Calibration Plans for the Mid Infrared Instrument (MIRI) on JWST James Rhoads

Calibration Plans for the Mid Infrared

Instrument (MIRI) on JWST

James Rhoads

for the

MIRI Calibration Working Group:

Meixner, Rhoads, Engelbracht, Rieke, Brandl,

Glasse, Lim, Hutchinson & Ressler

TIPS/JIM: MIRI Calibration Plans James Rhoads (STScI) - October 21, 2004

1

Scope and Context of Presentation

MIRI Calibration Planning is under way.

This is a “midstream” presentation to

• Summarize planning effort so far;

• Solicit expert input from the STScI community;

• Incorporate experience from other instruments in

MIRI calibration planning.


2

MIRI Calibration Context and Status

We are “midstream” in MIRI calibration planning.

Four documents outline plans:

• MIRI Calibration Requirements Document;

• MIRI Calibration Plan (Overview and routine onorbit calibrations)

• MIRI Performance Test Specification (Ground testing)

• MIRI Commissioning Plan (On-orbit checkout)

So far, drafts exist for three of these, and two are fairly mature.

The plans need to remain flexible at this early date.


3

Instrument Calibration

• STScI will coordinate the development of an integrated calibration plan by all the instruments

– I&T = PI responsibility

– Commissioning = PI responsibility

– Post-commissioning = STScI responsibility

• STScI benefits from HST experience

– Calibrations planned using the integrated planning tool

– Yearly cycles for calibration programs tied to TAC

• Calibration data will come from 4 sources:

1) science data

2) observations done in parallel with science observations

3) observing time dedicated to calibration

4) ground testing calibration files


4

MIRI has four Science Modes

1. Photometric Imaging

2. Low Resolution Spectroscopy

3. Coronagraphy

TIPS/JIM: MIRI Calibration Plans

James Rhoads (STScI) - October 21, 2004

5

MIRI has four Science Modes

4. Integral Field Unit Spectroscopy



6

MIRI Calibration Requirements Document:

FRD Requirement Number FRD Requirement

2.2 Photometric Imaging

2.2.1 General Characteristics

2.2.1.1 Field of view The imager field of view shall have an area equivalent to at least 2.2 square arc minutes ´(6/D)

2

. The ratio of long to short side of the field shall be no greater than

2.2.1.2 Pixel scale

PSF at 7(TBR)µm

Test ID(s)

IMG-OPT-01

IMG-OPT-02

2.2.1.3 Spectral bands MIRI shall provide imaging from 5 to 27mm in a total of

12 passbands. Approximately 6 of these passbands shall be used for broad spectral energy distribution determination, with the remainder reserved for photometric identification of broad spectral featu

IMG-RAD-09

Rationale MTS Requirements On orbit checkout?

SODRM program ID

The FOV scan will go beyond the MIRI imager FOV edges, establishing FOV size and instrument offset

This test will establish the PSF size, the pixel size will then be determined relative to this.

Dedicated spectral passband measurement

MTS 513.02, MTS 522.01,

MTS 523.02, MTS 524.01,

MTS 524.02, MTS 524.05,

MTS 524.07

MTS 521.01, MTS 522.01,

MTS 524.06

MTS 541.01, MTS 542.02,

MTS 542.03

Yes

Yes

No

Monitor under SODRM

329

Monitor under SODRM

329

Monitor photometric color terms under

SODRM 325



7

Calibration Philosophy Overview

• Consider a draft data reduction pipeline.

• Determine calibration files needed for pipeline.

• Decide how those files can be generated (in-orbit, commissioning, ground test, analysis).

• Look for “missing links” (beyond pipeline).

• Some guiding principles:

– No end-to-end test (Telescope+MIRI) possible before flight

– Stand-alone ground testing of MIRI is planned

– (Almost) all ground-test results will be verified on-orbit with celestial calibrators

– Some additional on-orbit tests will plug “gaps” in ground testing, too.



8

MIRI Calibration Plan: MIRI Calibration Process: A

Data frame from

Multi-Accum

SlowMode

ID bad pixels

Bad Pixel Mask

Or Table

Library

Dark Frames

Subtract

Reference

Pixels and

Dark frames

Reference Pixel Data:

Reference pixels for rows

Reference output

Corrected single

Frame


9

Focal Plane Array Calibrations

Some calibration needs are same for all three FPAs in MIRI.

• Read noise (infer from short darks)

• Dark-bias frames

• Subarrays: Dedicated calibrations for subarrays

limit # supported.

• Latent image reduction through anneals

– Also helps with persistence due to CR hits.

– No associated calibration file.


10

MIRI Imager Calibration Process: B

Corrected

Individual

Frames from

One Integration

Nonlinearity Correction;

Up-the-Ramp Fitting

with Cosmic Ray

Rejection and

Saturation Flagging

Nonlinearity coefficient maps

Local background

Frames or

Library Sky frames

Background

Subtraction

Populate the

Header w/ diagnostics

Flux calibrated

Data frame,

Uncertainty frame,

Mask


Flat Field frame

Absolute

Flux

Calibration

Flat fields:

Pixel flat

Low Freq. Flat

Absolute

Flux

Conversion

Factors


11

MIRI Imager Calibration Process: C

Flux calibrated data frames at a dither position

Drizzle dither positions together into one mosaic

Source extraction & catalog generation

Gap free final image & catalogs

Offset files


12

MIRI Imager Calibration files

1. Bad pixel mask

2. Dark-bias frames

3. Short Dark frames (for Read noise and Bias measurements)

4. Library sky frames

5. Internal flat fields for high frequency variations

6. Sky flats and/or points of light flats for low frequency variations

7. Saturation counts map

8. Linearity counts map

9. Standard star measurements

10.Astrometric solutions file


13

MIRI coronagraphic calibration files

Coronagraphy: Add in

• Target acquisition image of target with neutral density filter

• Point spread function standard taken with the same corongraphic setup up and close in time to the science observation.

• Information on the location of the coronagraphic hole or center of the phase mask

Low Res Spectrograph: Add in

1. Wavelength calibration file

2. Location of the slit information on the FPA

Integral Field Unit: Add in

1. Table of slice and wavelength positions on the FPAs

2. Wavelength calibration spectra


14

Internal Calibration Unit

• Internal calibration source has hot filaments

(~800K, tunable) + concentrator (oblate spheroid,

10mm size) + relay optics.

• Calibration light feeds into pupil planes of both

IFU and imager at the central obscuration, using reflective optics.

• Redundant backup filament.

• In IFU, a third filament (lower intensity) will feed a wavelength calibration system.

• “Cheap” to use, but light does not pass through entire optical train.


15

Celestial calibrators

• Absolute flux calibration: use stars

~100 stars, may need Spitzer data for fainter MIRI appropriate standards

- used for flux, linearity, color

-may need ground based (VISIR) spectroscopy to check stellar atmosphere models of a few

- How do we choose stars w/o circumstellar dust? MIRI will be sensitive to this?

• Spectral calibrators: use PN in Mag. Clouds

• Astrometric standards: same clusters as NIRCam?

• Use telescope pointing for IFU?


16

In-orbit Internal Calibration Modes

1.

Dark Current + Bias

2.

Flat field calibration

3.

Wavelength calibration for the IFU spectrograph

4.

Wavelength Cal. For LRS?

5.

Read Noise Calibration


17

In orbit Monitoring Programs

•

321 Flat Field Monitoring for MIRI Imager

•

323 Dark Monitoring for MIRI Integral Field Unit (IFU) Spectrometer and Imager

•

325 Photometric Monitoring for MIRI Imager

•

329 Astrometric Monitoring for MIRI Imager

• 322 Flat Field Monitoring of the MIRI IFU

•

326 Spectrophotometric Monitoring of the MIRI IFU

•

324 Wavelength Calibration Monitoring for MIRI Integral Field Unit

(IFU) Spectrometer

•

327 Spectrophotometric Monitoring of the MIRI LRS

•

331 Wavelength Monitoring of the MIRI LRS

•

328 Coronagraph photometric monitoring

•

330 Coronagraph center location monitoring



18

MIRI Coronagraphic Calibration Process: C

Flux calibrated

Data frames

PSF subtraction

From individual frames

Coronagraphic

Image of PSF standard

Position of object

Behind hole

Co-addition of several

PSF-subtracted frames at multiple roll angles

Final flux calibrated

High S/N

PSF subtracted

Coronagraphic image


Target

Acquisition

Image and

Monitoring

Information


19

MIRI LRS Calibration Process: B

Corrected

Individual

Frames from

One Integration


Up-the-Ramp Fitting

with Cosmic Ray

Rejection and

Saturation Flagging


Local or library background frames;

Flat fields

Background subtract,

Flat field, and

Extract 2-D

LRS Spectrum

Absolute

Flux

Calibration

Absolute

Flux

Conversion

Factors

Wavelength

Calibration

Wavelength

Conversion

Factors

Populate the


Flux calibrated

Data frame

Uncertainty frame

Mask



20

MIRI LRS Calibration Process: C

Flux & wavelength

calibrated

2-D spectrum at a dither position

Drizzle dither

Positions together

Extract 1-D

Spectrum of

Source

Offset files

Gap free final

Spectrum



21

MIRI IFU Calibration Process: B

Corrected

Individual

Frames from

One Integration


Up-the-Ramp Fitting

with Cosmic Ray

Rejection and

Saturation Flagging


Local or library background frames

Background subtraction

Populate the


Wavelength calibration &

Data cube extraction

Flat fielding and

Absolute flux calibration

Mapping from x, y, and mode to

RA, Dec, _

Flat field frames and

Absolute flux conversion factors

Flux calibrated

Data frame

Uncertainty frame

Mask



22

MIRI IFU Calibration Process: C

Flux & wavelength

calibrated data cube at a dither position

Drizzle dither

Positions together

Offset files

Gap free final data cube

Extract 1D or

2D spectra,

Line images,

Spectral index maps, etc.


23

MIRI Calibration Plan

PROGRAM NO.: 321

AS-OF DATE: 8 JUNE 2004

PROGRAM TITLE:

FLAT FIELD MONITORING FOR MIRI IMAGER

SYNOPSIS: WE PROPOSE TO MONITOR THE FLAT FIELDING STABILITY

OF THE MIRI IMAGER. WE ARE CONCERNED BOTH BY LONG AND BY

SHORT TERM EFFECTS IN THE TELESCOPE OR THE IMAGER. EVERY

WEEK WE PLAN TO TAKE TWO INTERNAL FLATS IN EACH OF THE SIX

BROAD BAND FILTERS. THREE TIMES A YEAR, WE WILL OBTAIN SKY

FLATS IN SIX BROAD BAND FILTERS. TWICE A YEAR WE WILL OBTAIN

INTERNAL FLATS IN ALL FILTERS. ONCE A YEAR WE WILL OBTAIN

SKY FLATS IN ALL THE FILTERS, THE CORONAGRAPH FILTERS AND

THE LOW RESOLUTION SPECTROGRAPH (LRS) PRISM.

SAMPLE AND SKY COVERAGE:

TWO LOCATIONS IN THE ZODICAL LIGHT: ONE HIGH BACKGROUND

AND ONE LOW BACKGROUND.

WE MAY WANT TO CONSIDER CHOOSING TWO SPECIFIC SPOTS IN THE

ZODIACAL BELT THAT ARE “IDEAL” FOR SUCH MEASUREMENTS. IF

THE SAME ARE USED THESE COULD DOUBLE AS THROUGHPUT

MEASUREMENTS.

Basis for exposure time estimates (needed S/N and brightnesses):

S/N ~1000

Sky flats: depends on zodiacal light background

Internal flats: ~10^14 photons/second => short 10 second exposures

INSTRUMENTS AND OBSERVING CONFIGURATIONS:

DETECTOR READOUT: FASTMODE AND SLOWMODE

SKY FLATS 3 TIMES A YEARS:


24

MIRI Performance Test Specification easure the PSF, to verify that the pixel size corresponds to ë/2D of the PSF at To measure the an

1. IMAGER TESTS

1.1 OPTICAL PERFORMANCE TESTS

1.1.1 IMG-OPT-01 FOV Measurement

Goal: To measure the imager FOV and to detect ghosts.

Outline: A point source is scanned across the entire imager array, nominally in a raster pattern.

This could either be done via discrete steps (several pixels) or via a continuous scan. As long as a sufficient row length and number of columns are chosen, the edge of the FOV will be found, i.e.

this will need a larger area than the FOV as the instrument may move in cool down. As the whole

FOV is being scanned, at various positions ghosts may be detected. The positions of these will be noted and IMG-OPT-02 will be used for follow up measurements.

Equipment Needed: A point source imaged on to the imager FOV via a telescope simulator, this will need to have a FOV scanning capability which goes beyond the nominal edge of the FOV.

Number of Pixels/Positions: This should be done at all relevant filter wheel positions.

How Often: Once per model

Open Issues : None

1.1.2 IMG-OPT-02 PSF Measurement

Goal: To m

7(TBR)µm and to characterise ghosts.

Outline: A point source is scanned in a fine spatial resolution raster pattern across an area sufficiently large to sample the PSF.

Equipment Needed: A stable point source, imaged on to the imager FOV via a telescope simulator

Number of Pixels/Positions: This should be done in several areas of the array, at least one position in the centre, one at each corner plus one at each edge. If necessary this type of test can also follow up ghost characterisation discovered by IM-OPT-01


Open Issues : When we come to detailing the tests done, this test may be dropped if we consider that IMG-OPT-01 alone sufficiently samples the PSF.

1.1.3 IMG-OPT-03 Pupil Scanning

Goal: and sensitivity to sources near to the OTE primary mirror.

Outline: This test will scan the pupil plane both at the edge of the beam and beyond. If the pupil is scanned the edge of the beam gives a direct measurement of the angular extent of the beam.

Scanning the point source beyond the edge of the pupil then allows a measurement of out of field

(or external) stray light.

Equipment Needed: Ideally we would sample the pupil plane with a known point source in each cross-beam direction, finding the edges and characterising the external stray light on all sides of the beam. The edge of the beam should be fine sampled spatially in order to accurately determine the beam angular extent, while the out of field measurements can be more coarsely spaced.

Number of Pixels/Positions: The number of positions in the Pupil plane is TBD but there should be sufficient coverage to ensure the two goals of this test are met, if necessary, separately. All relevant filters should be tested.


Open Issues: The MTS design may limit what this test is capable of. The out of field sampling is likely to be limited to several points on either one direction or two opposite directions. The in-pupil points at present do not have accurate photometric requirements. Although useful for alignment


25

Calibration Plans for the Mid Infrared Instrument (MIRI) on JWST James Rhoads

Calibration Plans for the Mid Infrared

Instrument (MIRI) on JWST

James Rhoads

MIRI Calibration Plan: MIRI Calibration Process: A

MIRI Imager Calibration Process: B

MIRI Imager Calibration Process: C

MIRI Coronagraphic Calibration Process: C

MIRI LRS Calibration Process: B

MIRI LRS Calibration Process: C

MIRI IFU Calibration Process: B

MIRI IFU Calibration Process: C

Related documents

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Calibration Plans for the Mid Infrared Instrument (MIRI) on JWST James Rhoads

Calibration Plans for the Mid Infrared

Instrument (MIRI) on JWST

James Rhoads

MIRI Calibration Plan: MIRI Calibration Process: A

MIRI Imager Calibration Process: B

MIRI Imager Calibration Process: C

MIRI Coronagraphic Calibration Process: C

MIRI LRS Calibration Process: B

MIRI LRS Calibration Process: C

MIRI IFU Calibration Process: B

MIRI IFU Calibration Process: C

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