class_docstr: File handler for NC seviri files.
  
  **Calibration**
  
  See :mod:`satpy.readers.seviri_base`. Note that there is only one set of
  calibration coefficients available in the netCDF files and therefore there
  is no `calib_mode` argument.
  
  **Metadata**
  
  See :mod:`satpy.readers.seviri_base`.
docstr: Get actual satellite position in geodetic coordinates (WGS-84).
  
  Evaluate orbit polynomials at the start time of the scan.
  
  Returns: Longitude [deg east], Latitude [deg north] and Altitude [m]
code: def satpos(self):
      """Get actual satellite position in geodetic coordinates (WGS-84).
  
      Evaluate orbit polynomials at the start time of the scan.
  
      Returns: Longitude [deg east], Latitude [deg north] and Altitude [m]
      """
      start_times_poly = get_cds_time(
          days=self.nc["orbit_polynomial_start_time_day"].values,
          msecs=self.nc["orbit_polynomial_start_time_msec"].values,
      )
      end_times_poly = get_cds_time(
          days=self.nc["orbit_polynomial_end_time_day"].values,
          msecs=self.nc["orbit_polynomial_end_time_msec"].values,
      )
      orbit_polynomials = {
          "StartTime": np.array([start_times_poly]),
          "EndTime": np.array([end_times_poly]),
          "X": self.nc["orbit_polynomial_x"].values,
          "Y": self.nc["orbit_polynomial_y"].values,
          "Z": self.nc["orbit_polynomial_z"].values,
      }
      poly_finder = OrbitPolynomialFinder(orbit_polynomials)
      orbit_polynomial = poly_finder.get_orbit_polynomial(
          self.start_time
      )
      return get_satpos(
          orbit_polynomial=orbit_polynomial,
          time=self.start_time,
          semi_major_axis=self.mda["projection_parameters"]["a"],
          semi_minor_axis=self.mda["projection_parameters"]["b"],
      )
  
imports: import datetime
  import logging
  from datetime import timedelta
  import numpy
  from satpy._compat import cached_property
  from satpy.readers._geos_area import get_area_definition, get_geos_area_naming
  from satpy.readers.eum_base import get_service_mode
  from satpy.readers.file_handlers import BaseFileHandler, open_dataset
  from satpy.readers.seviri_base import CHANNEL_NAMES, SATNUM, NoValidOrbitParams, OrbitPolynomialFinder, SEVIRICalibrationHandler, add_scanline_acq_time, get_cds_time, get_satpos, mask_bad_quality, round_nom_time
  from satpy.utils import get_legacy_chunk_size
label_desc: Use image node_id 21 for calling the NCSEVIRIFileHandler obj's underlying member method code with example usage: obj.satpos() and returns: get_satpos