300B (I) 

on-telescope measurements by RAS, 1995; IJL & KGB, 1999
   3800      0.70        
   4000      0.73       
   4200      0.73       
   4400      0.72       
   4600      0.68       
   4800      0.68    
   5000      0.67    
   5200      0.65    
   5400      0.60    
   5600      0.57    
   5800      0.55    
   6000      0.51    
   6200      0.48    
   6400      0.45   
   6600      0.45    
   6800      0.41    
   7000      0.38
   7200      0.35
   7400      0.34
   7600      0.32
   7800      0.30
   8000      0.30