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skypix xray.xspatial


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

NAME

skypix -- convert and precess astronomical coordinate systems

USAGE

skypix isystem osystem ifile

DESCRIPTION

Skypix transforms a list of coordinates from one coordinate system to another. The EQUATORIAL keyword is optional as the actual system is specified by the type of epoch. For Julian epochs FK5 is assumed and for Besselain epochs FK4.

PARAMETERS

isystem, osystem = "J2000" prompt = input, output coordinate system

Input/Output coordinate systems. Specified with the following syntax:


<imagefile>	-- Image pixels.

[Equatorial] Jxxxx.xx
		-- FK5 system with Julian equinox.
[Equatorial] Bxxxx.xx[@xxxx.xx]
		-- FK4 system with Besselian equinox and
		   optional Bessalian observation epoch.

Ecliptic xxxx	-- Ecliptic system with equinox
Galactic	-- Galactic system
SuperGalactic	-- SuperGalactic system

Image		-- Pseudo system.  If one of the coordinate
		   systems (input or output) is a reference
		   image the other may be specified as Image.
		   The sky system of the image will be used
		   for this system.  This can be used to convert
	 	   between world and physical coordinates,
			e.g.  degrees -> pixels or
		  	      pixels -> degrees


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.

(iformat,oformat = "hours") [string]

The units of the output coordinate list (degrees, hours, radians). If the coordinate system is specified to be a reference image the units are taken to be pixels.

(clobber = yes) [boolean]

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

(display = 1) [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.
(istring = "NONE") [string]

Input string + formatting spec.

(ostring = "NONE") [string]

Output string + formatting spec.

EXAMPLES

Examples of coordinate system specification.


	xdata$snr.qp			# xdata$snr.qp pixels
	EQUATORIAL J2000		# FK5 equinox 2000
	J2010.9				# FK5 equinox 2010.9
	B1950				# FK4 equinox 1950

Execution Examples:

1. Transform a source position in the xdata$snr.qp file to J2000 coordinates ( xdata$snr.qp is in B1950 coordinates, observed in 1980 ) 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> skypix
input cooordinate system (xdata$snr.qp): 
output cooordinate system (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 hours


(Terminate interactive list with <cntl>-D)
22:08:41.56 45:44:49.6
  23:09:12.7          57:49:47.6        
<cntl-d>
xs>

    
    2.  Transform  the  list  of  Eoscat  sources  from  their FK5 J2000
    positions to their FK4 B1950 positions.   The  input  file  has  the
    positions  listed in radians.  The output will be sent to STDOUT and
    will be formatted in hours minutes seconds, degrees minutes  seconds
    units.
    
    cl>skypix iformat=rad oformat=hours
    input coordinate system : J2000
    output coordinate system : B1950
    input file list (STDIN): /Eoscat/2000R 
    
    Converting from    EQUATORIAL J2000.00 in radians
                 to    EQUATORIAL B1950.00 in hours
    
      0:00:36.00       21:41:59.93
      0:02:18.00      -42:12:59.76
      0:02:24.00      -30:50:59.62
      0:03:12.00       72:29:59.59
      ...
    
    
    3.  Transform  the  galactic coordinate to RA and Dec 
    showing the steps used to complete  the  transformation.   Here  the
    input  coordinate  is  read  from  STDIN  and  the  output  typed to
    STDOUT.  The value of display causes the steps  to  be  printed  and
    the  input coordinates to be echoed.  The pixels are referenced from
    the world coordinate system of the image xdata$snr.qp
    
    xs> skypix iformat=degrees display=4
    input cooordinate system (galactic): 
    output cooordinate system (xdata$snr.qp): 
    input file list (STDIN): 

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


    (Terminate interactive list with <cntl>-D)
    109.1 -.99
    Convert Galactic to B1950FK4
    Convert sky coordinates to image pixels
      109.1               -0.99               500.7361            516.321
<cntl-d>

xs> wcscoords
IRAF reference image (xdata$rp110590.qp[bl=30]): xdata$snr.qp
  Menu for coordinate conversion 
  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       
code for conversion type (0:12) (12): 5
input coordinate list (STDIN): 

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


(Terminate interactive list with <cntl>-D)
500.7361 516.321  
Convert image pixels to sky coordinates
  500.7361            516.321             22:59:07.2          58:37:14.0        
<cntl-d>
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.

Documentation on IRAF WCS coordinate conversions (help wcscoords ) for a decription of the coordinate conversions within IRAF.

See also help rimcursor ,

help tvlabel , and

help xexamine and help

wcslab

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


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