Class WCS

x.__init__(...) initializes x; see x.__class__.__doc__ for signature

Parameters:

• header - A PyFITS header object or a string containing the raw FITS header data.
• key - The key referring to a particular WCS transform in the header. This may be either ' ' or 'A'-'Z' and corresponds to the "a" part of "CTYPEia".
• relax - Degree of permissiveness:
  • False: Recognize only FITS keywords defined by the published WCS standard.
  • True: Admit all recognized informal extensions of the WCS standard.

Raises:

• MemoryError - Memory allocation failed.
• ValueError - Invalid key.
• KeyError - Key not found in FITS header.

Overrides: object.__init__

(inherited documentation)

Transforms world coordinates to pixel coordinates. pixel2world is a convenience wrapper around p2s. If intermediate values from the transform are needed, use the more complex p2s directly.

Parameters:

• x (array of double) - Array of x pixel coordinates, or if y is not provided, a 2-dimensional array of both x- and y-coordinates. Pixel coordinates are zero based.
• y (array of double or None) - Array of y pixel coordinates. If provided, x must be 1-dimensional and the same length as y.

Returns: world

If both x and y were provided, a 2-tuple of arrays, where the first element is latitude coordinates and the second element is longitude coordinates. Otherwise, a single 2D array containing both latitude and longitude.

Transforms world coordinates to pixel coordinates. world2pixel is a convenience wrapper around s2p. If intermediate values from the transform are needed, use the more complex s2p directly.

Parameters:

• ra (array of double) - Array of ra world coordinates, or if dec is not provided, a 2-dimensional array of both ra- and dec-coordinates. World coordinates are in decimal degrees.
• dec (array of double or None) - Array of dec world coordinates. If provided, ra must be 1-dimensional and the same length as dec.

Returns: pixel

If both ra and dec were provided, a 2-tuple of arrays, where the first element is x coordinates and the second element is y coordinates. Otherwise, a single 2D array containing both x and y. Pixel coordinates are zero-based.