class_docstr: Reader class for ICI L1B products in netCDF format.
class_docstr_tok: ["Reader","class","for","ICI","L1B","products","in","netCDF","format","."]
docstr: Perform the calibration to brightness temperature.
  
  Args:
      radiance: xarray DataArray or numpy ndarray containing the
          radiance values.
      cw: center wavenumber [cm-1].
      a: temperature coefficient [-].
      b: temperature coefficient [K].
  
  Returns:
      DataArray: array containing the calibrated brightness
          temperature values.
code: def _calibrate_bt(radiance, cw, a, b):
      """Perform the calibration to brightness temperature.
  
      Args:
          radiance: xarray DataArray or numpy ndarray containing the
              radiance values.
          cw: center wavenumber [cm-1].
          a: temperature coefficient [-].
          b: temperature coefficient [K].
  
      Returns:
          DataArray: array containing the calibrated brightness
              temperature values.
  
      """
      return b + (a * C2 * cw / np.log(1 + C1 * cw**3 / radiance))
  
imports: import logging
  from datetime import datetime
  from enum import Enum
  from functools import cached_property
  import dask.array
  import numpy
  import xarray
  from geotiepoints.geointerpolator import GeoInterpolator
  from satpy.readers.netcdf_utils import NetCDF4FileHandler
label_desc: Use image node_id 19 for calling the IciL1bNCFileHandler obj's underlying member method code with example usage: obj._calibrate_bt(radiance, cw, a, b) and returns: unknown