SIMBAD references

In this paper we revise and complete the photometric survey of the instability strip of the southern open cluster NGC 2516 published by (ref???)Antonello & Mantegazza. No variable stars with amplitudes larger than 0.02 mag were found. However, by means of an accurate analysis based on a new statistical method, two groups of small-amplitude variables have been disentangled: one with periods of less than 0.25 days (probably δ Scuti stars) and one with periods of greater than 0.025 days. The position in the H-R diagram and the apparent timescale may suggest that the stars of the second group belong to a recently discovered new class of variables, named γ Dor variables. They certainly deserve further study. We also present a comparison between the results of the photometric survey and the available pointed ROSAT observations of this cluster.