class_docstr: SEVIRI calibration algorithms.
class_docstr_tok: ["SEVIRI","calibration","algorithms","."]
docstr: Convert spectral radiance to brightness temperature.
docstr_tok: ["Convert","spectral","radiance","to","brightness","temperature","."]
code: def _srads2bt(self, data, channel_name):
      """Convert spectral radiance to brightness temperature."""
      a__, b__, c__ = BTFIT[channel_name]
      wavenumber = CALIB[self._platform_id][channel_name]["VC"]
      temp = self._tl15(data, wavenumber)
  
      return a__ * temp * temp + b__ * temp + c__
  
imports: from __future__ import annotations
  import warnings
  from datetime import datetime, timedelta
  import dask.array
  import numpy
  import pyproj
  from numpy.polynomial.chebyshev import Chebyshev
  from satpy.readers.eum_base import issue_revision, time_cds_short
  from satpy.readers.utils import apply_earthsun_distance_correction
  from satpy.utils import get_legacy_chunk_size
label_desc: Use image node_id 5 for calling the SEVIRICalibrationAlgorithm obj's underlying member method code with example usage: obj._srads2bt(data, channel_name) and returns: unknown