code: def celToGal(ra, dec):
      
      dec = np.radians(dec)
      sin_dec = np.sin(dec)
      cos_dec = np.cos(dec)
  
      ra = np.radians(ra)    
      ra_gp = np.radians(192.85948)
      de_gp = np.radians(27.12825)
  
      sin_ra_gp = np.sin(ra - ra_gp)
      cos_ra_gp = np.cos(ra - ra_gp)
  
      lcp = np.radians(122.932)    
      sin_b = (np.sin(de_gp) * sin_dec) \
              + (np.cos(de_gp) * cos_dec * cos_ra_gp)
      lcpml = np.arctan2(cos_dec * sin_ra_gp,
                            (np.cos(de_gp) * sin_dec) \
                            - (np.sin(de_gp) * cos_dec * cos_ra_gp))
      bb = np.arcsin(sin_b)
      ll = (lcp - lcpml + (2. * np.pi)) % (2. * np.pi)
      return np.degrees(ll), np.degrees(bb)
docs: Converts Celestial J2000 (deg) to Calactic (deg) coordinates