wiki:BuildThreeWork

Build 3 changes and additions to the pipeline

Build 3 will include changes and additions to several areas of the JWST calibration pipeline:

Level-2a processing
Updates to several of the calibration steps, as well as the addition of new steps
Level-2b processing
Updates to a few generic steps that are applicable to both imaging and spectroscopy
Level-2b processing
Add infrastructure for NIRSpec IFU and MSA modes. Add algorithms for MIRI LRS and MRS modes, NIRSpec Fixed Slits, and NIRISS SOSS mode.
Association Generator
Design and build the generator tool that will be used to create association tables from association pools (imaging mode only for Build 3)
Image Combination and Resampling
Design and build the infrastructure for producing Level-3 products from imaging mode singletons and associations

Lists of Steps

Level 2a Pipeline Flows

All level-2a processing steps are common to both imaging and spectroscopic modes, and nearly all are common to all instruments. The only exceptions to instrument commonality are the reset and last_frame corrections, which are unique to MIRI. The following table lists the level-2a steps.

All NIR MIRI
ipc ipc
dq_init dq_init
bias_drift saturation
saturation bias_drift
reset
last_frame
dark_current dark_current
linearity linearity
jump jump
ramp_fit ramp_fit

Level-2b Pipeline Flows

Many, but not all, of the level-2b processing steps are common to all instrument modes, but some steps will behave differently when applied to different instrument modes. The full list of available steps is:

assign_wcs
Assign WCS and distortion models to the input level-2a slope image
extract_2d
Extraction of 2-d "stamp" or "cutout" images for individual spectra, when necessary
flat_field
Apply flat field and throughput corrections to 2-d images
persistence
Persistence/Latent correction (still just a placeholder for now)
emission
Correct for telescope emission
straylight
Straylight correction (MIRI MRS and LRS only)
fringe
Apply fringe flat (MIRI MRS only)
photom
Assign flux conversion/calibration to 2-d image; output is Level-2b calibrated slope image
resample
Resample 2-d image to rectified space; output is Level-2b calibrated and rectified image
extract_1d
Extract 1-d spectrum from rectified 2-d image; includes background subtraction, where possible; output is Level-2b calibrated spectrum

The pipeline flows for particular instrument modes are listed in the following table.

Imaging MIRI LRS Fixed Slit MIRI LRS Slitless MIRI MRS NIRISS SOSS NIRSpec Fixed Slits NIRSpec MSA NIRSpec IFU
assign_wcs assign_wcs assign_wcs assign_wcs assign_wcs assign_wcs assign_wcs assign_wcs
extract_2d extract_2d extract_2d
flat_field flat_field flat_field flat_field flat_field flat_field flat_field flat_field
persistence persistence persistence persistence persistence persistence persistence persistence
emission straylight straylight
fringe
photom photom photom photom photom photom photom photom
resample resample resample resample resample
extract_1d extract_1d extract_1d extract_1d extract_1d

Spectroscopic Input Level-2a Images

The input slope images will come in a variety of formats, depending on the instrument mode.

  • MIRI LRS Fixed Slit images
    • Always full frame
  • MIRI LRS Slitless Single Source images
    • Always uses the SLITLESSPRISM subarray
  • MIRI MRS (IFU) images
    • Always full frame for both SW and LW detectors
  • NIRISS Single Object Slitless images
    • Full frame or subarray readouts
    • Default is 256x2048 subarray (covers all 3 orders)
    • 80x2048 subarray possible (covers 2 partial orders)
  • NIRSpec Fixed Slit images
    • Full frame, ALLSLITS subarray, or individual slit subarrays
    • Full frame and ALLSLITS subarray contain data from all 5 slits
  • NIRSpec MSA
    • Always full frame
  • NIRSpec IFU
    • Always full frame

Specifics of Each Spectroscopic Step

Assign WCS

Extract 2-d cutout

MIRI LRS Fixed Slit

LRS fixed slit exposures will always use a full-frame readout and all subsequent processing will be done on the full image, hence extract_2d is not needed for this mode.

MIRI LRS Slitless

LRS slitless exposures will always use the SLITLESSPRISM subarray readout and all subsequent processing will be done on the subarray image, hence extract_2d is not needed for this mode.

MIRI MRS (IFU)

MRS exposures will always use a full-frame readout and all subsequent processing will be done on the full image, hence extract_2d is not needed for this mode.

NIRISS Single Object Slitless

NIRISS SOSS exposures will usually use the 256x2048 subarray, and sometimes the smaller 80x2048 subarray. If either of the subarrays has been used, the extract_2d step is not needed. Only in the event that a full-frame readout was used for an SOSS exposure will we apply extract_2d and will use it to extract the equivalent 256x2048 subarray that is normally used. All subsequent processing will be applied to the 256x2048 or 80x2048 subarrays.

NIRSpec Fixed Slit

These exposures can be obtained using either a full-frame readout, the ALLSLITS subarray (which covers all 5 fixed slits), or a subarray containing one of the slits. For full-frame and ALLSLITS exposures, extract_2d will be applied to extract cutouts for all 5 fixed slits. All subsequent processing will then be applied to each of the 5 slit objects.

NIRSpec MSA

These exposures will always be obtained in full-frame mode, hence extract_2d will be used to extract cutouts for all slitlets defined for the exposure (both target and background slitlets). Subsequent processing will then be applied to each of the multi-slit objects that were extracted.

NIRSpec IFU

These exposures will always be obtained in full-frame mode and all processing is performed on the full frame, hence extract_2d will not be applied to these exposures.

Identifying input images that need extractions performed:

  • INSTRUME='NIRISS' and GRATING='GR700XD' and SUBARRAY='FULL'
  • INSTRUME='NIRSPEC' and EXP_TYPE='FIXEDSLIT' and GRATING!='MIRROR' and (SUBARRAY='FULL' or SUBARRAY='ALLSLITS')
Last modified 4 years ago Last modified on 08/15/14 16:47:06