A User's Guide for the Flexible Image Transport System (FITS)

Version 4.0

April 14, 1997

Contents

• Preface
• 1 The Origin and Purpose of FITS
  • 1.1 The Need for FITS
  • 1.2 What FITS Is
  • 1.3 The Philosophy of FITS
• 2 History
• 2.1 The First Agreement
• 2.2 Random Groups
• 2.3 Generalized Extensions
• 2.4 ASCII Tables
• 2.5 Floating Point
• 2.6 Physical Blocking
• 2.7 Image Extension
• 2.8 Binary Tables
• 2.9 How FITS Evolves
• 3 FITS Fundamentals
  • 3.1 Basic FITS
    • 3.1.1 Primary Header
      • 3.1.1.1 Required Keywords
      • 3.1.1.2 Reserved Keywords
      • 3.1.1.3 Some Hints on Keyword Usage
      • 3.1.1.4 Units
    • 3.1.2Primary Data Array
      • 3.1.2.1 Scaled Integers
      • 3.1.2.2 Undefined Integers
      • 3.1.2.3 IEEE Floating Point Data
  • 3.2 Random Groups
    • 3.2.1 Header
      • 3.2.1.1 Required Keywords
      • 3.2.1.2 Random Parameter Reserved Keywords
    • 3.2.2 Data Records
  • 3.3 Extensions
    • 3.3.1 Required Keywords for an Extension Header
    • 3.3.2 Reserved Keywords for Extension Headers
    • 3.3.3 Creating New Extensions
  • 3.4 ASCII Table Extension
    • 3.4.1 Required Keywords for ASCII Table Extension
    • 3.4.2 Reserved Keywords for ASCII Table Extension
    • 3.4.3 Data Records in an ASCII Table Extension
  • 3.5 The Image Extension
    • 3.5.1 Header
    • 3.5.2 Data Records
  • 3.6 Binary Tables
    • 3.6.1 Required Keywords for Binary Table Extension Headers
    • 3.6.2 Reserved Keywords for Binary Table Extension Header
    • 3.6.3 Binary Table Extension Data Records
  • 3.7 Reading FITS Format
  • 3.8 FITS Files and Physical Media
• 4 World Coordinate Systems
  • 4.1 Indexes and Physical Coordinates
  • 4.2 Proposed Conventions
    • 4.2.1 Improved Axis Descriptions
    • 4.2.2 Sky Images
      • 4.2.2.1 Pixel Regularization
      • 4.2.2.2 Transforming to Projected Sky Coordinate
      • 4.2.2.3 From Pixel to Physical Values
      • 4.2.2.4 Deprojection
      • 4.2.2.5 Conversion to Standard Celestial Coordinates
  • 4.3 Coordinate Keywords
  • 4.4 Current Status
• 5 Advanced FITS
  • 5.1 Registered Extension Type Names
  • 5.2 Conventions for Binary Tables
    • 5.2.1 Variable Length Arrays
    • 5.2.2 Arrays of Strings
    • 5.2.3 Multidimensional Arrays in Binary Tables
      • 5.2.3.1 TDIMn Keyword
      • 5.2.3.2 Green Bank Convention
    • 5.2.4 Some Applications of Binary Tables
      • 5.2.4.1 Replacing Random Groups
      • 5.2.4.2 Multiple Arrays in One HDU
  • 5.3 Hierarchical Grouping Proposal
  • 5.4 STScI Inheritance Convention
  • 5.5 Checksum Proposal
  • 5.6 Other Proposed Conventions
    • 5.6.1 HEASARC
      • 5.6.1.1 Keywords and column names
      • 5.6.1.2 Proposed CREATOR Keyword
      • 5.6.1.3 Proposed TSORTKEY Convention
      • 5.6.1.4 Maximum and Mininum Values in Table Columns
    • 5.6.2 World Coordinates in Tables
    • 5.6.3 Compression
    • 5.6.4 Other Reserved Type Names
    • 5.6.5 Developing New Conventions
  • 5.7 Keyword Domains
  • 5.8 Polarization
  • 5.9 Spectra
  • 5.10 High Energy Astrophysics Applications
• 6 Resources
  • 6.1 The FITS Support Office
    • 6.1.1 On-line Information
    • 6.1.2 Documents
    • 6.1.3 Software and Test Files
    • 6.1.4 Contact Information
  • 6.2 NRAO FITS Resources
  • 6.3 HEASARC
  • 6.4 Some Additional Software Resources
  • 6.5 Other Network Resources

  Appendixes

• A Examples of FITS Headers

• Example 1: VLA Image Header
• Discussion of Example 1 (VLA Image Header)
• Example 2: M87 and Jet (KPNO)
• Discussion of Example 2 (M87 and Jet)
• Example 3: ASCII Table
• Discussion of Example 3 (A Galaxy Catalog in an ASCII Table)
• Example 4: Binary Table Containing Spectra
• Discussion of Example 4 (A Binary Table Containing Spectra)
• Example 5: ADC FITS Table Header for AGK3 Catalog
• Discussion of Example ADC FITS Table Header for AGK3 Catalog
• Example 6: DIRBE FITS Headers
• Discussion of Example 6: DIRBE FITS Headers
• Example 7: ASCA FITS Header
• Discussion of Example 7: ASCA FITS Header

• B IEEE Formats
• References