wcs

wcs is a legacy astrometry program from the OCAAS suite that calculates the ‘world coordinate system’ (WCS) parameters for FITS images and write the resulting keywords in the FITS header. It can use either the GSC catalog or the USNO catalog, both of which are installed on deimos in their default folders. Solving for the WCS keywords  allows any FITS display program that understands WCS keywords (e.g. Maxim, DS9, camera) to convert pixel location to celestial coordinates. 

wcs is a command-line program. To run, simply type wcs myfile.fts. It understands wildcards so an entire folder can be solved using the command: wcs *.fts

The optional inputs can be listed using the -h (help) switch:

wcs: usage: [options] [file.fts ...]

  -r dir:  use GSC from cdrom at dir (default is off)

  -c dir:  alternate GSC cache directory (default is archive/catalogs/gsc)

  -n dir:  alternate USNO directory (default is archive/catalogs/usno)

  -v:      verbose

  -i path: alternate ip.cfg file path (default is archive/config/ip.cfg)

  -o:      allow overwriting any existing WCS/astrometry fields

  -w:      write header (default is read-only)

  -d:      delete any WCS/astrometry header fields (requires -w)

  -s:      use USNO SA catalog in addition to GSC  Note: This is incorrect! Use switch -2

  -u rad:  hunt radius, degrees (default is 1)

  -f file: name of file containing filenames.

Version: latest Talon/OCAAS release

Known bugs: The -s switch to use USNO is listed incorrectly: It is -2. 

Sample usage:

DEIMOS:/usr/local/telescope/user/images> wcs -v foc13139.fts

foc13139.fts:

CTYPE1 = RA---TAN

CRVAL1 = 285

CDELT1 = -0.000299338

CRPIX1 = 768

CROTA1 = 0

CTYPE2 = DEC--TAN

CRVAL2 = 30.0004

CDELT2 = -0.000299659

CRPIX2 = 511.5

CROTA2 = 0.329776

AMDX0 = 4.9742              AMDY0 = 0.523605

AMDX1 = -5.22071E-06        AMDY1 = -5.2277E-06

AMDX2 = 3.61122E-08         AMDY2 = -2.83825E-08

AMDX3 = 0.00399005          AMDY3 = 0.00269204

AMDX4 = -2.26798E-12        AMDY4 = -1.7311E-13

AMDX5 = -9.59071E-13        AMDY5 = -2.99642E-12

AMDX6 = -6.16409E-12        AMDY6 = -3.50106E-13

ip.cfg path: archive/config/ip.cfg

    MAXRESID  = 3

    MAXISTARS = 200

    MAXCSTARS = 1200

    BRCSTAR   = 6

    MAXPAIR   = 300

    TRYSTARS  = 12

    MATCHDIST = 6

    REJECTDIST= 3

    ORDER     = 2

found 1228 image stars

RA=19:00:00.0 DEC= 30:00:00 FOV=0.552607

found 171 GSC stars at 19:00:00.0  30:00:00, 171 fainter than mag 6

Fit residual (mean): 0.53 pixels

found 171 GSC stars at 19:00:00.1  30:00:01, 171 fainter than mag 6

Fit residual (mean): 0.55 pixels

Higher order fit residual (rms): 0.77 arcsec

CTYPE1 = RA---TAN

CRVAL1 = 285

CDELT1 = -0.000299361

CRPIX1 = 768

CROTA1 = 0

CTYPE2 = DEC--TAN

CRVAL2 = 30.0004

CDELT2 = -0.00029964

CRPIX2 = 511.5

CROTA2 = 0.332019

AMDX0 = 4.9742              AMDY0 = 0.523605

AMDX1 = -5.2195E-06         AMDY1 = -5.2237E-06

AMDX2 = 4.0019E-08          AMDY2 = -2.96775E-08

AMDX3 = 0.00398904          AMDY3 = 0.00269163

AMDX4 = -2.82073E-12        AMDY4 = -3.41997E-12

AMDX5 = -2.13944E-12        AMDY5 = -3.76238E-12

AMDX6 = -9.2602E-12         AMDY6 = 4.6362E-13

foc13139.fts: no -w -- file unchanged.


© Robert Mutel 2018