MIRI MRS Cross Grating Engineering Template Parameters

JWST's MIRI MRS Cross Grating Engineering template, available in the Astronomer’s Proposal Tool (APT), is used for calibration observations for the MIRI instrument.   

Introduction

 Format definitions...

JWST Proposal Parameters Home

Purple text indicates the parameter is Limited Access.

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

(warning)Red text indicates restrictions on a parameter.

(red star) 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.

The MIRI MRS Cross Grating Engineering template performs a health check of the MRS spectral function, which is an internal observation (i.e., it does not require an external spectral line source). The visit template uses non-science combinations of the dichroic filters. For completeness, all nine possible combinations, each of the three gratings on each of two grating wheels are used. Note that this type of observation cannot be obtained as a parallel to normal science observations, nor can it have normal science observations attached to it in parallel.

The MIRI MRS Cross Grating Engineering template consists of the following parameters:

 FieldDetails Values Notes 
General Information 
Observation Numberassign observation numbernumber
Observation Labelprovide observation labeltextoptional
Observations Commentsprovide observation commentstextoptional
Mosaic Propertiesspecify mosaic parametersnumberif needed
Special Requirementsspecify special requirementschoose from listif needed
Template Specific Information 

Target Name

select Target Name

choose from list or NONE

from Target list

Lamp Useselect if observation with lamp off is desired ON ONLY, OFF THEN ON, OFF ONLY 
Number of Long Groupsspecify the number of groups per integration on the long wavelength detector number 
Number of Short Groupsspecify the number of groups per integration on the short wavelength detector number 
Number of Long Integrationsspecify the number of integrations per exposure on the long wavelength detectornumber 
Number of Short Integrationsspecify the number of integrations per exposure on the short wavelength detector number 
Number of Exposures/Ditherspecify the number of times to repeat the cross grating exposure at each dither positionnumber 

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, Mosaic Properties, and Special Requirements.

Target Name 

Select the TARGET NAME [TBD] from the list of targets previously entered; see list of targets.   

Lamp Use 

LAMP USE = ON ONLY, OFF THEN ON, OFF ONLY

This field indicates if the observation is to be executed with the calibration lamp off, on, or both off and on (to permit subtraction of external objects from the lamp on data). Note that if OFF THEN ON is requested, you will be prompted separately for the NUMBER OF INTEGRATIONS and NUMBER OF GROUPS for the OFF exposures and the ON exposures.

Note for developers: If LAMP USE = ON ONLY, then populate Lamp Power field in the exposure spec [LAMP_POWER] with ON. If LAMP USE = OFF THEN ON, then populate Lamp Power field in the exposure spec [LAMP_POWER] with all the OFF exposures then all the ON exposures.

Note for developers: If TARGET=NONE and LAMP USE=OFF, APT should generate a warning.

When the user selects the MRS Cross Grating Engineering option, the following 9 exposures will be created with the appropriate setting for the Lamp Power. (There will be 18 exposures created if LAMP USE = OFF THEN ON.)

Exposure Specification

number

DETECTOR

READOUT

PATTERN

NGROUPSSHORT

NGROUPSLONG

(defaults)

NINTSSHORT

NINTSLONG

(defaults)

WAVELENGTH_1_4

WAVELENGTH_2_3

1

MRS

FAST

20

5

SHORT

SHORT

2

MRS

FAST

20

5

SHORT

MEDIUM

3

MRS

FAST

20

5

SHORT

LONG

4

MRS

FAST

20

5

MEDIUM

SHORT

5

MRS

FAST

20

5

MEDIUM

MEDIUM

6

MRS

FAST

20

5

MEDIUM

LONG

7

MRS

FAST

20

5

LONG

SHORT

8

MRS

FAST

20

5

LONG

MEDIUM

9

MRS

FAST

20

5

LONG

LONG

Exposure Specifications 

For each exposure to be executed, specify the NUMBER OF GROUPS, NUMBER OF INTEGRATIONS, and the NUMBER OF EXPOSURES/DITHER,.

Number of Groups 

NUMBER OF GROUPS LONG [NGROUPSLONG] specifies the number of groups in an integration on the long wavelength detector. The default value is 20.

NUMBER OF GROUPS SHORT [NGROUPSSHORT] specifies the number of groups in an integration on the short wavelength detector. The default value is 20.

These values must be added for all nine exposures.

Note for developers: if NGROUPS LONG or SHORT is less than 4, APT should issue a stern warning.

Number of Integrations 

NUMBER OF INTEGRATIONS LONG [NINTSLONG] field specifies the number of times the integration is repeated on the long wavelength detector. The default value is 5.

NUMBER OF INTEGRATIONS SHORT [NINTSSHORT] field specifies the number of times the integration is repeated on the short wavelength detector. The default value is 5.

These values must be added for all nine exposures.

Number of Exposures/Dither 

NUMBER OF EXPOSURES/DITHER [NEXP] specifies the number of times the cross grating calibration exposure is to be repeated. The default value is 1.

Change log

 Click here to expand...

Version 3 (April 18, 2019)

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


Version 2 (August 25, 2017)

  1. PR 87895 - updated Exposure field names


Version 1 (November 07, 2016)

This is the converted Word File from Chapter 19.