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James Webb Space Telescope User Documentation

 

 

JWST's NIRSpec Focus template, available in the Astronomer’s Proposal Tool (APT), is used to perform Internal Lamp exposures.

These parameters are required to obtain Internal Lamp observations. Note that this type of observation cannot be obtained as a parallel to normal science observations, but can be in parallel with slews.

In addition to the following template parameters, this template will have the Special Requirements NO PARALLEL and PARALLEL SLEW ONLY  added.

For each Internal Lamp exposure in an observation, specify all the parameters listed below.

FieldDetailsValueNotes
General Information
Observation Numberassign observation numbernumber
Observation Labelprovide observation labeltextoptional
Observation Commentsprovide observation commentstextoptional
Special Requirementsspecify special requirementschoose from listif needed
Template specific information
Operating Modeselect operating modechoose from list
Subarrayselect subarraychoose from listsee Table 1
MSA Configurationselect MSA configurationALLOPEN, ALLCLOSEDsee Table 2
Lampselect a lampchoose from list
Gratingselect a gratingchoose from list
Readout Patternselect readout patternchoose from list
Number of Groups/Integrationspecify number of groups/integrationnumber
Number of Integrations/Exposurespecify number of integrations/exposurenumber

 General information  

The following parameters are generic to all templates, and are not discussed in this article:  Observation Number, Observation Label, Observation Comments,  and Special Requirements.

Operating Mode

OPERATING MODE [OPMODE] = MSASPEC, IFU, IMAGE, FIXEDSLIT, BRIGHTOBJ, GRATING_ONLY

Select the OPERATING MODE to be used for the exposure. If dispersed data is desired as seen through the MSA, select MSASPEC. If dispersed data is desired as seen through the IFU, select IFU. If imaging data is desired, select IMAGE. If dispersed data is desired through the Fixed Slit, select FIXEDSLIT. If dispersed data is desired through the large square aperture (S1600A1), select BRIGHTOBJ.

Subarray

SUBARRAY [SUBARRAY] = FULL, ALLSLITS, SUBS200A1, SUBS200A2, SUBS200B1, SUBS400A1, SUB2048, SUB1024A, SUB1024B, SUB512, SUB512S, SUB32

This parameter specifies the subarray that is to be read out for each detector. Some subarrays are unavailable depending on selection of OPERATING MODE (see Table 1 for details).

Table 1. Subarrays for NIRSpec Internal Lamp Observations


Operating mode
SubarrayIMAGEMSASPECIFUFIXEDSLITBRIGHTOBJGRATING_ONLY

FULL

X

X

X

X


X

ALLSLITS

X



X



SUBS200A1

X



X



SUBS200A2

X



X



SUBS200B1

X



X



SUBS400A1

X



X



SUB2048

X



X

X


SUB1024A

X



X

X


SUB1024B

X



X

X


SUB512

X



X

X


SUB512SX


X
SUB32X




MSA Configuration

MSA CONFIG ALLOPEN, ALLCLOSED

Select the configuration for the micro-shutter assembly (MSA). For this template, the MSA CONFIGURATION may be ALLOPEN or ALLCLOSED (see Table 2).

Table 2. MSA configuration options

Operating ModeMSA Configurations
MSASpecALLOPEN, ALLCLOSED
IMAGEALLOPEN, ALLCLOSED
FIXEDSLITALLCLOSED (default)
BRIGHTJOBALLCLOSED (default)
GRATING ONLY
IFU

Lamp

LAMP [LAMP] = NONE, FLAT1, FLAT2, FLAT3, FLAT4, FLAT5, LINE1, LINE2, LINE3, LINE4, REF, TEST

Select the lamp    you wish to use for the exposure.

Grating

GRATING [GRATING] = G140M, G235M, G395M, G140H, G235H, G395H, PRISM, MIRROR

If the OPERATING MODE is MSASPEC FIXEDSLIT, IFU, or BRIGHTOBJ select the grating   you wish to use for the exposure. (warning) Note: If OPERATING MODE = IMAGE, the grating will not be selectable; the MIRROR will be automatically used instead. If OPERATING MODE = BRIGHTOBJ, MIRROR is not available.

Note for developer: In this case, APT needn't populate the grating field in the sql export; it will be set to NULL by the database.

Exposure Specifications

For each exposure to be executed, specify the READOUT PATTERN, NUMBER OF GROUPS/INTEGRATION,  and the NUMBER OF INTEGRATIONS/EXPOSURE. 

Readout Pattern

READOUT PATTERN [READOUT PATTERN] = NRS, NRSRAPID, NRSIRS2, NRSIRS2RAPID

This field specifies the readout pattern to be used to obtain the data. The IRS2 readout patterns will only be available when SUBARRAY=FULL has been chosen.

Note that there is a 100 second overhead associated with switching between IRS2 and non-IRS2 readout patterns in an observation.

(warning)Note that NUMBER OF GROUPS/INTEGRATION x NUMBER OF INTEGRATIONS/EXPOSURE must be less than 256 for NRISIRS2 and 1024 for NRSIRS2RAPID.

Note for developers: If there is interleaving of IRS2 and non-IRS2 readout patterns, issue a warning alerting the user to the 100s overhead.

Number of Groups/Integration

NUMBER OF GROUPS/INTEGRATION [NGROUPS] specifies the number of groups in an integration.

Number of Integrations/Exposure

NUMBER OF INTEGRATIONS/EXPOSURE [NINTS] field specifies the number of times the integration is performed.

Change log

 Click here to expand...

Version 3 (April 19, 2019)

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


Version 2 (October 16, 2017)

  1. PR 88968 - revised overhead time for switching between IRS and IRS2 readout patterns
  2. PR 88047 - added restriction on NGroups x NINTs for IRS2 readout patterns


Version 1 (June 15, 2017)

  1. This is the converted Word File from Chapter 39.
  2. PR 87895 - revised names of Number of Groups and Integrations
  3. PR 79394 - added additional subarray options
  4. To match GUI - removed restriction on NINTs which was never implemented

 

Keywords

NIRSpec Internal Lamp Template

NIRSpec Internal Lamp Template Parameters

Format definitions

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

(warning)Red text indicates restrictions on a parameter.

Brown text indicates notes for the developers.

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

On this page

JWST Proposal Parameters

Change log

Change log