Explanatory Supplement to the 2MASS Spring 1999 Incremental Data Release




I. Introduction

  1. 2MASS Overview
  2. The 2MASS Sky
  3. Executive Summary of 2MASS Spring 1999 Incremental Data Products
    1. Point Source Catalog
    2. Extended Source Catalog
    3. Image Products
  4. Distribution Mode for 2MASS Products
  5. Data Release Plan
  6. Cautionary Notes
    1. General
      1. Preliminary Nature of Catalogs
      2. Photometric System
      3. Global Photometric Uniformity
      4. Scan Overlap Regions
      5. Artifacts
    2. Point Source Catalog (PSC)
      1. Origin and Quality of Photometry
      2. Out-of-Field Bright Source Artifacts
      3. Photometric Uncertainties
      4. Cross-Scan Photometric Bias
      5. High Source Density Regions
      6. H-band Detection Thresholds and Atmospheric OH Airglow
      7. Asteroids
      8. Extremely Faint Sources
      9. Optical Associations
      10. Position Reconstruction
    3. Extended Source Catalog (XSC)
      1. Definition of Extended Sources
      2. Selection Criteria
      3. Lower Reliability for "E" Sources and at Low Galactic Latitudes
      4. Unreliability and Incompleteness Due to Bright Stars
      5. Other Artifacts
      6. Untracked Seeing
      7. Additional Photometric Uncertainty
    4. Atlas Images
      1. Low Coverage Areas
      2. Backgrounds
      3. Transients
  7. Acknowledgments
    1. 2MASS Personnel
  8. Referencing 2MASS
    1. 2MASS Source Naming Convention
    2. Acknowledging 2MASS in Publications

II. Contents of the First 2MASS Incremental Data Release

  1. General Properties of the Data Release
  2. Point Source Catalog
    1. Format
    2. Selection Criteria
    3. General Properties
    4. Photometric Properties
    5. Astrometric Properties
    6. Miscellaneous
  3. Extended Source Catalog
    1. Format
    2. Selection Criteria
    3. General Properties
    4. Photometric Properties
    5. Size Distribution
    6. Relevant Images
  4. Atlas Images
  5. Extended Source Postage Stamp Images
  6. Ancillary Files
    1. Point Source Record Format
    2. Extended Source Record Format
    3. Atlas Image Header Description
    4. Scan Information Table
    5. Known Asteroid Detection List
    6. Known Comet Detection List
    7. PSC and XSC Anomaly Files

III. 2MASS Details

  1. Facilities
    1. Telescopes
    2. Camera and Detectors
    3. Observatory Sites and Site Conditions
  2. Data Acquisition
    1. Scanning Strategy
    2. Survey Strategy
    3. Photometric Calibration Strategy
  3. Data Processing
    1. Instrumental Frame Correction
    2. Atlas Image Generation
      1. Image Estimation Using Kernel Smoothing
    3. Point Source Detection and Photometry
      1. Band Merging and Bandfills
      2. Optical Source Associations
    4. Extended Source Identification and Photometry
    5. Position Reconstruction
    6. Artifact Identification
    7. Photometric Calibration
    8. Known Asteroid and Comet Associations
    9. Catalog Generation

This document prepared by R. Cutri, S. Van Dyk, and the 2MASS team.

Last modified 1999 May 6. For assistance, contact 2mass@ipac.caltech.edu