Loading an HMI synoptic map#

In this example we load a synoptic map produced by the HMI team. This data is an interesting demonstration of sunpy’s Map class as it is not in the more common Helioprojective coordinate system, but in heliographic Carrington coordinates and a cylindrical equal area (CEA) projection.

import matplotlib.pyplot as plt

from astropy.utils.data import download_file

import sunpy.map

Download the file and read it into a Map.

filename = download_file(
    'http://jsoc.stanford.edu/data/hmi/synoptic/hmi.Synoptic_Mr.2191.fits', cache=True)
syn_map = sunpy.map.Map(filename)

Plot the results.

fig = plt.figure(figsize=(12, 5))
ax = plt.subplot(projection=syn_map)
im = syn_map.plot(axes=ax)

ax.coords[0].set_axislabel("Carrington Longitude [deg]")
ax.coords[1].set_axislabel("Latitude [deg]")

ax.coords.grid(color='black', alpha=0.6, linestyle='dotted', linewidth=0.5)

cb = plt.colorbar(im, fraction=0.019, pad=0.1)
cb.set_label(f"Radial magnetic field [{syn_map.unit}]")

# In order to make the x-axis ticks show, the bottom y-limit has to be adjusted slightly
ax.set_ylim(bottom=0)
ax.set_title(f"{syn_map.meta['content']},\n"
             f"Carrington rotation {syn_map.meta['CAR_ROT']}")

plt.show()
Carrington Synoptic Chart Of Br Field, Carrington rotation 2191
INFO: Missing metadata for solar radius: assuming the standard radius of the photosphere. [sunpy.map.mapbase]
/home/docs/checkouts/readthedocs.org/user_builds/sunpy/conda/stable/lib/python3.10/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: crlt_obs,dsun_obs,crln_obs

  obs_coord = self.observer_coordinate

Total running time of the script: (0 minutes 2.053 seconds)

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