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
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:
Field | Details | Values | Notes |
---|---|---|---|
General Information | |||
Observation Number | assign observation number | number | |
Observation Label | provide observation label | text | optional |
Observation Comments | provide observation comments | text | optional |
Target Name | select Target Name | choose from list | from Target List |
specify ETC Workbook Calculation ID | number | for science exposures (optional) and target acquisition exposures | |
Special Requirements | specify special requirements | choose from list | if needed |
Template Specific Information | |||
SW Channel Mode | Select mode for Short Wavelength Channel | IMAGING, GRISM | New with Cycle 4 |
Target Acquisition Exposure | |||
Acquisition Target | select acquisition target | choose from list | if offset target |
Acquisition Subarray | default value | SUB32TATSGRISM, SUB32TA_DHS | |
Acquisition Filter | select acquisition filter | F335M, F405N+F444W | |
Acquisition Readout Pattern | select acquisition readout pattern | choose from list | |
Acquisition Number of Groups/Integration | select number of groups per integration | choose number from list | |
Acquisition Number of Integrations/Exposure | select number of integrations per exposure | 1 | only 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
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.
Short Wavelength Channel Mode
SW CHANNEL MODE = IMAGING, GRISM
This is a new selector available starting with Cycle 4. This parameter is not available for Cycle 3 or earlier.
- If IMAGING is selected, the template works as it has in previous cycles: the LW grism is paired with weak lens imaging in the SW channel.
- If GRISM is selected the SW channel will be configured with the Dispersed Hartman Sensor (DHS) grisms, which provide spectra of the target.
For details on how the SW DHS grisms work in coordination with the LW grism for time-series observations, see NIRCam Short Wavelength Grism Time Series.
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 MODE | Available Subarrays |
---|---|
IMAGING | FULL, SUBGRISM256, SUBGRISM128, SUBGRISM64 |
GRISM | SUB40S1_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 MODE | Available 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. 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. The range is 1 - 65535.
Note for developer: APT should generate a warning if the visit duration is greater than 100 hours.