Modelling of Infrared emission from Cyg X-3 and the UKIRT IRCAM3 point   spread function
  Modelling of the point spread function of the UKIRT IRCAM3 array was conducted in order to test any extended emission around the X-ray binary Cyg X-3. We found that the point spread function cannot be represented by a simple Gaussian, but modelling of the stars required additional functions namely Lorrentzian and exponential components. After modelling for the PSF, we found that Cyg X-3 could be represented by two stellar-type profiles, 0.56" apart. 
R.N. Ogley, S.J. Bell Burnell, R.P. Fender