NIRCam Grism Time Series Imaging Template Parameters

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

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.

The NIRCam Grism Time Series Imaging template is used for the Grism time series imaging mode of NIRCam, and this article describes allowed values for all parameters. Advice on how to choose values which optimize your science can be found in the NIRCam Grism Time-Series APT Template article.  

The NIRCam Grism Time Series Imaging 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   
SW Channel ModeSelect mode for Short Wavelength ChannelIMAGING, GRISMNew with Cycle 4
Target Acquisition Exposure
Acquisition Targetselect acquisition targetchoose from listif offset target
Acquisition Subarraydefault valueSUB32TATSGRISM, SUB32TA_DHS
Acquisition Filterselect acquisition filterF335M, F405N+F444W
Acquisition Readout Patternselect acquisition readout patternchoose from list
Acquisition Number of Groups/Integrationselect number of groups per integrationchoose number from list
Acquisition Number of Integrations/Exposureselect number of integrations per exposure1only allowed value
Science Exposure
select a module

A

 only allowed value
select subarray

choose from list


specify number of detector output channels

1 or 4


specify number of exposures per dither

number


select pupil+filter pair names

choose from lists


select readout pattern

choose from list


specify number of groups per integration

number


specify number of integrations per exposure

number


Note for developer: This template cannot be used in parallel and cannot have parallels attached to it; the NO PARALLEL special requirement should be added. The TIME SERIES OBSERVATION special requirement should also be added.

Note for developer: This template cannot be used with a mosaic.

General Information 

Short Wavelength Channel Mode

Target Acquisition 

The following parameters are used to define NIRCam Target Acquisition observations.

Acquisition Target Name 

The default for this parameter is "Same Target as Observation."  If an offset star is to be used for the target acquisition observation, select the TARGET NAME [TACQ TARGET] from the list of fixed 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.

Note for developer: If the  acquisition  target is different from the science  target, APT should provide a warning 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.

Acquisition Subarray  

For Cycle 3 or earlier, the acquisition SUBARRAY is SUB32TATSGRISM.

For Cycle 4 or later, the acquisition SUBARRAY depends on the selected SW CHANNEL MODE:

  • For SW CHANNEL MODE=IMAGING, SUBARRAY=SUB32TATSGRISM
  • For SW CHANNEL MODE=GRISM, SUBARRAY=SUB32TA_DHS

Acquisition Filter 

TARGET ACQUISITION FILTER [TACQ FILTER] = F335M, F405N+F444W

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

Acquisition Readout Pattern 

ACQUISITION READOUT PATTERN [TACQ PATTERN] = RAPID, BRIGHT1, BRIGHT2, SHALLOW2, SHALLOW4, MEDIUM2, MEDIUM8, MEDIUMDEEP2, MEDIUMDEEP8, DEEP2, DEEP8

This field specifies the readout pattern to be used to obtain the acquisition data. MEDIUMDEEP2 and MEDIUMDEEP8 are available only for Cycle 4 or greater. 

Acquisition Number of Groups/Integration

NUMBER OF GROUPS/INTEGRATION [TACQ NGROUPS] = 3, 5, 9, 17, 33, 65

This parameter specifies the number of groups in an integration.

Acquisition Number of Integrations/Exposure

NUMBER OF INTEGRATIONS/EXPOSURE specifies the number of times the integration is repeated, and is always 1.

Science Exposures

Module 

MODULE [MODULE] = A

There is only one choice for MODULE in this template, so there is only one long wavelength detector and two short wavelength detectors.

Subarray 

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 NIRCam Grism Time-Series APT Template article.

For Cycle 3 or earlier, available subarrays are:

SUBARRAY [SUBARRAY] = FULL, SUBGRISM256, SUBGRISM128, SUBGRISM64

For Cycle 4 or later, available subarrays depend on the selected SW CHANNEL MODE as shown in Table 1. 

Table 1. Subarrays for Imaging and Grism (Cycle 4 or later)

SW CHANNEL MODEAvailable Subarrays
IMAGINGFULL, SUBGRISM256, SUBGRISM128, SUBGRISM64
GRISMSUB40S1_2-SPECTRA, SUB80S2_4-SPECTRA, SUB160S4_8-SPECTRA, SUB256S4_8-SPECTRA

Number of Detector Output Channels

This field specifies the number of detector output channels to use. For more details, see Number of Output Channels.

For Cycle 3 or earlier (or Cycle 4 with SW CHANNEL MODE = IMAGING ):

NUMBER OF DETECTOR OUTPUT CHANNELS [NOUTPUTS] = 1 , 4 (default)

For Cycle 4 or later:

If SW CHANNEL MODE = GRISM, this parameter is set to 4 and cannot be changed.

Note for developer: Add a label in the gui to the right of No. of Outputs to indicate the Frame Readout time.

Number of Exposures/Dither 

NUMBER OF EXPOSURES/DITHER [NEXP] field specifies the number of times the exposure is to be repeated.

This parameter is named Exposures/Dith (exposures per dither) for consistency with other observing modes, even though no dithering is allowed in this mode.

Exposure Specification 

For the science exposure  specify the PUPIL+FILTER pairs, READOUT PATTERN, NUMBER OF GROUPS/INTEGRATION,  and NUMBER OF INTEGRATIONS/EXPOSURE.

For the filter bandpasses, see NIRCam Filters while for pupil information, see NIRCam Pupil and Filter Wheels. Note that only one exposure specification is allowed, and this will be used with both the long- and short-wavelength cameras. For more information on defining an exposure specification, see Exposure Time in the NIRCam Grism Time-Series APT Template article.

Filter and Pupil Names 

Select the name of each PUPIL+FILTER [FILTSHORT, FILTLONG] pair you wish to use (one for the Short Wavelength and one for the Long Wavelength cameras)

For Cycle 3 and earlier, available PUPIL+FILTER names are shown in Table 2.

For Cycle 4 and later, available PUPIL+FILTER names depend on selected SW CHANNEL MODE and are shown in Table 3.

 Table 2. Cycle 3 and Earlier: Pupil+Filter Pairs Available for NIRCam Grism Time Series Imagin

Short Wavelength Camera Filter+Pupil
Long Wavelength Camera Filter+Pupil

CLEAR+WLP4,  WLP8+F070W, WLP8+F140M, WLP8+F182M, WLP8+F210M, WLP8+F187N, WLP8+F212N


GRISMR+F277W, GRISMR+F322W2, GRISMR+F356W, GRISMR+F444W



Table 3. Cycle 4 and Later: Pupil+Filter Pairs Available for NIRCam Grism Time Series Imaging 

Short Wavelength Camera Filter+Pupil
Long Wavelength Camera Filter+Pupil

for SW CHANNEL MODE = IMAGING

CLEAR+WLP4, WLP8+F070W, WLP8+F140M, WLP8+F182M, WLP8+F210M, WLP8+F187N, WLP8+F212N  


GRISMR+F277W, GRISMR+F322W2, GRISMR+F356W, GRISMR+F444W

for SW CHANNEL MODE = GRISM

GDHS0 + F070W, GDHS0 + F090W, GDHS0 + F115W, GDHS0 + F150W, GDHS0 + F150W2, GDHS0 + F200W

GRISMR+F277W, GRISMR+F322W2, GRISMR+F356W, GRISMR+F444W

Readout Pattern 

This parameter specifies the READOUT PATTERN to be used to obtain the data. Available patterns depend on the selected SW CHANNEL MODE as shown in Table 4.

Table 4. Readout Patterns for Imaging and Grism

SW CHANNEL MODEAvailable READOUT PATTERN
IMAGING (≤ Cycle 3)RAPID, BRIGHT1, BRIGHT2, SHALLOW2, SHALLOW4, MEDIUM2, MEDIUM8, DEEP2, DEEP8
IMAGING (≥ Cycle 4)RAPID, BRIGHT1, BRIGHT2, SHALLOW2, SHALLOW4, MEDIUM2, MEDIUM8, MEDIUMDEEP2, MEDIUMDEEP8, DEEP2, DEEP8
GRISM (≤ Cycle 3)RAPID, BRIGHT1, BRIGHT2, SHALLOW2, SHALLOW4, MEDIUM2, MEDIUM8, DEEP2, DEEP8
GRISM  (≥ Cycle 4) RAPID, BRIGHT1, DHS3, DHS4, DHS5, DHS6, DHS7

Number of Groups/Integration

NUMBER OF GROUPS/INTEGRATION [NGROUPS] specifies the number of groups in an integration. (warning)The range is 1 - 30, inclusive.

Number of Integrations/Exposure 

NUMBER OF INTEGRATIONS/EXPOSURE [NINTS] field specifies the number of times the integration is repeated. (warning)The range is 1 - 65535.

Note for developer: APT should generate a warning if the visit duration is greater than 100 hours.

Change log

The initial version of this chapter was provided by Marsha Allen.

 

  1. PROPINSTJWST-91686 Added MEDIUMDEEP2-8 patterns to Readout Patterns sections for Target Acquisition and Science.
  2. PROPINSTJWST-91689 Added DHS3-7 patterns to Readout Patterns section (Table 4).


 

  1. PROPINSTJWST-90434 Added SW Channel Mode section and related changes throughout the article.


Version 13 (May 11, 2022)

  1. PROPINSTJWST-91468 Added developer note about warning for visit splitting distance to Acquisition Target Name section.


Version 12 (August 9, 2021)

  1. Editorial change - Anchor links fixed in parameter table by removing pagename from link.


Version 11 (December 23, 2019)

  1. PROPINSTJWST-89005 - Added new filter to Acquistion Filter section.


Version 10 (September 24, 2019)

  1. PROPINSTJWST-88134 - Added description of TA=NONE option to Acquisition Target Name section.
  2. PROPINSTJWST-87170 - Added two new SW filters.


Version 9 (April 17, 2019)

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


Version 8 (December 21, 2018)

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


Version 7 (December 27, 2017)

  1. PR 89483 - added restriction on Acq Target for SS observations
  2. PR 88411 - revised developer note to add TSO requirement


Version 6 (December 21, 2017)

  1. PR 89646 - updated the Acq Subarray name


Version 5 (September 5, 2017)

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

Version 4 (May 11, 2017)

  1. PR 87783 - revised TA NGroups


Version 3 (February 21, 2017)

  1. PR 87071 - removed mosaic option


Version 2 (November 14, 2016)

  1. PR 85330 - added target acquisition


Version 1 (April 19, 2016)

This is the converted Word File from Chapter 23.