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

Introduction

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:

FieldDetailsValuesNotes
General Information
Observation Numberassign observation number

number


Observation Label provide observation labeltextoptional
Observations Commentsprovide observation commentstextoptional
Target Nameselect Target Namechoose from listfrom Target List
Special Requirementsspecify special requirementschoose from listif needed
Template Specific Information

Target Name

select Target Name

choose from list

from Target list

Module

select Module

choose A or B


Filter

select Filter

choose from list


Pupil

select Pupil

choose from list


Readout Patternselect readout patternchoose from list
Number of Groups/Integrationspecify number of groups per integrationnumber
Number of Integrations/Exposurespecify number of integrations per exposurenumber
Linear Actuators
Starting position in Stepsspecify starting position of actuators in stepsnumber
Starting Position in Sensor Unitsspecify starting position of actuators in sensor unitsnumber
Starting Motor Phasesspecify starting motor phases of actuatorsnumber
Linear Actuator Positionsspecify array of positions for each actuatorarray 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

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. (warning)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. (warning)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; (warning)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; (warning)the range is -32767 to +32767.

Starting Motor Phases

This parameter specifies the STARTING MOTOR PHASE [LAPHASELIST] of each of the 3 actuators; (warning)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). (warning)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.

Change log

 Click here to expand...

Version 4 (April 17, 2019)

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


Version 3 (December 21, 2018)

  1. PROPINSTJWST-91368 - Added developer note for constraint on actuator steps.


Version 2 (September 6, 2017)

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


Version 1 (April 6, 2017)

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

Keywords

JWST NIRCam Focus Template

JWST NIRCam Focus template parameters

Format definitions

Boldface italics type indicates the name of an APT parameter or a value for a parameter.

Brown text indicates notes for the developers.

Green text indicates the name of the parameter used by Commanding.

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