Smoothly Broken Power Law Spectra of Gamma-Ray Bursts
  A five-parameter expression for a smoothly broken power law is presented. It is used to fit Gamma-Ray Burst (GRB) spectra observed by BATSE. The function is compared to previously used four-parameter functions, such as a sharply broken power law and the Band et al. (1993) function. The presented function exists as a WINGSPAN routine at http://www.astro.su.se/~felix/wing.html 
Felix Ryde