$$\varvec{U\!BV\!I}$$ U B V I CCD photometry of Ber

Fundamental astrophysical parameters have been derived for Berkeley 55 (Be 55) open cluster based on the UBVI charge-coupled device (CCD) photometric data observed using a AZT-22 1.5 m telescope at Maidanak Astronomical Observatory (MAO) in Uzbekistan. The mean reddening is obtained as $$E(B-V)=1.77\pm 0.10\,\mathrm {mag}$$ E ( B - V ) = 1.77 ± 0.10 mag from early-type members. The zero-age main sequence fitting in the $$Q_{V\lambda }$$ Q V λ – $$Q'$$ Q ′ diagrams indicates the distance modulus, $$(V_{0}-M_{V})=12.4\pm 0.20\,\mathrm {mag}\,(d=3.02\pm 0.28\,\mathrm {kpc}$$ ( V 0 - M V ) = 12.4 ± 0.20 mag ( d = 3.02 ± 0.28 kpc ). This photometric distance is consistent with the distances of Gaia EDR3 ( $$d = 3.09 \pm 0.16\,\mathrm {kpc}$$ d = 3.09 ± 0.16 kpc ) and period–luminosity relation ( $$d =$$ d = 2.78 ± 0.32 kpc) of its Cepheid S 5 within the uncertainties. This distance also locates the cluster near the Perseus spiral arm. The Geneva isochrone fittings to the Hertzsprung–Russell diagram and observational colour–magnitude diagrams derive turn-off age, 85 ± 13 Myr, by taking care of five red supergiants/bright giants. The possible inconsistencies in the locations of the bright giants with the rotating/non-rotating isochrones may be due to both the age spread of stars in young open clusters and the diversity in rotational velocities.