class_docstr: JMA HRIT format reader.
  
  By default, the reader uses the start time parsed from the filename. To use exact time, computed
  from the metadata, the user can define a keyword argument::
  
      scene = Scene(filenames=filenames,
                    reader='ahi_hrit',
                    reader_kwargs={'use_acquisition_time_as_start_time': True})
  
  As this time is different for every channel, time-dependent calculations like SZA correction
  can be pretty slow when multiple channels are used.
  
  The exact scanline times are always available as coordinates of an individual channels::
  
      scene.load(["B03"])
      print(scene["B03].coords["acq_time"].data)
  
  would print something similar to::
  
      array(['2021-12-08T06:00:20.131200000', '2021-12-08T06:00:20.191948000',
             '2021-12-08T06:00:20.252695000', ...,
             '2021-12-08T06:09:39.449390000', '2021-12-08T06:09:39.510295000',
             '2021-12-08T06:09:39.571200000'], dtype='datetime64[ns]')
  
  The first value represents the exact start time, and the last one the exact end time of the data
  acquisition.
docstr: Get the area definition of the band.
docstr_tok: ["Get","the","area","definition","of","the","band","."]
code: def _get_area_def(self):
      """Get the area definition of the band."""
      pdict = {
          "cfac": np.int32(self.mda["cfac"]),
          "lfac": np.int32(self.mda["lfac"]),
          "coff": np.float32(self.mda["coff"]),
          "loff": self._get_line_offset(),
          "ncols": int(self.mda["number_of_columns"]),
          "nlines": int(self.mda["number_of_lines"]),
          "scandir": "N2S",
          "a": float(self.mda["projection_parameters"]["a"]),
          "b": float(self.mda["projection_parameters"]["b"]),
          "h": float(self.mda["projection_parameters"]["h"]),
          "ssp_lon": float(
              self.mda["projection_parameters"]["SSP_longitude"]
          ),
          "a_name": AREA_NAMES[self.area_id]["short"],
          "a_desc": AREA_NAMES[self.area_id]["long"],
          "p_id": "geosmsg",
      }
      area_extent = get_area_extent(pdict)
      return get_area_definition(pdict, area_extent)
  
imports: import logging
  from datetime import datetime
  import numpy
  import xarray
  from satpy.readers._geos_area import get_area_definition, get_area_extent
  from satpy.readers.hrit_base import HRITFileHandler, ancillary_text, annotation_header, base_hdr_map, image_data_function
  from satpy.readers.utils import get_geostationary_mask
label_desc: Use image node_id 5 for calling the HRITJMAFileHandler obj's underlying member method code with example usage: obj._get_area_def() and returns: get_area_definition