Calibration of the EUSO-TA detector with stars

TL;DR

This paper details the calibration of the EUSO-TA detector using stars as natural calibration sources, discussing atmospheric and detector influences, and estimating star signals and the detector's point spread function for improved cosmic ray observations.

Contribution

It introduces a novel calibration method using stars for the EUSO-TA detector, complementing artificial sources and enhancing future JEM-EUSO missions.

Findings

Star signals can be used for detector calibration.

Atmospheric effects influence star observations.

Estimated the detector's point spread function using stars.

Abstract

The Extreme Universe Space Observatory-Telescope Array (EUSO-TA) is a ground-based experiment, part of the JEM-EUSO (Joint Experiment Missions -- Extreme Universe Space Observatory) dedicated to the observation of Ultra High Energy Cosmic Rays (UHECRs) in parallel with the Telescope Array (TA) experiment. The main goal of EUSO-TA operations is to test the hardware and calibrate the EUSO detector to obtain optimal performance for cosmic ray observations. Apart from the artificial source calibration such as the Central Laser Facility (CLF), mobile lasers and UV diodes, natural signals from stars can be also used as a calibration source. This work presents the results of the calibration of the EUSO-TA detector. The influence of the atmosphere and of the detector parameters on star observations are discussed. Considering, stars as point-like sources with well known UV emission parameters, signal amplitudes from stars as well as the EUSO-TA detector point spread function were estimated. This unique calibration method could be used in future missions of the JEM-EUSO program such as EUSO-SPB2 (Super-Pressure Balloon).