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.
Red text indicates restrictions on a parameter.
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:
| Field | Details | Values | Notes |
|---|---|---|---|
| General Information | |||
| Observation Number | assign observation number | number | |
| Observation Label | provide observation label | text | optional |
| Observations Comments | provide observation comments | text | optional |
| Special Requirements | specify special requirements | choose from list | if needed |
| Template Specific Information | |||
| Science Template | select science template | choose from list | |
| Coronagraphic Mask | select coronagraphic mask | choose from list | only available when SCIENCE TEMPLATE = CORONAGRAPHY |
select subarray | choose from list | ||
select module | choose from list | ||
| Number of Output Channels | select number of output channels | 1, 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 Template | Subarray | Module | Number of Output Channels |
|---|---|---|---|
| Imaging | FULL | A, B, ALL, A1, A2, A3, A4, ALONG, B1, B2, B3, B4, BLONG | 4 |
| Imaging | SUB640, SUB320, SUB160 | A, B | 1 |
| TimeSeries | SUB400P, SUB160P, SUB64P | A, B | 1 |
| GrismTimeSeries | FULL | A | 1 |
| GrismTimeSeries | SUBGRISM64, SUBGRISM128, SUBGRISM256 | A | 1 (default), 4 |
| Coronagraphy MASK210R | SUB640A210R | A | 1 |
| Coronagraphy MASKSWB | SUB640ASWB | A | 1 |
| Coronagraphy MASK335R | SUB320A335R | A | 1 |
| Coronagraphy MASK430R | SUB320A430R | A | 1 |
| Coronagraphy MASKLWB | SUB400X256ALWB | A | 1 |
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. 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. See Table 3 for the values for each READOUT PATTERN.
Table 3. Number of Integrations/Exposure and Groups/Integration for Darks
| Readout Pattern | Number of Groups/Integration | Number of Integrations/Exposure |
|---|---|---|
| RAPID | 1-10 | 1-400 |
| RAPID (MODULES=ALL) | 2 1 | 1-2 1-20 |
| BRIGHT1 | 1-10 | 1-10 |
| BRIGHT2 | 1-10 | 1-10 |
| BRIGHT2 (MODULES=ALL) | 2-10 | 1-10 |
| SHALLOW2 | 1-10 | 1-10 |
| SHALLOW4 | 1-10 | 1-10 |
| MEDIUM2 | 1-20 | 1-10 |
| MEDIUM8 | 1-20 | 1-10 |
| DEEP2 | 1-20 | 1-10 |
| DEEP8 | 1-20 | 1-10 |
Number of Exposures/Dither
NUMBER OF EXPOSURES/DITHER [NEXP] specifies the number of times the dark exposure is to be repeated. The default value is 1.