code: def mean_obliquity(jd_tdb):
      
      # Compute time in Julian centuries from epoch J2000.0.
  
      t = (jd_tdb - T0) / 36525.0
  
      # Compute the mean obliquity in arcseconds.  Use expression from the
      # reference's eq. (39) with obliquity at J2000.0 taken from eq. (37)
      # or Table 8.
  
      epsilon = (((( -  0.0000000434   * t
                     -  0.000000576  ) * t
                     +  0.00200340   ) * t
                     -  0.0001831    ) * t
                     - 46.836769     ) * t + 84381.406
  
      return epsilon
docs: Return the mean obliquity of the ecliptic in arcseconds.
  
      `jd_tt` - TDB time as a Julian date float, or NumPy array of floats