Mateja Dumbović, Bojan Vršnak, Roman Brajša

The double solar telescope at the Hvar Observatory consists of two Carl Zeiss refractors, attached as one unit on a German parallax mounting. The photosphere telescope has an objective diameter of 217 mm and the chromosphere telescope has a diameter of 130 mm. It provides a valuable instrument to study rapid changes of chromospheric and photospheric features. Using a field of view of about 11 and 7 arcmin, it aims to produce high-resolution and high-cadence imaging of active regions on the Sun. Modern Pulnix TM-4200GE 12-bit 4 megapixel CCD cameras allow to obtain time series with a cadence up to 30 images per minute. High-cadence chromosphere ground-based observations are an important tool to identify and study solar flares, filaments and other solar phenomena that are associated with coronal mass ejections and their propagation to the Earth. Hence these observations can be also used to improve space weather forecasts. This work has been supported by the ESF project PoKRet and the Croatian Science Foundation project SOLSTEL.