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wcsqpedit xray.xproto


NAME · USAGE · DESCRIPTION · PARAMETERS · EXAMPLES · TIME_REQUIREMENTS
BUGS · SEE_ALSO

NAME

wcsqpedit -- Edit the WCS parameters in a QPOE file.

USAGE

wcsqpedit input_qpoe crval1 crval2 crpix1 crpix2 equinox radecsys

DESCRIPTION

wcsqpedit allows users to modify any of 7 WCS keywords in the QPOE file. The available values are CRPIX1, CRPIX2, CRVAL1, CRVAL2, CROTA2, EQUINOX and RADECSYS. These values appear as simple keywords in a long imheader listing, but are inaccessible as header parameters using either hedit or qphedit. Users should exercise caution when making these modifications, since all knowledge of the original coordinate system is then lost.

PARAMETERS

qpfile = "" prompt = QPOE file to change

The input qpoe file name to modify. User must have both read and write permission on the file. The file will be modified in place.

cdelt= "-999.9" prompt = cdelt1 (-999.9 no change)

This is the value to be assigned to the axis 1 pixel size (in degrees). This is stored as a double precision real value, so be sure to express the value accurately. A value of -999.9 indicates the value currently in the QPOE file should NOT be changed.

cdelt= "-999.9" prompt = cdelt2 (-999.9 no change)

This is the value to be assigned to the axis 2 pixel size (in degrees). This is stored as a double precision real value, so be sure to express the value accurately. A value of -999.9 indicates the value currently in the QPOE file should NOT be changed.

crval= "-1" prompt = CRVAL1

This is the value to be assigned to the axis 1 reference pixel. Normally this would be the Celestial RA. This is stored as a double precision real value, so be sure to express the value accurately. Only positive values are currently allowed. A value of -1 indicates the value currently in the QPOE file should NOT be changed.

crval= "-100" prompt = CRVAL2

This is the value corresponding to the axis 2 reference pixel. Normally this would be the Celestial Dec. This is stored as a double precision real value, so be sure to express the value accurately. Only values between -90.0 and +90.0 degrees are allowed. A value of -100, indicates the value currently in the QPOE file should NOT be changed.

crota= "-1000.0" prompt = CROTA2

This is the value corresponding to the image rotation relative to north. This is stored as a double precision real value, so be sure to express the value accurately. Only values between -360.0 and +360.0 degrees are allowed. A value of -1000.0, indicates the value currently in the QPOE file should NOT be changed.

crpix= "-1" prompt = CRPIX1

This is the number of the reference pixel. It is the point in the physical data file to which the CRVAL1 value corresponds. It is often a value near the center of the axis, though this is not rEQUIRed. This is stored as a double precision real value, so be sure to express the value accurately. A value of -1 indicates that the value currently in the QPOE file should NOT be changed.

crpix= "-1" prompt = CRPIX2

This is the number of the reference pixel. It is the point in the physical data file to which the CRVAL2 value corresponds. It is often a value near the center of the axis, though this is not required. This is stored as a double precision real value, so be sure to express the value accurately. A value of -1 indicates that the value currently in the QPOE file should NOT be changed.

equinox = "-1" prompt = EQUINOX

This is the year of the EQUINOX. Often either 1950. or 2000. A value of -1 will cause the existing value in the file to be retained.

ctype= "" prompt = ctype1 (null - no change)

This is the name of the axis 1 coordinate system. Some possible values are RA---TAN, RA---SIN, LINEAR.

ctype= "" prompt = ctype2 (null - no change)

This is the name of the axis 1 coordinate system. Some possible values are DEC--TAN, DEC--SIN, LINEAR.

radecsys = "" prompt = RADECSYS

Label for the Coordinate system FK4 = B1950. FK5 = J2000. A NULL string will cause the current value in the file to be retained.

axlen= "" prompt = X dimension (0 - no change)

This is the length of the axis 1 coordinate system.

axlen= "" prompt = Y dimension (0 - no change)

This is the length of the axis 2 coordinate system.

(display = 1) [int]

This is the display level. A value of 1 or greater will display the value currently in the file before prompting for a new value. A value of 2 or greater will display the value to be writtin to the file.

EXAMPLES

1. Change the WCS in the file from B1950 coordinates to J2000 coordinates. Note this changes the reference point only and does NOT reproject the data.

	cl> xray
	xr> ximages
	xi> qpcopy xdata$snr.qp "" snr.qp ""
	xi> xspatial
	xs> skypix oformat="degrees"
	input cooordinate system (xdata$snr.qp[bl=8]): xdata$snr.qp
	output cooordinate system (xdata$snr.qp): J2000
	input file list (STDIN): 

	Converting from xdata$snr.qp is 
                TANGENT 512. 513. -0.002222222 0.002222222 = 
                22:58:55.66 58:36:47.5 0.
                   EQUATORIAL B1950.   in pixels
             to    EQUATORIAL J2000.   in degrees


	(Terminate interactive list with <cntl>-D)
	512. 513.
	  345.2539            58.882            
	xp> wcsqpedit snr.qp
	current CDELT1: -0.002222222000 
	cdelt1 (-999.9 no change) (-999.9): -0.0025
	current CDELT2: 0.002222222000 
	cdelt2 (-999.9 no change) (-999.9):       
	current CRVAL1: 344.731900000000   (22:58:55.6560)
	CRVAL1 (-1.0 no change) (-1.:360.) (-1.): 345.2539
	current CRVAL2: 58.613190000000   (58:36:47.4840)
	CRVAL2 (-100.0 no change) (-100.:90.) (-100.): 58.882
	current CROTA2: 0.000000
	CROTA2 (-1000.0 no change) (-1000.:360.) (-1000.): 
	current CRPIX1: 512.0000   
	CRPIX1 (-1.0 no change) (-1.): 
	current CRPIX2: 513.0000   
	CRPIX2 (-1.0 no change) (-1.): 
	current EQUINOX: 1950.0000   
	EQUINOX (-1.0 no change) (-1.): 
	current CTYPE1: RA---TAN   
	ctype1 (null - no change): 
	current CTYPE2: DEC--TAN   
	ctype2 (null - no change): 
	current RADECSYS: FK4   
	RADECSYS( e.g. FK4,FK5) (NULL - no change): FK5
	current AXLEN1: 1024   
	X dimension (0 = no change) (0): 
	current AXLEN2: 1024   
	Y dimension (0 = no change) (0): 

TIME REQUIREMENTS

neglible

BUGS

SEE ALSO

The documention for task skypix and the task wcsedit


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