GalsimWCS

class snappl.wcs.GalsimWCS(gsimwcs=None)

Bases: BaseWCS

A WCS speicifc to Galsim.

Methods Summary

from_header(header)	Create a GalsimWCS from a FITS header.
get_galsim_wcs()	Return a glasim.AstropyWCS object, if possible.
pixel_to_world(x, y)	Go from (x, y) coordinates to ICRS (ra, dec)
to_fits_header()	Return an astropy.io.fits.Header object, if possible, with the WCS in it.
world_to_pixel(ra, dec)	Go from (ra, dec) coordinates to (x, y)

Methods Documentation

classmethod from_header(header)

Create a GalsimWCS from a FITS header.

Does TAN-TPV conversion the same as AstropyWCS.from_header.

Parameters:

header (astropy.io.fits.header.Header) – See AstropyWCS.from_header

Return type:

GalsimWCS

get_galsim_wcs()

Return a glasim.AstropyWCS object, if possible.

pixel_to_world(x, y)

Go from (x, y) coordinates to ICRS (ra, dec)

Parameters:

• x (float or sequence of float) – The x position on the image. The center of the lower-left pixel is at x=0.0

• y (float or sequence of float) – The y position on the image. The center of the lower-left pixle is y=0.0

Returns:

• ra, dec (floats or arrays of floats, decimal degrees)

• You will get back two floats if x an y were floats. If x and

• y were lists (or other sequences), you will get back two numpy

• arrays of floats.

to_fits_header()

Return an astropy.io.fits.Header object, if possible, with the WCS in it.

world_to_pixel(ra, dec)

Go from (ra, dec) coordinates to (x, y)

Parameters:

• ra (float or sequence of float) – RA in decimal degrees

• dec (float or sequence of float) – Dec in decimal degrees

Returns:

• x, y (floats or arrays of floats)

• Pixel position on the image; the center of the lower-left pixel is (0.0, 0.0).

• If ra and dec were floats, x and y are floats. If ra and dec

• were sequences of floats, x and y will be numpy arrays of floats.