docs: def calibration(date, satellite):
      """
      Return the calibration dictionary.
  
      Keyword arguments:
      satellite -- the name of the satellite.
      date --  the datetime of an image.
      """
      counts_shift = CountsShift()
      space_measurement = SpaceMeasurement()
      prelaunch = PreLaunch()
      postlaunch = PostLaunch()
      return {
          'counts_shift': counts_shift.coefficient(satellite),
          'space_measurement': space_measurement.coefficient(satellite),
          'prelaunch': prelaunch.coefficient(satellite),
          'postlaunch': postlaunch.coefficient(date, satellite)
      }