SIMBAD references

CCD observations in the Johnson V, Kron-Cousins I and the Washington system C and T₁passbands have been used to generate colour-magnitude diagrams (CMDs) reaching down to V ∼ 21.0 mag and T₁∼ 19.0 for Trumpler 5, an old open cluster located towards the Galactic anticentre. Our data analysis confirms the existence of non-uniform extinction over the face of the cluster, the mean E (V -I) and E (C -T₁) values being 0.80±0.05 and 1.17±0.15, respectively. Through comparison of the cluster CMDs with theoretical isochrones of the Geneva group, Washington Standard Giant Branches and measures of δV and δT₁indices, we derive the following values for the cluster apparent distance modulus, age, and metallicity: V -M_V= 13.80±0.30 (corresponding to a distance from the Sun of 2.4±0.5 kpc and 0.04 kpc above the Galactic plane), t = 5.0±0.5 Gyr and [Fe/H]=-0.30 ±0.15. We estimate the cluster angular radius to be about 7.7 arcmin (=5.4 pc) from star counts carried out within and outside the cluster field.