On 5th October 2024, BL Lacertae exhibited extreme broadband activity. Fermi-LAT detected a flux increase by a factor of approximately 20 compared to the average flux reported in the Fourth Fermi-LAT Catalog. The LHAASO-WCDA real-time monitoring system was also triggered by a very-high-energy (VHE; E>100 GeV) gamma-ray flaring event from this source. A series of multi- wavelength and multi-messenger follow-up observations were carried out using facilities, including MAGIC, VERITAS, Swift-XRT, Swift-UVOT, LAST, and the neutrino detector IceCube. This work presents preliminary results from the multi-wavelength analysis of this flaring event.
Xiang et al. (Wed,) studied this question.