Monitoring the TeV sky on hours long timescales with HAWC

TL;DR

This paper describes HAWC's continuous, real-time monitoring of the TeV sky on hours timescales, enabling detection of transient events and rapid response to external alerts for high-energy astrophysical phenomena.

Contribution

It introduces an unbiased real-time monitoring system with daily flux measurements for the entire observable sky, enhancing transient detection and multi-instrument coordination.

Findings

Real-time daily flux measurements for the entire sky.

Detection of transient TeV events and flares.

Public alerts facilitating follow-up observations.

Abstract

The High-Altitude Water Cherenkov Observatory (HAWC) is a large field of view ($\sim$2sr) instrument sensitive to very-high energy gamma rays ($\sim$0.5-100TeV). It is located in central Mexico (19$^\circ$N) and has a high duty cycle ($\sim$95%). These characteristics allow it to continuously monitor $\sim$2/3 of the sky, looking for transient events, such as flares from Active Galactic Nuclei or possibly other unknown phenomena. Presented here is an unbiased real-time monitoring on hours timescales which provides daily flux measurements for all locations in our observable sky promptly after they leave our field of view. These measurements are then used to follow known TeV sources and to perform a blind search. The alerts generated from these analyses, some of which have been made public through the Astronomer's Telegraph, can trigger small field of view instruments, enabling deep observations of sources during their high state activity which can constrain acceleration mechanisms. Additionally, these measurements allow us to respond quickly to external alerts.