1imwcs(1)(WCSTools)                                          imwcs(1)(WCSTools)
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Name

6       imwcs - Set WCS in FITS and IRAF image files
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Synopsis

9       imwcs [options] FITS or IRAF filename
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Description

12       imwcs  (pronounced im-W-C-S) is a utility for setting the world coordi‐
13       nate system (WCS) of a FITS or IRAF image. The WCS is the  relationship
14       between  sky  coordinates  and  image  pixels and can be described in a
15       standard way in the header of an  image.  The  program  was  originally
16       written  at  the University of Iowa, but has been adapted and amplified
17       by Doug Mink at the Smithsonian Astrophysical Observatory.
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19       imwcs currently works only on images where the rotation about the  cen‐
20       ter  is  known  to  within a few degrees It has been tested extensively
21       only on images with near-zero rotation.
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23       A plane-tangent projection (center  right  ascension  and  declination,
24       plate  scale, and rotation angle) is fit based on matches between stars
25       in the image and stars in a reference catalog. The HST Guide Star Cata‐
26       log,  the  USNO  A 1.0, SA 1.0, or UJ Catalog, or a user-supplied, tab-
27       delimited Starbase catalog may be used.
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Options

31       -a <angle>
32              Initial rotation angle in degrees (default 0)
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34       -b <RA> <Dec>
35              Initial center in B1950 (FK4) RA and  Dec  (default=RA,DEC  from
36              file)
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38       -c <catalog name>
39              Reference  catalog  (gsc(=HST  GSC), ua2(=USNO-A2.0), TMC(=2MASS
40              Point Source Catalog),  gsc2(=GSC  II),  ub1(=USNO-B1.0),  local
41              file, etc.)
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43       -d <catalog name>
44              Use  this  DAOFIND output catalog of X, Y, and magnitude instead
45              of searching for stars in  the  image.   The  format  is  simply
46              white-space-separated  X,  Y,  and magnitue on a line, with # at
47              the beginning of comment lines.
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49       -e     Erase image WCS keywords, getting initial WCS from command line
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51       -f     Write FITS output no matter what input
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53       -g <class>
54              Guide Star Catalog class (-1=all,0,3) (default -1)
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56       -h <number>
57              Change the maximum number of reference stars to match from 25 to
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59       -i <counts>
60              Minimum  peak  value  for  star  in  image.   If  negative,  use
61              -<counts> standard deviations as minimum.
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63       -j <RA> <Dec>
64              Initial  center  in  J2000 (FK5) RA and Dec (default=RA,DEC from
65              file)
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67       -k <magnum>
68              Use this magnitude to sort brightest catalog stars.
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70       -l     Reflect left<->right before rotating and fitting
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72       -m [<bright magnitude>] <faint magnitude>
73              Limiting catalog magnitude(s) (default none, bright -2  if  only
74              faint is given)
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76       -n <number>
77              Number  of parameters to fit (1-8, or digit string). The default
78              is 2 (RA+Dec) if <3 stars are matched, 3  (RA+Dec+scale)  if  <5
79              stars  are  matched,  or 4 (RA+Dec+scale+rot) if 5 or more stars
80              are matched.  Alternatively this may be a list  of  all  of  the
81              parameters to fit, in the form nnnnnn.., where 1=RA, 2=Dec, 3=RA
82              scale, 4=Dec scale, 5=rotation  angle,  6=Y  axis  rotation  (CD
83              matrix), 7=RA reference pixel, and 8=Dec reference pixel.
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85       -o <filename>
86              Write  output to this file; may be the same as input file.  This
87              option automatically sets the -w option to write the file.
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89       -p <scale>
90              Initial plate scale in arcsec per pixel (default 0)
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92       -q <option list>
93              <i>terate, <r>ecenter, <s>igma clip,  <p>olynomial,  <t>olerance
94              reduce  (half for each iteration).  A number following an option
95              repeats the option that many times.
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97       -r <angle>
98              Rotation angle in degrees  before  fitting  (0,  90,  180,  270)
99              (default 0)
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101       -s <frac>
102              Use this fraction extra stars (default 1.0)
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104       -t <num>
105              Offset tolerance in pixels (default 20)
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107       -u <file>
108              -u: File of X Y RA Dec assignments for initial WCS
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110       -v     Verbose listing of processing intermediate results
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112       -w     Write  WCS to a new file (default is read-only) -x X and Y coor‐
113              dinates of reference pixel (default is image center) -y multiply
114              image  dimensions  by this for search (default is 1) -z Use AIPS
115              classic projections instead of WCSLIB; use CD  matrix  or  CDELT
116              instead of polynomial solution.
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Web Page

120       http://tdc-www.harvard.edu/software/wcstools/imwcs/
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Author

124       Doug Mink, SAO (dmink@cfa.harvard.edu)
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128                                30 January 2003             imwcs(1)(WCSTools)
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