code: def interpret_header(self):
          
          # handle special cases since date-obs field changed names
          if 'DATE_OBS' in self.header:
              self.date = self.header['DATE_OBS']
          elif 'DATE-OBS' in self.header:
              self.date = self.header['DATE-OBS']
          else:
              raise Exception("Image does not have a DATE_OBS or DATE-OBS field")
  
          self.cy, self.cx = self.header['CRPIX1'], self.header['CRPIX2']
          sun_radius_angular = sun.solar_semidiameter_angular_size(t=time.parse_time(self.date)).arcsec
          arcsec_per_pixel = self.header['CDELT1']
          self.sun_radius_pixel = (sun_radius_angular / arcsec_per_pixel)
docs: Read pertinent information from the image headers,
           especially location and radius of the Sun to calculate the default thematic map
          :return: setes self.date, self.cy, self.cx, and self.sun_radius_pixel