9.3.2 Read and Write the Required Keywords

1

Write the primary header or IMAGE extension keywords into the CHU. The simpler fits_write_imghdr routine is equivalent to calling fits_write_grphdr with the default values of simple = TRUE, pcount = 0, gcount = 1, and extend = TRUE. The PCOUNT, GCOUNT and EXTEND keywords are not required in the primary header and are only written if pcount is not equal to zero, gcount is not equal to zero or one, and if extend is TRUE, respectively. When writing to an IMAGE extension, the SIMPLE and EXTEND parameters are ignored. It is recommended that fits_create_image or fits_create_tbl be used instead of these routines to write the required header keywords.    

  int fits_write_imghdr / ffphps
      (fitsfile *fptr, int bitpix, int naxis, long *naxes, > int *status)

  int fits_write_grphdr / ffphpr
      (fitsfile *fptr, int simple, int bitpix, int naxis, long *naxes,
       long pcount, long gcount, int extend, > int *status)

2

Write the ASCII table header keywords into the CHU. The optional TUNITn and EXTNAME keywords are written only if the input pointers are not null. A null pointer may given for the *tbcol parameter in which case a single space will be inserted between each column of the table. Similarly, if rowlen is given = 0, then CFITSIO will calculate the default rowlength based on the tbcol and ttype values.  

  int fits_write_atblhdr / ffphtb
      (fitsfile *fptr, long rowlen, long nrows, int tfields, char **ttype,
       long *tbcol, char **tform, char **tunit, char *extname, > int *status)

3

Write the binary table header keywords into the CHU. The optional TUNITn and EXTNAME keywords are written only if the input pointers are not null. The pcount parameter, which specifies the size of the variable length array heap, should initially = 0; CFITSIO will automatically update the PCOUNT keyword value if any variable length array data is written to the heap. The TFORM keyword value for variable length vector columns should have the form 'Pt(len)' or '1Pt(len)' where `t' is the data type code letter (A,I,J,E,D, etc.) and `len' is an integer specifying the maximum length of the vectors in that column (len must be greater than or equal to the longest vector in the column). If `len' is not specified when the table is created (e.g., the input TFORMn value is just '1Pt') then CFITSIO will scan the column when the table is first closed and will append the maximum length to the TFORM keyword value. Note that if the table is subsequently modified to increase the maximum length of the vectors then the modifying program is responsible for also updating the TFORM keyword value.  

  int fits_write_btblhdr / ffphbn
      (fitsfile *fptr, long nrows, int tfields, char **ttype,
       char **tform, char **tunit, char *extname, long pcount, > int *status)

4

Read the required keywords from the CHDU (image or table). When reading from an IMAGE extension the SIMPLE and EXTEND parameters are ignored. A null pointer may be supplied for any of the returned parameters that are not needed.      

  int fits_read_imghdr / ffghpr
      (fitsfile *fptr, int maxdim, > int *simple, int *bitpix, int *naxis,
       long *naxes, long *pcount, long *gcount, int *extend, int *status)

  int fits_read_atblhdr / ffghtb
      (fitsfile *fptr,int maxdim, > long *rowlen, long *nrows,
       int *tfields, char **ttype, long *tbcol, char **tform, char **tunit,
       char *extname,  int *status)

  int fits_read_btblhdr / ffghbn
      (fitsfile *fptr, int maxdim, > long *nrows, int *tfields,
       char **ttype, char **tform, char **tunit, char *extname,
       long *pcount, int *status)