Solar Orbiter/STIX Visibility Imaging

Imports

import pickle
import urllib.request

import astropy.units as apu
import matplotlib.pyplot as plt

from xrayvision.clean import vis_clean
from xrayvision.imaging import vis_psf_map, vis_to_map
from xrayvision.mem import mem

Create images from STIX visibility data.

The STIX data has already been prepared and stored in python pickle format the variables can be simply restored.

stix_data = pickle.load(urllib.request.urlopen("https://pub099.cs.technik.fhnw.ch/demo/stix_vis.pkl"))

time_range, energy_range, offset, stix_vis = stix_data
stix_vis.offset = offset

Lets have a look at the point spread function (PSF) or dirty beam

psf_map = vis_psf_map(stix_vis, shape=(129, 129) * apu.pixel, pixel_size=2 * apu.arcsec, natural=False)
psf_map.plot()

/home/docs/checkouts/readthedocs.org/user_builds/xrayvision/envs/latest/lib/python3.9/site-packages/sunpy/map/mapbase.py:892: SunpyMetadataWarning: Missing metadata for observation time, setting observation time to current time. Set the 'DATE-AVG' FITS keyword to prevent this warning.
  warn_metadata("Missing metadata for observation time, "
INFO: Missing metadata for solar radius: assuming the standard radius of the photosphere. [sunpy.map.mapbase]
/home/docs/checkouts/readthedocs.org/user_builds/xrayvision/envs/latest/lib/python3.9/site-packages/sunpy/map/mapbase.py:633: SunpyMetadataWarning: Missing metadata for observer: assuming Earth-based observer.
For frame 'heliographic_stonyhurst' the following metadata is missing: hglt_obs,dsun_obs,hgln_obs
For frame 'heliographic_carrington' the following metadata is missing: crln_obs,dsun_obs,crlt_obs

  obs_coord = self.observer_coordinate

<matplotlib.image.AxesImage object at 0x7f53c04a4a30>

Back projection

backproj_map = vis_to_map(stix_vis, shape=(129, 129) * apu.pixel, pixel_size=2 * apu.arcsec, natural=False)
backproj_map.plot()

/home/docs/checkouts/readthedocs.org/user_builds/xrayvision/envs/latest/lib/python3.9/site-packages/sunpy/map/mapbase.py:892: SunpyMetadataWarning: Missing metadata for observation time, setting observation time to current time. Set the 'DATE-AVG' FITS keyword to prevent this warning.
  warn_metadata("Missing metadata for observation time, "
INFO: Missing metadata for solar radius: assuming the standard radius of the photosphere. [sunpy.map.mapbase]
/home/docs/checkouts/readthedocs.org/user_builds/xrayvision/envs/latest/lib/python3.9/site-packages/sunpy/map/mapbase.py:633: SunpyMetadataWarning: Missing metadata for observer: assuming Earth-based observer.
For frame 'heliographic_stonyhurst' the following metadata is missing: hglt_obs,dsun_obs,hgln_obs
For frame 'heliographic_carrington' the following metadata is missing: crln_obs,dsun_obs,crlt_obs

  obs_coord = self.observer_coordinate

<matplotlib.image.AxesImage object at 0x7f53be3c9580>

Clean

clean_map, model_map, resid_map = vis_clean(
    stix_vis, shape=[129, 129] * apu.pixel, pixel=[2, 2] * apu.arcsec, niter=100, clean_beam_width=20 * apu.arcsec
)
clean_map.plot()

/home/docs/checkouts/readthedocs.org/user_builds/xrayvision/envs/latest/lib/python3.9/site-packages/sunpy/map/mapbase.py:892: SunpyMetadataWarning: Missing metadata for observation time, setting observation time to current time. Set the 'DATE-AVG' FITS keyword to prevent this warning.
  warn_metadata("Missing metadata for observation time, "
INFO: Missing metadata for solar radius: assuming the standard radius of the photosphere. [sunpy.map.mapbase]
/home/docs/checkouts/readthedocs.org/user_builds/xrayvision/envs/latest/lib/python3.9/site-packages/sunpy/map/mapbase.py:633: SunpyMetadataWarning: Missing metadata for observer: assuming Earth-based observer.
For frame 'heliographic_stonyhurst' the following metadata is missing: hglt_obs,dsun_obs,hgln_obs
For frame 'heliographic_carrington' the following metadata is missing: crln_obs,dsun_obs,crlt_obs

  obs_coord = self.observer_coordinate

<matplotlib.image.AxesImage object at 0x7f53be33bfd0>

MEM

mem_map = mem(stix_vis, shape=[129, 129] * apu.pixel, pixel=[2, 2] * apu.arcsec)
mem_map.plot()

/home/docs/checkouts/readthedocs.org/user_builds/xrayvision/envs/latest/lib/python3.9/site-packages/sunpy/map/mapbase.py:892: SunpyMetadataWarning: Missing metadata for observation time, setting observation time to current time. Set the 'DATE-AVG' FITS keyword to prevent this warning.
  warn_metadata("Missing metadata for observation time, "
INFO: Missing metadata for solar radius: assuming the standard radius of the photosphere. [sunpy.map.mapbase]
/home/docs/checkouts/readthedocs.org/user_builds/xrayvision/envs/latest/lib/python3.9/site-packages/sunpy/map/mapbase.py:633: SunpyMetadataWarning: Missing metadata for observer: assuming Earth-based observer.
For frame 'heliographic_stonyhurst' the following metadata is missing: hglt_obs,dsun_obs,hgln_obs
For frame 'heliographic_carrington' the following metadata is missing: crln_obs,dsun_obs,crlt_obs

  obs_coord = self.observer_coordinate

<matplotlib.image.AxesImage object at 0x7f53be2b9490>

Comparison

fig = plt.figure(figsize=(10, 10))
fig.add_subplot(221, projection=psf_map)
fig.add_subplot(222, projection=backproj_map)
fig.add_subplot(223, projection=clean_map)
fig.add_subplot(224, projection=mem_map)
axs = fig.get_axes()
psf_map.plot(axes=axs[0])
axs[0].set_title("PSF")
backproj_map.plot(axes=axs[1])
axs[1].set_title("Back Projection")
clean_map.plot(axes=axs[2])
axs[2].set_title("Clean")
mem_map.plot(axes=axs[3])
axs[3].set_title("MEM")
plt.show()