The 2MASS Homepage

Explanatory Supplement to the 2MASS All Sky Data Release and Extended Mission Products




Cutri, R.M. (IPAC/Caltech), Skrutskie, M.F. (U.Virginia), Van Dyk, S. (IPAC/Caltech), Beichman, C.A. (JPL), Carpenter, J.M. (Caltech), Chester, T. (IPAC/Caltech), Cambresy, L. (CDS), Evans, T., Fowler, J. (IPAC/Caltech), Gizis, J. (U.Delaware), Howard, E. (UMASS), Huchra, J. (Harvard-Smithsonian CfA), Jarrett, T., Kopan, E.L., Kirkpatrick, J.D., Light, R.M, Marsh, K.A., McCallon, H. (IPAC/Caltech), Schneider, S., Stiening, R. (UMASS), Sykes, M. (U.Arizona), Weinberg, M. (UMASS), Wheaton, W.A., Wheelock, S. (IPAC/Caltech), Zacharias, N. (USNO)

Table of Contents

I. Introduction

  1. 2MASS Overview
  2. The 2MASS Sky
  3. Executive Summary of 2MASS All-Sky Data Products
    1. Point Source Catalog
    2. Extended Source Catalog
    3. Image Products
  4. Distribution Mode for 2MASS Products
  5. Data Release History
  6. Cautionary Notes
    1. General
    2. Point Source Catalog (PSC)
    3. Extended Source Catalog (XSC)
    4. Atlas Images
  7. Acknowledgments
    1. 2MASS Personnel
  8. Referencing 2MASS
    1. 2MASS Source Naming Convention
    2. Acknowledging 2MASS in Publications
  9. Document Change History

II. User's Guide to the 2MASS All Sky Data Release

  1. General Properties of the Data Release
  2. Point Source Catalog
    1. Format
    2. How to Use the 2MASS PSC
    3. Selection Criteria
    4. General Properties
    5. Photometric Properties
    6. Astrometric Properties
    7. Solar System Objects
  3. Extended Source Catalog
    1. Format
    2. How to Use the 2MASS XSC
    3. Selection Criteria
    4. General Properties
    5. Photometric Properties
    6. Size Distribution
    7. Relevant Images
  4. Atlas Images
    1. Atlas Image Header Description
    2. Image Anomalies
  5. Extended Source Postage Stamp Images
  6. Ancillary Files
    1. Scan Information Table Format
    2. Atlas Image Information Table Format
    3. Known Asteroid Detection List
    4. Known Comet Detection List
    5. Known Planet and Satellite Detection List
    6. XSC Coverage Maps
    7. PSC and XSC Anomaly File
    8. All-Sky DVD Release Updates

III. 2MASS Facilities and Operations

  1. Facilities
    1. Telescopes
    2. Camera and Detectors
    3. Observatory Site Conditions
  2. Data Acquisition
    1. Scanning Strategy
    2. Survey Strategy
    3. Sky Coverage
    4. Photometric Calibration Strategy

IV. 2MASS Data Processing

  1. Processing Pipeline Overview
    1. Data Processing Strategy
    2. Nightly Data Processing Steps
    3. Improvements Incorporated in Final Processing (2MAPPS v3.0)
  2. Instrumental Frame Correction
    1. Frame Readouts
    2. Darks/Electronics Bias Characterization
    3. Flatfield/Responsivity Characterization
    4. Frame Calibration Procedure
    5. Non-Linearity/Saturation Flagging
  3. Atlas Image Generation
  4. Point Source Detection and Photometry
    1. Frame Source Detection and Aperture Photometry
    2. Profile-Fit Photometry
    3. Aperture Photometry and Curve of Growth Correction
    4. The Default Magnitude
    5. Band Merging and Bandfills
    6. Optical Source Associations
  5. Extended Source Identification and Photometry
    1. The Extended Source Processor
    2. Summary of Modifications to the Extended Source Processor
    3. Stellar Number Density Metric: "density"
    4. Improved Ellipse Fitting and Isophotal Photometry in Crowded Fields
    5. Large Aperture Photometry: Profile Fitting, Isophotal and Total Magnitudes
    6. Galaxy Photometry Error Tree
    7. Stellar Number Density and Confusion Noise
  6. Position Reconstruction
  7. Artifact Identification
  8. Photometric Calibration
  9. Known Asteroid, Comet, Planet, and Satellite Associations
  10. Quality Assurance

V. Catalog Generation

  1. Overview
  2. Scan Selection
  3. Source Selection
  4. Multiple Source Detection Resolution

VI. Analysis of Release Catalogs

  1. Comparison of Achieved Performance of the All-Sky Release Catalogs with Level 1 Science Specification
  2. Photometric Sensitivity
  3. Global Photometric Properties
  4. 2MASS Photometric System
    1. Absolute Calibration
    2. Color Transformations
  5. Completeness and Reliability
  6. Position Reconstruction Performance
    1. Point Source Catalog Position Reconstruction Performance
    2. Extended Source Catalog Position Reconstruction Performance
  7. Galactic Plane Performance
  8. Atlas Image Analysis
    1. Estimating Photometric Errors Using 2MASS Atlas Images
  9. Compromised J-band Photometry for Sources with dist_edge_ew=251E and hemis='s'

A1. Introduction to the 2MASS Extended Mission and Ancillary Data Products

  1. Overview
    1. The Ancillary Data Products
    2. Ancillary Product Documentation
    3. Acknowledgements
  2. Executive Summary of the 2MASS Ancillary Data Products
    1. Survey Source "Reject" Tables and Full Image Atlas
    2. Long Exposure (6x) Source Working Databases, Catalogs and Images
    3. Calibration Scan Source Working Databases and Images
    4. Merged Source Information Tables
    5. Combined Calibration Scan Images and Source Tables
  3. Distribution Mode for the 2MASS Ancillary Data Products
  4. Cautionary Notes
    1. General
    2. Point Source Reject Table, Working Databases and 6x Catalog
    3. Extended Source Reject Table, Working Databases and 6x Catalog
    4. Atlas Images
  5. Source Naming Convention
  6. Auxiliary Tables
    1. Known Asteroid Association Lists
    2. Known Comet Association Lists
    3. Planet and Planetary Satellite Association Lists

A2. Full Survey Image Atlas and Source "Reject" Tables

  1. Overview
    1. Multi-Epoch Observations
    2. Low SNR and Other Unreliable Extractions
    3. Cautionary Notes
  2. General Properties
    1. Scope
    2. Survey "Reject" Table Contents
    3. Survey Sky Coverage
    4. "Reject" Table Reliability
    5. Photometric and Astrometric Properties
  3. Survey "Reject" Table and Metadata Table Formats
    1. Survey Point Source "Reject" Table
    2. Survey Extended Source "Reject" Table
    3. Survey Scan Information Table

A3. Long Exposure (6X) Scan Databases, Catalogs and Images

  1. Overview
    1. 6x Target Fields
    2. Relationship to Main 2MASS Survey
    3. Additional 6x Scan Products
    4. Cautionary Notes
  2. General Properties
    1. Scope of the 6x Observations
    2. Detailed 6x Field Properties
    3. Analysis of 6x Position Reconstruction
  3. 6x Working Database and Metadata Table Formats
    1. 6x Point Source Working Database
    2. 6x Extended Source Working Database
    3. 6x Scan Information Table
  4. Data Acquisition
    1. Differences in Scanning Strategy from Main Survey
    2. Sky Coverage
    3. Photometric Calibration Strategy
  5. Data Processing
    1. Pipeline Modifications Relative to Final Survey Processing (2MAPPS v3.0)
    2. Position Reconstruction
    3. Photometric Calibration
    4. Extended Source Processing
    5. Artifact Identification
  6. 6x Catalog Generation
    1. Overview
    2. Scan Selection
    3. Source Selection
    4. Multiple Source Detection Resolution

A4. Calibration Scan Working Databases and Images

  1. Overview
    1. Multi-Epoch Measurements
    2. Additional Calibration Scan Products
    3. Cautionary Notes
  2. General Properties of the Calibration Scan Working Databases
  3. Calibration Scan Working Database and Metadata Table Formats
    1. Calibration Point Source Working Database
    2. Calibration Extended Source Working Database
    3. Calibration Scan Information Table
  4. Calibration Scan Data Processing
    1. Photometric Calibration
    2. Position Reconstruction
    3. Data Quality Assessment

A5. Working Database Source Reliability Estimation

  1. Introduction
    1. The Reliability Score
    2. Estimating Source Reliability
    3. Other Reliability Indicators
  2. Point Sources
  3. Extended Sources

A6. Merged Working Databases

  1. Overview
    1. Scope and Usage
    2. Cautionary Notes
  2. The Merging Process
    1. Associating Groups of Detections
    2. Pre-filtering the WDB Tables
    3. Computing Merged Source Parameters
  3. Merged Database Table Formats
    1. Merged Point Source Information Tables
    2. Merged Extended Source Information Tables
    3. Merged Source Cross-Reference (Link) Tables
  4. Analysis of Merged Source Information Tables

A7. Combined Calibration Scan Images and Source Lists

  1. Overview
    1. Inventory of Calibration Scans
    2. Cautionary Notes
  2. Calibration Scan Image Combination
    1. Image Registration
    2. Position Correction
    3. Sensitivity Scaling
    4. Image Anomaly Identification
    5. Depth-of-Coverage
  3. Source Lists
    1. Source Extraction
    2. Astrometric and Photometric Calibration
    3. Artifact Identification
    4. Source Table Format
  4. Combined Calibration Scan Data Access
  5. General Properties of the Combined Calibration Field Data

Last modified 2008 September 7. For assistance, contact The 2MASS Helpdesk