This is a first draft proposal of a pointing table. It is not being used yet by data producers or science tools. Please note that the format is likely subject to change.


The POINTING extension is a binary FITS table that contains for a number of time stamps the pointing direction of the telescopes. A pointing is here defined as the centre of the field of view (or centre of the camera coordinates). In reality, all telescopes may point to different positions (for example for divergent pointing mode). The main purpose of the POINTING extension is to provide time dependent information on how to transform between celestial and terrestial coordinates.

See also HFWG Recommendation R3 for the OGIP standard.

Mandatory columns

  • TIME type: float64, unit: s
    • Pointing time (see Time)
  • RA_PNT type: float, unit: deg
    • Pointing Right Ascension (see RA / DEC).
  • DEC_PNT type: float, unit: deg

Optional columns

  • ALT_PNT type: float, unit: deg
  • AZ_PNT type: float, unit: deg

Mandatory header keywords

The standard FITS reference time header keywords should be used (see Formats). An observatory Earth location should be given as well (see Earth location).