Photometry of transients and variable sources at the Osservatorio Polifunzionale del Chianti (OPC)

The Osservatorio Polifunzionale del Chianti is a new astronomical site located in the neighbourhoods of San Donato in Poggio (Firenze), on top of one of the highest hills of the Chianti area, among the darkest places in Tuscany, and it is managed by the University of Florence. The name takes origin from the different observatories that are hosted in the building. Beside the Astronomical Observatory, Geo-seismic, Meteorological and Environmental Observatories fully operate in a fruitful synergic collaboration among themselves. Presently, the main research activity at OPC concerns the observation and follow-up of transiting exoplanets while the team is involved in national and international collaborations, like TESS SG1 follow-up for the observation of exoplanet candidates and GAPS, which exploits several telescopes and facilities in Italy (Asiago, OAVdA) and Canary Islands (HARPS-North and GIANO instruments as well as their improved combined version) for exoplanetary characterization. OPC researchers perform their activity in the framework of collaborations with Osservatorio Astrofisico di Torino and Osservatorio Autonomo della Val d'Aosta. From July 2017, to date, commissioning observing runs have been done in order to test the telescope and mount capabilities, systematics and limits and to eventually improve the accuracy of the overall system. A software algorithm has been developed1 in order to estimate the accuracy of any transit observation, so that parameters like the integration time and telescope focus can be chosen to obtain a higher signal to noise ratio, and also to understand the observational limits of the instruments. Currently, the system is able to work within±1 mmag of accuracy and differential photometry error (refer to the error bars in Figure 6) so that exoplanet transits with (see abstract for symbol _5 mmag) of relative depth can be observed fruitfully. The OPC Research Team also aims at the observation of the optical/visible counterpart of gamma ray bursts afterglows, supernovae and GW ToO (Gravitational Waves events / Targets of Opportunity) follow-up along with transiting exoplanets follow-up. The reason is twofold. First of all, the scientific interest on these events of the researchers supporting OPC, and then the demand of the astronomical community for follow-up observations with small telescopes, around the 1-m class, since larger telescopes are often used for primary targets observations. To pursue the target of observing GRBs and the optical counterpart of GW events, it is planned to improve the main instrument accuracy and to develop a consolidated observation procedure, to be ready for the next LIGO-VIRGO O3 run scheduled for the Autumn, 2018.