NIRISS Aperture Masking Interferometry (AMI) Template Parameters

JWST's Aperture Masking Interferometry (AMI) template, available in the Astronomer’s Proposal Tool (APT), has parameters for specifying and scheduling observations.

Introduction

 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 NIRISS Aperture Masking Interferometry (AMI) template is used for the AMI mode of NIRISS, and this article describes allowed values for all parameters. The AMI template includes an option to take direct images; the direct imaging mode of NIRISS is discussed in more detail in NIRISS Imaging Template Parameters and the NIRISS Imaging APT Template article. Advice on how to choose values which optimize your science can be found in the NIRISS Aperture Masking Interferometry APT Template article. 

The NIRISS AMI template consists of the following parameters:

FieldDetailsValues Notes
General Information   
Observation Numberassign observation number

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

select acquisition target

choose from list


Acquisition Filterdefault valueF480M
select acquisition mode

AMIBRIGHT, AMIFAINT


select acquisition readout pattern

NIS, NISRAPID


select number of groups per integration

choose from list


Science Imaging Exposures

select subarray

choose from list


select number of steps

choose from list


select number of positions

choose from list


select filter name

choose from list


select readout pattern

choose from list


specify number of groups per integration

number


specify number of integrations per exposure

number


Direct Imaging Exposures (optional)

specify if image(s) desired

TRUE or FALSE


select number of steps

choose from list


select readout pattern

choose from list


specify number of groups per integration

number


specify number of integrations per exposur

number


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  

Target Acquisition Exposures

Acquisition Target 

If an offset star is to be used for the target acquisition observation, select the ACQUISITION TARGET [TACQ TARGET] from the list of targets previously entered. When the science target is a Solar System target, the acquisition target MUST be the science target. Or, if no target acquisition is needed, select ACQUISITION TARGET to be NONE; the latter option is only allowed if SUBARRAY is FULL see Subarray in the NIRISS Aperture Masking Interferometry APT Template article). 

Note for developers: For APT, the ACQUISITION TARGET NAME field should always be present, but should be defaulted to the SAME TARGET AS OBSERVATION.

Note for developers: If the  acquisition  target is different from the science  target, APT should provide an error if the distance between the ACQ and Science targets is greater than the Visit splitting distance found in the PRD. Also, if there are multiple pointings within a visit, then the rules have to apply to the greatest separation between acq target and pointing within the visit.

Note for developers: If the observation target is a fixed target, remove solar system targets from the acquisition target options. If the observation target is a Solar system target, remove all options from the acquisition target list except for the observation target and NONE.

Acquisition Filter 

The Target Acquisition FILTER is F480M.

Acquisition Mode 

ACQUISITION MODE [TACQ MODE] = AMIBRIGHT, AMIFAINT

This field specifies the target acquisition mode to be used to obtain the acquisition data for a “bright” or “faint” target. In this context, "bright" refers to M-band magnitudes in the range 3.0 ≤ M ≤ 9.3 (in the Vegamag system), while "faint" refers to 9.3 ≤ M ≤ 14.5.  

Acquisition Readout Pattern 

READOUT PATTERN [TACQ PATTERN] = NIS, NISRAPID

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

Note for developer: The NIS option is only available when TACQ MODE = AMIFAINT.

Acquisition Number of Groups/Integration

NUMBER OF GROUPS/INTEGRATION [TACQ NGROUPS] = 3, 5, 7, 9, 11, 13, 15, 17, 19

This parameter specifies the number of groups in an integration.

Note that the NUMBER OF INTEGRATIONS/EXPOSURE is set to 1 for target acquisition observations.

Science Exposures 

Subarray  

              SUBARRAY [SUBARRAY] = SUB80 (default), FULL

This parameter specifies the region of the SCA detector that is to be read out. For more details about these subarrays, see Subarray in the NIRISS Aperture Masking Interferometry APT Template article. 

Dither Pattern  

The following parameters are used to define dithers (or dither patterns). The dither patterns for the AMI science exposures are different from those for the direct images (if selected). The dither patterns for direct images are described in Image Dithers. For more details about dither patterns, see Direct image in the NIRISS Aperture Masking Interferometry APT Template article.

Primary Dithers  

PRIMARY DITHERS [PRIMARY DITHERS] = NONE, 2, 3, 4 (default)

This parameter indicates the number of steps in the primary dither pattern.

Subpixel Positions  

 SUBPIXEL POSITIONS [SUBPIXEL POSITIONS] = NONE (default), 5, 9, 25

This parameter indicates the number of subpixel positions, which will be executed at each step of the primary dither pattern.

Note for developers: see NIRISS Dithering Details for dithering details.

Filter(s)    

Exposures are grouped by filter. For each set of exposures, specify the FILTER, READOUT PATTERN, NUMBER OF GROUPS/INTEGRATION, and the NUMBER OF INTEGRATIONS/EXPOSURE.  For more information on defining an exposure specification, see Filters in the NIRISS Aperture Masking Interferometry APT Template article.

Filter Names 

FILTER [FILTER] = F277W, F380M, F430M, F480

This parameter specifies the filter to be used for the exposure. For the filter bandpasses, see NIRISS Filters.

Readout Pattern 

READOUT PATTERN [READOUT PATTERN] = NISRAPID (default), NIS

This field specifies the readout pattern to be used to obtain the AMI image. (warning)The NIS option is only available when SUBARRAY = FULL.

Number of Groups/Integration 

NUMBER OF GROUPS/INTEGRATION [NGROUPS] specifies the number of groups in each AMI image integration. (warning)For readout pattern NIS, the range is 1-200, while for NISRAPID the range is 1-800.

Number of Integrations/Exposure

NUMBER OF INTEGRATIONS/EXPOSURE [NINTS] field specifies the number of times the AMI image integration is repeated within an exposure. (warning)The range is 1-10000

.

Direct Imaging Exposures 

Direct Imaging 

DIRECT IMAGE [DIRECT_IMAGE] = FALSE (default), TRUE

This parameter specifies if a direct image(s) are to be obtained. The same filter(s) and subarray used for the AMI observations will be used for the direct image(s). The following parameters should be specified if DIRECT IMAGE = TRUE.

Image Dithers 

IMAGE DITHERS [IMAGE DITHERS] = NONE, 2, 3, 4 (default)

This field specifies the number of steps in the dither pattern used to obtain the direct image.

Readout Pattern 

READOUT PATTERN [READOUT PATTERN] = NISRAPID (default), NIS

This field specifies the readout pattern to be used to obtain the direct image. (warning)The NIS option is only available when SUBARRAY = FULL.

Number of Groups 

NUMBER OF GROUPS [NGROUPS] specifies the number of groups in each direct image integration. (warning)For readout pattern NIS, the range is 1-200, while for NISRAPID the range is 1-120.

Number of Integrations 

NUMBER OF INTEGRATIONS [NINTS] field specifies the number of times the direct image integration is repeated within an exposure. (warning)The range is 1-65535

Note for developer: The direct image flag should be set to YES for each direct image exposure specification in the database to distinguish between the required AMI image and direct image. The order of operation is all the AMI exposures are executed, followed by all the Direct Images. Since the same fields in the database are used for both AMI and Direct, APT needs to populate the exposures in this order.

PSF Reference Observations 

AMI observations generally have associated PSF reference observation(s). 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 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.

Change log

 Click here to expand...

The initial version of this chapter was provided by Lily Liu.


Version 8 (April 18, 2019)

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


Version 7 (December 21, 2018)

  1. PROPINSTJWST-91122 - Added developer note  in Acquisition Target section restricting acquisition target options for fixed vs. solar system observations.


Version 6 (December 26, 2017)

  1. PR 89483 - added restriction on Acq Target for SS observations


Version 5 (November 15, 2017)

  1. PR 87895 - updated Exposure field labels to Groups/Integration and Integrations/Exposure
  2. PR 88629 - revised wording on exclusive access period
  3. PR 87961 - updated TA Readout Pattern to includes NIS
  4. PR 88816 - updated text for Acquisition Mode


Version 4 (July 13, 2017)

  1. PR 87944 - updated NINTS under Direct Imaging Exposures


Version 3 (February 21, 2017)

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


Version 2 (January 4, 2017)

  1. PR 85863 - updated developer note for Acquisition Target
  2. PR 85608 - removed statement about Acq Flux, and added new section to state default Acq Filter
  3. PR 85591 - updated Subpixel Positions values


Version 1 (March 22, 2016)

This is the converted Word File from Chapter 43.