class_docstr: Reader class for VII L1B products in netCDF format.
class_docstr_tok: ["Reader","class","for","VII","L1B","products","in","netCDF","format","."]
docstr: Perform the calibration to brightness temperature.
  
  Args:
      radiance: numpy ndarray containing the radiance values.
      cw: center wavelength [μm].
      a: temperature coefficient [-].
      b: temperature coefficient [K].
  
  Returns:
      numpy ndarray: array containing the calibrated brightness temperature values.
docstr_tok: ["Perform","the","calibration","to","brightness","temperature",".","Args",":","radiance",":","numpy","ndarray","containing","the","radiance","values",".","cw",":","center","wavelength","[","\u03bcm","]",".","a",":","temperature","coefficient","[","-","]",".","b",":","temperature","coefficient","[","K","]",".","Returns",":","numpy","ndarray",":","array","containing","the","calibrated","brightness","temperature","values","."]
code: def _calibrate_bt(radiance, cw, a, b):
      """Perform the calibration to brightness temperature.
  
      Args:
          radiance: numpy ndarray containing the radiance values.
          cw: center wavelength [μm].
          a: temperature coefficient [-].
          b: temperature coefficient [K].
  
      Returns:
          numpy ndarray: array containing the calibrated brightness temperature values.
  
      """
      log_expr = np.log(1.0 + C1 / ((cw**5) * radiance))
      bt_values = b + (a * C2 / (cw * log_expr))
      return bt_values
  
file_path: satpy/satpy/readers/vii_l1b_nc.py
imports: import logging
  import numpy
  from satpy.readers.vii_base_nc import ViiNCBaseFileHandler
  from satpy.readers.vii_utils import C1, C2, MEAN_EARTH_RADIUS
label_desc: Use image node_id 4 for calling the ViiL1bNCFileHandler obj's underlying member method code with example usage: obj._calibrate_bt(radiance, cw, a, b) and returns: bt_values