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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
  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
  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
  4. 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
  5. 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