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WE report results from the first stellar occultation by Titan ever observed. As predicted by Wasserman1, on 3 July 1989 the bright star 28 Sagittarii (visual magnitude, V ≈ 5.5), passed behind Saturn's giant moon ( V ≈ 8.3), which is the only body in the Solar System that, like the Earth, has a dense, nitrogen-rich atmosphere2. The event, visible from Europe, North Africa and the Middle East, allowed us to probe Titan's atmosphere in an altitude range of ∼ 250–500 km (a pressure range of ∼250-1 μbar), where until now, there has been an 'information gap' between infrared and ultraviolet Voyager observations3–5. We also detected a central flash as the centre of Titan's shadow passed at a few tens of kilometres from Paris. This central flash allows us to estimate a finite oblateness of Titan's stratosphere, which could arise from a super-rotation of Titan's atmosphere.

In this paper the results recently obtained at Catania from the observations of the flare stars PZ Mon, YZ CMi, AD Leo, BD +55°1823, BD +51°2402 and EV Lac are summarized.

From our observations, and other previous ones, we found the period of the KO Aql systern to be increasing by 3 X 10-8 days per period. V light observations carried out during 1965 show a secondary minimum which becomes shallower in the 1967 and 1969 observations. The solutions of the light curves obtained were possible ouly by assuming the primary minimum to be an occultation. The elements of the system have been deduced on two hypotheses: (I) The primary component is a main-sequence star and the secondary fit's its Roche lobe; (2) The system is in the pre-main-sequence evolutionary phase. Key words: eclipsing binary - photometry - photometric elements