NAME

wcscoords -- Use WCS to convert between IRAF coordinate systems

USAGE

wcscoords image convtype ilist

DESCRIPTION

wcscoords transforms a list of coordinates from one coordinate system to another. It uses the IRAF WCS information and converts between tv, logical, physical and world coordinates.

PARAMETERS

image = "" prompt = reference image file defining the WCS

convtype = prompt = code for type of conversion.

The codes for types of conversion are defined as follows:

	     	1 = world   -> physical 
    		2 = world   -> tv       
		3 = world   -> logical  
		4 = physical-> logical  
		5 = physical-> world   
		6 = physical-> tv     
		7 = tv      -> physical 
		8 = tv      -> world   
		9 = tv      -> logical
		10= logical -> physical
		11= logical -> world  
		12= logical -> tv       

The logical, physical and world coordinate systems are defined in the document mwcs$MWCS.hlp. The TV coordinate system is what is used by the IRAF/IMTOOL facility. It is therefore needed in region files that are to be read into SAOIMAGE.

ifile = "STDIN" prompt = input file list

Comma separated list of the input files to be read. STDIN is allowed (Remember to use ^D end of file for STDIN).

(ofile = "STDOUT") [string]

Name of the output file to be created.

(clobber = no) [boolean]

Boolean flag specifying whether or not the output coordinate list file can be overwritten, if it already exists.

(display = 3) [int]

Display level print out flag.

	0 -- print only the converted coordinates
	1 -- print parsed conversion specification to STDERR
	2 -- print  both input  and converted  coordinates in
	     output  file  and  short  informative  header to
	     output (but not STDOUT).
	3 -- show coordinate conversions as they are done.
	4 -- show units conversions.

Display level of 0 is best when an output file is being generated and the only a coordinate list is desired.

EXAMPLES

1. Transform a position in RA and Dec to a pixel position in a particular image. The RA and Dec ("22:08:41.56 45:44:49.6") were typed in as standard input (STDIN). Typing "^D" ended the standard input.

xs> wcscoords "xdata$rp110590.qp[bl=30]" 3
input file list (STDIN):

Converting from    EQUATORIAL J2000.   in hours
             to xdata$rp110590.qp[bl=30] is
              TANGENT 256. 256. -0.004166667 0.004166667 = 332.0239 45.51389 0.
                   EQUATORIAL J2000.   in pixels

22:08:41.56 45:44:49.6
  230.9993            311.997
xs>

2. Transform a pixel position (7020, 7830) in an image to RA and Dec. Standard input is used as in the example above to input the pixels. Because the "oformat" parameter is left at its default, the output will be in decimal degrees.

xs> wcscoords "xdata$rp110590.qp" 5
input file list (STDIN):

Converting from xdata$rp110590.qp is
            TANGENT 7680. 7680. -1.388889E-4 1.388889E-4 = 332.0239 45.51389 0.
                   EQUATORIAL J2000.   in pixels
             to    EQUATORIAL J2000.   in degrees

7020 7830
  332.1548            45.53465
xs>

TIME REQUIREMENTS

The time requirements for this tasks are negligible.

BUGS

SEE ALSO

Documentation on precess (help precess ) for a description of the precess task.

MWCS help file (mwcs$MWCS.hlp fi+ ) for a description of the Mini-WCS (World Coordinate System) Interface.

SKYPIX helap file (help skypix)