterchoose from list
Acquisition Readout Patternselect acquisition readout patternchoose from list
Acquisition Number of Groups/Integrationselect number of groups per integrationnumber
Acquisition Number of Integrations/Exposureselect number of integrations per exposure1only allowed value
Coronagraphic Exposures
Science Observation Coronagraphic Mask/Filterselect mask/filterchoose from list
Readout Patternselect readout patternchoose from list
Number of Groups/Integrationspecify number of groups per integrationnumber
Number of Integrations/Exposurespecify number of integrations per exposurenumber
Number of Exposures/Ditherspecify number of times to repeat the exposure for each dither positionnumber

Dither Type

select dither typechoose from list
Repeat Observationspecify if repeat acq and observation neededYES, NO
PSF Reference Observations
This is a PSF Reference Observationindicate if PSF

PSF Reference Observationsselect PSF Observationschoose from list
Additional Justificationindicate that there will be no specific PSF Obs

General Information 

 The following parameters are generic to all templates, and are not discussed in this article: Observation Number,  Observation Label, Observations Comments, Target Name, ETC Wkbk. Calc. ID, and Special Requirements.

Target Acquisition 

The following parameter is used to define MIRI Target Acquisition observations. Note that for MIRI Coronagraphic Imaging, the science target is used for the acquisition (unlike NIRCam Coronagraphy, where an offset target may be used). For more information on defining a target acquisition specification, see MIRI Coronagraphic Imaging Target Acquisition.

Note for developers: Target acquisition with the LYOT coronagraph will use the MASKLYOT subarray. With the 1550 4QPM will use the MASK1550 subarray. Same for 1140 and 1065.

Target Acquisition Quadrant  

Select the TARGET ACQUISITION QUADRANT [TACQ QUADRANT] (1 - 4) in which the initial target acquisition will be performed.

Target Acquisition Filter 


This parameter specifies the TARGET ACQUISITION FILTER to be used for the target acquisition.

Acquisition Readout Pattern    


This field specifies the readout pattern to be used to obtain the acquisition data. 

Acquisition Number of Groups/Integration     

NUMBER OF GROUPS/INTEGRATION[TACQ NGROUPS] = 4, 6, 8, 10, 12, 22, 36, 44, 66, 86, 98

This field specifies the number of groups in an integration.

Acquisition Number of Integrations/Exposure

TheNUMBER OF INTEGRATIONS/EXPOSURE [TACQ NINTS] is set to 1 for target acquisition observations.

Coronagraphic Exposures

For the exposures to be executed, specify the MASK/FILTER, READOUT PATTERN, NUMBER OF GROUPS/INTEGRATION, NUMBER OF INTEGRATIONS/EXPOSURE, and theNUMBER OF EXPOSURES/DITHER.For more information on defining an exposure specification, see  Exposure time in the MIRI Coronagraphic APT Template article. Optional DITHER TYPE and REPEAT OBSERVATION may also be selected.   

Note for developers: Observations with this template must fit into a single visit. If more than one visit is created for an observation, give an error.


Select the coronagraphic mask  and filter  combination you wish to use to obtain the data; for the mask properties, see MIRI Coronagraph Masks, while for the filter bandpasses, see Coronagraphic filters in MIRI Coronagraphic Imaging.

Note for developers: The following SUBARRAY values are used for the specified mask: 4QPM/F1065C - MASK1065, 4QPM/F1104C- MASK1140, 4QPM/F1550C - MASK1550, and LYOT/F2300C - MASKLYOT.

Note for developers: for now, only 1 mask/filter can be selected for an observation.  However, in the future, it may be possible to use all 4. Also, APT will need to break the selection into their component values for the scripts. Also note that only 1 exposure time per Mask/Filter will be supported.

Readout Pattern


This field specifies the readout pattern to be used to obtain the data.

Number of Groups/Integration

NUMBER OF GROUPS/INTEGRATION[NGROUPS] specifies the number of groups in each integration.

(warning) NUMBER OF GROUPS/INTEGRATIONmust be 2 or greater.

(warning) If READOUT PATTERN = FASTGRPAVG, it is recommended that NUMBER OF GROUPS/INTEGRATION be at least 4. For all other READOUT PATTERNs, a number of 2-4 is allowed but not recommended.

Number of Integrations/Exposure

NUMBER OF INTEGRATIONS/EXPOSURE[NINTS] field specifies the number of times the integration is repeated in each exposure; default = 1.

Number of Exposures/Dither 

NUMBER OF EXPOSURES/DITHER [NEXP]  specifies the number of times the exposure is to be repeated at each dither position. The default value is 1.

(warning)IfNUMBER OF EXPOSURES/DITHER > 1, the NO PARALLELspecial requirement is required.

Note for developer: If NUMBER OF EXPOSURES/DITHER > 1. provide the following error: " The Special Requirement NO PARALLEL must be used with this Observation." and the following diagnostic explanation: "The NO PARALLEL requirement is required for Coordinated Parallels; Time Series observations; external observations with NUMBER OF EXPOSURES/DITHER > 1 and dithering; NIRSpec observations with Auto Calibrations; NIRCam Grism Time Series; and engineering templates (FGS Internal Flat, MIRI Anneal, MIRI External Flat, NIRSpec Internal Lamp, NIRSpec MSA Masking, NIRSpec MSA Anneal, NIRISS Internal Flat, all WFSC)." 

Dither Type


This parameter specifies the type of dithering needed.

Repeat Observation


If YES is selected, the target acquisition (followed by a science exposure) will be repeated starting in the quadrant diagonally across the central spot from the initial TARGET ACQUISITION QUADRANT, as follows:

First QuadrantSecond Quadrant

Note for developer:

  •  Disable REPEAT OBSERVATION option if TARGET ACQUISITION QUADRANT is not selected.
  • When TARGET ACQUISITION QUADRANT has a valid value, show the text "(with Target Acquisition in quadrant X)" where X is the value of the diagonal quadrant.
  •  Store the second TACQ QUADRANT value instead of this boolean in the database.

PSF Reference Observations

Coronagraphic observations generally have two science observations with an APERTURE PA OFFSET between them of 1-14 degrees as well as an associated PSF reference observation. These observations should be done back-to-back using the SEQUENCE NON-INT special requirement. Warning and errors will help guide the user to correctly set up these links.

This is a PSF Reference Observation

Choosing this option indicates that this observation is a PSF observation.

Note to developer: If this option is chosen, display on the GUI "exclusive access period will be 0 months".

PSF Reference Observations

If this is a science observation, designated PSF Reference Observations must be selected from this list. (The exception is for a "self reference survey" where all observations serve as PSF observations for each other. In this case select the science observations which will be used.)

Note to developer: Only list observations which use the same instrument, same coronagraphic mask, and same filter (ordered so that ones with the PSF Reference Observation checked come first and then the ones without the check).

Additional Justification

Choosing this option indicates that this observation will not have a separate designated PSF observation because it is part of a self reference survey which will be described in the science justification.

Note to developer: It is an error to have nothing checked in the PSF Reference Observations. And it is still an error for a science observation to only choose other science observations and not choose a designated PSF observation, but in that case choosing the Additional Justification option replaces that error with a warning that a self reference survey must be justified.This field specifies the number of groups in an integration.

Change log

 Click here to expand...

Version 11 (November 18, 2019)

  1. PROPINSTJWST-91317 Updated developer note in Repeat Observation section and Coronagraphic Exposures section.

Version 10 (September 23, 2019)

  1. PROPINSTJWST-91395 - added new Acq Readout Pattern options. Changed FASTGRAVP from LAP (purple) to non-LAP based on discussion in meeting: https://innerspace.stsci.edu/display/JPI/2017-08-31+Meeting+about+MIRI+Slow+Read+Out

Version 9 (June 7, 2019)

  1. PROPINSTJWST-91381 - updated Acquisition Number of Groups/Integration section.

Version 8 (April 18, 2019)

  1. Editorial change (moved change log to main article).

Version 7 (December 3, 2018)

  1. PROPINSTJWST-91038 - renamed Second Exposure section to Repeat Observation; reorganized developer note.

Version 6 (August 10. 2018)

  1. PR 89798 - Updated Acquisition Number of Groups/Integration section.

Version 5 (May 14, 2018)

  1. PR 89879 - NO PARALLEL special requirement required for external observations with NEXP>1, added red note and developer note.
  2. PR 89323 - Updated red notes in Number of Groups/Integration for FASTGRAVP

Version 4 (September 25, 2017)

  1. PR 88629 - revised name of exclusive access period
  2. PR 83845 - removed SLOW from readout pattern
  3. PR 87895 - updated Exposure field labels to Groups/Integration and Integrations/Exposure 

Version 3 (February 21, 2017)

  1. PR 87071 - removed mosaic option 
  2. PR 83117 - added PSF Reference Observation section

Version 2 (November 14, 2016)

  1. PR 83365 - added TA Quadrant parameter
  2.  PR 83365 - added Second Exposure parameter
  3. PR 80734 - added Number of Exposures parameter  
  4.  PR 85608 - added TA Readout Pattern, Num Groups, Num Ints
  5. PR 83373 - added small grid dither
  6. PR 85925 - added restriction on Number of Groups

Version 1 (April 27, 2016)

This is the converted Word File from Chapter 13.