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

Introduction

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 MIRI Dark template consists of the following parameters:

FieldDetailsValuesNotes
General Information  
 Observation Numberassign observation number

number


Observation Label provide observation labeltextoptional
Observations Comments provide observation commentstextoptional
Special Requirementsspecify special requirementschoose from listif needed
Template Specific Information  

Detector

select detector

choose from list


 Test Pattern

select test patternchoose from list

Imager Subarray

select the subarray

choose from list

 

Readout Patternselect readout pattern choose from list 
Number of Groups/Integrationspecify number of groups/integrationnumber
Number of Integrations/Exposurespecify number of integrations/exposurenumber
Number of Exposures/Ditherspecify number of times to repeat the dark exposure/dithernumber

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.

Detector

DETECTOR [DETECTOR] = IMAGER, MRS, ALL

This parameter specifies the detector array(s) on which data will be collected. If IMAGER is selected, data is collected on the single IMAGER detector array.  If the selection is MRS, data is collected on both of the IFU detector arrays.  When the selection is ALL, data is collected from all three detector arrays.

Note for developers: The following tables show what should be displayed in the GUI, along with the appropriate commanding name for the database, for each value of DETECTOR.


Imager

#

Readout Pattern

No. of Groups/Integration

No. of Integrations/Exposure

No. of Exposures/Dither

1

[READOUT PATTERN]

[NGROUPS]

[NINTS]

[NEXP]


MRS

#

Detector

Readout Pattern

No. of Groups/Integration

No. of Integrations/Exposure

No. of Exposures/Dither

1

MRSLong

[READOUT PATTERN]

[NGROUPSLONG]

[NINTLONG]

[NEXP]

1

MRSShort

copied from above

[NGROUPSSHORT]

[NINTSHORT]

copied from above


ALL

#

Detector

Readout Pattern

No. of Groups/Integration

No. of Integrations/Exposure

No. of Exposures/Dither

1

Imager

[READOUT PATTERN]

[NGROUPS]

[NINTS]

[NEXP]

1

MRSLong

[READOUT PATTERN LONG]

[NGROUPSLONG]

[NINTSLONG]

copied from above

1

MRSShort

[READOUT PATTERN SHORT]

[NGROUPSSHORT]

[NINTSSHORT]

copied from above

Test Pattern

MIRI detector "test patterns" are almost like real exposures, with the main difference being that the science pixels are fed known values generated by the Focal Plane Electronics (FPE) instead of the pixels being sampled. The patterns are allowed for the three MIRI Detectors: two MRS, plus the IMAGER.

TEST PATTERN [TEST_PATTERN] = NONE (default), COLUMNS, ROWS, FRAMES, ALL

This field specifies the the test pattern to use.

If TEST PATTERN = COLUMNS all the pixels in Column 1 are given the value of 1, all the pixels in Column 2 are given the value of 2 and so on up to 258.

If TEST PATTERN = ROWS all the pixels in Row 1 are given the value of 1, all the pixels in Row 2 are given the value of 2 and so on up to 1024.

If TEST PATTERN = FRAMES all the pixels have the same value in the first frame and that value is the number of frames (which is Groups/Integration) requested. In the next frame all the pixels have the same value again, but that value is one less than the number of frame requested and so on down to 1.

If TEST PATTERN = ALL Output 1 has COLUMNS, Output 2 has ROWS, Output 3 has FRAMES, and Output 4 has all pixels set to 0 as the reference channel. Note that for the first three modes, the same data is sent to each of the 5 outputs.

The default value of NONE is used for regular calibration exposures.  If another value is selected, a test pattern image will be generated.

Imager Subarray

IMAGER SUBARRAY [SUBARRAY] = FULL, BRIGHTSKY, SUB256, SUB128, SUB64, SLITLESSPRISM, MASK1550, MASK1140, MASK1065, MASKLYOT

This parameter specifies the region of the detector that is to be read out; see Table 1 for details. Note that this parameter is only valid for DETECTOR=IMAGER or DETECTOR=ALL.

The value of SUBARRAY for the MRS detectors will always be FULL and will be set to that value by the scripts.


Table 1. Subarrays for MIRI Dark

Subarray

Rows

Columns

Light Sensitive Columns

FULL

1024

1032

1024

BRIGHTSKY

512

968

964

SUB256

256

668

664

SUB128

128

136

132

SUB64

64

72

68

SLITLESSPRISM

512

72

68

MASK1550

224

288

284

MASK1140

224

288

284

MASK1065

224

288

284

MASKLYOT

304

320

316

Note for developers: users can specify one or more combinations of the parameters below for DARK.

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] = SLOW, FAST, FASTGRPAVG

This field specifies the readout pattern to be used to obtain the data. (warning)Note that SLOW is only allowed when SUBARRAY=FULL.

Number of Groups/Integration

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

If READOUT PATTERN = FASTGRPAVG, NUMBER OF GROUPS/INTEGRATION must be 2 or greater.  It is recommended that it be at least 4.

Number of Integrations/Exposure

 NUMBER OF INTEGRATIONS/EXPOSURE [NINTS] specifies the number of times the integration is repeated on the detector.

Number of Exposures/Dither

NUMBER OF EXPOSURES/DITHER [NEXP] specifies the number of times the dark exposure is to be repeated. (warning)The default value is 1. If TEST PATTERN is not NONE, then the NUMBER OF EXPOSURES/DITHER must be 1.

Change log

 Click here to expand...

Change Log

Version 7 (April 18, 2019)

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


Version 6 (May 14, 2018)

  1. PR 89323 - Updated red notes in Number of Groups/Integration for FASTGRAVP


Version 5 (September 27, 2017)

  1. PR 88372 - revised developer note on Detector for MRS/ALL
  2. PR 83485 - added note about using of readout pattern when Subarray not Full
  3. PR 87895 - updated tables in Detector parameters for new parameter names (previously missed)


Version 4 (July 12, 2017)

  1. Editorial - updated description of Test Pattern parameter


Version 3 (May 11, 2017)

  1. PR 85324 - added Test Pattern exposures
  2. PR 87895 - revised names of exposure parameters


Version 2 (December 14, 2016)

  1. PR 85922 - revised the name of the SUBPRISM subarray to be SLITLESSPRISM


Version 1 (November 04, 2016)

This is the converted Word File from Chapter 19.

Keywords

JWST MIRI Dark Template

JWST MIRI Dark 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.

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