fparkey -- Write a parameter value to a FITS header keyword.


        fparkey value fitsfile keyword 


This task changes the value of a header keyword (in the first FITS extension, by default). If the value of the task parameter 'add' is "yes", the task allows a new keyword to be added to the header, otherwise, attempting to add a new keyword will cause an error. The data type of the keyword value is determined implicitly from the keyword value. The values of T, TRUE, Y, YES, F, FALSE, N, or NO (in upper or lower case) are interpreted as boolean values. Enclosing the value string in single quotes will force it to be interpreted as a string, rather than as a numeric or boolean value.

A keyword many be deleted from the FITS header by prefixing the keyword name with a minus sign (-).


value [string]
Input value to be written to the header keyword. (Strings are case sensitive.)

fitsfile [file name]
The name, including extension and extension number in square brackets (e.g., 'myfile.fits[3]') of the FITS file whose header is to be changed. If no FITS extension name or number is specified, this task will operate on the first extension header (and not the primary array header).

keyword [string]
Name of the header keyword to be modified, added, or deleted (The name is not case sensitive). To delete a keyword, prefix the name with a minus sign (-).

(comm = " ") [string]
The comment string to be written to the keyword. If 'comm' is a blank string, then the existing keyword comment string, if any, will not be modified.

(add = no) [boolean]
Allow new header keywords to be added? If 'add = no', then existing keywords can take new values but no new keywords can be added to the file.

(insert = 0) [integer]
Keyword after which to insert the new keyword. All subsequent keywords will be shifted down. If insert consists only of digits, the new keyword will be inserted at that position. When insert is blank or has a value of '0', new keywords will be appended to the header.


1. Set the header keyword EXTNAME in the 3rd extension in the 'myfile.fits' FITS file to the value of 'RATEFILE', leaving the comment string unchanged.

          ft> fparkey RATEFILE 'myfile.fits[3]' extname 

2. Add the header keyword NEWKEY to the primary header in the 'myfile.fits' FITS file with a value of 15.25 and a comment of 'New keyword':

          ft> fparkey 15.25 'myfile.fits[0]' newkey comm='New keyword' add=yes

3. Delete the header keyword XVALUE in the 1st extension of the data.fits FITS file:

          ft> fparkey dummy data.fits -xvalue



fthedit, ftkeypar, ftedit, ftlist, heatools


Jun92 ftools.futils