NIRCam Dark Template Parameters

JWST's NIRCam Dark Engineering template, available in the Astronomer’s Proposal Tool (APT), is used for calibration observations for the NIRCam instrument. 

Introduction

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.

These parameters are required to obtain Dark observations. Note that this type of observation can be obtained as a parallel to normal science observations.

The NIRCam Dark template consists of the following parameters:

 FieldDetails Values  Notes 
General Information  
Observation Numberassign observation number

number


Observation Labelprovide observation labeltextoptional
Observations Commentsprovide observation commentstextoptional
Special Requirementsspecify special requirementschoose from listif needed
Template Specific Information
Science Templateselect science templatechoose from list
Coronagraphic Maskselect coronagraphic maskchoose from listonly available when SCIENCE TEMPLATE  = CORONAGRAPHY

select subarray

choose from list


select module

choose from list


Number of Output Channelsselect number of output channels1, 4
select readout pattern 

choose from list


specify number of groups per integration

number 


specify number of integrations per exposure

number 


specify number of times to repeat the exposure

number


General Information     

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

Science Template

SCIENCE TEMPLATE = IMAGING, CORONAGRAPHY, TIMESERIES, GRISMTIMESERIES

The selected NIRCam SCIENCE TEMPLATE determines the subarrays, masks, and modules available for the Dark observation (see Table 1). 

Coronagraphic Mask

CORONAGRAPHIC MASK [CORON] = MASK210R, MASKSWB, MASK335R, MASK430R, MASKLWB

This parameter is only available when SCIENCE TEMPLATE = CORONAGRAPHY. The selected CORONAGRAPHIC MASK determines the subarrays and modules available for the Dark observation (see Table 1).

Subarray  

SUBARRAY [SUBARRAY] = FULL, SUB640, SUB320, SUB160, SUB400P, SUB160P, SUB64P, SUBGRISM64, SUBGRISM128, SUBGRISM256, SUB640A210R, SUB640ASWB, SUB320A335R, SUB320A430R, SUB320ALWB, SUB400X256ALWB

This value specifies the region of the SCA that is to be read out. The SCIENCE TEMPLATE and SUBARRAY selected determine which subarrays and modules are available (see Table 1). For more information. see NIRCam Detector Subarrays. Dimensions (rows and columns) of each subarray are specified in the NIRCam_Subarrays table of the PRD. 

Table 1. Subarrays and Modules for selected Science Template

Science TemplateSubarray

Module

Number of Output Channels

ImagingFULLA, B, ALL, A1, A2, A3, A4, ALONG, B1, B2, B3, B4, BLONG4
ImagingSUB640, SUB320, SUB160A, B1
TimeSeriesSUB400P, SUB160P, SUB64PA, B1
GrismTimeSeriesFULLA1
GrismTimeSeriesSUBGRISM64, SUBGRISM128, SUBGRISM256A1 (default), 4
Coronagraphy MASK210RSUB640A210RA1
Coronagraphy MASKSWBSUB640ASWBA1
Coronagraphy MASK335RSUB320A335RA1
Coronagraphy MASK430RSUB320A430RA1
Coronagraphy MASKLWBSUB400X256ALWBA1


Module  

MODULE [MODULE] = A, B, ALL, A1, A2, A3, A4, ALONG, B1, B2, B3, B4, BLONG

This parameter specifies the module that is to be used. Modules are described in Table 2. For more information see NIRCam Modules. The SCIENCE TEMPLATE and SUBARRAY selected determine which subarrays and modules are available (see Table 1 above).

Table 2. Modules for NIRCam Darks 

Module

Definition

A

All short and long wavelength detectors in Module A

B

All short and long wavelength detectors in Module B

ALL

All detectors in Module A and then all detectors in Module B

A1-A4

SCA Ax in Module A, where x = 1-4

ALONG

The long wavelength detector in Module A

B1-B4

SCA Bx in Module B, where x = 1-4

BLONG

The long wavelength detector in Module B


Number of Output Channels

NUMBER OF OUTPUT CHANNELS [NOUTPUTS] = 1, 4

This parameter specifies the number of detector output channels to use. For more details, see Number of Output Channels. The selected SUBARRAY and MODULE determine the number available (see Table 1).

Exposure Specification

For each exposure, specify the READOUT PATTERN, NUMBER OF GROUPS/INTEGRATION, NUMBER OF INTEGRATIONS/EXPOSURE, and NUMBER OF EXPOSURES/DITHER.

Readout Pattern

READOUT PATTERN [READOUT PATTERN] = RAPID, BRIGHT1, BRIGHT2, SHALLOW2, SHALLOW4, MEDIUM2, MEDIUM8, DEEP2, DEEP8

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 an integration.  (warning)See Table 3 for the values for each READOUT PATTERN.

Number of Integrations/Exposure 

NUMBER OF INTEGRATIONS/EXPOSURE [NINTS] field specifies the number of times the integration is repeated. (warning)See Table 3 for the values for each READOUT PATTERN.

Table 3. Number of Integrations/Exposure and Groups/Integration for Darks

Readout PatternNumber of Groups/IntegrationNumber of Integrations/Exposure
RAPID1-10 

1-400

RAPID (MODULES=ALL)

2

1-2

1-20

BRIGHT11-10 

1-10

BRIGHT21-10 

1-10

BRIGHT2 (MODULES=ALL)2-10 

1-10

SHALLOW21-10

1-10

SHALLOW41-10

1-10

MEDIUM21-20

1-10

MEDIUM81-20 

1-10

DEEP21-20

1-10

DEEP81-20

1-10

Number of Exposures/Dither 

NUMBER OF EXPOSURES/DITHER [NEXP] specifies the number of times the dark exposure is to be repeated. (warning)The default value is 1.

Change log

 

  1. PROPINSTJWST-91583  Updates made to Table 1 for Coronography. 


 

  1. PROPINSTJWST-91594 In Subarray section and Modules section, updated previous edits for cycle-dependent subarrays, removed references to OSS versions.


February 10, 2023

  1.  PROPINSTJWST-91542 Updated Modules in Table 1 in Subarrays section for Coronagraphy template.


November 20, 2022

  1. PROPINSTJWST-91564  Updated Table 1 with new subarrays, added cycle dependencies for coronagraphy.
  2. PROPINSTJWST-91531 Added new values to SUBARRAY section.


Version 5 (August 10, 2021)

  1. PROPINSTJWST-85999 Added new subarrays and a template chooser.


Version 4 (April 17, 2019)

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


Version 3 (April 9, 2018)

  1. PR 89484 - updated exposure constraints for RAPID, BRIGHT2


Version 2 (September 6, 2017)

  1. PR 87895 - updated Exposure field labels to Groups/Integration and Integrations/Exposure


Version 1 (March 30, 2017)

  1. This is the converted Word File from Chapter 29.

The documents I used in preparing this chapter are the Preliminary Definition of Observing Templates for JWST Engineering Activities (Beck, Aug. 2008, Final) , the Eng/Cal templates powerpoint presentation of Balzano (May 2008), and the NIRCam OCD (Sahu, V4, Jan 2008).  Updates from the December 2, 2008 meeting are also included (new vocabulary, Readout Region à Subarray, Detector à Module, clarify need for filter pairs).