8 Conclusions

1. We have carried out multicolor (BVRI) photometry for more than 3000 stars in the field of the LMC populous cluster NGC 1978. We find reasonably good agreement of our photometry with Olszewski (1984) but note a discrepancy of zero points of V magnitudes, by approximately $0\hbox{$.\!\!^{\rm m}$}4$, between our CCD photometry and the CCD photometry by Bomans et al. (1995).

2. Our study of color distributions of HB stars in different parts of the cluster does not exclude the presence of two subpopulations in the cluster. The same follows from the positions of lower-giant-branch stars in the color-magnitude diagrams for different cluster zones. Comparison with isochrones shows that, to explain the observations, a difference in [Fe/H] by $\sim0.1-0.2$between the two subpopulations would be sufficient.

Acknowledgements

The authors are most grateful to the referee, Dr. T. Richtler, for his most stimulating suggestions.