Performance study update of observations in divergent mode for the Cherenkov Telescope Array

TL;DR

This paper evaluates a divergent pointing mode for the Cherenkov Telescope Array, which increases the field of view and enhances transient source detection, offering a promising alternative to traditional observation strategies.

Contribution

It introduces a new divergent mode observation strategy for CTA and provides the first preliminary performance estimates for the southern array.

Findings

Increased instantaneous field of view with divergent mode.

Potential for faster coverage of large sky regions.

Enhanced detection capabilities for transient sources.

Abstract

Due to the limited field of view (FoV) of Cherenkov telescopes, the time needed to achieve target sensitivity for surveys of the extragalactic and Galactic sky is large. To optimize the time spent to perform such surveys, a so-called "divergent mode" of the Cherenkov Telescope Array Observatory (CTAO) was proposed as an alternative observation strategy to the traditional parallel pointing. In the divergent mode, each telescope points to a position in the sky that is slightly offset, in the outward direction, from the original center of the field of view. This bring the advantage of increasing the total instantaneous arrays' FoV. From an enlarged field of view also benefits the search for very-high-energy transient sources, making it possible to cover large sky regions in follow-up observations, or to quickly cover the probability sky map in case of Gamma Ray Bursts (GRB), Gravitational Waves (GW), and other transient events. In this contribution, we present the proposed implementation of the divergent pointing mode and its first preliminary performance estimation for the southern CTAO array.