NAME:
CHECK_FITS
PURPOSE:
Given a FITS array IM, and a associated FITS or STSDAS header HDR, this
procedure will check that
(1) HDR is a string array, and IM is defined and numeric
(2) The NAXISi values in HDR are appropiate to the dimensions
of IM
(3) The BITPIX value in HDR is appropiate to the datatype of IM
If HDR contains a DATATYPE keyword (as in STSDAS files), then this is
also checked against the datatype of of IM
If the UPDATE keyword is present, then FITS header will be modified, if
necessary, to force agreement with the image array
CALLING SEQUENCE:
check_FITS, im, hdr, [ dimen, idltype, /UPDATE, /NOTYPE, /SDAS ]
INPUTS:
IM - FITS or STSDAS array, (e.g. as read by SXREAD or READFITS )
HDR - FITS or STSDAS header (string array) associated with IM
OPTIONAL OUTPUTS:
dimen - vector containing actual array dimensions
idltype- data type of the FITS array as specified in the IDL SIZE
function (1 for BYTE, 2 for INTEGER*2, 3 for INTEGER*4, etc.)
OPTIONAL KEYWORD INPUTS:
/NOTYPE - If this keyword is set, then only agreement of the array
dimensions with the FITS header are checked, and not the
data type.
/UPDATE - If this keyword is set then the BITPIX, NAXIS and DATATYPE
FITS keywords will be updated to agree with the array
/SDAS - If this keyword is set then the header is assumed to be from
an SDAS (.hhh) file. CHECK_FITS will then ensure that (1)
a DATATYPE keyword is included in the header and (2) BITPIX
is always written with positive values.
/FITS - If this keyword is present then CHECK_FITS assumes that it is
dealing with a FITS header and not an SDAS header, see notes
below.
SYSTEM VARIBLE:
If there is a fatal problem with the FITS array or header then !ERR is
set to -1. ( If the UPDATE keyword was supplied, and the header could
be fixed then !ERR = 0.)
PROCEDURE:
Program checks the NAXIS1 and NAXIS2 parameters in the header to
see if they match the image array dimensions.
NOTES:
An important distinction between an STSDAS header and a FITS header
is that the BITPIX value in an STSDAS is always positive, e.g. BITPIX=32
for REAL*4 data. Users should use either the /SDAS or the /FITS
keyword if it is important whether the STSDAS or FITS convention for
REAL*4 data is used. Otherwise, CHECK_FITS assumes that if a
DATATYPE keyword is present then it is dealing with an STSDAS header.
MODIFICATION HISTORY:
Written, December 1991 W. Landsman Hughes/STX to replace CHKIMHD
No error returned if NAXIS=0 and IM is a scalar W. Landsman Feb 93
Fixed bug for REAL*8 STSDAS data W. Landsman July 93
Make sure NAXIS agrees with NAXISi W. Landsman October 93
(See /usr/local/idl/lib/zastron/fits/check_fits.pro)
NAME: DFITSRD PURPOSE: Convert true disk FITS formatted file(s) into STSDAS formatted file(s). Disk FITS refers to files (that can be created by IRAF or AIPS) that keep the exact format (e.g. 2880 byte record length) of a FITS tape. STSDAS files have a detached header and 512 byte record length. CALLING SEQUNCE: DFITSRD, infile, outname, [ /NOPROMPT ] INPUTS: INFILE = input FITS file name (default extension .DAT), scalar string OUTNAME = output file name (ALWAYS has extensions .hhh for header and .hhd for data; user supplied extensions are ignored. Scalar string INTERACTIVE INPUT: User will be prompted if INFILE or OUTNAME are undefined or integers. NOTES: Output files are always created with the extensions .hhh (header) and .hhd (data). DFITSRD is a shell for the procedure DFITSREAD which does the actual processing of the FITS file. INPUT KEYWORD PARAMETERS: NOPROMPT - If this keyword is set then DFITSRD will not prompt for another file name to be processed. This keyword is useful when DFITSRD is called from a driver procedure. SIDE EFFECTS: For each FITS disk file STSDAS disk files will be created with names: name.hhh and name.hhd Fits extension files will have names: name_x.HHH and name_x.HHD where x runs from 1 to the number of extensions. EXAMPLES: (1) Prompt for input and output file names IDL> dfitsrd,1 (2) Write FITS image, ngc598.fits to an STSDAS files m33.hhh/d IDL> dfitsrd,'ngc598.fits','m33' PROCEDURES USED: dfitsread, fdecomp, datatype MODIFICATION HISTORY: B. Pfarr - adapted from FITSRD, modified to read from disk 8/88 W. Lansdman - display calling sequence if no params suplied Sep. 92
(See /usr/local/idl/lib/zastron/fits/dfitsrd.pro)
NAME:
DFITSRD_LARGE
PURPOSE:
Convert true disk FITS formatted file(s) into STSDAS formatted file(s).
Disk FITS refers to files (that can be created by IRAF or AIPS) that
keep the exact format (e.g. 2880 byte record length) of a FITS tape.
STSDAS files have a detached header and 512 byte record length.
CALLING SEQUNCE:
DFITSRD_LARGE,infile,outname
OPTIONAL INPUTS:
INFILE = string, input file name (default extension .DAT)
OUTNAME = string, output file name (ALWAYS has extensions
.hhh for header and .hhd for data; user supplied extensions
are ignored.
INTERACTIVE INPUT:
If user does not pass infile and/or outname in as parameters,
user will be prompted for input file names (default extension .DAT),
and output file names. Output files are always created with the
extensions .hhh (header) and .hhd (data).
INPUT KEYWORD PARAMETERS:
NOPROMPT - If this keyword is set then DFITSRD_LARGE will not prompt for
another file name to be processed. This keyword is useful when
DFITSRD_LARGE is called from a driver procedure.
SIDE NOTES:
Use DFITSRD instead of DFITSRD_LARGE for small to moderately sized
files. It is much faster. Use DFITSRD_LARGE if you do not have a
large enough dynamic memory allocation to read the file with DFITSRD.
SIDE EFFECTS:
For each FITS disk file STSDAS disk files will be created
with names:
name.hhh and name.hhd
Fits extension files will have names:
name_x.HHH and name_x.HHD
where x runs from 1 to the number of extensions.
MODIFICATION HISTORY:
B. Pfarr - adapted from FITSRD, modified to read from disk 8/88
W. Thompson - changed call to DFITSREAD to DFITSREAD_LARGE, 4/91
(See /usr/local/idl/lib/zastron/fits/dfitsrd_large.pro)
NAME: DFITSREAD PURPOSE: Procedure will read a disk FITS file and write to a STSDAS disk file. The header is placed in.HHH and the data is placed in the file .HHD. This procedure is called by DFITSRD which is the procedure that an interactive user would normally use. CALLING SEQUENCE: dfitsread, unit, name, [ EXTEN= , NBTYES = ] INPUTs: unit - unit number of opened input file name - file name (without an extension) OPTIONAL OUTPUT KEYWORDS: EXTEN = This keyword is set to 1 if the FITS header contains the keyword EXTEND = T, otherwise, exten = 0 NOTE: exten = 1 does NOT gaurantee extensions are present NBYTES - Contains the number of bytes written to disk, integer scalar OUTPUT: name - name of file if input keyword parameter is supplied SIDE EFFECTS: files name.hhh and name.hhd are created HISTORY: B. Pfarr - adapted from FITSREAD to handle disk files Converted to Version 2 IDL, K. Bhagat, August 1990 Added call to IEEE_TO_HOST, single I/O calls, W. Landsman Jan, 1992 Force SIMPLE = 'F' in STSDAS file W. Landsman Aug 1993
(See /usr/local/idl/lib/zastron/fits/dfitsread.pro)
NAME: DFITSREAD_LARGE PURPOSE: Procedure will read a disk FITS file The header is placed in.HHH and the data is placed in the file .HHD. Called by DFITSRD_LARGE CALLING SEQUENCE: dfitsread_large,unit,name,exten=exten INPUTs: unit - unit number of opened input file name - file name (without an extension) KEYWORD: exten = exten - If header keyword EXTEND = T, exten = 1, otherwise, exten = 0 exten = 1 does NOT gaurantee extensions are present OUTPUT: name - name of file if input keyword parameter is supplied SIDE NOTES: Use DFITSREAD instead of DFITSREAD_LARGE for small to moderately sized files. It is much faster. Use DFITSREAD_LARGE if you do not have a large enough dynamic memory allocation to read the file with DFITSREAD. SIDE EFFECTS: files name.hhh and name.hhd are created HISTORY: B. Pfarr - adapted from FITSREAD to handle disk files Converted to Version 2 IDL, K. Bhagat, August 1990 W. T. Thompson May, 1990, changed to write data to disk in pieces rather than all at once at the end of a group.
(See /usr/local/idl/lib/zastron/fits/dfitsread_large.pro)
NAME: DFITSWRITE PURPOSE: Procedure will write an internal SDAS file to a FITS file on disk. Note: Called by DFITSWRT CALLING SEQUENCE: DFITSWRITE, unit, file [, KEYWORD] INPUTS: unit - IDL logical unit number file - internal FITS file name without extension (extension is assumed to be .HHH and .HHD) OPTIONAL INPUT: keyword - FITS keyword to place file name into. if not supplied or equals '' then the file name is not put into the header before writing it to disk FITS file. SIDE EFFECT: A FITS file is written to disk. PROCEDURE CALLS: remchar, sxhread, sxpar, fdecomp, sxaddpar, host_to_ieee HISTORY: version 3 D. Lindler Nov. 1986 version 5 B. Pfarr modified from FITSWRITE Added HOST_TO_IEEE call W. Landsman January, 1992 Remove dummy SDAS group parameters February, 1992
(See /usr/local/idl/lib/zastron/fits/dfitswrite.pro)
NAME:
DFITSWRT
PURPOSE:
Convert ST/SDAS formatted files to true disk FITS formatted file(s).
D(isk) fits: refers to files (that can be created by IRAF or AIPS) that
keep the exact format (e.g. 2880 byte record length) of a FITS tape.
ST/SDAS files: has detached header and 512 byte record length.
CALLING SEQUENCE:
DFITSWRT , iname, oname, [ EXTEND = ]
INPUT:
iname - name of existing ST/SDAS formatted file to be converted.
if iname is set to 1, then user will be prompted for file names.
oname - output file name for to disk FITS file [default DFITS]
note: user may also specify extension for filename...default
is .FITS (i.e. DFITS.FITS).
KEYWORD:
EXTEND - Set this keyword nonzero if you want DFITSWRT to include
any SDAS table extensions files into the disk FITS output.
The table extensions must be of the form iname_extnumber
(see example).
EXAMPLES:
(1) Run DFITSWRT interactively
IDL> dfitswrt,1
(2) You have files SDAS.HHH and SDAS.HHD plus additional SDAS tables
or other groups:
DFITSWRT,'SDAS','SDAS',/EXTEND
Note: as the disk FITS file is created, it will look for
the SDAS group (or tables) named:
sdas_1.hhh and sdas_1.hhd
sdas_2.hhh and sdas_2.hhd
.
:
Note: the number of group(or table) files depends on the
number of existing SDAS group(or table) input files.
The output file will be named SDAS.FITS
NOTES:
DFITSWRT does not do any validity checking on the FITS header
In particular, be sure that the FITS header has EXTEND = 'T'
if extensions are included.
MODIFICATION HISTORY:
version 3 D. Lindler Nov 86
Fixed use of /EXTEND keyword, cleaned up documentation
W. Landsman ST Systems October 91
(See /usr/local/idl/lib/zastron/fits/dfitswrt.pro)
NAME:
FITSDIR
PURPOSE:
Provide a brief description of the FITS files on a disk. The values
of the FITS keywords NAXISi, OBS-DATE, TELESCOPE, OBJECT, EXPTIME are
displayed. All of these are commonly used FITS keywords and all
except EXPTIME are officially reserved FITS keywords.
CALLING SEQUENCE:
FITSDIR , [ directory, TEXTOUT =, NoTelescope = ]
OPTIONAL INPUT PARAMETERS:
DIRECTORY - Scalar string giving file name, disk or directory to be
searched. Wildcard file names are allowed. Examples of
valid VMS or Unix names include '*.fit' or 'tape*'. An example
of a valid VMS name is 'UIT$USER2:[JONES]*.FIT' while a valid
Unix string is 'iraf/*.fits'.
If not given, FITSDIR searches *.fits files in the default
directory.
OPTIONAL KEYWORD INPUT PARAMETER
NOTELESCOPE - If this keyword is set and non-zero then the value of
the (usually less important) TELESCOPE keyword is not displayed,
and more space is available to display the other keyword values
TEXTOUT - Controls output device as described in TEXTOUT procedure
textout=1 TERMINAL using /more option
textout=2 TERMINAL without /more option
textout=3 .prt
textout=4 laser.tmp
textout=5 user must open file
textout = filename (default extension of .prt)
OUTPUT PARAMETERS:
None.
RESTRICTIONS:
(1) Field values may be truncated if their length exceeds the default
format.
File name NAXISi OBS-DATE TELESCOPE OBJECT EXPTIME
A18 A11 A10 A10 A20 F7.1
A20 A12 A10 A29 F7.1
(2) Only reads the primary FITS headers. FITS files containing
only extensions (binary or ASCII tables) may have little
information in their primary header.
(3) Users may wish to modify the program to display other FITS
keywords of particular interest to them
EXAMPLES:
IDL> fitsdir ;Print info on all '*.fits' files in current
directory.
IDL> fitsdir ,'*.fit' ;Lists all '*.fit' files in current directory
IDL> fitsdir ,'tape*' ;Print info on all tape* files in current
;directory. Files meeting the wildcard name
;that are not FITS files are ignored
Write info on all *.fits files in the Unix directory /usr2/smith, to a
file 'smith.txt' and don't display the value of the TELESCOPE keyword
IDL> fitsdir ,'/usr2/smith/*.fits',t='smith.txt', /NoTel
PROCEDURE:
FINDFILE is used to find the specified FITS files. The header of
each file is read, and rejected if the file is not FITS. Each header
searched for the parameters NAXISi, TELESCOP, OBJECT, DATE-OBS and
EXPTIME.
SYSTEM VARIABLES:
If textout keyword is not used to select an output device, then the
non-standard system variable !TEXTOUT will be the default.
PROCEDURES USED:
ZPARCHECK, FDECOMP, SPEC_DIR, TEXTOPEN, TEXTCLOSE
MODIFICATION HISTORY:
Written, W. Landsman, HSTX February, 1993
(See /usr/local/idl/lib/zastron/fits/fitsdir.pro)
NAME: FITS_INFO PURPOSE: Provide information about the contents of a FITS file, (primary header and data if any + extensions). Information is printed at the terminal and/or stored in a common block CALLING SEQUENCE: FITS_INFO, filename, [ SILENT = , TEXTOUT = , N_ext = ] INPUT: FILENAME = Scalar or vector string giving the name of the FITS file(s) Can include wildcards such as '*.fits' OPTIONAL INPUT KEYWORDS: SILENT - This key word will suppress display of the file description on the terminal TEXTOUT - specifies output device. textout=1 TERMINAL using /more option textout=2 TERMINAL without /more option textout=3.prt textout=4 laser.tmp textout=5 user must open file, see TEXTOPEN textout = filename (default extension of .prt) OPTIONAL OUTPUT KEYWORD: N_ext - Returns an integer scalar giving the number of extensions in the FITS file COMMON BLOCKS DESCRIPTOR = File descriptor string of the form N_hdrrec Naxis IDL_type Naxis1 Naxis2 ... Naxisn [N_hdrrec table_type Naxis IDL_type Naxis1 ... Naxisn] (repeated for each extension) See the procedure RDFITS_STRUCT for an example of the use of this common block EXAMPLE: Display info about all FITS files of the form '*.fit' in the current directory IDL> fits_info, '*.fit' Any time a *.fit file is found which is *not* in FITS format, an error message is displayed at the terminal and the program continues PROCEDURES USED: GETTOK, STRN, SXPAR, TEXTOPEN, TEXTCLOSE SYSTEM VARIABLES: Uses the non-standard system variable !TEXTOUT to select an output device if the TEXTOUT keyword is not supplied MODIFICATION HISTORY: Written, K. Venkatakrishna, Hughes STX, May 1992 Added N_ext keyword, and table_name info, G. Reichert Some cleaning up of the code W. Landsman October 1992 Work on *very* large FITS files October 92
(See /usr/local/idl/lib/zastron/fits/fits_info.pro)
NAME: HEADFITS CALLING SEQUENCE: Result = headfits( filename ,[ EXTEN = ]) PURPOSE: Read a FITS file header record INPUTS: FILENAME = String containing the name of the FITS file to be read. OPTIONAL INPUT KEYWORD: EXTEN = integer scalar, specifying which FITS extension to read. For example, to read the header of the first extension set EXTEN = 1. Default is to read the primary FITS header (EXTEN = 0). OUTPUTS: Result of function = FITS header, string array EXAMPLE: Read the FITS header of a file 'test.fits' into a string variable, h IDL> h = headfits( 'test.fits') MODIFICATION HISTORY: adapted by Frank Varosi from READFITS by Jim Wofford, January, 24 1989 Keyword EXTEN added, K.Venkatakrishna, May 1992 Make sure first 8 characters are 'SIMPLE' W. Landsman October 1993
(See /usr/local/idl/lib/zastron/fits/headfits.pro)
NAME:
MKHDR
PURPOSE:
Make a minimal primary FITS image header or a minimal FITS IMAGE
extension header. If an array is supplied then the
created FITS header will be appropiate 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
appropiate 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 more than 2 parameters are supplied, then the second parameter
is intepreted as an integer giving the IDL datatype e.g.
1 - LOGICAL*1, 2 - INTEGER*2, 4 - REAL*4, 3 - INTEGER*4
NAXISX - Vector giving the size of each dimension (NAXIS1, NAXIS2,
etc.).
OUTPUT:
HDR - 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).
RESTRICTIONS:
(1) MKHDR should not be used to make an STSDAS header or a FITS
ASCII or Binary Table header. Instead use
SXHMAKE - to create a minimal STSDAS header
FXHMAKE - 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
(See /usr/local/idl/lib/zastron/fits/mkhdr.pro)
NAME:
RDFITS_STRUCT
PURPOSE:
Read an entire FITS file into an IDL structure. Each header, image
or table array is placed in a separate structure tag.
CALLING SEQUENCE:
RDFITS_STRUCT, filename, struct, [ /NODELETE, /SILENT ]
INPUT:
FILENAME = Scalar string giving the name of the FITS file
OPTIONAL KEYWORD:
NODELETE - RDFITS_STRUCT creates a temporary file with the name
temp_'fitsname'.pro which contains the IDL structure definition
Normally, this temporary file is deleted -- set the /NODELETE
keyword to keep it.
SILENT - Set this keyword to suppress informational displays at the
terminal.
OUTPUT:
struct = structure into which FITS data is read. The primary header
and image are placed into tag names HDR0 and IM0. Any
extensions are placed into the tag names HDRi, TABi
PROCEDURES USED:
FITS_INFO, HEADFITS, GETTOK, READFITS, STRN, FDECOMP
METHOD:
The procedure FITS_INFO is used to determine whether a primary image
exists and the number of extensions. The number and type of
structure tags required is written to a temporary file and assigned
to an appropiate HEADFITS or READFITS call. The temporary file
is executed using CALL_PROCEDURE.
EXAMPLE:
Read the FITS file 'm33.fits' into an IDL structure, st
IDL> rdfits_struct, 'm33.fits', st
IDL> help, /str, st ;Display info about the structure
RESTRICTIONS:
The current algorithm is not particularly efficient. The user must delete the
temporary file under MacOS.
MODIFICATION HISTORY:
Written K. Venkatakrishna, STX April 1992
Code cleaned up a bit W. Landsman STX October 92
Modified for MacOS I. Freedman HSTX April 1994
(See /usr/local/idl/lib/zastron/fits/rdfits_struct.pro)
NAME: READFITS PURPOSE: Read a FITS file into IDL data and header variables. CALLING SEQUENCE: Result = READFITS( Filename,[ Header, /NOSCALE, EXTEN_NO = , /SILENT , NaNVALUE = , STARTROW = , NUMROW = ] ) INPUTS: FILENAME = Scalar string containing the name of the FITS file (including extension) to be read. OUTPUTS: Result = FITS data array constructed from designated record. OPTIONAL OUTPUT: Header = String array containing the header from the FITS file. OPTIONAL INPUT KEYWORDS: NOSCALE - If present and non-zero, then the ouput data will not be scaled using the optional BSCALE and BZERO keywords in the FITS header. Default is to scale. SILENT - Normally, READFITS will display the size the array at the terminal. The SILENT keyword will suppress this NaNVALUE - This scalar is only needed on Vax architectures. It specifies the value to translate any IEEE "not a number" values in the FITS data array. It is needed because the Vax does not recognize the "not a number" convention. EXTEN_NO - scalar integer specify the FITS extension to read. For example, specify EXTEN = 1 or /EXTEN to read the first FITS extension. Extensions are read using recursive calls to READFITS. POINT_LUN - Position (in bytes) in the FITS file at which to start reading. Useful if READFITS is called by another procedure which needs to directly read a FITS extension. Should always be a multiple of 2880. STARTROW - This keyword only applies when reading a FITS extension It specifies the row (scalar integer) of the extension table at which to begin reading. Useful when one does not want to read the entire table. NUMROW - This keyword only applies when reading a FITS extension. If specifies the number of rows (scalar integer) of the extension table to read. Useful when one does not want to read the entire table. EXAMPLE: Read a FITS file TEST.FITS into an IDL image array, IM and FITS header array, H. Do not scale the data with BSCALE and BZERO. IDL> im = READFITS( 'TEST.FITS', h, /NOSCALE) If the file contain a FITS extension, it could be read with IDL> tab = READFITS( 'TEST.FITS', htab, /EXTEN ) To read only rows 100-149 of the FITS extension, IDL> tab = READFITS( 'TEST.FITS', htab, /EXTEN, STARTR=100, NUMR = 50 ) RESTRICTIONS: Cannot handle random group FITS NOTES: The procedure FXREAD can be used as an alternative to READFITS. FXREAD has the option of reading a subsection of the primary FITS data. PROCEDURES USED: Functions: SXPAR, WHERENAN Procedures: IEEE_TO_HOST, SXADDPAR MODIFICATION HISTORY: MODIFIED, Wayne Landsman October, 1991 Added call to TEMPORARY function to speed processing Feb-92 Added STARTROW and NUMROW keywords for FITS tables Jul-92 Close logical unit if EOF encountered Make SILENT keyword work for tables Oct-92 Work under "windows" R. Isaacman Jan-93 Check for SIMPLE keyword in first 8 characters Feb-93 Removed EOF function for DECNET access Aug-93 Work under "alpha" Sep-93
(See /usr/local/idl/lib/zastron/fits/readfits.pro)
NAME:
WRITEFITS
PURPOSE:
Write an an IDL array into a disk FITS file. Works with all types
of FITS files except random groups
CALLING SEQUENCE:
writefits, filename, data [, header, NaNvalue = , /APPEND]
INPUTS:
FILENAME = String containing the name of the file to be written.
DATA = Image array to be written to FITS file. If DATA is
undefined or a scalar, then only the FITS header (which
must have NAXIS = 0) will be written to disk
OPTIONAL INPUT:
HEADER = String array containing the header for the FITS file.
If variable HEADER is not given, the program will generate
a minimal FITS header.
OPTIONAL INPUT KEYWORD:
NaNvalue - Value in the data array to be set to the IEEE NaN
condition. This is the FITS representation of undefined
values
APPEND - If this keyword is set then the supplied header and data
array are assumed to be an extension and are appended onto
the end of an existing FITS file. Note that the primary
header in the existing file must already have an EXTEND
keyword to indicate the presence of an FITS extension.
OUTPUTS:
None
RESTRICTIONS:
(1) It recommended that BSCALE and BZERO not be used (or set equal
to 1. and 0) with REAL*4 or REAL*8 data.
(2) WRITEFITS will remove any group parameters from the FITS header
EXAMPLE:
Write a randomn 50 x 50 array as a FITS file creating a minimal header.
IDL> im = randomn(seed, 50, 50) ;Create array
IDL> writefits, 'test', im ;Write to a FITS file "test"
PROCEDURES USED:
CHECK_FITS, HOST_TO_IEEE, SXDELPAR, SXADDPAR, SXPAR
MODIFICATION HISTORY:
WRITTEN, Jim Wofford, January, 29 1989
MODIFIED, Wayne Landsman, added BITPIX = -32,-64 support for UNIX
Use new BYTEODER keywords 22-Feb-92
Modify OPENW for V3.0.0 W. Landsman Dec 92
Work for "windows" R. Isaacman Jan 93
More checks for null data Mar 94
(See /usr/local/idl/lib/zastron/fits/writefits.pro)