Correction to: Nature Astronomy https://doi.org/10.1038/s41550-023-02052-3, published online 5 October 2023.

In the version of the article initially published, R. Zanin, M. Kerr, S. Johnston, R. M. Shannon and D. A. Smith mistakenly appeared in the main author list but are now instead listed as members of The H.E.S.S. Collaboration et al. in the HTML and PDF versions of the article.