MKHDR
Name
MKHDR
Purpose
Make a minimal primary (or IMAGE extension) FITS header
Explanation
If an array is supplied, then the created FITS header will be
appropriate to the supplied array. Otherwise, the user can specify
the dimensions and datatype.
Calling Sequence
MKHDR, header ;Prompt for image size and type
or
MKHDR, header, im, [ /IMAGE, /EXTEND ]
or
MKHDR, header, type, naxisx, [/IMAGE, /EXTEND ]
Optional Inputs
IM - If IM is a vector or array then the header will be made
appropriate to the size and type of IM. IM does not have
to be the actual data; it can be a dummy array of the same
type and size as the data. Set IM = '' to create a dummy
header with NAXIS = 0.
TYPE - If 2 parameters are supplied, then the second parameter
is interpreted as an integer giving the IDL datatype e.g.
1 - Byte, 2 - 16 bit integer, 4 - float, 3 - Long
NAXISX - Vector giving the size of each dimension (NAXIS1, NAXIS2,
etc.).
Output
HEADER - image header, (string array) with required keywords
BITPIX, NAXIS, NAXIS1, ... Further keywords can be added
to the header with SXADDPAR.
Optional Input Keywords
/IMAGE = If set, then a minimal header for a FITS IMAGE extension
is created. An IMAGE extension header is identical to
a primary FITS header except the first keyword is
'XTENSION' = 'IMAGE' instead of 'SIMPLE ' = 'T'
/EXTEND = If set, then the keyword EXTEND is inserted into the file,
with the value of "T" (true). The EXTEND keyword can
optionally be included in a primary header, if the FITS file
contains extensions.
Restrictions
(1) MKHDR should not be used to make an STSDAS header or a FITS
ASCII or Binary Table extension header. Instead use
SXHMAKE - to create a minimal STSDAS header
FXBHMAKE - to create a minimal FITS binary table header
FTCREATE - to create a minimal FITS ASCII table header
(2) Any data already in the header before calling MKHDR
will be destroyed.
Example
Create a minimal FITS header, Hdr, for a 30 x 40 x 50 INTEGER*2 array
IDL> mkhdr, Hdr, 2, [30,40,50]
Alternatively, if the array already exists as an IDL variable, Array,
IDL> mkhdr, Hdr, Array
Procedures Called
SXADDPAR, GET_DATE
Revision History
Written November, 1988 W. Landsman
May, 1990, Adapted for IDL Version 2.0, J. Isensee
Aug, 1997, Use SYSTIME(), new DATE format W. Landsman
Allow unsigned data types W. Landsman December 1999
Set BZERO = 0 for unsigned integer data W. Landsman January 2000
EXTEND keyword must immediately follow last NAXISi W. Landsman Sep 2000
Add FITS definition COMMENT to primary headers W. Landsman Oct. 2001
Allow (nonstandard) 64 bit integers W. Landsman Feb. 2003
Add V6.0 notation W. Landsman July 2012