We have detected , for the first time , Cepheid variables in the Sculptor Group SB ( s ) m galaxy NGC 55 .
From wide-field images obtained in the optical V and I bands during 77 nights in 2002-2003 , we have found 143 Cepheids with periods ranging from 5.6 to 175.9 days .
133 of these objects have periods longer than 10 days , making NGC 55 to-date the galaxy with the largest known number of long-period Cepheids in the Sculptor Group .
We construct period-luminosity relations from our data and obtain distance moduli corrected for the small foreground reddening to NGC 55 of 26.79 \pm 0.04 mag ( internal error ) in V , 26.66 \pm 0.03 mag in I and 26.40 \pm 0.05 mag in the reddening-independent V-I Wesenheit index .
The trend of increasing distance moduli with shorter wavelength hints at the existence of significant reddening intrinsic to NGC 55 which affects the measured Cepheid magnitudes .
From our data , we determine the intrinsic mean reddening of the Cepheids in NGC 55 as E ( B-V ) = 0.102 mag which brings the distance determinations from the different bands into excellent agreement .
Our best distance estimate for NGC 55 from the present optical Cepheid photometry is 26.40 mag \pm 0.05 mag ( internal error ) \pm 0.09 mag ( systematic error ) .
This value is tied to an assumed LMC distance of 18.50 mag .
Our quoted systematic error of the present NGC 55 Cepheid distance does not take into account the current uncertainty on the distance of the fiducial LMC galaxy itself .

Within the small respective uncertainties , the Sculptor Group galaxies NGC 55 and NGC 300 are at the same distance of 1.9 Mpc , strengthening the case for a physical association of these galaxies .