Slicing an EISCube

Slicing an EISCube using real-world coordinates

>>> import eispac
>>> import astropy.units as u
>>> from astropy.coordinates import SkyCoord, SpectralCoord
>>> from astropy.wcs.utils import wcs_to_celestial_frame

>>> data_filename = 'eis_20190404_131513.data.h5'
>>> data_cube = eispac.read_cube(data_filename, 195.119)
>>> eis_frame = wcs_to_celestial_frame(data_cube.wcs)
>>> lower_left = [SpectralCoord(195.0, unit=u.angstrom),
...               SkyCoord(Tx=48, Ty=225, unit=u.arcsec, frame=eis_frame)]
>>> upper_right = [SpectralCoord(195.3, unit=u.AA),
...                SkyCoord(Tx=165, Ty=378, unit=u.arcsec, frame=eis_frame)]
>>> data_cutout = data_cube.crop(lower_left, upper_right)

>>> data_cube.dimensions
[512, 87, 24] pix

>>> data_cutout.dimensions
[154, 48, 14] pix