SIRTF Science Center Data Pipeline Products

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SIRTF Science CenterData Pipeline Products

• William B. Latter
• SSC/MIPS Lead Instrument Scientist
• Mehrdad Moshir
• SSC Downlink Development Lead
• and
• The SSC Team

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SIRTF Data ProductsSummary

• Basic Calibrated Data products (BCDs)
• Derived from a single data collection event (DCE
  or single frame exposure).
• The most reliable product achievable by automated
  processing.
• Calibrated in flux and/or wavelength (when
  appropriate).
• Examples of BCDs include
• Single-frame images from IRAC
• Single-frame images from MIPS imaging modes
• Echellogram (spatial-wavelength) from IRS (see
  figure)
• Observers should not have to re-derive this
  product. BCDs will be easy to manipulate and
  analyze in common data analysis environments,
  such as IRAF and IDL.
• The final definition of SIRTF data products will
  be made available at the time of the LegSci Call
  for Proposals.

• Browse Quality Data products (BQD)
• Derived from an AOR, e.g, a map or a cube or a
  stack of spectra
• Results from combining BCDs
• BQDs are the combined results of a SIRTF
  observation request (AOR). Enhancements to the
  pipeline from earlier planning facilitate a more
  detailed scientific analysis of the BQDs.
• Raw Data products
• FITS formatted no processing

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An Enhancement ofPipeline Products

• As a result of recommendations made by the
  Williams Committee and accepted by NASA, the
  SSC is now able to commit additional resources to
  the data processing pipeline.
• Higher level of processing beyond the Basic
  Calibrated Data, for example
• Assembly of maps and dithered images into
  positionally matched images
• Matching of images in overlap regions to a
  statistically significant level
• Point source extraction and corresponding data.
• More sophisticated treatment of time-dependent
  effects.
• Cross-wavelength processing, e.g. registering
  separate MIPS or IRAC bands, combining individual
  IRS spectral segments.
• The full definition of SIRTF data products
  continues to evolve. A final definition will be
  made available at the time of the LegSci Call for
  Proposals.

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Imager Pipeline Products

• IRAC and MIPS Imaging Basic Calibrated Data
  (BCD)
• Single frame FITS files and a full set of header
  keywords, includes
• standard FITS FOV distortion keywords
• standard FITS epoch
• Pipeline and calibration version keywords
• Image will be in physical units
• Image will be accompanied by ancillary data
  planes in FITS files
• Traceable uncertainties per pixel (error image)
• Calibration and pipeline reduction pedigree per
  pixel
• Appropriate flux conversion factors
• For a uniform diffuse background, the pixels will
  report equal values (within noise statistics).
• Processing will include removal of basic
  electronic signatures (as applicable) such as
  droop, linearity, robust estimations of ramp
  slopes, flagging of cosmic ray hits.

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Infrared Array CameraPipeline Products

• IRAC Browse Quality Data (BQD) per observation
  request
• FITS files of size MxN, result of optimally
  mapping the constituent processed images into the
  BQD frame with minimal loss in resolution
• The pointing offsets used in mapping of
  individual frames into the BQD will be derived
  from an optimal offset estimation method (e.g.,
  point source extraction)
• Individual frames will be adjusted such that the
  overlap regions will be statistically similar
• The zodiacal background will be maintained only
  within an individual observation.
• BQD-specific as well as BCD-type keywords will be
  provided
• Ancillary data processing images similar to that
  with the BCDs will be provided.

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Multiband Imaging Photometer for SIRTF Pipeline
Products

• MIPS Browse Quality Data per observation request
• FITS files of size MxN, result of optimally
  mapping the constituent frames into the BQD frame
  with minimal loss in resolution
• The pointing offsets used in mapping of
  individual frames into the BQD will be derived
  from an optimal offset estimation method (e.g.,
  point source extraction)
• Individual frames will be adjusted such that the
  overlap regions will be statistically similar,
  within the limitations of the large scale
  background and slow response characteristics of
  the GeGa detectors.
• The zodiacal backgrounds will be maintained only
  within an individual observation.
• Characterizable GeGa long-term transients will
  be accounted
• BQD-specific as well as BCD-type keywords will be
  provided
• Ancillary images similar to BCDs will be provided

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Additional Enhanced Imager Products

• Additional IRAC and MIPS pipeline products
• A list of extracted point sources will be
  provided.
• The list will include at least positions, fluxes
  (aperture and profile), signal to noise ratio,
  and associated uncertainties.
• For data within an observation request, a list of
  band-merged point sources (IRAC at 3.6, 4.5,
  5.8, and 8mm MIPS at 24, 70 and 160 mm) will be
  provided.
• The list will include at least the refined
  positions, fluxes (aperture and profile), signal
  to noise ratio, and associated uncertainties. For
  bands with no detection, a statistically
  meaningful flux upper limit will be estimated
  from the underlying data frames (when they
  exist).
• Potential moving objects within an observation
  request will be flagged.

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Infrared SpectrographPipeline Products

• IRS Basic Calibrated Data
• Single frame FITS files and a full set of header
  keywords, includes
• standard FITS epoch, position keywords for center
  of slit.
• Pipeline and calibration version keywords.
• 2D spectra will be in physical units
• high resolution data might require additional
  processing to obtain best results
• Images will be accompanied by ancillary 128x128
  FITS files
• The ancillary images contain
• Traceable uncertainties per pixel
• Pipeline reduction pedigree per pixel
• Wavelength map, flat field image, illumination
  correction, etc.
• Processing will include removal of basic
  electronic signatures (as applicable) such as
  droop, linearity, robust estimations of ramp
  slopes, flagging of cosmic ray hits.

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More IRS PipelineProducts

• IRS Browse Quality Data per observation request
• Extracted high resolution spectral segments.
• Low resolution data will be 2D spatially
  rectified spectra.
• Files in physical flux units vs. wavelength
  (format to be resolved) with full set of
  keywords, including
• Standard FITS-like epoch, position for the center
  of slit
• Location of extraction ridge within order
• Pipeline and calibration version keywords
• Will be accompanied by ancillary data files
• The ancillary tables will contain
• Traceable uncertainties per resolution element
• calibration and pipeline reduction pedigree per
  resolution element
• Spectra will be the result of automated
  extraction.

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Possible EnhancedIRS Products

• Enhanced tools for observer use
• Observer optimized extraction of low resolution
  and high resolution spectra
• Handling of fringing
• Combination of multi-exposure datasets
• Combination of single- or multi-module data
  (lowhigh resolution data)