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Explanatory Supplement to the
NEOWISE Data Release Products

R. M. Cutri (Caltech/IPAC), A. Mainzer (Univ. of Arizona), T. Conrow (Caltech/IPAC), F. Masci (Caltech/IPAC), J. Bauer (Univ. of Maryland), J. Dailey (Caltech/IPAC), J. D. Kirkpatrick (Caltech/IPAC), S. Fajardo-Acosta (Caltech/IPAC), C. Gelino (Caltech/IPAC), C. Grillmair (Caltech/IPAC), S. L. Wheelock (Caltech/IPAC), L. Yan (Caltech/IPAC), M. Harbut (Caltech/IPAC), R. Beck (Caltech/IPAC), M. Wittman (Caltech/IPAC), E. L. Wright (UCLA), J. Masiero (Caltech/IPAC), T. Grav (Univ. of Arizona), S. Sonnett (PSI), C. Nugent (Olin College), E. Kramer (JPL), R. Stevenson (PSI), P. R. M. Eisenhardt (JPL), B. Fabinsky (JPL), D. Tholen (Univ. of Hawaii), M. Papin (Caltech/IPAC), J. W. Fowler (Caltech/IPAC), H. L. McCallon (Caltech/IPAC)


Table of Contents

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I. Introduction

  1. NEOWISE Overview
    1. NEOWISE Data Releases
      1. The NEOWISE 2015 Data Release - March 26, 2015
      2. The NEOWISE 2016 Data Release - March 23, 2016
      3. The NEOWISE 2017 Data Release - June 1, 2017
      4. The NEOWISE 2018 Data Release - April 19, 2018
      5. The NEOWISE 2019 Data Release - April 11, 2019
      6. The NEOWISE 2020 Data Release - March 26, 2020
      7. The NEOWISE 2021 Data Release - March 24, 2021
      8. The NEOWISE 2022 Data Release - March 23, 2022
      9. The NEOWISE 2023 Data Release - March 22, 2023
    2. About This Document
    3. Acknowledgments
  2. WISE/NEOWISE Overview
    1. WISE/NEOWISE Flight System
      1. Spacecraft
      2. Payload
    2. Survey Strategy
      1. Sky Coverage
    3. NEOWISE Timeline
      1. Hibernation
      2. Reactivation
      3. Survey Operations
      4. Command Timing Anomaly
      5. Image Byte-shift Anomaly
      6. Flash Memory Card Disabling
      7. Scan Identifier Change-over
      8. Attitude Rate Error Anomaly
  3. Executive Summary of the NEOWISE Data Products
    1. Single-exposure Images
    2. Single-exposure Source Database
    3. Moving Object Tracklets
    4. Known Solar-System Object Possible Association List
  4. Top Ten (or so) Things You Should Know About NEOWISE Data Products
  5. How to Access NEOWISE Data Products
    1. Online Access
      1. Single-exposure Source Database and Other Tables
      2. Images
      3. Moving Object Tracklets
      4. Solar System Object Diameters and Albedos
    2. Application Programming Interface
    3. Electronic Access to the Full Source Databases
  6. Referencing NEOWISE
    1. NEOWISE Source Naming Convention
    2. Acknowledging NEOWISE in Publications
  7. Acronym List
  8. Document Change History

II. NEOWISE Single-exposure Source Database

  1. General Properties
    1. Format and Column Descriptions
    2. Database Contents
    3. Photometric Information
      1. Different Photometric Measurements in the Source Database
      2. Comparison to AllWISE
      3. Photometric Sensitivity
      4. Saturated Source Photometry
    4. Astrometric Information
    5. Completeness and Reliability
      1. Detection Completeness
      2. Detection Reliability
    6. Additional Information
      1. AllWISE and 2MASS Associations
  2. Cautionary Notes
    1. Multiple, independent measurements
    2. No new W3 or W4 measurement
    3. Unreliable detections
    4. Detections from low-quality framesets
    5. Contamination from single-frame events
    6. Solar system object associations are not necessarily valid detections
    7. Brightnesses of saturated source are systematically overestimated
    8. Profile-fit and standard aperture photometry underestimate the brightness of resolved sources
    9. Single-exposure aperture photometry measurements are not as robust as the profile-fitting photometry measurements
    10. W2 photometric calibration exhibits small uncorrected seasonal variations of up to ~0.03 mags
    11. Reflected light glint artifact flagging is less effective
    12. NEOWISE position reconstruction takes into account the reference frame motion between 2MASS and NEOWISE epochs
    13. Observation times are slightly earlier than the value given by the Modified Julian Data parameter mjd.
  3. Advice for Using the Single-exposure Source Database
    1. Selecting Detections from Good Quality Framesets
    2. Selecting Reliable Detections
    3. Identifying Reliable Solar System Object Detections

III. NEOWISE Single-exposure Images

  1. General Properties
    1. Description and Format
    2. Single-exposure Image Header Descriptions
    3. Single-exposure (Level 1) Image Metadata Column Descriptions
    4. Single-exposure (Level 1) Image Inventory Table Column Descriptions
  2. Cautionary Notes
    1. Same limitations as in previous data releases
    2. The intensity units of image pixels are Digital Numbers (DN) - Photometric Calibration
    3. Image Anomalies and Features
      1. Temporal Evolution of Glints: Comparing NEOWISE 2016 Data to All-Sky Data
      2. The Resonant Pixel in W2 (4.6 micron) Data
    4. Beware of Low-Quality Images
    5. Anomalies from inaccurate channel-noise/bias corrections
    6. Spatial (residual) gain variations from inaccurate flat-fielding
    7. Dynamic calibrations are not always possible
    8. "NaNs" from the masking of bad and saturated pixels
    9. Missed (unmasked) Bad Pixels
    10. No evidence of unmasked saturated pixels in the NEOWISE Single-exposure Images
    11. No evidence of pixels having the same value near the frame median as in the All-Sky Data Release
    12. Uncertainty estimates in the Single-exposure uncertainty images could be over/under-estimated
    13. Differences in the astrometry of image-derived source positions relative to positions in the Single-exposure Source Database
    14. Image Distortion and Pixel Scale
    15. Astrometry attached to the NEOWISE Single-exposure images is reconstructed with respect to sources in the 2MASS Point Source Catalog that have been corrected for proper motion in the >14 years separating these surveys
    16. True observation mid-point times are slightly earlier than values in image headers and metadata files
  3. Advice on using the Single-exposure Image Products
    1. Co-addition of the multiple Single-exposure Images
    2. Performing your own photometry or source-extraction
    3. Converting from DN to calibrated magnitude or absolute flux
    4. Using the Single-exposure Bit-Mask Images
    5. Using the Single-exposure Uncertainty Images

IV. NEOWISE Data Processing

  1. Overview
    1. The WISE Science Data System
      1. Ingest
      2. Pipelines
      3. Final Product Generation (FPG)
      4. Quality Assurance (QA)
      5. Archive
    2. Synopsis of the WSDS Improvements for NEOWISE
      1. Ingest System
      2. Scan/Frame Pipeline
      3. Moving Object Pipeline System
      4. QA
      5. Archive
    3. Basic Data Processing Terminology
  2. Scan/Frame Pipeline Updates
    1. Instrumental Calibration
      1. Overview
      2. Bad-pixel Masking and Saturation Tagging
      3. Bit-Mask Definitions
      4. Electronic Gain, Read-Noise, and Pixel Uncertainty Estimation
      5. Dark and Relative Bias Calibrations
      6. Channel-noise Corrections
      7. Linearity Calibration
      8. Relative Responsivity (Flat-field) Calibrations
      9. Dynamic Calibrations
      10. Spatial-outlier (Glitch) Replacement and Masking
      11. Generic Pixel-Calibration Performance
    2. Source Extraction
      1. Point Spread Function
      2. Astrometry
    3. Artifact Flagging
    4. Photometric Calibration
      1. Initial photometric zero point determination
      2. Photometric zero point stability
    5. Known Solar System Object Search Updates
      1. Known Solar System Object Possible Association List (KSSOPAL) Format and Column Descriptions
      2. Known Solar System Object Search Updates for NEOWISE
  3. WISE Moving Object Pipeline Subsystem (WMOPS)
    1. Introduction
    2. NEOWISE-Reactivation Adaptations
    3. Subsystem Overview
      1. Operational Description
      2. Caveats
      3. Finding WMOPS Objects
  4. Quality Assurance
    1. Daily "Quicklook" Scan QA
    2. ScanFrame QA
      1. Scan-level QA checks
      2. Frame-level QA checks
    3. Quality Scores in the NEOWISE Data Releases
    4. Image Quality Behavior with Time
    5. Update to the Image Quality (qi) Metric
  5. Archive Preparation
    1. NEOWISE Single-exposure Source Database
    2. NEOWISE Single-exposure Frame Metadata


Last update: 14 March 2023

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