SIMBAD references

We present a new frequency-analysis of Johnson UBV-data of the β Cephei star IL Vel, obtained between 1977 and 1979. This new analysis was inspired by more recent measurements of IL Vel in the Walraven five-colour photometric system. These data suggested the presence of frequencies not found in the original analysis of the UBV-data. From the new analysis, we conclude that four frequencies can be identified with certainty in the variations of IL Vel: f₀=5.464973±0.000005, f₁=5.363229±0.000006, f₂=5.48838±0.00002 and f₃=5.44184±0.00003, in cycles per day. The frequencies f₀, f₂ and f₃ form a closely spaced triplet.