Possible design of a FITS Binary table containing WCS information

Here follows a draft schematic for the contents of the FITS header:
XTENSION= 'BINTABLE'           / Binary table extension
BITPIX  =                    8 / number of bits per data pixel
NAXIS   =                    2 / always 2 for a FITS table
NAXIS1  =                  xxx / number of chars needed to describe columns
NAXIS2  =                  yyy / number of rows of WCSs stored in the table
PCOUNT  =                    0 / required FITS extension keyword
GCOUNT  =                    1 / required FITS extension keyword
TFIELDS =                   nn / Number of columns in the table

EXTNAME = 'DEI_WCS'            / This table describes a group
DATE    = 'dd/mm/yy'           / Date of construction of grouping table
CTIME   = 'WkD CcYy Mon Dt Hr:Mn:Ss TZn' / Time of construction of table

COMMENT This document does not attempt to describe any particular
COMMENT ordering for these columns.  In real applications the columns
COMMENT need not be in any particular order.

COMMENT Note that on architectures with alignment requirements it will be
COMMENT much more efficient if NAXIS1 is a multiple of the word size.
COMMENT Thus it is probably wise to add extra columns as necessary such
COMMENT that NAXIS1 is a multiple of 8.
COMMENT Ordering of the columns within each row should be chosen with
COMMENT the same constraint in mind.

TFORMn  = '8A'                 / size and type of column data
TTYPEn  = 'CCDPOS'             / In which position was this CCD?

TFORMn  = '8A'                 / size and type of column data
TTYPEn  = 'AMPPOS'             / In which position is this amplifier?

TFORMn  = '16A'                / size and type of column data
TTYPEn  = 'CTYPE'              / WCS keyword array
TDIMn   = '(8,2)'              / Dimension of array

TFORMn  = '2E'                 / size and type of column data
TTYPEn  = 'CRPIX'              / WCS keyword
TDIMn   = '(2)'                / Dimension of array
TDISPn  = 'F10.3'              / Fortran 90 format for display

TFORMn  = '2E'                 / size and type of column data
TTYPEn  = 'CRVAL'              / WCS keyword
TDIMn   = '(2)'                / Dimension of array

TFORMn  = '2E'                 / size and type of column data
TTYPEn  = 'CDELT'              / WCS keyword
TDIMn   = '(2)'                / Dimension of array

TFORMn  = '4E'                 / size and type of column data
TTYPEn  = 'PC'                 / WCS keyword
TDIMn   = '(2,2)'              / Dimension of array

TFORMn  = '16A'                / size and type of column data
TTYPEn  = 'CUNIT'              / WCS keyword
TDIMn   = '(8,2)'              / Dimension of array

TFORMn  = '8A'                 / size and type of column data
TTYPEn  = 'RADECSYS'           / WCS keyword

TFORMn  = '8A'                 / size and type of column data
TTYPEn  = 'EQUINOX'            / WCS keyword
TDISPn  = 'F13.6'              / Fortran 90 format for display

TFORMn  = 'D'                  / size and type of column data
TTYPEn  = 'MJD_WCS'            / UCO/Lick keyword
TDISPn  = 'F17.9'              / Fortran 90 format for display

TFORMn  = '8A'                 / size and type of column data
TTYPEn  = 'DOMAIN'             / DEI_WCS keyword

TFORMn  = 'nE'                 / size and type of column data
TTYPEn  = 'PROJP'              / WCS keyword array
COMMENT It is not clear that we will need the PROJPn WCS keywords.
COMMENT It is not clear how to denote the possibility of zero-based
COMMENT index in PROJP0, or what the highest-numbered index is.

END
The header is padded with ASCII blanks such that it consists of a positive integer multiple of 2880 bytes (36 card images of 80 characters).

The semantics of the keywords/columns which are not derived from the draft WCS standard document are described in this data dictionary.


Back to the WCS table idea page.
Back to the DEIMOS home page.
Steve Allen <sla@ucolick.org>
$Date: 1996/08/19 06:11:11 $