NIRCam Focus Template Parameters
JWST's NIRCam Focus 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 Focus observations. An exposure with these parameters will be taken before any position change and then after each position change requested. At the end of the visit the focus position will be left in the last specified focus position (i.e., does not automatically return to the starting focus position). Note that this type of observation can be obtained as a parallel to normal science observations.
The NIRCam Focus 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 |
| Target Name | select Target Name | choose from list | from Target List |
| Special Requirements | specify special requirements | choose from list | if needed |
| Template Specific Information | |||
select Target Name | choose from list | from Target list | |
select Module | choose A or B | ||
select Filter | choose from list | ||
select Pupil | choose from list | ||
| Readout Pattern | select readout pattern | choose from list | |
| Number of Groups/Integration | specify number of groups per integration | number | |
| Number of Integrations/Exposure | specify number of integrations per exposure | number | |
| Linear Actuators | |||
| Starting position in Steps | specify starting position of actuators in steps | number | |
| Starting Position in Sensor Units | specify starting position of actuators in sensor units | number | |
| Starting Motor Phases | specify starting motor phases of actuators | number | |
| Linear Actuator Positions | specify array of positions for each actuator | array of 1-10 positions | |
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, and Special Requirements.
Target Name
Select the TARGET NAME [TBD] from the list of targets previously entered (see list of targets).
Module
MODULE [MODULE] = A, B
This parameter specifies the module that is to be used.
Filter
Select the FILTERs [FILTLONG, FILTSHORT] (see Table 1 and Table 2) you wish to use (one for the Short Wavelength and one for the Long Wavelength cameras). You may select a filter pair, a single filter, or no filters.
Table 1. Filters Available for NIRCam Short Wavelength Camera Focus Observations
Filter | Center Wavelength λ0 (μm) | Filter Bandpass Δλ (mm) | Comment |
|---|---|---|---|
F070W | 0.70 | 0.175 | |
F090W | 0.90 | 0.225 | |
F115W | 1.15 | 0.288 | |
F150W | 1.50 | 0.375 | |
F150W2 | 1.50 | 1.000 | |
F200W | 2.00 | 0.500 | |
F140M | 1.14 | 0.140 | |
F182M | 1.82 | 0.221 | |
F210M | 2.10 | 0.210 | |
F187N | 1.87 | 0.019 | Pα |
F212N | 2.12 | 0.021 | H2 |
WLP4 | Weak Lens, +4 waves defocus |
Table 2. Filters Available for NIRCam Long Wavelength Camera Focus Observation
Filter | Center Wavelength λ0 (mm) | Filter Bandpass Δλ (mm) | Comment |
|---|---|---|---|
F277W | 2.77 | 0.693 | |
F322W2 | 3.22 | 1.610 | |
F356W | 3.56 | 0.890 | |
F444W | 4.44 | 1.110 | |
F250M | 2.50 | 0.167 | |
F300M | 3.00 | 0.300 | |
F335M | 3.35 | 0.335 | |
F360M | 3.60 | 0.360 | |
F410M | 4.10 | 0.410 | |
F430M | 4.30 | 0.200 | |
F460M | 4.60 | 0.200 | |
F480M | 4.80 | 0.400 |
Pupil
Select the PUPILs [PUPILLONG, PUPILSHORT] (see Table 3 and Table 4) you wish to use (one for the Short Wavelength and one for the Long Wavelength cameras). You may select a pupil pair, a single pupil, or no pupils.
Table 3. Pupils Available for NIRCam Short Wavelength Camera Focus Observations
Pupil | Center Wavelength λ0 (mm) | Filter Bandpass Δλ (mm) | Comment |
|---|---|---|---|
CLEAR | Imaging pupil | ||
MASKRND | Round mask | ||
MASKBAR | Bar mask | ||
MASKIPR | Internal Phase Retrieval Wedge (for External Flat only) | ||
F162M | 1.62 | 0.151 | CO (6-3) |
F164N | 1.64 | 0.016 | Fe II |
GDHS0 | Dispersed Hartman Sensor 0 degrees | ||
GDHS60 | Dispersed Hartman Sensor 60 degrees | ||
PINHOLES | (for Focus only) | ||
WLP8 | Weak Lens (-8 waves defocus) | ||
WLM8 | Weak lens (+8 waves defocus) |
Table 4. Pupils Available for NIRCam Long Wavelength Camera Focus Observations
Pupil | Center Wavelength λ0 (mm) | Filter Bandpass Δλ (mm) | Comment |
|---|---|---|---|
CLEAR | Imaging pupil | ||
MASKRND | Round mask | ||
MASKBAR | Bar mask | ||
MASKIPR | Internal Phase Retrieval Wedge (for External Flat only) | ||
F323N | 3.23 | 0.032 | H2 |
F405N | 4.05 | 0.041 | Brα |
F466N | 4.66 | 0.047 | |
F470N | 4.70 | 0.047 | |
GRISMR | Spectrum parallel to detector rows (V2) | ||
GRISMC | Spectrum parallel to detector columns (V3) | ||
PINHOLES | (for Focus only) |
Exposure Specification
For each exposure, specify the READOUT PATTERN, NUMBER OF GROUPS/INTEGRATION, and NUMBER OF INTEGRATIONS/EXPOSURE.
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. The maximum NUMBER OF GROUPS is 10 for all READOUT PATTERNs except DEEP2 and DEEP8, for which it is 20.
Number of Integrations/Exposure
NUMBER OF INTEGRATIONS/EXPOSURE [NINTS] field specifies the number of times the integration is repeated. The maximum value is 10.
Linear Actuators
The Linear Actuators are the devices that control the image focus.
Starting Position in Steps
This parameter specifies the STARTING POSITION [LASTEPSLIST] of each of the 3 actuators in Steps; the range is (-11900 to +11900).
Note for developers: If any two LA positions are greater than 1500 steps apart, give an error.
Starting Position in Sensor Units
This parameter specifies the STARTING POSITION [LASUNITSLIST] of each of the 3 actuators in Sensor units; the range is -32767 to +32767.
Starting Motor Phases
This parameter specifies the STARTING MOTOR PHASE [LAPHASELIST] of each of the 3 actuators; the range is 1-6.
Note for developers: The three values above are all integers, with the first two requiring a sign.
Linear Actuator Positions
The LINEAR ACTUATOR POSITIONS [LA1LIST, LA2LIST, LA3LIST] parameter specifies an array of 1 to 10 sets of positions (each composed of a value for each of the three actuators). Individual actuator values can range from -11900 to +11900. If only one position is listed the focus will be adjusted to that position and stay there. If multiple positions are listed they will be executed in the exact order specified.
Note for developers: If one actuator position is specified, the parameter should not be set.
Note for developers: If any two LA positions within each set are greater than 1500 steps apart, give an error.