Name

---

    SKY2XY

Purpose

---

    Converts between sky coordinates and pixel coordinates of a FITS image
    using the WCSTOOLS sky2xy routine. Useful for images with WCS keywords
    that are not implemented in the astronomy library (such as the TNX
    convention for distortions).

Category

---

    Astro

Calling Sequence

---

    Result = SKY2XY(FITSFile, Ra, Dec)

Inputs

---

    FITSFile: Name of FITS file that contains the WCS to use.
    Ra: Vector of right ascensions. Assumed to be in decimal degrees unless
          /STRING is set.
    Dec: Vector of declinations. Assumed to be in decimal degrees unless
          /STRING is set.

Keyword Parameters

---

    STRING: If set, Ra and Dec are strings in HH:MM:SS, DD:MM:SS format.
    WCSTOOLSDIR: Path to the location of the binary sky2xy files in wcstools.

Outputs

---

    The function returns a structure with fields .X and .Y which are arrays
    containing the x and y pixel values.

Notes

---

    Requires WCSTOOLS to be installed, along with the UWashington TMPFILE
    and DIR_EXIST routines.

Modification History

---

    Written by: Jeremy Bailin
    20 August 2010 Initial release
    10 Feb 2011 Made WCSTOOLSDIR a keyword parameter.