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Last modified: Tue Dec 20 11:48:25 2005.
NAME: FITS_ADD_AXIS_PAR PURPOSE: Add to FITS header the FITS parameters necessary to specify a coordinate axis. CALLING SEQUENCE: FITS_ADD_AXIS_PAR, axis, hdr, axisnum INPUTS: AXIS - vector containing values of coordinate axis. HDR - FITS header. AXISNUM - The number of the coordinate axis. KEYWORD PARAMETERS: CTYPE - name of the coordinate axis, a character string. CUNIT - name of units of coordinate, a character string. AXIS_PAR - Set this keyword to a variable in order to return the AXIS_PAR stucture: .NAXIS - size of the axis .CDELT - coordinate increment along axis .CRPIX - coordinate system reference pixel .CRVAL - coordinate system value at reference pixel .CTYPE - name of the coordinate axis OUTPUTS: None. COMMON BLOCKS: None. SIDE EFFECTS: The coordinate axis header keywords are added or changed in the FITS header. PROCEDURES CALLED: FITS_GET_AXIS_PAR(), SXPAR(), SXADDPAR EXAMPLE: Create a header for a data cube... IDL> cube = bytarr(512,12,36) IDL> mkhdr, hdr, cube Now make coordinate axes for the cube... IDL> axis1 = findgen(512)*0.33 - 100 IDL> axis2 = findgen(12) IDL> axis3 = findgen(36)*0.5 + 50 Add the NAXISn, CRVALn, CRPIXn and CRDELTn header keywords to HDR... IDL> fits_add_axis_par, axis1, hdr, 1 IDL> fits_add_axis_par, axis2, hdr, 2 IDL> fits_add_axis_par, axis3, hdr, 3 Also add the CTYPEn and CUNITn keywords... IDL> fits_add_axis_par, axis1, hdr, 1, $ IDL> CTYPE='Right Ascension (B1950)', CUNIT='deg' RELATED PROCEDURES: FITS_MAKE_AXIS() MODIFICATION HISTORY: 20 Aug 2003 Written by Tim Robishaw, Berkeley
(See /dzd2/heiles/idl/gen/fits/fits_add_axis_par.pro)
NAME: FITS_GET_AXIS_PAR PURPOSE: Return, in structure form, the FITS parameters necessary to specify a coordinate axis. CALLING SEQUENCE: Result = FITS_GET_AXIS_PAR(axis) INPUTS: AXIS - vector containing values of coordinate axis. OUTPUTS: Returns the AXIS_PAR structure: AXIS_PAR.NAXIS - size of the axis .CDELT - coordinate increment along axis .CRPIX - coordinate system reference pixel .CRVAL - coordinate system value at reference pixel .CTYPE - name of the coordinate axis COMMON BLOCKS: None. EXAMPLE: AXIS is vector containing the values of an axis... IDL> axis_par = fits_get_axis_par(axis) IDL> help, axis_par, /structure ** Structure <39fc40>, 4 tags, length=16, refs=1: NAXIS LONG 2048 CDELT FLOAT 1.00000 CRPIX FLOAT 1025.00 CRVAL FLOAT 1024.00 RELATED PROCEDURES: FITS_ADD_AXIS_PAR, FITS_MAKE_AXIS() MODIFICATION HISTORY: 20 Aug 2003 Written by Tim Robishaw, Berkeley
(See /dzd2/heiles/idl/gen/fits/fits_get_axis_par.pro)
NAME: FITS_MAKE_AXIS -- create axis values from a FITS header PURPOSE: To create the axis values from the NAXISn, CDELTn, CRPIXn, and CRVALn keyword values stored in a FITS header. CALLING SEQUENCE: Result = FITS_MAKE_AXIS(hdr, axisnum) INPUTS: HDR - FITS header (string array) AXISNUM - The number of the axis to be created. KEYWORD PARAMETERS: None. OUTPUTS: Returns a vector of length NAXISn containing the axis values. COMMON BLOCKS: None. PROCEDURES CALLED: SXPAR() EXAMPLE: Get the header from a FITS file... IDL> hdr = headfits('datacube.fits') Make the 1st and 2nd axes... IDL> xaxis = fits_make_axis(hdr,1) IDL> yaxis = fits_make_axis(hdr,2) RELATED PROCEDURES: FITS_ADD_AXIS_PAR MODIFICATION HISTORY: 20 Aug 2003 Written by Tim Robishaw, Berkeley
(See /dzd2/heiles/idl/gen/fits/fits_make_axis.pro)