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Low-Level FITS Header I/O Subroutines

1

Put (append) an 80-character record into the CHU.

FTPREC(unit,card, > status)

2

Put (append) a COMMENT keyword into the CHU. Multiple COMMENT keywords will be written if the input comment string is longer than 70 characters.

FTPCOM(unit,comment, > status)

3

Put (append) a HISTORY keyword into the CHU. Multiple HISTORY keywords will be written if the input history string is longer than 70 characters.

FTPHIS(unit,history, > status)

4

Put (append) the DATE keyword into the CHU. The keyword value will contain the current system date as a character string in 'dd/mm/yy' format. If a DATE keyword already exists in the header, then this subroutine will simply update the keyword value in-place with the current date.

FTPDAT(unit, > status)

5

Put (append) a new keyword into the CHU.

FTPKY[JLS](unit,keyword,keyval,comment, > status)
        FTPKY[EDFG](unit,keyword,keyval,decimals,comment, > status)

6

Put (append) a numbered sequence of keywords into the CHU. One may append the same comment to every keyword (and eliminate the need to have an array of identical comment strings, one for each keyword) by including the ampersand character as the last non-blank character in the (first) COMMENTS string parameter. This same string will then be used for the comment field in all the keywords. (Note that the SPP version of these routines only supports a single comment string).

FTPKN[JLS](unit,keyroot,startno,no_keys,keyvals,comments, > status)
        FTPKN[EDFG](unit,keyroot,startno,no_keys,keyvals,decimals,comments, >
                   status)

7

Put (append) a 'triple precision' keyword into the CHU in F28.16 format. The floating point keyword value is constructed by concatenating the input integer value with the input double precision fraction value (which must have a value between 0.0 and 1.0). The FTGKYT routine should be used to read this keyword value, because the other keyword reading subroutines will not preserve the full precision of the value.

FTPKYT(unit,keyword,intval,dblval,comment, > status)

8

Insert a new keyword into the CHU. The new keyword is inserted immediately following the last keyword that has been read from the header. These 'insert keyword' subroutines are somewhat less efficient then the 'append keyword' subroutines described above because the remaining keywords in the header have to be shifted down one slot.

FTIKY[JLS](unit,keyword,keyval,comment, > status)
        FTIKY[EDFG](unit,keyword,keyval,decimals,comment, > status)

9

Get the nth 80-character header record from the CHU

FTGREC(unit,key_no, > card,status)

10

Get the name, value (as a string), and comment of the nth keyword in CHU

FTGKYN(unit,key_no, > keyword,value,comment,status)

11

Get the 80-character header record for the named keyword

FTGCRD(unit,keyword, > card,status)

12

Get a keyword value and comment from the CHU

FTGKY[EDJLS](unit,keyword, > keyval,comment,status)
        FTGKEY(unit,keyword, > value,comment,status)

13

Get a sequence of numbered keyword values

FTGKN[EDJLS](unit,keyroot,startno,max_keys, > keyvals,nfound,status)

14

Get the value of a floating point keyword, returning the integer and fractional parts of the value in separate subroutine arguments. This subroutine may be used to read any keyword but is especially useful for reading the 'triple precision' keywords written by FTPKYT.

FTGKYT(unit,keyword, > intval,dblval,comment,status)

15

Modify (overwrite) the nth 80-character header record in the CHU

FTMREC(unit,key_no,card, > status)

16

Modify (overwrite) the 80-character header record for the named keyword in the CHU. This can be used to overwrite the name of the keyword as well as its value and comment fields.

FTMCRD(unit,keyword,card, > status)

17

Modify (overwrite) the name of an existing keyword in the CHU preserving the current value and comment fields.

FTMNAM(unit,oldkey,keyword, > status)

18

Modify (overwrite) the comment field of an existing keyword in the CHU

FTMCOM(unit,keyword,comment, > status)

19

Modify the value and comment fields of an existing keyword in the CHU. Optionally, one may modify only the value field and leave the comment field unchanged by setting the input COMMENT parameter equal to the ampersand character (&).

FTMKY[JLS](unit,keyword,keyval,comment, > status)
        FTMKY[EDFG](unit,keyword,keyval,decimals,comment, > status)

20

Delete an existing keyword record. The space previously occupied by the keyword is reclaimed by moving all the following header records up one row in the header.

FTDKEY(unit,keyword, > status)

21

Return the number of existing keywords in the CHU and the remaining space available to write additional keywords in the CHU. (returns KEYSADD = -1 if the header has not yet been closed). Note that FITSIO will attempt to dynamically add space for more keywords if required when appending new keywords to a header.

FTGHSP(iunit, > keysexist,keysadd,status)