Speaker
Description
The next generation of imaging atmospheric Cherenkov telescopes, in particular the four LSTs (Large-Sized Telescopes) of the CTAO (Cherenkov Telescope Array Observatory), will provide substantially improved sensitivity compared to previous instruments. This increased sensitivity also makes precise atmospheric characterization more important, since even moderate atmospheric disturbances can affect the transmission of Cherenkov light and, consequently, the reconstruction of cosmic gamma rays. At the ORM (Roque de los Muchachos Observatory) on La Palma, besides clouds, one of the most relevant atmospheric disturbances is calima, i.e. Saharan dust intrusion.
In this work, we modeled plausible vertical distributions of calima above ORM and used the MODTRAN (MODerate resolution atmospheric TRANsmission) code to calculate wavelength-dependent atmospheric extinction profiles. Five dust-concentration levels at telescope altitude, from weak to strong calima, were considered, using values motivated by measurements from the TNG (Telescopio Nazionale Galileo) on La Palma. The resulting extinction tables were then used as input to air-shower and detector-response simulations with CORSIKA (COsmic Ray SImulations for KAscade) and sim_telarray in order to evaluate the impact of dust-induced atmospheric extinction on key performance parameters of the LST system.
The main goals of the study are to determine the dust-concentration limit at telescope level up to which observations remain scientifically useful, and to quantify the impact of calima on reconstructed shower and image parameters in order to support the development of an adequate correction method for dust-affected observations. The results are also relevant for atmospheric monitoring, data-quality assessment, and observing strategy for present and future Cherenkov-telescope experiments.