Imaging Atmospheric Cherenkov Telescopes pointing determination using the trajectories of the stars in the field of view

TL;DR

This paper introduces a universal, hardware-independent method for determining the pointing accuracy of Imaging Atmospheric Cherenkov Telescopes by analyzing star trajectories in the field of view, validated on LST-1 data.

Contribution

A novel, adaptable approach using star trajectories and orthogonal distance regression for precise telescope pointing without extra hardware.

Findings

Method achieves stable and accurate pointing performance.

Applicable to any IACT observation mode.

Validated with LST-1 commissioning data.

Abstract

We present a new approach to the pointing determination of Imaging Atmospheric Cherenkov Telescopes (IACTs). This method is universal and can be applied to any IACT with minor modifications. It uses the trajectories of the stars in the field of view of the IACT's main camera and requires neither dedicated auxiliary hardware nor a specific data taking mode. The method consists of two parts: firstly, we reconstruct individual star positions as a function of time, taking into account the point spread function of the telescope; secondly, we perform a simultaneous fit of all reconstructed star trajectories using the orthogonal distance regression method. The method does not assume any particular star trajectories, does not require a long integration time, and can be applied to any IACT observation mode. The performance of the method is assessed with commissioning data of the Large-Sized Telescope prototype (LST-1), showing the method's stability and remarkable pointing performance of the LST-1 telescope.