We have obtained deep B and R -band CCD photometry for five dwarf elliptical galaxies that were previously identified on Schmidt films covering the region of the Centaurus A ( Cen A ) group .
From a Fourier analysis of the R -band CCD images we determined the surface brightness fluctuation ( SBF ) magnitude \bar { m } _ { R } for each stellar system .
All magnitudes are similar and , given the small colour spread , suggest that these low surface brightness galaxies lie approximately at the same distance , regardless of the assumed SBF zero point .
Long-slit spectra have been acquired to derive redshifts for two of the dwarfs , ESO269-066 and ESO384-016 .
The velocities , v _ { \odot } = 784 km s ^ { -1 } and v _ { \odot } = 561 km s ^ { -1 } , respectively , identify them unambiguously as Cen A group members .
An age ( H \delta _ { \mbox { A } } ) – metallicity ( C _ { 2 } \lambda 4668 ) analysis of the spectra reveals an underlying old and metal-poor stellar population in both cases .
Combining photometric and spectroscopic results we find strong evidence that indeed all dwarf galaxies are Cen A group members .

Based on Cepheid , TRGB , and PNLF distances published for the two main Cen A group galaxies NGC5128 and NGC5253 , we adopted a mean group distance of 3.96 Mpc to calibrate the apparent fluctuation magnitudes .
The resulting absolute SBF magnitudes \bar { M } _ { R } of the dEs correlate with the dereddened colours ( B - R ) _ { 0 } as predicted by Worthey ’ s stellar synthesis models using the theoretical isochrones of Bertelli and collaborators .
This good agreement allows a calibration of the SBF method for dwarf ellipticals in the colour range 0.8 < ( B - R ) _ { 0 } < 1.5 .
However , two branches of stellar populations appear in the \bar { M } _ { R } -colour plane , and care has to be taken to decide which branch applies to a given observed dwarf .
For dwarfs with ( B - R ) _ { 0 } < 1 there is very little colour dependence ( \bar { M } _ { R } \approx - 1.2 ) , in accord with our previous SBF analysis of faint , blue Sculptor group dEs .
For red dwarfs , ( B - R ) _ { 0 } > 1.2 , the \bar { M } _ { R } -colour relation is steep , and accurate colours are needed to achieve SBF distances with an uncertainty of only 10 % .
One of the dwarfs , ESO219-010 , is located slightly behind the core of the Cen A group at \sim 4.8 Mpc , while the remaining four recover the mean group distance of 3.96 Mpc that was put into the calibration .
The depth of the group is only 0.5 Mpc which identifies the Cen A group as a spatially well isolated galaxy aggregate , in contrast to the nearby Sculptor group .