CTbend: A Bayesian open-source framework to model pointing corrections for Cherenkov telescopes

TL;DR

CTbend is an open-source Bayesian framework designed to accurately model and correct pointing deviations in Cherenkov telescopes, accounting for measurement outliers to improve pointing precision.

Contribution

It introduces a Bayesian approach with an outlier-resilient likelihood for modeling telescope pointing errors, enhancing existing methods like TPoint.

Findings

Robust modeling of pointing deviations using Bayesian analysis

Effective outlier handling improves model accuracy

Open-source implementation facilitates adoption and testing

Abstract

The pointing of Cherenkov telescopes is subject to imperfections which are, for example, related to the bending of the telescopes mechanical structure. These imperfections must be measured, modeled, and finally corrected to achieve an optimal telescope pointing precision. The measurement of pointing deviations is often performed while the telescope points to different stars and a CCD camera monitors the offsets of the star images to the center of the focal plane. Outliers in these measurements can propagate into the pointing model and lead to imprecise model predictions. CTbend is a simple and standalone open-source framework that uses a Bayesian analysis with an outlier resilient likelihood function to model the pointing of Cherenkov telescopes with parametric standard models like TPoint. The framework is described in the following.