Cherenkov light lateral distribution function approximation that describes an individual extensive air shower was found. It is designed for showers from various primary nuclei in the 1-100 PeV energy range with zenith angles up to 20 • and distances from the shower axis of up to 500 meters. Approximation accuracy is better than 10%. Initially, the approximation was intended for processing events of the SPHERE-2 experiment, but it can also be applied to any other experiment that uses the Cherenkov light lateral distribution function at the ground level. A comparison was made with simpler approximating functions used in the SPHERE-2 processing and in the TAIGA experiment. *** 27th European Cosmic Ray Symposium -ECRS *** *** 25-29 July 2022 *** *** Nijmegen, the Netherlands *** * Speaker

Current technical design of the SPHERE project's new detector is presented. The SPHERE project is aimed at primary cosmic ray studies in the 1-1000 PeV energy range using reflected Cherenkov light. The concept of a drone-mounted detector with a photosensitive camera based on silicon photomultipliers is discussed. The combination of the reflected CL registration method with specific data analysis approaches is a unique feature of this project. The developed earlier event-by-event data analysis approach allows to carry out primary particle mass reconstruction and primary cosmic ray mass composition studies with high accuracy. This is achieved through careful analysis of each EAS Cherenkov light lateral distribution function without building any kind of intermediate distributions of any 'typical' characteristics.