We derive the luminosity functions in three bands ( BVR ) for the rich galaxy cluster ABCG 209 at z=0.21 .
The data cover an area of \sim 78 arcmin ^ { 2 } in the B and R bands , while a mosaic of three pointings was obtained in the V band , covering an area of approximately 160 arcmin ^ { 2 } .
The galaxy sample is complete to B = 22.8 ( \mathrm { N _ { gal } } = 339 ) , V = 22.5 ( \mathrm { N _ { gal } } = 1078 ) and R = 22.0 ( \mathrm { N _ { gal } } = 679 ) .
Although the fit of a single Schechter function can not be rejected in any band , the luminosity functions are better described by a sum of two Schechter functions for bright and faint galaxies , respectively .
There is an indication for a presence of a dip in the luminosity functions in the range V = 20.5–21.5 and R = 20.0–21.0 .
We find a marked luminosity segregation , in the sense that the number ratio of bright–to–faint galaxies decreases by a factor 4 from the center to outer regions .
Our analysis supports the idea that ABCG 209 is an evolved cluster , resulting from the merger of two or more sub–clusters .