The WISE Homepage

Explanatory Supplement to the WISE Preliminary Data Release Products




R.M. Cutri (IPAC/Caltech), E.L. Wright (UCLA), T. Conrow (IPAC/Caltech), J. Bauer (IPAC/Caltech), D. Benford (GSFC), H. Brandenburg (IPAC/Caltech), J. Dailey (IPAC/Caltech), P.R.M. Eisenhardt (JPL), T. Evans (IPAC/Caltech), S. Fajardo-Acosta (IPAC/Caltech), J. Fowler (IPAC/Caltech), C. Gelino (IPAC/Caltech), C. Grillmair (IPAC/Caltech), M. Harbut (IPAC/Caltech), D. Hoffman (IPAC/Caltech), T. Jarrett (IPAC/Caltech), J.D. Kirkpatrick (IPAC/Caltech), W.Liu (IPAC/Caltech), A. Mainzer (JPL), K. Marsh (IPAC/Caltech), F. Masci (IPAC/Caltech), H. McCallon (IPAC/Caltech), D. Padgett (IPAC/Caltech), M.E. Ressler (JPL), D. Royer (JPL), M.F. Skrutskie (U. Virgina), S.A. Stanford (UC Davis), P.L. Wyatt (IPAC/Caltech), D. Tholen (U. Hawaii), C.-W. Tsai (IPAC/Caltech), S. Wachter (IPAC/Caltech), S.L. Wheelock (IPAC/Caltech), L. Yan (IPAC/Caltech), R. Alles (IPAC/Caltech), R. Beck (IPAC/Caltech), T. Grav (JHU), J. Masiero (JPL), B. McCollum (IPAC/Caltech), P. McGehee (IPAC/Caltech), M. Wittman (IPAC/Caltech)

Table of Contents

I. Introduction

  1. Mission Overview
    1. WISE
    2. NEOWISE
    3. WISE At-a-Glance
    4. The Preliminary Data Release
    5. About this Document
  2. Executive Summary of WISE Preliminary Release Data Products
    1. Image Atlas
    2. Source Catalog
    3. Ancillary Products
      1. Single-exposure Images
      2. Single-exposure Source Database
      3. Moving Object Tracklets
      4. Known Solar System Object Possible Association List
  3. Distribution Mode for WISE Data Products
  4. Cautionary Notes
    1. General
    2. Source Catalog
    3. Atlas Images
    4. Ancillary Products
  5. Acknowledgments
    1. WISE Personnel
  6. Referencing WISE and NEOWISE
    1. WISE Source Naming Convention
    2. Acknowledging WISE and NEOWISE in Publications
  7. Acronym List
  8. Document Change History

II. User's Guide to the WISE Preliminary Data Release

  1. General Properties of the Data Release
  2. Source Catalog
    1. Format and Column Descriptions
    2. Source Selection Criteria
    3. General Properties
    4. Photometric Properties
    5. Astrometric Properties
  3. Atlas Images
    1. Description and Format
    2. Atlas Image Header Description
    3. Image Anomalies
    4. Depth-of-Coverage Maps
    5. Uncertainty Maps
      1. Checking the Plausibility of Uncertainty Map Values
    6. Aperture Photometry using the Atlas Images
      1. Correlated Pixel Noise
      2. Confusion Noise Term
    7. Astrometry of Image-derived Source Positions
      1. Methods to Correct Image-derived Coordinates and WCS
      2. Source Position Biases in Single-exposure Images
  4. Ancillary Products
    1. Single-Exposure Images, Bit Masks, Uncertainty Maps
      1. Single-Exposure Image Header Descriptions
      2. Image Anomalies
    2. Single-Exposure Source Working Database
      1. Format and Column Descriptions
    3. Atlas Image Frame Cross Reference Table
    4. WISE Moving Object Pipeline Tracklets
      1. Introduction
      2. Retrieving WMOPS Objects
      3. Tracklet Description
    5. Atlas Metadata Table Format
    6. Atlas Image Inventory Table Format
    7. Single-Exposure (L1) Frame Metadata Table Format
    8. Single-Exposure (L1) Image Inventory Table Format
    9. Known Solar System Object Possible Association List Format

III. WISE Flight System and Operations

  1. Spacecraft
  2. Payload
    1. Focal Planes
    2. Optics
    3. Cryostat
  3. Mission Operations
  4. Survey Design and Data Acquisition
    1. Scanning Strategy
    2. Survey Strategy
    3. Sky Coverage

IV. WISE Data Processing

  1. Processing Overview - The WISE Science Data System (WSDS)
    1. Basic Terminology
    2. Data Processing Levels
    3. Data Processing Stages
  2. Data Ingest
    1. Data Transfer
    2. MOS Ingest
    3. HRP Ingest
    4. Quicklook Processing
  3. Scan/Frame Pipeline
    1. Single Frame Exposure Instrumental Image Calibration (ICAL)
      1. Overview
        1. Input Calibration Summary
        2. Bit-Mask Definitions
      2. Pixel Error Model
        1. Electronic Gain and Read-Noise Calibration
      3. Frame-mask Initialization and Bad-pixel Masking
        1. Prior Masking of Bad hardware Pixels
      4. Band 3 and 4 Droop Correction
        1. Intra-Quadrant Split-Droop
        2. Global Inter-Quadrant Droop
        3. Final Droop Refinement
        4. Droop Correction Anomalies and Liens
      5. Dark Calibration
      6. Non-linearity Calibration
        1. Validation
      7. Relative Responsivity (Flat-field) Calibration
        1. Methodologies
        2. Flat-fielding Accuracy
      8. Dynamic Calibration
        1. Sky-offset Correction
        2. Transient Bad-pixel Masking
      9. Spatial-outlier (Glitch) Masking
      10. Instrumental Calibration Performance
        1. Analysis of Residual Spatial Variations
        2. Residual Responsivity Variations Using Relative Photometry
    2. Source Detection (MDET)
      1. Overview
      2. Theoretical Basis
        1. Measurement Model
        2. Detection Algorithm
        3. Allowance for Cross-band Source Blending
      3. Implementation
        1. Procedure
        2. Effects of Confusion
        3. Dealing with Bright Saturated Stars
    3. Source Photometry (WPHOT)
      1. Overview
      2. WPHOT Executive
        1. Coordinate Translation
        2. Local Background Estimation
        3. Bright Stars
      3. Profile-fitting Photometry
        1. The Point Spread Function
        2. WPRO Magnitude Upper Limits
      4. Aperture Photometry
        1. Circular Apertures
        2. Confusion and Warning Flags
        3. Magnitude Upper Limits
    4. Position Reconstruction (SFPREX)
      1. SFPRex Input
      2. SFPRex Processing: Initialization
      3. SFPRex Processing: Group Merging
      4. SFPRex Processing: Pattern Matching
        1. Bar Separation Algorithm
        2. Bar-Match Parameter Uncertainties
        3. Bar-Match Solution Averaging
      5. SFPRex Processing: Parameter Fitting
      6. Constrained Solutions and Reduced Systems of Equations
        1. Fixed Parameters
        2. Scale Changes Equal
      7. Distortion Calibration
      8. Cautionary Notes
        1. Differential Aberration
        2. Error in W4 Band-Frame Positions
        3. Proper Motions
    5. Known Solar System Object Association
      1. Orbit Data
      2. Orbit Computation
      3. SSO/Wise Assocation
      4. Cautionary Notes
        1. Background Contamination
        2. SSO Name Variation
    6. Artifact Identification (ARTID)
      1. Diffraction Spikes and Halos
      2. Optical Ghosts
      3. Persistence (Latent Images)
        1. Short-term Latents: HgCdTe and Si:As arrays
        2. Long-term Latents (Si:As arrays only)
        3. Treatment of Latents by Single-frame WISE Pipeline
    7. Photometric Calibration
      1. Introduction
      2. The WISE Photometric System
      3. Photometric Zero Point Evaluation
      4. Calibrated Magnitudes
      5. WISE Filter Bandpasses and Zero Magnitude Attributes
      6. Flux Corrections and Colors for Power Laws and Blackbodies
      7. Calibration Uncertainties
  4. WISE Moving Object Pipeline
    1. Introduction
    2. Subsystem Overview
      1. Operational Description
      2. Caveats
      3. Finding WMOPS Objects
    3. Summary
  5. Multiframe Pipeline
    1. Atlas Image Generation
      1. Overview
        1. Sky Tiling and Footprint Definition
      2. Throughput (Gain) Matching
      3. Frame Background/Level Matching
      4. Flagging Moon-affected Frames Using Prior Mask
        1. Prior Moon-masks
        2. Moon-contamination Processing
      5. Pixel Outlier Detection and Masking
        1. First-Pass Computations
        2. Second-Pass Computations
        3. Outlier Expansion
      6. Frame-Based Rejection
      7. Frame Coaddition Using PRF Interpolation
    2. Source Detection (MDET)
      1. Overview
      2. Theoretical Basis
        1. Measurement Model
        2. Detection Algorithm
        3. Allowance for Cross-band Source Blending
      3. Implementation
        1. Procedure
        2. Effects of Confusion
        3. Dealing with Bright Saturated Stars
    3. WISE Photometry System (WPHOT)
      1. Overview
      2. WPHOT Executive
        1. Memory Optimization
        2. Coordinate Translation
        3. Local Background Estimation
        4. Bright Stars
      3. Profile-fitting Photometry
        1. The Point Spread Function
        2. WPRO Magnitude Upper Limits
        3. Frame Detection and Flux Repeatability Statistics
        4. Variability and Flagging
      4. Aperture Photometry
        1. Special Inputs
        2. Circular Apertures
        3. Confusion and Warning Flags
        4. Magnitude Upper Limits
      5. 2MASS Galaxies and Elliptical Apertures
      6. Resolved Sources
    4. Position Reconstruction
    5. Photometric Calibration
    6. Artifact Identification (ARTID)
      1. Diffraction Spikes
      2. Scattered-light Halos
      3. Optical Ghosts
      4. Persistence (Latent Images)
  6. Quality Assurance
    1. Overview
      1. Quicklook QA
      2. ScanFrame QA
      3. Multiframe QA
      4. Final Products QA
    2. Steps in the QA Process
      1. Quicklook QA
      2. ScanFrame QA
      3. Multiframe QA
    3. QA Scores in the Preliminary Release Data
    4. Ancillary Notes
      1. Noise Pixels
      2. PSF Moments
  7. Archive Preparation and Loading
    1. Source Data and Metadata
    2. Image Data and Metadata
    3. Data Output
    4. Data and Metadata Transfer to IRSA

V. Atlas and Catalog Generation

  1. Overview
  2. Scan, Tile and Frameset Selection
    1. Scan Selection
    2. Tile Selection
    3. Frameset and Frame Selection
  3. Catalog Source Selection
    1. Tile Edge Boundaries
    2. Source Reliability Criteria
    3. Duplicate Source Resolution
  4. Duplicate Source Resolution
    1. Groups
    2. Associating Groups of Detections Using WAX
      1. Source Confusion
      2. Search Radius
    3. Detection Selection
      1. Pre-Filter
      2. Distance to Edge Selection

VI. Analysis of Release Products

  1. Summary of Achieved Performance
  2. Sky Coverage
    1. Preliminary Release Data Area
    2. Sky Coverage Statistics
    3. Caveats About Low Coverage
  3. WISE Photometric System
  4. Photometric Properties
    1. Photometric Sensitivity
      1. External Sensitivity Checks
    2. Photometric Accuracy
    3. Photometric Biases
    4. Characteristic Source Brightness for the Onset of Saturation
      1. Saturated Source Characterization
      2. Source Catalog
      3. Single-Exposure Source Database
      4. Bright Source Photometry Limits
  5. Position Reconstruction Performance
    1. Overview
    2. WISE Positional Residuals With Respect to 2MASS
    3. Astrometric Positions of Faint Sources
    4. Atlas Image Astrometry
    5. Astrometric Quality of W3 and W4-dominated Sources
    6. Summary
  6. Catalog Completeness
    1. Requirement
    2. Methodology
    3. Completeness Estimate
  7. Catalog Reliability
    1. Internal Reliability
    2. Comparison with 2MASS
    3. Comparison with Spitzer

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Last update: 2011 August 15 For assistance, contact The WISE Helpdesk