Performance studies of the new stereoscopic Sum-Trigger-II of MAGIC after one year of operation

TL;DR

This paper evaluates the performance of the new stereoscopic Sum-Trigger-II system of MAGIC telescopes after one year, demonstrating its potential to lower the energy threshold in gamma-ray astronomy.

Contribution

It presents the implementation and initial performance analysis of the novel stereoscopic Sum-Trigger-II system for MAGIC telescopes, a significant advancement over traditional digital triggers.

Findings

Lowered energy threshold achieved in stereoscopic mode

Successful implementation of analogue sum trigger strategy

Potential for further reduction of energy threshold

Abstract

MAGIC is a stereoscopic system of two Imaging Air Cherenkov Telescopes (IACTs) located at La Palma (Canary Islands, Spain) and working in the field of very high energy gamma-ray astronomy. It makes use of a traditional digital trigger with an energy threshold of around 55 GeV. A novel trigger strategy, based on the analogue sum of signals from partially overlapped patches of pixels, leads to a lower threshold. In 2008, this principle was proven by the detection of the Crab Pulsar at 25 GeV by MAGIC in single telescope operation. During Winter 2013/14, a new system, based on this concept, was implemented for stereoscopic observations after several years of development. In this contribution the strategy of the operative stereoscopic trigger system, as well as the first performance studies, are presented. Finally, some possible future improvements to further reduce the energy threshold of this trigger are addressed.