Realization of the U B V R I system on the 2-m telescope of NAO "Rozhen"  
 

U: 2mm UG1   + 1mm BG39
B: 1mm BG14  + 1mm GG11 + 1mm BG23
V: 2mm GG495 + 1mm BG39
R: 1mm OG570 + 2mm KG3    Rem.: Till Maj'2000
   2mm OG570 + 1mm KG3          After Maj'2000
I: 3mm RG9
 

    Rem.: The information is from Dr. Tsvetan Georgiev

E-mail:  petrov@astro.bas.bg
http://www.astro.bas.bg/~petrov