funhead - Online in the Cloud

PROGRAM:

NAME

funhead - display a header in a Funtools file

SYNOPSIS

funhead [-a] [-s] [-t] [-L] <iname> [oname ename]

OPTIONS

-a # display all extension headers
-s # display 79 chars instead of 80 before the new-line
-t # prepend data type char to each line of output
-L # output in rdb/starbase list format

DESCRIPTION

funhead displays the FITS header parameters in the specified FITS Extension.

The first argument to the program specifies the Funtools input file to display. If
"stdin" is specified, data are read from the standard input. Funtools Bracket Notation is
used to specify particular FITS extension to process. Normally, the full 80 characters of
each header card is output, followed by a new-line.

If the -a switch is specified, the header from each FITS extensions in the file is
displayed. Note, however, that the -a switch does not work with FITS files input via
stdin. We hope to remove this restriction in a future release.

If the -s switch is specified, only 79 characters are output before the new-line. This
helps the display on 80 character terminals.

If the -t switch is specified, the data type of the parameter is output as a one character
prefix, followed by 77 characters of the param. The parameter data types are defined as:
FUN_PAR_UNKNOWN ('u'), FUN_PAR_COMMENT ('c'), FUN_PAR_LOGICAL ('l'), FUN_PAR_INTEGER
('i'), FUN_PAR_STRING ('s'), FUN_PAR_REAL ('r'), FUN_PAR_COMPLEX ('x').

If the -L (rdb table) switch is used, the output will conform to starbase/rdb data base
list format.

For example to display the EVENTS extension (binary table):

[sh] funhead "foo.fits[EVENTS]"
XTENSION= 'BINTABLE' / FITS 3D BINARY TABLE
BITPIX = 8 / Binary data
NAXIS = 2 / Table is a matrix
NAXIS1 = 20 / Width of table in bytes
NAXIS2 = 30760 / Number of entries in table
PCOUNT = 0 / Random parameter count
GCOUNT = 1 / Group count
TFIELDS = 7 / Number of fields in each row
EXTNAME = 'EVENTS ' / Table name
EXTVER = 1 / Version number of table
TFORM1 = '1I ' / Data type for field
TTYPE1 = 'X ' / Label for field
TUNIT1 = ' ' / Physical units for field
TFORM2 = '1I ' / Data type for field
etc. ...
END

To display the third header:

[sh] funhead "foo.fits[3]"
XTENSION= 'BINTABLE' / FITS 3D BINARY TABLE
BITPIX = 8 / Binary data
NAXIS = 2 / Table is a matrix
NAXIS1 = 32 / Width of table in bytes
NAXIS2 = 40 / Number of entries in table
PCOUNT = 0 / Random parameter count
GCOUNT = 1 / Group count
TFIELDS = 7 / Number of fields in each row
EXTNAME = 'TGR ' / Table name
EXTVER = 1 / Version number of table
TFORM1 = '1D ' / Data type for field
etc. ...
END

To display the primary header (i.e., extension 0):

sh> funhead "coma.fits[0]"
SIMPLE = T /STANDARD FITS FORMAT
BITPIX = 16 /2-BYTE TWOS-COMPL INTEGER
NAXIS = 2 /NUMBER OF AXES
NAXIS1 = 800 /
NAXIS2 = 800 /
DATATYPE= 'INTEGER*2' /SHORT INTEGER
END

The funhead program also can edit (i.e. add, delete, or modify) or display individual
headers parameters. Edit mode is signalled by the presence of two additional command-line
arguments: output file and edit command file, in that order. Edit mode acts as a filter:
the output file will contain the entire input FITS file, including other extensions. The
edit command file can be "stdin", in which case edit command are read from the standard
input.

The edit command file contains parameter comments (having '#' in the first column) and
delete and assignment(modify or add) operations. A delete operation is specified by
preceding the parameter name with a minus sign "-". A display operation (very useful in
interactive sessions, i.e., where the edit commands are taken from stdin) is specified by
preceding the parameter name with a question mark "?". In either case, a parameter value
need not be specified. An assignment operation is specified in the same two ways that a
parameter is specified in a text header (but without the comment character that precedes
header params), i.e.:

· FITS-style comments have an equal sign "=" between the keyword and value and an
optional slash "/" to signify a comment. The strict FITS rules on column positions are
not enforced.

· Free-form comments can have an optional colon separator between the keyword and value.
In the absence of quote, all tokens after the keyword are part of the value, i.e. no
comment is allowed.

For example, the following interactive session checks for the existence of parameters,
adds new parameters, modifies them, and modifies and deletes existing parameters:

sh$ ./funhead snr.ev foo.fits -
# look for FOO1
? FOO1
WARNING: FOO1 not found
# add new foo1
FOO1 = 100
# add foo2
FOO2 = 200
# reset foo1 to a different value
FOO1 -1
# delete foo2
-FOO2
# change existing value
EXTVER 2
? XS-SORT
XS-SORT = 'EOF ' / type of event sort
# delete existing value
-XS-SORT
# exit
^D

See Column-based Text Files for more information about header parameter format.

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