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WFC3 Pipeline Calibration

WFC3 Pipeline Calibration. Overall Architecture Outline of Processing Reuse of CALACS and CALNIC Code Processing Steps and Keywords Reference Files. Introductory Remarks.

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WFC3 Pipeline Calibration

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  1. WFC3 Pipeline Calibration Overall Architecture Outline of Processing Reuse of CALACS and CALNIC Code Processing Steps and Keywords Reference Files

  2. Introductory Remarks • This review covers only those portions of CALWF3 that will apply instrumental calibrations and combine stacked images (i.e. CR-SPLITs and REPEAT-OBS) • “Value added” portions – distortion correction and combination of dithered/mosaiced images – To Be Reviewed Later[TBRL] • AV-03 • Data calibration requirements and specifications • WFC3 design based on ACS & NICMOS, developed by: • Hack, Greenfield, Stiavelli, Clampin • Skinner, Bushouse, MacKenty, Axon CALWF3

  3. Basic Functions • Apply instrumental calibrations to individual images • must include handling of binned and subarray images • combination of IR MultiAccum readouts into single image • Perform various types of combining for associated images • combine CR-SPLIT and REPEAT-OBS images • combine dithered/mosaiced images [TBRL] • Grism/Prism images receive 2-D processing only; agreement in progress for spectral extraction/analysis tools to be supplied by ST-ECF (reuse of ST-ECF supplied ACS tools) CALWF3

  4. CALWF3 Overview • CALWF3 code written in ANSI C • no new languages! • Uses association tables to control processing of logically related exposures • Maximal reuse of ACS and NICMOS calibration software • CALWF3 based on CALACS flow model • Single and multiple image operations integrated within one shell • no “a” and “b” pieces like CALNIC • UVIS and IR images treated as similarly as possible • UVIS identical to ACS WFC • IR nearly identical to NICMOS CALWF3

  5. CALWF3 Flow Diagram Another set of CR-SPLITs or RPT-OBS images? CRCORR WF3CCD DQI Blev Bias Flash WF3CCD Dark Flat Shad Phot UVIS Yes Yes Yes Another Image In CR-SPLIT or RPT-OBS set? DRZCORR Detector WF3REJ CR Rejection WF3DRZ Drizzling WF3REJ CR Rejection IR RPTCORR WF3IR Zoff DQI Dark Blev Nlin Flat Phot Crrej Another Image in RPT-OBS set? Another set of RPT-OBS images? [TBRL] CALWF3

  6. Code Reuse • CALACS backbone used for overall flow control • CALACS module reuse: • acsccd: CALWF3 UVIS processing • acsrej: CALWF3 CR-SPLIT & REPEAT-OBS combination • CALNICA reuse: • All applicable MultiAccum mode calibration modules • Backwards compatibility with CALACS and CALNIC allows easy implementation of future developments of value to WFC3 (e.g. NICMOS post-SAA persistence corrections, ACS Drizzle development, etc.) • Prototype version of CALWF3, constructed via merger of above ACS & NICMOS code, is up and running now CALWF3

  7. Required Upgrades • UVIS binned images • ACS: no binning capabilities • WFC3: will be handled via binned reference data • No new code necessary • “safe” approach in case calibrations are binning dependent • IR subarray images • necessary for short exposures of bright standards • not supported in CALNIC; will use algorithms from CALACS • IR reference pixel subtraction • used to track bias levels in each non-destructive readout • new capability; need to develop new methods (in progress) CALWF3

  8. IR Reference Pixels Active Reference E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E B C D A B C D D C B A D C B A 8 7 6 5 4 3 2 1 Row 1 2 3 4 5 6 7 8 Column • Reference pixels located in outer 5 rows and columns of array • 5 different “flavors” (unique capacitance) • Outermost row and column steps through 4 capacitances • Rows and columns 2-5 have same capacitance • Take quadrant mean or median of best fitting set and subtract CALWF3

  9. Flat Field Strategy Will use same approach as WFPC2 and ACS: • Flats obtained and maintained in “raw” space, i.e. pixels with larger projected area have more counts • Division into raw science images produces constant counts per pixel for uniform extended sources, but leaves point sources incorrect • Point source photometry will have to be corrected by other means (e.g. correction look-up tables or drizzle resampling) CALWF3

  10. Phased Implementation • Initial delivery of “core” CALWF3 to DST in 2002 Q2 • Includes basic UVIS and IR calibration capabilities • Supports testing of SLTV processing system • Updates delivered 2003 Q2 based on SLTV experience, as well as 3-4 months post-launch (2004 Q2-3?) based on SMOV and early science experience CALWF3

  11. CALWF3 UVIS Cal Steps CALWF3

  12. CALWF3 UVIS Steps (cont.) CALWF3

  13. CALWF3 IR Cal Steps CALWF3

  14. CALWF3 IR Cal Steps (cont.) CALWF3

  15. CALWF3 Reference Images 1Separate reference images will be maintained in CDBS for each binning mode. CALWF3

  16. CALWF3 Reference Tables CALWF3

  17. CALWF3 Ref Tables (cont.) CALWF3

  18. CALWF3 Ref Tables (cont.) CALWF3

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