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JWST MIRI Imaging Processing: Lessons from EROs

JWST MIRI Imaging Processing: Lessons from EROs

Karl Gordon

July 15, 2022
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  1. MIRI Imaging Processing
    Lessons from EROs
    Karl D. Gordon
    STScI, Baltimore, MD USA
    MIRI Instrument Team
    20 June 2022
    [email protected]
    @karllark2000
    karllark@github

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  2. Workflow

    Run detector1
    – Fix bug in creation of rate files from rateints files
    – Bug seen around saturated regions

    Run image2

    Update the WCS based on tweakreg results on shortest wavelength filter
    (see following slide)

    For “sparse” targets: create average sky and subtract (see following slide)

    Run image3
    – Background matching turned off
    – Not needed and causes issues around mosaic when on
    – Tweakreg off

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  3. Astrometry workflow

    Shortest wavelength filter
    – Run image3 with tweakreg including align_to_gaia
    – Highest precision astrometry as the most stars detected

    Analyze tweakreg results based on optional output
    – Determine average x,y shifts per mosaic tile

    All filters taken together for each mosaic tile
    – All share the same guide star and show the same shifts

    Apply the tile average x,y shifts to all filters

    Results in sharp stars and well aligned mosaics

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  4. Example Astrometric Shifts
    F770W LMC Flat Region

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  5. Misaligned Tile in Mosaic

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  6. Sky Subtraction Workflow

    For targets that are sufficiently sparse

    Create a sigma clipped (+1, -3 sigma) average in pixel coordinates
    – Option to automatically clip pixels above some threshold
    – Option to automatically exclude ds9 defined regions

    Subtract average sky from each image

    Removes
    – Residual instrumental structure
    – Scattered light off edges (including Lyot and knife edge)
    – Long lived latents

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  7. Reference Files

    Reset Anomoly: 09.00.05, Jane derived

    Dark: 09.01.00, Jane derived

    Linearity: 09.00.09, Jane derived
    – F2550W: 09.00.06 (specific for this filter)

    Flats: 09.02.01, Ors derived
    – Remove 8 cols/rows around array

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  8. Example: LMC Flat Region

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  9. F560W

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  10. F770W

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  11. F1000W

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  12. F1130W

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  13. F1280W

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  14. F1500W

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  15. F1800W

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  16. F2100W

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  17. F2550W

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  18. F1000W, F770W, F560W
    (highest res)

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  19. F1280W, F1130W, F770W
    Aromatic/PAH Features

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  20. F1280W, F1000W, F560W
    Grean Galaxies!

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  21. F1800W, F1000W, F560W
    Red Galaxies!

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  22. F2100W, F1800W, F1500W
    Dust Continuum

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