Plotting fits image with matplotlib.imshow with WCS as x and y axes

Question

I was wondering if anyone knew how to plot a fits image with the python package matplotlib.imshow with the corresponding world coordinate system values or perhaps even Right Ascension or Declination as the x and y values rather than the physical pixel values, similar to the bottom plot of this page: http://astroplotlib.stsci.edu/page_images.htm

Unfortunately, the script provided is in IDL...something I am not yet proficient in...

It would probably be helpful if I outlined my gridspec layout:

fig = pyplot.figure(figsize=(11,11))

gridspec_layout = gridspec.GridSpec(3,3)
gridspec_layout.update(hspace=0.0, wspace=0.0)

hdulist_org_M33_UVM2 = fits.open('myfits.fits')
wcs = WCS(hdulist_org_M33_UVM2[0].header)

pyplot_2 = fig.add_subplot(gridspec_layout[2])

ax = WCSAxes(fig, [0.1, 0.1, 0.8, 0.8], wcs=wcs)

pyplot_2.add_axes(ax)

But to no luck.

Many thanks.

Answer 1

One solution might be to use the subplot parameter to FITSFigure, and obtain the bounds from your gridspec.

Something along the following lines:

from matplotlib import pyplot
from matplotlib import gridspec
import aplpy

fig = pyplot.figure(figsize=(11, 11))
gridspec_layout = gridspec.GridSpec(3, 3)
gridspec_layout.update(hspace=0.0, wspace=0.0)
axes = fig.add_subplot(gridspec_layout[2])
m33 = aplpy.FITSFigure('wfpcii.fits', figure=fig,
                       subplot=list(gridspec_layout[2].get_position(fig).bounds),
                       # dimensions and slices are not normally necessary;
                       # my test-figure has 3 axes
                       dimensions=[0, 1], slices=[0])
print(dir(gridspec_layout[2]))
print(gridspec_layout[2].get_position(fig).bounds)
m33.show_colorscale()
pyplot.show()

Not really pretty, but it'll work. if I come across an easier way to attach a FITSFigure directly to an axes, I'll amend this answer or put a new one.