FREGCON (Feb96)              ftools.heasarc              FREGCON (Feb96)



NAME
    fixregion --> image region file converter from  the  image  file  it
    was extracted, to another instrument/detector system.
    
    
USAGE
    regfile 1 imgfile convfile[extnum] out_regfile
    
    or
    
    regfile  2  cdelt1  cdelt2 crpix1 crpix2 crval1 crval2 crota2 ctype1
    convfile[extnum] out_regfile
    
    
DESCRIPTION
    This  task  converts  a  region  from  one   system   (system1)   of 
    observation  to another (system2) based on the reference coordinates
    in  the FITS files of the two systems of observations.   The  region
    file  is produced by SAOimage and save the image file before exiting
    SAOimage.  This image file is then input  file  for  the  converter.
    The  convfile  is  the  file  containing  the coordinate information
    (CDELT*, CRPIX*, CRVAL*, CROTA*, CTYPE*) to be converted to.   NOTE:
    BE  SURE  WHILE RUNNING FIXREGION, THIS FILE SHOULD BE SUPPLIED WITH
    APPROPRIATE   EXTENSION   NUMBER   (e.g.   filename[extnum]).    The  
    usefulness  of the region converter is that selected region from one
    image file can be used in another  system,  provided  the  reference
    coordinates  in  both systems are known.  The maximum no. of regions
    to be selected in the region file is 40.  This  task  is  introduced
    to  mask  nearby sources.  The acceptable shapes for the regions are
    the following:
    
    circle
    box
    ellipse
    point
    annulus
    
    The following reference keywords and their values are read from the FITS files.
    
    They are passed to the ftwldp.f and xy2sky.f routines which compute the new
    coordinates.
    
    CRPIX1  =  X axis reference pixel
    CRPIX2  =  Y axis reference pixel
    CRVAL1  =  Sky coord of X ref pixel (degrees)
    CRVAL2  =  Sky coord of Y ref pixel (degrees)
    CDELT1  =  X axis increment (degrees)
    CDELT2  =  Y axis increment (degrees)
    CROTA2  =  Rotation angle
    CTYPE1  =  RA projection type 
    
    If the input system1 file (imgfile) is not present then it asks for these 
    relevant keywords from the user.  
    
    
    
    
PARAMETERS
    
    regfile [character string]
        The region file containing region file data to be converted.
    
    option [integer]
        Either 1 or 2 depending on if one has the image file  (option=1)
        or  if  one  supplies  the  coordinates  CRPIX*, CRVAL*, CDELT*,
        CROTA2, CTYPE1 (option=2) of the image file  from  which  region
        is being extracted.
    
    imgfile [character string]
        The  input  FITS  file  for  system1  coordinate  system  to  be 
        converted from.
    
    convfile [character string]
        The  input  FITS  file  for  system2  coordinate  system  to  be 
        converted to WITH EXTENSION NUMBER.
    
    out_regfile [character string]
        The output file containing converted region file data.
    
    cdelt1 [real]
        X-axis increment value.
    
    cdelt2 [real]
        Y-axis increment value.
    
    crpix1 [real]
        X-axis reference pixel
    
    crpix2 [real]
        Y-axis reference pixel
    
    crval1 [real] 
        Sky coordinate of X reference pixel in degrees
    
    crval2 [real]
        Sky coordinate of Y reference pixel in degrees
    
    crota2 [real] 
        Rotation angle
    
    ctype1 [character string]
        Type of projection for RA.  e.g. -TAN,-SIN etc.
    
    (chatter=9) [integer]
        Flag  to  set the chattyness at execution.  Default value is set
        to 9, which gives the user the task version  and  few  warnings.
        Lower/higher  values  produces  quieter/verbose  output  on  the 
        screen.
    
    (clobber = false) [boolean]
        Flag specifying whether or not  a  pre-existing  file  with  the
        same  name  as  that requested as the output file from this task
        will be overwritten.
    
    
BUGS
    None known. The convfile should be used with  its  extension  number
    where the coordinate information to be found.
    
    
SEE ALSO
    help on fregcon, ftwldp.f, xy2sky.f
    
    
EXAMPLE:
    
    For  example,  if  the  region filename is REG.IN, image filename is
    REG.IMG, the convfile name is CONV.FITS with primary  extension  for
    coordinate  information,  the outfile name REG.OUT, then the command
    line
    
    
    fixregion reg.in 1 reg.img[0] convfile=conv.fits out_regfile=reg.out
    
    
LOG OF SIGNIFICANT CHANGES:
    v1.1.0 (July, 1996) provision to handle any type of convfile
    v1.0.0 (May, 1996) created
    
    
PRIMARY AUTHOR:
    Banashree Mitra Seifert
    HEASARC, NASA/GSFC
    http://heasarc.gsfc.nasa.gov/cgi-bin/ftoolshelp
    (301).286.5307